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Page, Steven M. "Investigation into the Behavior of Bolted Joints." Wright State University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=wright1163527930.
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Choudhury, Marcel. "Member stiffness of bolted joints." Thesis, Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/17882.
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Chen, Zao. "Pull-through failure of bolted composite joints." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119398.
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The design and certification of composite aircraft structures requires extensive and costly testing of bolted joints since no robust predictive tools are available. The majority of investigations in this field focus on the shear loading of bolted carbon fibre-reinforced polymer matrix composites while studies on the behaviour of pull-through are limited. Thus, this work presents an extensive investigation of the factors affecting bolted composite panels subjected to out-of-plane loading with the objective to develop a semi-empirical predictive model. First, an experimental investigation is presented where the influence of fastener size and laminate thickness was systematically studied. The effect of the laminate layup and fastener clamping torque was also examined. Specimens manufactured from out-of-autoclave carbon-epoxy prepregs were transversely loaded in an electromechanical testing machine. The load-displacement response was measured and the failure mechanisms were examined by optical microscopy. Relatively thick specimens were used to ensure that the head depth of the countersink fasteners did not exceed seventy percent of the laminate thickness. Second, numerical analysis was conducted to predict joint failure by using a simplified axisymmetric 3-D finite element approach. Contact elements were used under the region of the fastener head and the failure was predicted using the maximum principal strain criterion. The experimental results showed that failures were dominated by inter-ply delamination and through-thickness shear failure of the laminate. A conical damage zone was found under the fastener head with damage radially dispersed from the fastener hole. The opening angles of the cones varied with the fastener head geometry. The load-displacement behaviour was affected by the fastener type. The finite element analysis showed that a concentrated shear stress area under the fastener head caused the cone damage initiation. Maximum fibre direction stresses and out-of-plane shear were both found near the fastener hole on the opposite side of the loading face. Transverse deformation and inter-laminar shear caused the final failure in the form of inter-ply delamination. The numerical analysis also indicated that the pull-through load resistance was more sensitive to the contact area under the fastener head and the head geometry than to the fastener shank size. Finally, a semi-empirical equation for the prediction of the pull-through resistance that includes the joint characteristic factors was developed.La conception et la certification des structures aéronautiques en matériaux composites avec assemblages boulonnés nécessitent un important programme de tests très coûteux car il n'existe pas d'outils de prédiction robuste de la rupture des joints boulonnés. La majorité des études dans ce domaine portent sur la résistance en cisaillement des boulons alors que les études sur le comportement hors plan des assemblages boulonnés sont très limitées. Ainsi, cette thèse présente une étude approfondie des facteurs affectant les assemblages boulonnés en matériau composite soumis à des charges hors plan avec l'objectif de développer un modèle semi-empirique de la charge de rupture du joint. Premièrement, une étude expérimentale est présentée où l'influence du diamètre du boulon et de l'épaisseur du laminé est menée de façon systématique. L'effet de la configuration du laminé et du couple de serrage a aussi été étudié. Des échantillons fabriqués hors-autoclave composés de fibres de carbone pré-imprégnées d'une matrice époxy ont été chargés transversalement dans la machine d'essai électromécanique. La courbe force–déplacement a été mesurée et les mécanismes de rupture ont été examinés par microscope optique. Des échantillons relativement épais ont été utilisés pour s'assurer que l'épaisseur de la tête du boulon n'excède pas soixante-dix pourcent de l'épaisseur du laminé. Deuxièmement, des simulations numériques par la méthode des éléments finis ont été effectuées afin de prédire la rupture de l'assemblage en utilisant un modèle 3-D axisymétrique simplifié. Des éléments de contact ont été utilisés sous la région de la tête de vis et la rupture a été prédite en utilisant le critère de déformation principale maximale. Les résultats expérimentaux ont montré que les mécanismes de rupture comportent un délaminage inter-pli et un cisaillement à travers l'épaisseur du laminé. Une zone d'endommagement conique a été observée sous la tête du boulon avec des fissures réparties radialement autour du trou. Les angles d'ouverture des cônes varient selon la géométrie de la tête de vis. Le comportement charge-déplacement variait en fonction du type de boulon. L'analyse par éléments finis a démontré qu'une concentration de contraintes de cisaillement située sous la tête du boulon causait l'initiation des dommages conique. Les contraintes de tension maximale et de cisaillement hors-plan ont été observées près du trou, du côté opposé de la charge. La déformation transversale et le cisaillement inter-laminaire causent la rupture finale sous forme de délaminage inter-pli. Le modèle numérique indique également que la résistance au chargement hors plan est plus sensible à la région de contact sous la tête du boulon et sa géométrie. Finalement, une équation semi-empirique pour prédire la résistance hors plan des joints boulonnés a été développée.
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Schmitt, Ron R. "Viscoelastic relaxation in bolted thermoplastic composite joints." Thesis, Wichita State University, 1991. http://hdl.handle.net/10057/3988.
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Results from a research program to investigate the long term effects of
through-the-thickness fastener clamp-up force (preload) relaxation on the
strength of mechanically fastened joints for two graphite/thermoplastic
composite materials (Dupont's IM6/KIII and ICI-Fiberite's IM8/APC(HTA)) are
summarized and compared with analytical methods. An experimental program
was conducted in which 56 mechanically fastened single-shear joints were
tested. Phase I static tests established joint bearing strength as a function of
clamp-up force for two types of fasteners (protruding head and countersink) with
no relaxation of preload. Phase II testing monitored short-term fastener preload
relaxation (up to 1 ,000 hours), with special bolt force sensor washers. Inservice
parameters included were temperature, in-plane loads, and torque. The
jOints were tested to failure at the end of the relaxation time period to determine
any subsequent effect on joint strength.
Phase I test results indicated that joint bearing strength increased by as
much as twenty-eight percent over the clamp-up force range of a Ibs (fingertight)
to 3,500 Ibs for both materials. Fastener head type, material, and
temperature also affected the resultant bearing strength. For Phase II, fastener
clamp-up force at room temperature (78°F) relaxed an average of six percent
from the initial value during the short-term test period. The relaxation was
projected to be as high as fourteen and sixteen percent at 100,000 hours for
HTA and Kill, respectively. The elevated temperature condition (250°F)
significantly increased the relaxation rate with the projected 100,000 hour
relaxation amount being as high as thirty-seven percent for HTA and sixty
percent for Kill. Comparison of the Phase II bearing strengths to the Phase I
results indicated that portions of the data correlated well, while others did not. It
was concluded that relaxation of the clamp-up force over the short-term time
period did not significantly lower the bearing strength of either material,
however an extended exposure to 250°F could affect the bearing strength.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering.
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Wentzel, Sten Henrik Vilhelm. "Models and mechanisms of dissipation in bolted joints." Licentiate thesis, Stockholm, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4326.
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Tilaveridis, Ioannis. "Detection of friction variations in bolted joints during tightening." Thesis, KTH, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-213389.
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Tightening describes the process of rotating a screw with the purpose of binding two surfaces together. It is widely applied in the assembly process of structures, where bolted joints are used to connect the different parts with each other, e.g. robot arms, vehicles, aircrafts. A certain torque is applied with a tool in order to develop the desired clamping force that keeps the surfaces together. A challenge during this process is the fact that friction variations occur unexpectedly, thus increasing the risk of not achieving the necessary clamping force to ensure successful tightening. In this thesis, a diagnosis method is implemented in order to detect friction variations during highly dynamic tightening. Different detection algorithms are investigated (e.g. CUSUM, Particle Filter, Linear regression), and an approach that makes use of the torque and angle signals while estimating the clamping force is implemented. Investigations of signal noise and filtering operations during data extraction are conducted, and the signal channels are evaluated with regards to accuracy and noise bias. An approach using a sliding window is used to estimate the torque rate, and the CUSUM detection algorithm is implemented to indicate variations and provide a diagnostic report. The analysis is performed using a highly dynamic tightening strategy programmed in an electrical tightening tool, allowing for the process to be conducted in milliseconds. Investigations of the tuning parameters of the detection algorithm are also conducted, and value thresholds are identified. Finally, a statistical analysis of the system’s behaviour, as well as the influence of the operator holding the tool, is performed for evaluation.Åtdragning beskriver processen att rotera en skruv i syfte att binda två ytor ihop. Det tillämpas allmänt i monteringsprocessen av strukturer, där skruvförband används för att ansluta de olika delarna med varandra, t.ex. robotarmar, fordon, flygplan. Ett visst vridmoment appliceras med ett verktyg för att utveckla önskad klämkraft som håller ytorna ihop. En utmaning under denna process är att friktionsvariationer uppträder oväntat, vilket ökar risken för att inte uppnå den nödvändiga klämkraften för att säkerställa en framgångsrik åtdragning. I denna avhandling implementeras en diagnosmetod för att detektera friktionsvariationer vid hög dynamisk åtdragning. Olika detekterings algoritmer undersöks (t.ex. CUSUM, Partikelfilter, Linjärregression), och ett tillvägagångssätt som utnyttjar vridmoment- och vinkelsignalerna vid uppskattning av klämkraften implementeras. Undersökningar av signalbrus samt filtreringsoperationer under datautvinningen utförs, och signalerna utvärderas. Ett variabelt fönster används för att uppskatta vridmomentet, som används i detekteringsalgoritmen för att indikera variationer och utföra en diagnostisk rapport. Analysen utförs med en starkt dynamisk åtdragningsstrategi, programmerad i ett elektriskt åtdragningsverktyg, vilket gör att processen kan utföras på millisekunder. Undersökningar av parametrarna för detekteringsalgoritmen genomförs också, och värdetrösklarna identifieras. Slutligen utförs en statistisk analys av systemets beteende, liksom påverkan av operatören som håller verktyget, för utvärdering.
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Grosse, Ian R. "Nonlinear axial stiffness characteristics of axisymmetric bolted joints." Diss., Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/82622.
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A critical assessment of the current design theory for bolted joints which is based on a linear, one-dimensional stiffness analysis is presented. A detailed nonlinear finite element analysis of a bolted joint conforming to ANSI standards was performed. The finite element results arc presented in the classical bolted joint diagram and compared with the linear theory. The results revealed that the joint stiffness is highly dependent on the magnitude of the applied load. The joint stiffness changes continuously from extremely high for small applied loads to extremely low for large applied loads, contrary to the constant joint stiffness of the linear theory. The linear theory is shown to be extremely inadequate in characterizing the joint stiffness. The significance of the results in terms of the failure of bolted joints is discussed. Straight-forward analytical procedures are proposed for establishing estimates of the nonlinear stiffness description and the associate bolt loading in fatigue environments. The linear theory should be discarded and the more accurate nonlinear joint description be used. These results also provide the finite element community an improved model for the interconnection of substructures.
The two-dimensional, axisymmetric finite element model includes bilinear gap elements to model the interfaces. Special orthotropic elements were used to model the bolt/nut thread interaction. A free-body-diagram approach was taken by applying loads to the outer diameter of the joint model which correspond to internal, uniformly distributed line-shear and line-moment loads in the joint. A number of convergence studies were performed to validate the solution.Ph. D.
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Lutz, Cyprien. "Structural integrity of bolted joints for pultruded GRP profiles." Thesis, University of Warwick, 2004. http://wrap.warwick.ac.uk/110311/.
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Presented in this thesis is a combined physical testing and computational modelling programme of research for the structural integrity of bolted joints for Pultruded Fibre Reinforced Polymer (PFRP) profiles. The work was carried out in a joint EPSRC funded Structural Integrity (SI) project between the Universities of Warwick and Lancaster. It will be shown in the thesis that it provides a significant new body of scientific understanding and relevant independent joint test data, which can be used in the future preparation of design guidance for the safe and rational design of joints. The contribution from the author to this SI project on plate-to-plate steel bolted joints can subdivided into four parts. The first part includes the evaluation of the 10 single-bolted and the 5 multi-bolted double lap-joint test series that appeared before 2001. This identifies that the 15 test series, from 10 centres, are often different because the researchers chose different parameters to study. Of the 800 concentric strength tests 640 were single-bolted and 160 were multi-bolted. It is noteworthy that few of these previous tests include environmental conditioning of the joints. A review of design methods is given in this part of the thesis. This shows that significant joint test data is required to appraise SI design methods for PFRP bolted joints, such as presented in the EUROCOMP Design Code and Handbook of 1996 and in 1981 by Hart-Smith. The EUROCOMP simplified and rigorous methods are expected to be generic and involve damage tolerance to increase the strength of the joint design. It is further found that application of these methods requires Finite Element (FE) stress calculations for the target analysis due to bolt bearing, and for the source analysis, for multi-bolted joints, to determine the bolt load distribution and by-pass loads. Parts two and three of the contribution from the author are combinations of experimental and FE analysis work that focuses on the target and the source problems, respectively. The strain field close to a notch is measured in part two using a pin-bearing test method and strain gauged specimens. To find out if FEA can predict the target strains/stresses an ABAQUS© FE model is developed. The PFRP material is assumed to be homogeneous and possess orthotropic properties. It is shown that a linear elastic analysis, with contact and friction modelled, gives strains that are similar to those measured. This observation is supported by a small photo-elastic strain analysis using the GFP 1000 system from Stress Photonics. By way of the evaluation of previous testing in part one it was decided in part three to conduct a comprehensive series of multi-bolted joint tests. Constant variables in this series of concentric loaded tests are the PFRP material, the plate thickness, the material orientation, the bolt diameter, the clearance hole size, and the bolt torque. This test series, design using a method by Taguchi, comprised four different joint configurations, twelve different joint geometries and four different environmental conditionings (including a temperature of 60oC and ‘wet’ ageing for 1000hrs). The author presents the testing procedure and 432 resistance results for 144 different joints, having a batch size of three. Mechanisms and modes of failure are identified, and several unrelated to the distinct modes of bearing, shear-out and net-tension used in current design approaches are presented. Using this fairly large number of consistent data points an evaluation is made on the influence of the various variables. It is shown that is not straightforward to establish simple strength trends. Furthermore, the findings of this test series suggest that a batch size of three is too small, as batch strength variability is relatively high. By way of a Round-Robin exercise between the two Universities, with joints having a batch size of 10, it is shown that the high strength variability can be associated with the non-homogeneity of the reinforcement arrangement in the PFRP material. Two multi-bolted joints having three rows of three bolts are instrumented with strain gauges to determine the strain distributions linked to bolt load distribution and by-pass loads. Measured strains are compared to numerical predictions from an ABAQUS FE analysis using the same modelling methodology as for the pin-bearing target analysis. The source analysis comparison is acceptable, but like many of the results presented in the thesis it appears likely that the experimental measurements are affected by the non-homogeneity in the macrostructure of the PFRP. Presented in part four is a preliminary appraisal of the EUROCOMP simplified design method and the Hart-Smith design method. The EUROCOMP method is shown to possess deficiencies, via a critique by Lancaster University, which indicates that it cannot be used in practice. By taking information from the multi-bolted joint test series in part three the author constructs semi-universal design charts using the Hart-Smith method, which can be used to design joints with changing geometry. An important finding from this preliminary appraisal is that the SI design methods are difficult to apply since they require lots of physical test data and relevant and reliable stress results from FEA. Finally, despite the programme of research providing a significant new body of scientific understanding and relevant independent joint test data it is concluded that further work is needed before an SI method for the universal design of plate-to-plate PFRP bolted joints can be considered for a code of practice.
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Elflah, Mohamed A. Hussaen. "Structural behaviour of stainless steel bolted beam to column joints." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8545/.
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Initially, two experimental programmes studying the structural behaviour of stainless steel beam-to-open column joints and beam-to-tubular column joints under static loads are reported in detail. The joint configurations tested include flush and extended end plate connections, top and seat cleat connections and top, seat and web cleat connections. The full moment-rotation characteristics are reported in detail. It is observed that the connections displayed excellent ductility, superior than that of equivalent carbon steel connections, and attained loads much higher than the ones predicted by design standards for carbon steel joints. Nonlinear FE models have been developed and validated against the experimental results. The FE models are shown to accurately replicate the experimentally determined, initial stiffness, ultimate resistance, overall moment-rotation response and observed failure modes. In addition, a comprehensive parametric study is conducted. The design rules for stainless steel connections, which are based on the specifications of EN 1993-1-8 for carbon steel joints, are reviewed and are found to be overly conservative in terms of strength and inaccurate in terms of stiffness thus necessitating the development of novel design guidance in line with the observed structural response. Hence, simplified mechanical models in line with the observed response are developed.
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Kradinov, Vladimir Y. "Optimum design of bolted composite lap joints under mechanical and thermal loading." Diss., The University of Arizona, 2003. http://hdl.handle.net/10150/280296.
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A new approach is developed for the analysis and design of mechanically fastened composite lap joints under mechanical and thermal loading. Based on the combined complex potential and variational formulation, the solution method satisfies the equilibrium equations exactly while the boundary conditions are satisfied by minimizing the total potential. This approach is capable of modeling finite laminate planform dimensions, uniform and variable laminate thickness, laminate lay-up, interaction among bolts, bolt torque, bolt flexibility, bolt size, bolt-hole clearance and interference, insert dimensions and insert material properties. Comparing to the finite element analysis, the robustness of the method does not decrease when modeling the interaction of many bolts; also, the method is more suitable for parametric study and design optimization. The Genetic Algorithm (GA), a powerful optimization technique for multiple extrema functions in multiple dimensions search spaces, is applied in conjunction with the complex potential and variational formulation to achieve optimum designs of bolted composite lap joints. The objective of the optimization is to acquire such a design that ensures the highest strength of the joint. The fitness function for the GA optimization is based on the average stress failure criterion predicting net-section, shear-out, and bearing failure modes in bolted lap joints. The criterion accounts for the stress distribution in the thickness direction at the bolt location by applying an approach utilizing a beam on an elastic foundation formulation.
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Nukala, Ramanand. "Efficient finite element modeling of WT sections subjected to uniaxial tension." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=2091.
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Thesis (M.S.)--West Virginia University, 2001.Title from document title page. Document formatted into pages; contains vii, [90] p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 62-63).
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Tol, Serife. "Dynamic Modeling Of Structural Joints." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614368/index.pdf.
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Complex systems composed of many substructures include various structural joints connecting the substructures together. These mechanical connections play a significant role in predicting the dynamic characteristics of the assembled systems
accurately. Therefore, equivalent dynamic models of joints that consist of stiffness and damping elements should be developed and the joint parameters should be determined for an accurate vibration analysis. Since it is difficult to estimate joint
parameters accurately by using a pure analytical approach, it is a general practice to use experimental measurements to model joints connecting substructures. In this study an experimental identification method is suggested. In this approach the frequency response functions (FRFs) of substructures and the coupled structure are measured and FRF decoupling method is used to identify equivalent dynamic characteristics of bolted joints. Since rotational degrees of freedom (RDOF) in connection dynamics is very important, a structural joint is modeled with translational, rotational and cross-coupling stiffness and damping terms. FRF synthesis and finite-difference formulations are used for the estimation of unmeasured FRFs and RDOF related FRFs, respectively. The validity and application of the proposed method are demonstrated both numerically and experimentally. In simulation studies, simulated experimental values are used, and it is seen that the identification results are prone to high errors due to noise in
measurement and the matrix inversions in the identification equations. In order to reduce the effect of noise, it is proposed to extract the joint properties by taking the average of the results obtained at several frequencies in the frequency regions
sensitive to joint parameters. Yet, it is observed in practical applications that experimental errors combine with the measurement noise and the identification results still may not be so accurate. In order to solve this problem, an update
algorithm is developed. In the approach proposed, the identified dynamic parameters are used as initial estimates and then optimum dynamic parameters representing the joint are obtained by using an optimization algorithm. The application of the proposed method is performed on a bolted assembly. It is shown with experimental studies that this method is very successful in identifying bolted joint parameters. The accuracy and applicability of the identification method suggested are illustrated by using a dynamically identified bolt in a new structure, and showing that the calculated FRFs in which identified joint parameters are used, match perfectly with
the measured ones for the new structure. In this study, the effects of bolt size and quality of bolts, as well as the bolt torque on the joint properties are also studied by making a series of experiments and identifying the joint parameters for each case.
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Bond, Douglas Edward. "Analytical and experimental investigation of a flush moment end-plate connection with six bolts at the tension flange." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/76341.
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An analytical and experimental investigation was conducted to study the six bolt flush moment end-plate connection configuration which is used in steel frame construction. The limit states of plate yielding and bolt fracture were analyzed using yield-line theory to predict endplate thicknesses and a split-tee analogy to develop a method to predict bolt forces. Five experimental tests were conducted on four configurations within a matrix of geometric parameters. The predicted ultimate moment showed good . correlation to the yield moment obtained from the experimental deflection plots. The experimental bolt forces correlated well with the predicted bolt forces when plotted versus the applied moment. Additionally, an equation to model the moment-rotation relationship was developed from a regression analysis to determine the construction type suitable for a given connection configuration. Finally, a method of designing the six-bolt flush end-plate configuration is presented and an example given.Master of Science
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Mohammed, Usman Ali. "Analysis of Parameters Affecting Modal Frequencies in Bolted Joint Connections." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535709260529555.
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Yuan, Lie Ping. "Partial interaction behaviour of bolted side plated reinforced concrete beams." Title page, abstract and contents only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phl7161.pdf.
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Includes bibliographical references (p. 185-189) Aims to determine the effect of partial interaction on the behaviour of the concrete beam, plate and bolt connector components of the composite plated beam. Develops design rules for the determination of the ultimate capacity for bolted plate reinforced composite beams.
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Mårtensson, Daniel. "Utformningen av ett förstärkt skruvförband på en differentialväxel i bandvagnen BvS10 : Analys av olika förband med hjälp av CATIA och MATLAB." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-104626.
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This is a thesis presents a differential gear which is found in a tracked vehicle called BvS10. The tracked vehicle is manufactured by BAE Systems Hägglunds AB in Örnsköldsvik, Sweden. The differential gear has a bolted house. The differential meets the requirement specifications, but the problem is that the bolts are sheared off because of the extreme torque that the differential is exposed to resist. Previous report on the differential show pictures of bolts which have been sheared off at the threads. This report is also includes three lists that explain seven different proposals which some are approved and some are not, and the report also presents the force, tensile, and shear stress. In a bolted connection there is both axial tension stress and radial shear stress, which can lead to wear out and broken bolts. To solve the problem, better bolts are need for the differential gear housing halves. The bolts are from M8 to M10 and all bolts are not directly compatible, so geometric modifications might have to be done. This reports proposes several solutions to this complex problem and also analyzes the proposed solutions. The report also describes various theories from a technical and a historical point of view. Two flow charts have been created to show the work towards the presented solution. Although the analysis to welded joints and wedge joints have been included in the proposed solution. The report propose a tight-fit bolt with a tolerance specially made for the differential gear, so the shear stress occurs at the non-threaded part of the bolt. The tight-fitted bolt is recommended to be M8 12.9 UNB because of it’s safety factor. Larger bolts may not directly fit in the differential housing halves due to there is no enough material.
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Nagarajan, Vignesh. "Modelling and evaluation of fasteners under fatigue." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263921.
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At the calculations group in Sigma Industry East North, the traditional method for evaluating fasteners has been by use of the VDI2230 manual. As the complexity of a model increases the evaluation also becomes harder. The goal of this thesis is to set a robust evaluation method by combining the VDI2230 with the Finite Element (FE) method. Varied topics such as fastener and plate compliance, embedding effect, forces through the fastener and plate, minimum thread engagement length, service loads and the fatigue effect in fasteners is discussed. The flowchart discusses the process flow, as in, where to use the VDI2230 and where the FE method comes into use. The thesis also helps to understand designing of bolts like selection of the bolt diameter of varied applications and is user friendly to handle. The focus is also on reducing the time taken for fastener evaluation and setting up of an in-house technique for the evaluation. The evaluation method is verified using a test case.På beräkningsgruppen på Sigma Industry East North har den traditionella metoden för utvärdering av fästelement varit att använda sig av manualen VDI 2230. Ökad komplexitet gör utvärderingen svårare att genomföra. Målet med detta examensarbete är att föreslå en robust utvärderingsmetod som kombinerar VDI 2230 med Finita Element-Analys (FEA). Olika ämnen såsom vekhet för fästelement och plåtar, sättningar, kraftvägar genom fästelement eller plåtar, minsta ingreppslängd, laster och utmattningseffekter diskuteras. Flödesdiagrammet avhandlar processflödet, det vill säga var man ska använda VDI2230 och när FE-metoden bör användas. Examensarbetet är också till för att skapa förståelse för hur man konstruerar skruvar, såsom val av skruvdiameter vid olika tillämpningar. Fokus har också varit att minska tidsåtgången för utvärdering av fästelement och att sätta upp tekniker för utvärdering att användas i den dagliga verksamheten. Utvärderingsmetoden verifieras med hjälp av ett provfall.
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Madireddy, Sandeep Reddy. "Finite Element Modeling of Transverse Post-Tensioned Joints in Accelerated Bridge Construction." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1302.
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The Accelerated bridge construction (ABC) techniques are gaining popularity among the departments of transportation (DOTs) due to their reductions of on-site construction time and traffic delays. One ABC technique that utilizes precast deck panels has demonstrated some advantages over normal cast-in-place construction, but has also demonstrated some serviceability issues such as cracks and water leakage to the transverse joints. Some of these problems are addressed by applying longitudinal prestressing. This thesis evaluates the service and ultimate capacities in both flexure and shear, of the finite element models of the post-tensioned system currently used by Utah Department of Transportation (UDOT) and a proposed curved-bolt system to confirm the experimental results. The panels were built and tested under negative moment in order to investigate a known problem, namely, tension in the deck concrete. Shear tests were performed on specimens with geometry designed to investigate the effects of high shear across the joint. The curved-bolt connection not only provides the necessary compressive stress across the transverse joint but also makes future replacement of a single deck panel possible without replacing the entire deck. Load-deflection, shear-deflection curves were obtained using the experimental tests and were used to compare with the values obtained from finite element analysis. In flexure, the ultimate load predicted by the finite element model was lower than the experimental ultimate load by 1% for the post-tensioned connection and 3% for the curved-bolt connection. The shear models predicted the ultimate shear reached, within 5% of the experimental values. The cracking pattern also matched closely. The yield and cracking moment of the curved-bolt connection predicted by the finite element model were lower by 13% and 2%, respectively, compared to the post-tensioned connection in flexure.
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Kline, Donald Paul. "Performance of snug tight bolts in moment end-plate connections." Thesis, This resource online, 1989. http://scholar.lib.vt.edu/theses/available/etd-05092009-040552/.
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Oldfield, Matthew. "Harmonic excitation of bolted joints." Thesis, University of Liverpool, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.400233.
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Bolted joints provide one of the most common means of joining two structural components together. The joints themselves use friction to transmit force, torque and motion across a common interface from one component to another. In many cases a pretensioned bolt, running through a common hole at the joint interface, provides the clamping force. The friction force at a joint interface is highly nonlinear. This makes the analysis of dynamic systelTIS with joints unrealistic with conventional linear techniques. It has also been shown that the contact pressure at a joint interface is not necessarily uniform. A variable contact pressure results in a variable limiting friction load. Where the contact pressure can be shown to be smallest on an interface, local microslip can take place whilst the joint maintains its sticking contact elsewhere. Microslip is responsible for the dissipation of energy from within bolted joints that otherwise maintain their integrity. The level of energy dissipation caused by microslip can be significantly larger than that provided by other dissipative mechanisms within a structure. This provides an incentive to be able to describe and predict the energy losses and overall joint behaviour accurately. Difficulties arise when considering 3-Dimensional contact, changing contact conditions during dynamic loading and the nonlinear nature of friction phenomena. To investigate microslip behaviour in bolted joints a detailed finite element model of an isolated lap joint interface was constructed. The joint interface was subjected to a variety of preloads and applied torque. Output from the joint is in the form of hysteresis loops that reveal information about the energy dissipated and overall joint stiffness during a loading cycle. Representative models are presented that reduce the complexity of the joint, yet still maintain the defining characteristics of the hysteretic behaviour. The first representative model uses Jenkins elements that match the physical response of the joint at a number of discrete points during the loading cycle. Good agreement between the finite element model and the Jenkins element model is illustrated. The Jenkins element model is also capable of predicting the response of the finite element model when different magnitudes of preload and applied torque are applied. The second representative model is the Bouc-Wen representation of hysteresis. This model offers significant gains in efficiency when approximating the smooth transition from a fully sticking interface to the onset of joint failure. All of the hysteresis can be described using just four parameters, and matching with the finite element model is demonstrated. To demonstrate microslip behaviour physically an individual joint was experimentally analysed. A cantilever beam with a single lap joint near the clamped end is resonated to generate the dynamic joint hysteresis. The joint behaviour is monitored by local time domain measurements at a number of different preloads and excitation amplitudes. Microslip is demonstrated in the joint when the preload is reduced from a maximum "rigid" clamping value. Notably at low preloads the spectral content of the response reveals a large contribution from the superharmonics of the excitation frequency. Both the Jenkins element model and the Bouc-Wen model are successfully matched to the hysteresis output of the experimental joint.
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Stephen, Joseph Temitope. "Condition monitoring of bolted joints." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/10425/.
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Rail joints have been in existence for a long time of which their design has remained primarily unchanged over this period. Rail joints are a typical example of bolted joints. Like other bolted joints, their integrity depends on the quantitative representation of the contact pressure distribution at the interface during design. In service, rail joints are subjected to complex operating stresses, and they demand high maintenance cost because they are safety critical and have the lowest service life of the components on the rail tracks. In this study, non-intrusive ultrasonic techniques have been employed to investigate the parameter relevant to their design, operation and condition monitoring. The effect of variation in plate thickness and diameter of the bearing surface of the bolt head on the contact pressure distribution at bolted interfaces under varying axial loads was investigated. While it was observed that the contact pressure at the interface increases as the applied load increases, the distance from the edge of the bolt hole at which the distribution becomes stable is independent of the applied load on the bolted joint. However, the contact pressure distribution was observed to vary with the plate thickness. Although the variation in the peak value of average contact pressure distribution in bolted joints does not depend on the plate thickness, the distance from the edge of bolt hole at which the value of the distribution becomes stable increases as the plate thickness is increased. It was revealed that the peak value of the contact pressure distribution decreases as bearing diameter of the bolt head increases, and that the distance at which the normalised average contact pressure distributions become fairly constant also increases as the bearing diameter of the bolt head increases. In the majority of the cases, the distance falls between 3 and 4 of the bolt radius from the edge of the bolt hole. It was also observed that the edge of the bolt head has a pronounced effect on the position of the peak value of the contact pressure distribution at the interface. Furthermore, a model based on a Weibull distribution has been proposed to fit the experimental data, and a good correlation was observed. Non-intrusive experimental techniques were simultaneously used to investigate the relaxation of contact pressure and loosening of bolted joints subjected to cyclic shear loading. Three critical areas: the contact interface of bolted component, the bolt length and the rotation of the bolt head, were monitored during loosening of the joints. The results show that loosening of bolted joints can be grouped into four stages. The early stage of the loosening of bolted joints is characterised by cyclic strain ratcheting- loosening of the bolted joint during vibration without rotation of the bolt head. The higher the rate of relaxation at this early stage the lower is the resistance of the bolted joint to vibration induced loosening of bolted joints. Furthermore, the rate of loosening at the bolted joint interface is not the same but increases away from the bolt hole. While the rate of loosening of bolted joints largely depends on the amplitude and the number of cycles of the applied dynamic shear load, it is independent of the frequency of the applied load. In addition, increasing the bolt torque was found to increase the loosening resistance of the bolted joint. When joints are subjected to a constant shear load in addition to the dynamic shear load, the loosening rate increase, and this rate depend on the magnitude of this constant shear load. A normal incidence pulse-echo ultrasonic technique was used to monitor de-bonding at the interface of adhesive bonded insulated lap joints and insulated block joints, subjected to a shear load induced failure. The results revealed that the insulated joint exhibited elastic behaviour before a sudden failure (rupture) of the joint. The de-bonding of adhesive/insulating layer on the web sides of IBJs was found to occur earlier than at any other parts of the joint when the applied load was only a fraction of the peak of the shear load. However, the de-bonding at the top and foot of the rail occurred almost at the peak of the shear load. This same technique was used to monitor the degradation, and eventual failure of IBJs subjected to cyclic shear loading. The results showed that the degradation of the adhesive insulating layer has commenced, and was in progress when the joint was virtually intact and displayed elastic behaviours. The failure at the adhesive interface is indicated by a sudden change in the value of the measured reflection coefficient. After this, the failure of the joint is preceded by plastic behaviour of the joint. In addition, the change in the length of the bolts can also be monitored directly, as a complete failure at the interface of the bolted joints can be highlighted before the failure occurred. The results of this study have shown that, with further development, ultrasound can be used to monitor the condition of IBJs while in service.
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Lång, Marcus. "Static Friction in Slip Critical Bolt Joints : Coefficient of Friction in Steel, Aluminium and ED Coated Steel." Thesis, Karlstads universitet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-55223.
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This project was performed together with ÅF Industry AB in Trollhättan, Sweden. ÅF’s expertise in Trollhättan is oriented towards the automotive industry. It was conducted within the section of CAE and safety where they, for instance, dimension bolt joints in the cars. Bolt joints play an important role in the automotive industry. Slip critical bolt joints are used widely throughout the vehicles. With lack of good test data, the bolt joints need to be dimensioned conservatively. This may lead to that bolt joints are over-dimensioned, adding more mass to the car. On the contrary, the availability of reliable test data enables designers to optimize joint dimensions to achieve a safe design with minimized mass. A mechanical testing configuration has been designed as well as a testing procedure for a test to determine the static friction value between mating surfaces in bolt joints. The testing configuration has been used to perform tests to find the static friction coefficient in different materials. The study contains varied combinations of steel, aluminium and ED-Coated steel. The study resulted in tables with levels of probability. The developed test configuration is robust and relatively simple to use and is recommended for further use. For improved statistical significance, it was noted that more samples should be used than was used in this study. The aluminium has a smoother surface finish and that could be the reason why its coefficient of friction is lower than steel. It is therefore considered important to also include surface roughness when presenting coefficient of friction results.
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Barke, Derek Woolrich 1975. "An in situ test for stress corrosion damage and tension in bolts." Monash University, Dept. of Mechanical Engineering, 2002. http://arrow.monash.edu.au/hdl/1959.1/7686.
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Fox, David M. (David Michael). "Bolted joint studies in GRP." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37524.
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Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Sciences & Engineering, 1994.Vita.
Includes bibliographical references (leaves ).
by David M. Fox.
M.S.
Nav.E.
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Korolija, Alexandra. "FE modeling of bolted joints in structures." Thesis, Linköpings universitet, Hållfasthetslära, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81110.
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This paper presents the development of a finite element method for modeling fastener joints in aircraft structures. By using connector element in commercial software Abaqus, the finite element method can handle multi-bolt joints and secondary bending. The plates in the joints are modeled with shell elements or solid elements. First, a pre-study with linear elastic analyses is performed. The study is focused on the influence of using different connector element stiffness predicted by semi-empirical flexibility equations from the aircraft industry. The influence of using a surface coupling tool is also investigated, and proved to work well for solid models and not so well for shell models, according to a comparison with a benchmark model. Second, also in the pre-study, an elasto-plastic analysis and a damage analysis are performed. The elasto-plastic analysis is compared to experiment, but the damage analysis is not compared to any experiment. The damage analysis is only performed to gain more knowledge of the method of modeling finite element damage behavior. Finally, the best working FE method developed in the pre-study is used in an analysis of an I-beam with multi-bolt structure and compared to experiments to prove the abilities with the method. One global and one local model of the I-beam structure are used in the analysis, and with the advantage that force-displacement characteristic are taken from the experiment of the local model and assigned as a constitutive behavior to connector elements in the analysis of the global model.
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Fernandez, Mauricio. "Effects of Temperature and Creep on the Clamp-up Load in Hybrid Metal to Composite Bolted Joints." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/FernandezM2008.pdf.
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Wang, Rui. "Modelling of spacecraft structures incorporating damped bolted joints." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/714/.
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Yamaguchi, Takashi. "Fundamental Study on High Strength Bolted Tensile Joints." Kyoto University, 1996. http://hdl.handle.net/2433/160789.
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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものであるKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第6407号
工博第1504号
新制||工||1025(附属図書館)
UT51-96-F286
京都大学大学院工学研究科土木工学専攻
(主査)教授 渡邊 英一, 教授 小林 昭一, 教授 土岐 憲三
学位規則第4条第1項該当
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Andersson, Amanda, and Adam Eklund. "Vidareutveckling av friktionsbetingat förband för fixering av tankar." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40251.
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Scania CV AB is one of the world’s leading companies within heavy vehicles. The company have a broad selection of trucks, which all are equipped with gas, or fuel tanks, depending on the fuel type of the truck, The trucks also contain air tanks that are used for braking and air suspension. The tanks are assembled with straps, where the rubber spacers constitutes a protective layer between the tank and the strap, to protect the tank from wear. When installing different types of tanks there is a need for elements in the joint that increases the friction, compensates for manufacturing defects, prevents wear and permits electrical insulation. This has traditionally been done with rubber spacers. However, the rubber spacers increase the uncertainty of the actual preload of the joint, and movements in the joint usually make the spacers slip out of its position. The purpose of the project is to generate knowledge on what characteristics and conditions that affects the performance of the friction joint, and to find a conceptual solution of the underlaying problem. The following questions were created to be able to fulfill the purpose of the project: F1: Which underlying causes generate preload loss in the straps when assembling various tanks? F2: Which underlying causes makes rubber spacers tend to slip out of its position in various tank installations?F3: What operations need to be undertaken to prevent the preload loss in the straps and that the rubber spacers slip out of its position? A case study and a literature review was conducted. The literature review was done to get an overall understanding of all of the different subjects that can be of relevance in this project. The data was collected from books, research papers and scientific articles. Data was also collected from interviews, technical reports, deviation reports, legal requirements, drawings, statistics from the field quality and observations in production. The case study is based on a product development process where several different product development tools have been used. The case study also include material testing in terms of friction and settlement testing. The project resulted in a concept in the shape of a rubber spacer which is based on the existing solution that Scania is using today. The solution consists of four components: geometries that prevent the rubber from slipping away known as flanges and geometries in the shape of tips of a fir tree, rounded short sides and a dimpled underside. The size of the spacer will vary because of the different types of tank and strap sizes. The project also resulted in a design guideline, that will provide guidelines and guidance for further work and future design.Scania CV AB är ett av de världsledande företagen inom tunga fordon. Deras utbud av lastbilar är brett, och lastbilarna är utrustade med gas-, eller bränsletankar, beroende på fordonets drivmedel. Lastbilarna är även utrustade med trycktankar som används vid inbromsning och luftfjädring. Tankarna är monterade med spännband, där gummimellanlägg utgör ett skydd mellan tank och spännband för att skydda tanken mot nötning. Vid installation av olika lastbilstankar finns behov av element i förbandet som ökar friktionen, kompenserar formfel, förhindrar nötning, och medger elektrisk isolation. Detta har traditionellt gjorts genom att använda gummimellanlägg i förbandet. Gummimellanlägg ökar dock osäkerheten i den faktiska förspänningen av förbandet, samt rörelser i konstruktionen ofta får mellanlägget att vandra ur position. Syftet med projektet är att skapa förståelse för vilka egenskaper och förutsättningar som påverkar prestandan av ett friktionsbetingat förband, samt att hitta konceptuell lösning på grundproblematiken. För att kunna fullgöra syftet har följande frågeställningar utformats:F1: Vilka orsaker ligger till grund för att förspänningen i spännbanden släpper vid montering av diverse fordonstankar?F2: Vilka orsaker ligger till grund för att gummimellanlägg tenderar att vandra ur position i olika tankinstallationer?F3: Vilka åtgärder kan vidtas för att motverka att förspänningen i spännbanden släpper och att gummimellanläggen vandrar ur position? I arbetet har en fallstudie och en litteraturstudie genomförts. Litteraturstudien utfördes för att skapa övergripande förståelse i ämnen som kan vara relevanta för arbetet. Den insamlade informationen härrör från böcker, forskningsavhandlingar och vetenskapliga artiklar. Data har även samlats in i form av intervjuer, tekniska rapporter, felrapporter, lagkrav, ritningar, statistik i fältkvaliteten, och observationer i produktionen. Fallstudien baseras på en produktutvecklingsprocess där flera produktutvecklingsverktyg har använts. I fallstudien ingår även materialprov i form av friktion och sättning. Arbetet resulterade i ett koncept i form av ett gummimellanlägg och baseras på Scanias befintliga lösning. Lösningen består av fyra komponenter: geometrilåsning i form av flänsar och så kallade grantoppar, rundade kortsidor och gropig undersida. Storleken kan däremot variera på grund av spännbandens och tankarnas breda storleksspann. Arbetet har även resulterat i en design-guideline, som ska ge riktlinjer och vägledning för fortsatt arbete och framtida konstruktion.
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Pelletier, Keith N. "Influence of Stress Relaxation on Watertight Integrity of Hybrid Bolted Joints." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/PelletierKN2003.pdf.
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Counts, William Arthur. "Mechanical behavior of bolted composite joints at elevated temperature." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17315.
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Starikov, Roman. "Quasi-static and fatigue behaviour of composite bolted joints." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3163.
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Wang, Pu. "Structural integrity of bolted joints for pultruded GRP profiles." Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429955.
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Pultruded glass-fibre reinforced plastics (GRP) are becoming a popular alternative to conventional materials in Civil Engineering industry. The work presented in this thesis attempts to carry out an integrated and comprehensive programme of research on pultruded GRP bolted joints, in order to provide useful data, knowledge and guidance for design engineers seeking to use bolted joints in pultruded GRP structures. The research was sub-divided into three phases. Phase 1 included determining material properties, conducting tests in double-lap single-bolt tension joints at elevated temperature and starting to develop ANSYS FE models of single-bolt joints. Phase 2 covered testing of double-lap single-bolt tension joints under wet and hot-wet conditions, FE stress and displacement analyses of the tested joint geometries and assessing existing joint design approaches. In Phase 3 the focus was on testing concentrically loaded double-lap multi-bolt tension joints and FE modelling of these joints. In addition, work was undertaken on correlating strains around the hole edge, recorded using the PhotoStress method and conventional strain gauges, with FE analysis. Work was also undertaken on an assessment of current approaches to the design of bolted joints in fibre-reinforced polymeric composite materials, particularly the EUROCOMP Simplified and Hart-Smith design methods.
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Chlebek, David. "Simulation of ultrasonic time of flight in bolted joints." Thesis, KTH, Hållfasthetslära, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298342.
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Ultrasonic measurements of the preload in bolted joints is a very accurate method since it does not depend on the friction and other factors which cause difficulties for common methods. The ultrasonic method works by emitting an ultrasonic pulse into the bolt which is reflected at the end and returned to the transducer, the change in the time of flight (TOF) can be related to the elongation of the bolt and therefore the preload. One must account for the acoustoelastic effect which is the change in sound speed due to an initial stress state. The goal of this thesis project was to implement a Murnaghan hyperelastic material model in order to account for the acoustoelastic effect when conducting a numerical simulation using the finite element method (FEM). An experiment was also performed to validate the numerical simulation. The DeltaTOF as a function of a tensile force was obtained for an M8 and M10 test piece from the experiment. The material model was implemented by creating a user subroutine written in Fortran for the explicit solver Radioss. Hypermesh was used to set-up the numerical simulation. The material model has shown an expected behavior with an increased sound speed with compressive stresses and a decreased speed with tensile stresses. The numerical simulation showed a good correspondence to the experimental results.Ultraljudsmätning av klämklraften i skruvförband är en väldigt noggrann metod eftersom att metoden inte påverkas av friktion eller andra faktorer som innebär svårigheter för vanliga metoder. Ultraljudsmetoden fungerar genom att skicka in en ultraljudsvåg i skruven som reflekteras i botten och återvänder tillbaka till sensorn. Skillnaden i tiden för ekot att återvända kan relateras till förlängningen av skruven och därmed klämkraften. Det är viktigt att ta hänsyn till den akustoelastiska effekten, som är fenomenet där ljudhastigheten av en våg i en solid förändras med spänningstillståndet. Målet med det här arbetet är att implementera en hyperelastisk Murnaghan modell som tar hänsyn till den akustoelastiska effekten med FEM simuleringar. Ett experiment har också genomförts för att validera beräkningsmodellen. Tidsfördröjningen som en funktion av förspänningskraften togs fram för ett M8 och M10 provobjekt. Murnaghans hyperelastiska materialmodell implementerades genom att skapa ett användar material skriven i programmeringsspråket Fortran för den explicita lösaren Radioss. Hypermesh användes för att ställa upp FEM simuleringen. Materialmodellen har visat ett väntat beteende med en ökad ljudhastighet med tryckspänningar och minskad ljudhastighet med dragspänningar. Beräkningsmodellen visade en god överenstämmelse med resultatet från experimentet.
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Swanson, James A. "Characterization of the strength, stiffness, and ductility behavior of T-stub connections." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/24166.
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Nykänen, Robin. "Simulation of Bolted Joint with Frictional Contacts." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74490.
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An easy and reliable way to join two or more components is to use a bolted joint. When torque is applied on the bolt head, a clamp force is achieved. However about 90% of this torque will be used just to overcome the friction in the interfaces. To be able to fasten these in an ecient and precise manner the friction in the bolt threads and underhead area is important to understand. This is currently investigated at Atlas Copco by using a friction test rig, FTR, which measures the clamp force, the total torque and the shank torque. To evaluate the test rig and also to be able to evaluate dierent friction models, a parameterised simulation model of a bolted joint is built. This is a 3D-model of the joint containing a bolt, a nut and a test specimen. The stiness and frictional behaviour of the FTR is used in the model to get a good comparison between these two. Dierent contact formulations and settings are tested to achieve a good model. Also, mesh size, step size and material models are evaluated to see the eect of these. The results show a good correlation between the FTR data and the simulation model. For the total torque to clamp force ratio a dierence of about 1% is achieved. The average dierence in shank torque and underhead torque is at 3.1% and -1.6% respectively. The pressure distribution for this model is shown to be unevenly distributed along the threads. This is minimized by softening the contact, but this instead increases the error between the FTR data and the simulation model. For the evaluation of friction models that are based on the contact pressure this needs to be investigated further to nd a good compromise between the contact pressure and the frictional behaviour.
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Karlsson, Karolin. "An experimental study of rotationin a composite single bolted joint." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-176844.
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To design a bolted joint, the transition bearing stress and maximumbearing stress have to be regarded. Transition bearing stress is thebearing stress where bearing failure begins and maximum bearing stressis where the joint goes to total failure. A method for studying rotationin a bolted joint has been developed using an optical instrument calledDigital Speckle Photography, DSP, which is a non-contact extensometerusing digital cameras, together with a load frame. The data from DSPsystem is transformed and analyzed to get rotations for different partsof the joint. Thinner joints give higher values on transition bearingstress, higher maximum bearing stress and higher maximum bolt rotation,than thicker joints. Bolt torque has a big impact and higher torquegives the same positive results as thinner joints. Increased secondarybending makes the joint more resistant to bearing failure, whichincreases the transition bearing failure stress, maximum bearing failurestress and maximum bolt rotation. There is a relationship between thecurve slope in a bearing stress versus bolt rotation figure and thetransition bearing stress. If the joint has a lower value on boltrotation, in comparison with other joints, at the same bearing stress,this will lead to a higher transition bearing stress.
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Ganji, Nagesh Lankaranu Hamid M. "Parametric study of load transfer in two-bolted single lap hybrid (bonded/bolted) shear joints." Diss., A link to full text of this thesis in SOAR, 2007. http://soar.wichita.edu/dspace/handle/10057/1133.
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Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering."May 2007." Title from PDF title page (viewed on Dec. 20, 2007). Thesis adviser: Hamid M. Lankarani. Includes bibliographic references (leaves 62-64).
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Smallidge, Jeffrey M. "Behavior of bolted beam-to-column T-stub connections under cyclic loading." Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19534.
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Kratochvil, Jan. "Asymptotic Analysis of the Load Transfer on Double-Lap Bolted Joints." Phd thesis, Techn. Univ., Studienbereich Mechanik, 2012. https://tuprints.ulb.tu-darmstadt.de/2997/1/Diss_Kratochvil.pdf.
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In this thesis, the complex potential method along with the method of compound asymptotic expansions is applied to the analysis of selected problems of plane elasticity related to double-lap bolted joints. The contribution to the thesis lies in the construction of several closed-form approximations of solutions to the considered problems.
After a brief introduction of the basic theoretical concepts in Chapter 2, a mathematical model of a double-lap bolted joint is presented in Chapter 3. A very simple model is chosen in order to make an analytical treatment possible. This model assumes the (generalised) state of plane stress in each of the plates and a simple sinusoidal distribution of contact pressure in the bolt-to-hole contact and leads mathematically to the first fundamental problem of the plane theory of elasticity.
In Chapter 4, a formal asymptotic solution of the first fundamental problem for an infinite plane or half-plane weakened by a finite number or an infinite symmetric array of small holes is derived. The relative hole radius plays the role of the small parameter. Three different governing partial differential equations are considered, namely the Laplace equation, the bipotential equation and a more general linear elliptic fourth-order partial differential equation with constant coefficients. An asymptotic expansion of the complex potentials is derived for each equation. It is uniformly valid in the whole domain, i.e. in the vicinity of each of the holes as well as in the far-field. The solution is summarised in form of algorithms for a computer algebra system and implemented in Mathematica. Furthermore, a fully parametrised finite element model of the considered problem has been created using the commercial FE Software Abaqus and its Python programming interface in order to verify the results in an independent way.
This general solution is in Chapter 5 applied to three types of problems. The first one is the problem of stress concentration on unloaded holes. Its purpose is to evaluate the capability of the method by means of simple examples where a sufficiently high number of terms of the asymptotic series can be generated. The second type of problems involves the compliance of an infinite row of pin-loaded holes. A closed-form approximate formula for the compliance of an infinite row of pin-loaded holes in an infinite isotropic plane and a half-plane is derived. This formula, as opposed to semi-empirical formulae commonly used in the industrial environment, correctly takes into account the contributions of the plane deformation of the plates to the overall compliance of the joint. Finally, the third type deals with the determination of the load distribution on both finite number of bolts as well as infinite rows of bolts. Closed-form approximations of the load distribution factor for these configurations are presented.
A certain problem related to the nature of the proposed solution is the convergence of the asymptotic series. As expected from the nature of the asymptotic solution, the discrepancy between the asymptotic solution and a reference numerical one is the smallest for small radii and with increasing radii, it generally increases. However, results with the presented order of approximation are sufficiently accurate in the technically relevant domain.
In the case of anisotropic material behaviour, the formulae describing the dependence on the material parameters are too complex for practical use even in the simplest situations such as stress concentration on a single hole in a half-plane. A certain simplification can be achieved by assuming strong orthotropy and performing a Taylor expansion in terms of the corresponding small parameter. It appears that such an expansion exhibits good convergence and can be therefore used also for moderately orthotropic materials. Unfortunately, it was not possible to obtain analytical results for infinite rows of holes in anisotropic plates because the proposed algorithm leads to infinite sums that cannot be be evaluated analytically.
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Abd-El-Naby, Sherif F. M. "Experimental and theoretical investigations of bolted joints for pultruded composite materials." Thesis, University of Surrey, 1992. http://epubs.surrey.ac.uk/843013/.
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Fibre reinforced structural members are currently being produced using the pultrusion process. The mechanical properties of these members are fundamentally different from those of conventional metallic ones. Therefore, the approximate theories which are suitable for designing the latter elements have to be revised before they are applied to pultrusions. An important aspect of the design of building frames is that of joints. The bolting technique is considered as the most suitable method for on-site jointing. Accordingly, experimental investigations are undertaken in order to establish the behaviour of bolted joints in pultrusions. Numerical and analytical methods are used to investigate the stresses in these joints. Single and two-bolt joints were the subject of experimental investigations. It is shown that materials with high percentage of axial fibres do not develop bearing failure. However, provided the end distance is sufficient, the resulting shear failure will be ductile. The load distribution in joints with two bolts is measured and it is found that it varies with the load on the joint. The theoretical investigations compare the use of the laminated plate theory with three dimensional analyses. Because the use of the laminated plate theory is found to be reasonably accurate, an improvement for the case of a symmetrical laminate is proposed where the laminated shell theory is used to model half the plate only. This technique is based on the assumption of a bi-linear variation of the stress through the thickness of the laminate. The effect of the fastener is an important part of the behaviour of the joints. Three dimensional analyses are performed to assess its effect. To avoid the complications of performing three dimensional analyses, a two dimensional model for considering the effect of the washer on the joint is devised. In addition, a method which avoids iteration when considering the effect of friction is formulated. A finite element formulation for the non-linear and failure behaviour of uniaxial composite materials is developed to investigate the behaviour of the joints. Finally, a closed form analytical formula for calculating the tangential stress around a hole in an infinite orthotropic plate loaded on the hole is generated to simplify the design procedures.
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Huang, Yenwen. "Predictive equations for bolted connections." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41995.
Full textAbstract:
A FORTRAN computer program applying the ultimate strength/instantaneous center
of rotation method was written to generate the eccentricity coefficients used for the
study of this project.
For single line bolted connections, the value of the eccentricity coefficient is determined
by several independent variables: NR (number of rows in the bolted connection), B
(distance between two adjacent bolts in a vertical column), Xo (horizontal distance from
centroid to applied load), and 0 (the load angle). From the relationships between the
eccentricity coefficient and the independent variables, it was observed that a mathematical
model of the eccentricity coefficient with respect to the independent variables is hard
to determine. Hence, statistical equations for predicting the eccentricity coefficients were
developed by using the Buckingham's PI-Theorem and regression analysis. The precision
of the statistical equations is discussed, and several ways to improve the precision are
presented in this paper.
Master of Science
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Xu, Weiwei. "Effect of Bolted Joint Preload on Structural Damping." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4794.
Full textAbstract:
Bolted joints are integral parts of mechanical systems, and bolt preload loss is one of the major failure modes for bolted joint structures. Understanding the damping and frequency response to a varying preload in a single-bolted lap-joint structure can be very helpful in predicting and analyzing more complicated structures connected by these joints.
In this thesis, the relationship between the bolt preload and the natural frequency, and the relationship between the bolt preload and the structural damping, have both been investigated through impact hammer testing on a single-bolted lap-joint structure. The test data revealed that the bolt preload has nonlinear effects on the structural damping and on the natural frequency of the structure. The damping ratios of the test structure were determined to increase with decreasing preload. An increase in structural damping is beneficial in most engineering circumstances, for it will reduce the vibrational response and noise subjected to external excitations. It was also observed that the modal frequency increased with increasing preload, but remained approximately constant for preload larger than 30% in the bolt yield strength. One application for studying the preload effect is the detection for loose bolts in structures. The possibility of using impact testing for estimating preload loss has been confirmed, and the modal damping was determined to be a more sensitive indicator than the natural frequency in a single-bolted lap-joint structure.
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Zhu, Yong. "Retrofitting of reinforced concrete coupling beams by bolted side steel plates for strength and deformability." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B36434048.
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Mathew, Vinu Zacharia. "Characterization of new particulate MMC materials and bolted joints through applicable ASTM standards." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3148.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains viii, 89 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 79-80).
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Goteti, Vasudha. "Parametric modeling of bolted joints between components made of particulate composite materials." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3003.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 2003.Title from document title page. Document formatted into pages; contains xii, 79 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 78-79).
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Pearce, Garth Morgan Kendall Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "High strain-rate behaviour of bolted joints in carbon fibre composite structures." Awarded by:University of New South Wales. Mechanical & Manufacturing Engineering, 2009. http://handle.unsw.edu.au/1959.4/44593.
Full textAbstract:
An investigation is presented into the behaviour of carbon fibre composite joints subjected to dynamic loading rates in the range of 0.1 m/s to 10 m/s. The research is focused on the response of single fastener joints and more complex structural arrangements involving multiple fasteners and complex loads. Fasteners play a crucial role in the joining of aerospace components due to their ease of installation and inspection and their resistance to creep and environmental degradation. A consequence of the operating environment of aircraft is that many critical load cases involve impact and crash. These loading events are characterised by high loading rates, high kinetic energy and possibly loads well above the static design case. The properties of composite materials change with loading rate, so it is likely that the behaviour of bolted composite joints may also vary significantly. Dynamic behaviour of bolted joints is an area of research that has been given little attention to date. The few available papers on the topic are limited to the investigation of ideal bearing loads and include some contradictory results. The research developed a detailed understanding of the behaviour of bolted joints in composite structures through a combined numerical and experimental investigation. A set of quasi-static and dynamic single fastener joint tests was conducted to develop an understanding of the complex failure mechanisms present in bolted composite joints. Simple structural tests were developed to investigate the interaction of multiple bolts in a joint. High speed camera footage, full-field strain measurement and CT scanning techniques were all used to develop an understanding of the changes in the failure process with increased loading rate. Finite element analyses used implicit and explicit dynamic algorithms to model the tests. The finite element analysis contributed to the understanding of the experimental results as well as providing a predictive tool to minimise the need for further testing. A method of incorporating detailed information about bolt failure into large scale structural models was investigated and developed. The original contributions of this thesis involve novel dynamic joint testing including dynamic pull-through and structural tests. CT Scanning was utilised in a novel way to investigate the complex failure modes within a bolted joint. Novel finite element techniques were developed for modelling bolted joints at both a detailed level and a simplified level for structural analyses. These contributions significantly improve the current understanding of bolted joint failure, both quasi-statically and dynamically, and will allow for more efficient design of bolted composite structures for crash and impact loads.
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Zografos, Angelos. "Numerical and experimental investigation of fretting in wheel-hub type bolted joints." Thesis, Imperial College London, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539281.
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Alhasawi, Anas. "Computational tools for nonlinear analysis of steel and composite steelconcrete structures considering connection bahaviour : Application to buildings and bridges." Thesis, Rennes, INSA, 2017. http://www.theses.fr/2017ISAR0006/document.
Full textAbstract:
Cette thèse a pour objectifs de développer une modélisation aussi fine que possible des structures aciers et mixtes acier-béton sous sollicitations cycliques avec prise en compte d'une part du comportement des assemblages et d'autre part des non-linéarités géométriques et du contact à l'interface acier-béton. Notre attention porte en particulier sur l'assemblage de type poutre acier/mixte sur poteau métallique par platine d'extrémité boulonnée. L'objectif étant de proposer un modèle «élément fini» d'assemblage qui reproduit aussi fidèlement que possible le comportement cyclique de ce dernier pour ensuite l'assembler à un élément fini de poutre non-linéaire acier ou mixte avec prise en compte, pour ce dernier, du soulèvement à l'interface. Le travail se compose de 3 parties distinctes. Un premier modèle qui se base sur la méthode des composantes a été développé ayant pour objectif de suivre la déformation de chaque composante au cours des cycles et de prendre en compte les non-linéarités induites par la séparation entre la platine d'extrémité et la semelle du poteau auquel elle est boulonnée. Ce modèle type composantes, a été développé pour une rangée de boulons. Dans le cas le plus fréquent, de deux rangées de boulons, une résistance de groupe (en plus des résistances individuelles de chacune des rangées) est susceptible de se développer. Pour rendre compte de ce phénomène, nous avons implanté le modèle proposé par Cerfontaine qui repose sur la définition d'une surface de charge et une règle d'écoulement associée pour déterminer les allongements des ressorts équivalents. Seul le cas de plasticité parfaite est considéré. Il est mis en évidence que l'influence de l'effet de groupe s'avère non négligeable sur le comportement post-élastique de l'assemblage et donc de la structure. Dans une seconde phase, nous proposons un modèle de poutre métallique classique en grands déplacements (approche co-rotationnelle) avec rotules généralisées aux extrémités. Nous faisons l'hypothèse que les déformations plastiques sont concentrées aux rotules dont le comportement plastique est contrôlé par une surface de charge asymétrique (anisotrope) qui peut prendre différentes formes selon la valeur donnée à un facteur q dit « facteur de forme». Chacune de ces rotules plastiques comprend un ressort longitudinal pour l'effort normal Net un ressort spiral pour le moment fléchissant M. L'interaction (M-N) entre ces deux efforts dans le domaine plastique est régie par le critère de plasticité. Le modèle de rotule plastique généralisé proposé permet de rendre compte de l'adoucissement cyclique, de la ductilité et du « pinching effect ».Nous montrons aux travers de plusieurs exemples la pertinence mais également les limites d'une telle approche. Dans une troisième partie, nous proposons un nouvel élément fini de poutre mixte (à 6 ddl par nœud) en petits déplacements avec prise en compte de la non-linéarité matérielle de la poutre ainsi que du contact entre l'acier et le béton. Une stratégie efficace de type nœud mobile (Flying Node) est proposée pour déterminer l'étendue de la surface de contact au sein d'un élément fini et d'adapter le maillage de l'élément poutre/poteau. Pour la résolution du problème de contact, la technique du Lagrangien Augmenté a été retenue. On montre que dans certaines situations, le soulèvement modifie la redistribution des effortsThe goal of this thesis is to develop computational tools for the nonlinear analysis of steel and composite steel-concrete structures under cyclic loading taking into account the actual behaviour of joint, material and geometry non-linearities and contact conditions at the steel-to-concrete interface. In particular, our efforts focuses on typical bolted end-plate connection between steel or composite beam and steel column. The objective is to develop a new «joint finite element" able to reproduce accurately the cyclic behavior of the beam-to-column connection. Next this model is combined with a non-linear steel/composite beam element considering slip and possible uplift at the interface. The thesis consists of three major parts. The first part deals with the behavior of a steel beam-to-column bolted end-plate connection under arbitrarily cyclic loading. The proposed model is based on an improved component method that closely follows the deformation of each component taking into account non-linearities induced by possible gap between the column flange and the end-plate. This model has been developed for a single row connection. In the case of multiple row bolted connection group effects may develop. Possible group effect between two bolt-rows has been implemented considering the model proposed by Cerfontaine based on the definition of the multi-surface yield criterion and the associated flow rule that govern deformation of equivalent springs. Only the case of perfect plasticity is considered. It is shown that the influence of the group effect is not negligible on the nonlinear response of the joint. In the second part, we have developed a flexible co-rotational two-noded beam with generalized elasto-plastic hinges at the beam ends. It is assumed that plastic deformations concentrate at these hinges. These hinges have the ability to elongate/shorten along the beam axis and to rotate. A family of asymmetric and convex yield surfaces of super-elliptic shape is considered for the plastic behavior of the hinges. By varying the roundness factor, an infinite nun1ber of yield surface are obtained. It is shown that the nonlinear response of bolted connections subjected to both bending and tension are conveniently modeled with such a yield surface. It was observed that cyclic loading produces pinching effect, cyclic softening and ductile behavior. Advantages and limitations of the approach are discussed. Finally, the third part is dedicated to the problem of contact at the interface of steel-concrete composite beams. A "new" finite element for composite steelconcrete beam is proposed. The beam element has 6 degrees of freedom per node. The concrete beam is allowed to separate from the steel beam. An efficient contact algorithm is proposed. The Flying node concept is introduced and used to determine the extent of the contact area within a single element and modify the mesh of the beam structure. The contact problem is solve using the Augmented Lagrangian Method. The influence of contact on the loading capacity of the beam and its influence on some design variables are highlighted
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Do, Tan Dan. "The effect of bolt spacing on the tightness behavior of bolted flange joints." Mémoire, École de technologie supérieure, 2012. http://espace.etsmtl.ca/964/1/DO_Tan_Dan.pdf.
Full textAbstract:
Les assemblages à brides boulonnées munis de joints d’étanchéité sont les systèmes de
raccordement les plus répandus entre les différents éléments des réservoirs sous pression. Ils
sont largement utilisés dans l'industrie chimique, pétrochimique et nucléaire. Ce sont des
structures simples et des assemblages démontables. Ce qui les rend plus attractifs pour
connecter des équipements sous pression et la tuyauterie. En plus des risques de fuite, ils ont
besoin de maintenance en cours de fonctionnement au cas où les boulons doivent être
resserrés ou dévissés pour être remplacés. Bien que les arrêts de fonctionnement coûteux
soient à éviter, l’entretien en fonctionnement expose l'opérateur à un risque potentiel, car le
desserrement d’un boulon peut produire un déséquilibre de la contrainte de compression sur
le joint d’étanchéité entraînant un contact local du joint d’étanchéité en dessous d’une
certaine valeur critique, provoquant une fuite majeure et de ce fait pouvant mettre en péril la
vie de l'opérateur.
Cette proposition aborde la question de la variation de la déflexion du rebord de la bride afin
d'enquêter sur le déséquilibre de la contrainte de compression dans le joint lorsque les
boulons sont soumis à une modification de charge en fonctionnement. Cette étude peut être
utilisée pour aider à limiter l'augmentation de la charge de serrage ou le nombre maximum de
boulons qui doivent être remplacés en même temps et identifier les boulons qui ne peuvent
pas être remplacés en service.
L'objectif de cette étude est de développer une approche théorique pour identifier et analyser
les effets de la charge précontrainte et de la pression sur les assemblages à brides boulonnées
afin d’obtenir l'espacement optimal entre les boulons en fonction de la variation de la
contrainte de compression sur le joint d’étanchéité. Notre recherche comprend trois parties.
La première partie qui est une méthode analytique basée sur la théorie de la poutre circulaire
reposant sur une fondation élastique linéaire, sera développée pour prédire la distribution
circonférentielle de la contrainte de compression sur le joint d’étanchéité. Des modèles
éléments finis de brides boulonnées symétriques seront créés pour valider cette analyse. Une
comparaison des résultats d'études antérieures est nécessaire pour valider la solution
analytique linéaire. Ensuite, la deuxième étape de cette recherche consiste en une approche
qui a été construite à partir de la théorie de l'anneau sur le comportement d’une fondation non
linéaire élastique, permettant d’obtenir des résultats plus précis. La solution non-linéaire doit
être validée avec une analyse par la méthode des éléments finis. Dans la troisième partie, un
modèle de régression linéaire pour des brides boulonnées sera proposé pour une procédure de
calcul d’espacement de boulons. Ce travail aidera les services techniques sur la conception,
la maintenance et l'exploitation des réservoirs sous pression et systèmes de tuyauterie.