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1
Guz’, A. N., S. Yu Babich, and V. B. Rudnitsky. "Contact Problems for Elastic Bodies With Initial Stresses: Focus on Ukrainian Research." Applied Mechanics Reviews 51, no. 5 (1998): 343–71. http://dx.doi.org/10.1115/1.3099009.
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In the present review article general results concerning problems of contact interaction (contact problems) of pre-stressed bodies with rigid, and elastic punches (facings) are presented. The modern classification of investigations on contact problems for bodies with initial stresses is based on two approaches. The first approach is applicable to bodies with a specific type of elastic potential. The second approach is developed in parallel with the first one. It describes investigations on contact problems for pre-stressed bodies with an arbitrary structure of an elastic potential in a general form for compressible and incompressible materials. In the last case, investigations were carried out in a common form for the theory of large (finite) initial strains and various variants of the theory of small initial strains. The formulation of the problems is given, and methods of solving planar and spatial contact problems for bodies with initial stresses are developed. Procedures of the theory of complex variables and methods of Riemann-Hilbert are used. For planar problems, the authors introduce planar potentials of the linearized static and dynamic problems for elastic compressible and incompressible bodies with initial stresses. In the case of spatial contact problems, various procedures are used: general solutions of spatial static problems for elastic bodies with initial stresses, methods of harmonic potential theory, integral transformations, and integral equations using numerical methods of investigation. The essential numerical results in the form of graphs and tables are presented. These give the quantitative and qualitative analysis of the influence of initial stresses on the main characteristics of contact problems. This review contains 98 references.
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Kaczmarczyk, Jarosław, and Adam Grajcar. "Numerical Simulation and Experimental Investigation of Cold-Rolled Steel Cutting." Materials 11, no. 7 (2018): 1263. http://dx.doi.org/10.3390/ma11071263.
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The paper presents results of the investigations on numerical computations and experimental verification concerning the influence of selected parameters of the cutting process on the stress state in bundles of cold-rolled steel sheets being cut using a guillotine. The physical model and, corresponding to it, the mathematical model of the analysed steel sheet being cut were elaborated. In this work, the relationship between the cutting depth and the values of reduced Huber–Mises stresses as well as the mechanism of sheet separation were presented. The numerical simulations were conducted by means of the finite element method and the computer system LS-DYNA. The results of numerical computations are juxtaposed as graphs, tables, and contour maps of sheet deformation as well as reduced Huber–Mises strains and stresses for selected time instants. The microscopic tests revealed two distinct zones in the fracture areas. The ductile and brittle zones are separated at the depth of ca. 1/3 thickness of the cut steel sheet.
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Eryshev, Valeriy A. "Relation between Breaking Stresses in the Strength Calculations of Reinforced Concrete Elements under the Deformation Mode in the Edition of Russian and Foreign Regulatory Documents." Materials Science Forum 974 (December 2019): 653–58. http://dx.doi.org/10.4028/www.scientific.net/msf.974.653.
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Сorrespondence was established between the compressive strength grades of concrete numerically equal to the guaranteed compressive strength of a standard concrete cube and a standard concrete cylinder. Designated concrete resistances are assigned for the limiting states of the first group with a compressive strength grade of concrete. For the corresponding concrete grades, the reduction to unambiguous strains values at the base diagrams points is justified: at the top and at the end of the falling branch of the curvilinear diagrams. In accordance with the regulatory requirements, restrictions are imposed on the stress levels at the end of the falling diagrams branch at the maximum normalized strains values. Mathematical models establishing a uniform format for calculating single-valued strains values at base points of concrete diagrams have been developed taking into account accepted functional relations and the their assignment rules using the requirements documents tables. It is shown that with equal strains values and stresses at base points, analytical expressions describing diagrams recommended by requirement documents, different in their structure, give their identical outlines, the diagrams branches are the same. Relation between design models in the edition of Russian and foreign regulatory documents is correlated by the comparison of integral diagrams parameters and breaking stresses obtained with the calculation of reinforced concrete element under the deformation mode. As integral parameters of concrete deformation diagrams, it is recommended to use the areas bounded by diagrams branches and diagrams fineness coefficient. The diagram area for given values of the element curvature is equivalent to the magnitude of the breaking stress in the compressed concrete zone in the bent and compressed elements, and the stress diagram in outline corresponds to this diagram.
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Banović, Ivan, Jure Radnić, and Nikola Grgić. "Shake Table Study on the Efficiency of Seismic Base Isolation Using Natural Stone Pebbles." Advances in Materials Science and Engineering 2018 (December 20, 2018): 1–20. http://dx.doi.org/10.1155/2018/1012527.
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The results of a shake table study of the efficiency of a seismic base isolation using a layer of natural stone pebbles are presented. Models of stiff and medium-stiff buildings were tested. Case studies were conducted with the foundation of model on the rigid base and on four different layers of pebbles (thin and thick layer with small and large pebbles). Four different horizontal accelerograms were applied, and the characteristic displacements, accelerations, and strains were measured. Strains/stresses of the tested models remained in the elastic area. It was concluded that the effectiveness of the stone pebble layer under the foundation, i.e., the reduction in the seismic forces and stresses in the structure compared to the classical solution of foundation, significantly depends on the type of the applied excitation and depends relatively little on the layer thickness and pebble fraction. The results of the study showed that a layer of pebbles can significantly reduce the peak acceleration and strains/stresses of the model, with acceptable displacements. Further research is expected to confirm the effectiveness of this low-cost and low-tech seismic base isolation and to pave the way to its practical application.
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Varlamov, Andrew, Vladimir Rimshin, and Sergey Tverskoi. "A method for assessing the stress-strain state of reinforced concrete structures." E3S Web of Conferences 91 (2019): 02046. http://dx.doi.org/10.1051/e3sconf/20199102046.
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The article analyses the modern methods of estimation of stress-strain state of reinforced concrete structures. The result of the analysis is a new method for estimating the stress-strain state of reinforced concrete structures. The method is based on extracting a small sample of concrete from the array. The article describes the method of execution of works, the method of calculating the stresses. Previously, the method was investigated under laboratory conditions. The results are presented in graphs and tables. The research was conducted to assess the stress state of existing concrete structures. As the objects of research, two industrial buildings of 1933 and 1941 construction years were taken. An assessment of a stress state of a panel residential building was held. The measurement results were analyzed. The method for determining the stresses in reinforced concrete buildings and structures is recommended.
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Parfenov, S. G., and V. Ye Moschenkov. "EXPERIMENTAL STUDY OF CREEP AND SHRINKAGE STRAINS IN FINE- AGGREGATE CONCRETES." Proceedings of the Southwest State University 21, no. 4 (2017): 13–20. http://dx.doi.org/10.21869/2223-1560-2017-21-4-13-20.
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The paper studies creep and shrinkage processes running in fine-aggregate concretes with plasto-elastic properties (deformations) under short-time loading are different from those of standard heavy concretes. Experimental studies of creep and shrinkage strains in fine-aggregate concretes that are based on sands with different fineness moduluses permit to compare prestress losses resulting from the creep and shrinkage of concrete. Usually these factors produce an aggregate effect, which makes the study of the processes that run in concrete under long-time influence noticeably complicated. There paper contains analysis results obtained by experimental studies of concrete prisms at different initial strains in the range of , with loading age of t= 14 or 28 days and different properties of concrete mixes. Concrete mix properties were modified by using sands with different fineness modulus. Likewise in order to determine creep and shrinkage deformations due to long-time loads the samples were tested under stress during 14, 73 and 180 days. All experimental data have been systematized in tables and are represented by diagrams. The analysis has helped to investigate the effects of relative stains on the creep deformation in concrete and to define the boundary line between linear and non-linear creep with relation to the stresses in concrete. Analytical description of non-linear deformations was performed with the help of N.H.Arutyunyan’ and I.I.Ulitsky methods. The resultant calculations formed a basis for the recommendations to simplify problem solving methods considering non-linear creep of concrete.
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Ergün, Mustafa, and Şevket Ateş. "The stress analysis of a shear wall with matrix displacement method using rectangular finite element." Journal of Structural Engineering & Applied Mechanics 4, no. 1 (2021): 18–27. http://dx.doi.org/10.31462/jseam.2021.01018027.
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The aim in this study is to numerically present some characteristic features of the rectangular finite element using the matrix displacement method and to show the utility of this element in plane stress problems compared to the finite element method. The paper consisted of three parts. In the first part, all of the finite element formulation steps from choosing the convenient coordinate system to creating element stiffness matrix are presented respectively. In the second part of the study, a static finite element analysis of the shear wall is also made by ANSYS Mechanical APDL. In the final part, the results (displacements, strains and stresses) obtained from the previous parts are compared with each other by the help of tables and graphics. The results show that this method is effective and preferable for the stress analysis of shell structures. Further studies should be conducted in order to indicate the efficiency of the matrix displacement method for the solution of different types of plane stress problems using different finite elements.
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Lekhov, O. S., and A. V. Mikhalev. "Stress-strain state of metal in deformation zone during production of steel section billets on the unit of combined continuous casting and deformation. Report 2." Izvestiya. Ferrous Metallurgy 63, no. 9 (2020): 730–34. http://dx.doi.org/10.17073/0368-0797-2020-9-730-734.
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Stress state of metal in deformation zone during introduction of the separating collars of the grooved die into continuously casted steel slab was calculated for production of section billets on the unit of combined continuous casting and deformation. Calculation of axial, tangential and equivalent stresses arising in deformation zone of metal was made in four sections of deformation zone and its results are presented in specific points and lines. View of the section of deformation zone and location of specific points are provided. The stress state of metal in zone of cyclic deformation at formation of three steel section billets from continuously cast slab by separating collars of grooved die on the unit of combined continuous casting and deformation was determined by solving extensive problem of elasticity with the finite element method using the ANSYS package. The results of calculation of axial, tangential and equivalent stresses according to Mises in deformation zone are given in form of graphs and tables for working surfaces in four cross sections. The values and regularities of distribution of these stresses along the length and width of deformation zone were determined. The character of axial stresses distribution by characteristic lines located along the length of deformation zone is shown. Values of the highest compressive and tensile axial stresses arising in deformation zone during introduction of separating collars of grooved were obtained for the unit of combined continuous casting and deformation.
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Müller, Simon, and Sabine M. Weygand. "Numerical Investigations of Internal and Residual Stresses in Aluminium-Polymer Laminate Foils during Stretch Forming." Key Engineering Materials 742 (July 2017): 697–704. http://dx.doi.org/10.4028/www.scientific.net/kem.742.697.
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Aluminium-polymer laminate foils consisting of the layers PA, Al and PVC are used to manufacture high barrier pharmaceutical packages. These so called cold-formed blister packs are formed by stretch forming at room temperature. As due to the complex material structure the forming process is not yet well understood, the developers of cold-formed blister packaging machines design the punches for forming the cavities bigger than needed for the tablets being packed. Therefore, the aim of this work is to gain insight into the mechanical behavior of the composite during stretch forming. For this, internal and residual stresses in the layers are analyzed with the finite element method. With the help of a micromechanical and a stretch forming model simulations are performed. Furthermore, an analytical solution to calculate the internal and residual stresses during stretch forming the foil is presented. The calculation procedure can be used to determine stresses from surface strains which could be measured in forming experiments.
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Zaripov, R. M., and R. B. Masalimov. "Stress-strain state of an underwater offshore oil pipeline taking into account changes in ground conditions and operating parameters." Multiphase Systems 18, no. 1 (2023): 17–26. http://dx.doi.org/10.21662/mfs2023.1.003.
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The article briefly describes the construction of concreted pipes used in recent years in the construction of offshore gas and oil pipelines. In the formulation of the problem of the stress-strain state of an underwater offshore oil pipeline, the calculated section is conditionally divided into three parts: the middle blurred bare part and the underground parts adjacent to it on the left and right. A brief description of the solution of the problem is given. The results of calculations of the main characteristics of the stress-strain state of the underwater section of the offshore oil pipeline are presented in the form of a diagram of the pipeline deflection and bending stresses, as well as in tables through extreme values of deflection and bending stresses from span and support bending moments for various values of operating parameters and soil conditions in adjacent underground parts. By analyzing the stress- strain state of the calculated section of the offshore oil pipeline, the critical values of the operation parameters and the corresponding critical values of the equivalent longitudinal axial force were determined.
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Sawicki, Andrzej, Marek Kulczykowski, and Robert Jankowski. "Estimation of Stresses in a Dry Sand Layer Tested on Shaking Table." Archives of Hydro-Engineering and Environmental Mechanics 59, no. 3-4 (2012): 101–12. http://dx.doi.org/10.2478/heem-2013-0002.
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Abstract Theoretical analysis of shaking table experiments, simulating earthquake response of a dry sand layer, is presented. The aim of such experiments is to study seismic-induced compaction of soil and resulting settlements. In order to determine the soil compaction, the cyclic stresses and strains should be calculated first. These stresses are caused by the cyclic horizontal acceleration at the base of soil layer, so it is important to determine the stress field as function of the base acceleration. It is particularly important for a proper interpretation of shaking table tests, where the base acceleration is controlled but the stresses are hard to measure, and they can only be deduced. Preliminary experiments have shown that small accelerations do not lead to essential settlements, whilst large accelerations cause some phenomena typical for limit states, including a visible appearance of slip lines. All these problems should be well understood for rational planning of experiments. The analysis of these problems is presented in this paper. First, some heuristic considerations about the dynamics of experimental system are presented. Then, the analysis of boundary conditions, expressed as resultants of respective stresses is shown. A particular form of boundary conditions has been chosen, which satisfies the macroscopic boundary conditions and the equilibrium equations. Then, some considerations are presented in order to obtain statically admissible stress field, which does not exceed the Coulomb-Mohr yield conditions. Such an approach leads to determination of the limit base accelerations, which do not cause the plastic state in soil. It was shown that larger accelerations lead to increase of the lateral stresses, and the respective method, which may replace complex plasticity analyses, is proposed. It is shown that it is the lateral stress coefficient K0 that controls the statically admissible stress field during the shaking table experiments.
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Daniels, Calvin C., P. David Rogers, and Chasity M. Shelton. "A Review of Pneumococcal Vaccines: Current Polysaccharide Vaccine Recommendations and Future Protein Antigens." Journal of Pediatric Pharmacology and Therapeutics 21, no. 1 (2016): 27–35. http://dx.doi.org/10.5863/1551-6776-21.1.27.
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This review describes development of currently available pneumococcal vaccines, provides summary tables of current pneumococcal vaccine recommendations in children and adults, and describes new potential vaccine antigens in the pipeline. Streptococcus pneumoniae, the bacteria responsible for pneumonia, otitis media, meningitis and bacteremia, remains a cause of morbidity and mortality in both children and adults. Introductions of unconjugated and conjugated pneumococcal polysaccharide vaccines have each reduced the rate of pneumococcal infections caused by the organism S. pneumoniae. The first vaccine developed, the 23-valent pneumococcal polysaccharide vaccine (PPSV23), protected adults and children older than 2 years of age against invasive disease caused by the 23 capsular serotypes contained in the vaccine. Because PPSV23 did not elicit a protective immune response in children younger than 2 years of age, the 7-valent pneumococcal conjugate vaccine (PCV7) containing seven of the most common serotypes from PPSV23 in pediatric invasive disease was developed for use in children younger than 2 years of age. The last vaccine to be developed, the 13-valent pneumococcal conjugate vaccine (PCV13), contains the seven serotypes in PCV7, five additional serotypes from PPSV23, and a new serotype not contained in PPSV23 or PCV7. Serotype replacement with virulent strains that are not contained in the polysaccharide vaccines has been observed after vaccine implementation and stresses the need for continued research into novel vaccine antigens. We describe eight potential protein antigens that are in the pipeline for new pneumococcal vaccines.
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Abdelali, Hanane Moulay, Mounia El Kadiri, and Rhali Benamar. "A Semi-Analytical Approach for the Geometrically Nonlinear Analysis of Skew Plates." Applied Mechanics and Materials 704 (December 2014): 118–30. http://dx.doi.org/10.4028/www.scientific.net/amm.704.118.
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The present work concerns the nonlinear dynamic behaviour of fully clamped skew plates at large vibration amplitudes. A model based on Hamilton’s principle and spectral analysis has been used to study the large amplitude free vibration problem, reducing the non linear problem to solution of a set of non-linear algebraic equations. Two methods of solution have been adopted, the first method uses an improved version of the Newton-Raphson method, and the second leads to explicit analytical expressions for the higher mode contribution coefficients to the first non-linear mode shape of the skew plate examined. The amplitude dependent fundamental mode shape and the associated non-linear frequencies have been obtained by the two methods and a good convergence has been found. It was found that the non-linear frequencies increase with increasing the amplitude of vibration, which corresponds to the hardening type effect, expected in similar cases, due to the membrane forces induced by the large vibration amplitudes. The non-linear mode exhibits a higher bending stress near to the clamps at large deflections, compared with that predicted by linear theory. Numerical details are presented and the comparison made between the results obtained and previous ones available in the literature shows a satisfactory agreement. Tables of numerical results are given, corresponding to the linear and nonlinear cases for various values of the skew angle θ and various values of the vibration amplitude. These results, similar to those previously published for other plates, are expected to be useful to designers in the need of accurate estimates of the non-linear frequencies, the non linear strains and stresses induced by large vibration amplitudes of skew plates.
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Lekhov, O. S., and A. V. Mikhalev. "Stress-strain state of metal in deformation zone during production of steel section billets on the unit of combined continuous casting and deformation. Report 1." Izvestiya. Ferrous Metallurgy 63, no. 7 (2020): 548–53. http://dx.doi.org/10.17073/0368-0797-2020-7-548-553.
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Volumetric problem of determining stress-strain state of metal in deformation zone during forming of three section billets from the slab by separating collars of grooved strikers on the unit of combined continuous casting and deformation was set and solved. The expediency of using such unit was justified for longitudinal division mation are given for St3sp steel. The solid-state finite elements used in calculation of stress-strain state of metal in deformation zone and dimensions of the grid are described. The results of calculation of stress-strain state of metal in deformation zone were obtained by solving the problem of elasticity by the finite element method in volumetric formulation. The results of calculation of displacements and stresses in deformation zone are given in form of graphs and tables by working surfaces in four cross sections and are presented for characteristic points. Values and regularities of distribution of axial displacements in width and length of deformation center were determined during introduction of strikers separating collars into continuously cast slab in production of three section steel billets on the unit of combined continuous casting and deformation.
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Bouacha, Nadjet, and Mouloud Belachia. "Elaboration of an Expert System for Sizing, Designing and Verifying Flexible Pavements." Civil and Environmental Engineering Reports 30, no. 3 (2020): 94–121. http://dx.doi.org/10.2478/ceer-2020-0035.
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Abstract The use of expert systems in the world of civil engineering, and in particular for roads, has become a necessity for the reason of the particularity, complexity, and diversity of the influencing parameters at the level of the design calculation, the latter of which represents the major source of subsequent degradation. This system consists of proposing a tool for helping the user firstly to size the body of the roadway, with several analytical methods and models (Pre-project, Boussinesq, Westgaard, and Burmister), and secondly, to offer different design possibilities (thickness and type of the material) that make up the layers. Lastly, it is to calculate the stresses and strains in order to compare them with admissible limits. The management of a knowledge base of complex natures (words, sentences, numbers, symbols, tables, calculation methods, equations, conditions, etc.) requires an adequate methodology which goes beyond the simple use of the technology but enables you to imagine the process of regrouping this mass of complex data and classifying the data, which can then be integrated into a database or spreadsheets and external programs designed with code compatible with the expert system generator. Our contribution relates initially to the formulation, organization, and preparation of the algorithms, and then the starting of the programs in order to conceive fully executable programs, the latter of which we can call the expert system. The validation of such a system was made as the work progressed, changes were made in the formulation of the rules, and the order and orientation of the data in the knowledge that the advantage of this type of system is the possibility of permanently reinforcing the database with human expertise in the field, or in books, especially so that we can avoid data loss due to illnesses, retirement, etc.
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Stetukha, V., and I. Zheleznyak. "Methodology for Calculating the Stability of the Polymer Operating String in Permafrost." Journal of Mining Institute 241 (February 25, 2020): 22. http://dx.doi.org/10.31897/pmi.2020.1.22.
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The goal of this paper is to develop a methodology for calculating the stability of an annular cross-section string casing made of polymer material used for the development of mineral deposits by underground leaching in permafrost formations. The aim was to determine the geometric parameters of the casing and to ensure its operational reliability.The relevance of the research is associated with the peculiarities of external influences on the string, for example, a geotechnological well operating in permafrost formation under conditions of additional exposure to ice pressure during freezing of water in the borehole annulus. This effect is usually accompanied by deformation of the casing due to ice pressure, which can lead to string collapse, abnormal operation and the risk of contamination of the geological environment.The proposed calculation method for a polymer casing is based on simulation of objects using the finite element method. We used the spatial finite elements to model the interaction of key elements of the geotechnological natural-technogenic complex: a polymer casing, ice in the annulus space and homogeneous or heterogeneous rock masses adjacent to the well.The results of the study are presented in the form of tables and patterns of displacements, which reflect stresses and strains in the elements of the calculation scheme. The analysis of the obtained results confirms the possibility of using polymer casings of different technological purposes in various conditions of permafrost formation, including extreme ones. The results of the redistribution of pressure created by ice during the freezing of water in the borehole annulus to the rock mass and the string are evaluated. Interdependent deformations of the rock mass and operating string during freezing of water in the borehole annulus are determined. The necessity of considering the properties of the rock mass in determining the pressure on the string is established. The conditions for the collapse of the string with a different combination of its parameters are revealed.
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S., V. Borshchevskiy, D. Petrenko V., L. Tiutkin O., Yu. Kulazhenko Ye., and M. Kulazhenko O. "SCIENTIFIC EVIDENCE FOR WALLS FASTENING TECHNOLOGIES OF WORKING TRENCH BY THE SPECIAL METHOD "SLURRY WALL" FOR SHALLOW SUBWAYS' STATIONS." Science and Transport Progress, no. 6(54) (December 15, 2014): 154–63. https://doi.org/10.15802/stp2014/33740.
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<strong>Purpose. </strong>It’s necessary to carry out justification of fastening technology and the choice of the optimal variant, creating dependency diagrams of moving for idealized cases by means of automated methods of calculations. <strong>Methodology. </strong>To achieve this goal, the finite element solid models, which reflect the design of the working trench for the shallow subways’ stations, with four ways to fix the “slurry wall”, as well as a calculation and analysis of the stress-strain state of structures and fixtures calculated using the complex with using the finite element method (FEM) is built in the software package SCAD. <strong>Findings. </strong>The analysis of the stress-strain state and movements of various fundamental systems of soil nailing and comparing the results by displaying the calculations results of main and equivalent stresses, using the built-in postprocessors in software package SCAD. Namely, were identified extreme tensions arising in the wall and strut rail. It is built the tables and the resulting graph of behavior of the structural fastening condition; the parameters change of the surrounding array on the base of the research. It is possible to analyze and compare the operation of different constructions of slopes fastening of working trench by means of their help. <strong>Originality. </strong>In solving this problem have been analyzed and studied the behavior of the structure fastening the «slurry wall», and its stress-strain state, the location and the fastening areas that need further elaboration, study and introduction of measures to strengthen the construction of fences and auxiliary fixing elements, presented with metal strut rail. <strong>Practical value. </strong>In the era of highly advanced building technologies in the construction of underground facilities with using the special method of “slurry wall” the question arises about the quick selection of optimal parameters, elements and methods of securing its walls from excessive strain and avoidance of displacement to the calculation of possible combinations of permanent loads from soil in the construction of the working trench.
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Miner, Valerie, and Carol Anshaw. "Stresses and Strains." Women's Review of Books 19, no. 9 (2002): 14. http://dx.doi.org/10.2307/4023935.
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Ghasemi Nejhad, Mehrdad N., Chiling Pan, and Hongwei Feng. "Intrinsic Strain Modeling and Residual Stress Analysis for Thin-Film Processing of Layered Structures." Journal of Electronic Packaging 125, no. 1 (2003): 4–17. http://dx.doi.org/10.1115/1.1512295.
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Residual stresses develop due to intrinsic and extrinsic strains that form during the processing. Extrinsic strains can be determined using coefficient of thermal expansion, material properties, and processing conditions. An “Equivalent Reference Temperature (ERT)” technique is described and used to model and evaluate the intrinsic strains. piezoelectric microelectromechanical systems (P-MEMS) are considered in this work. Laminate theory with three-dimensional state of stress and strain is used to evaluate residual stresses using the ERT model. In finite element analysis (FEA), the residual stresses and strains of multi-layer P-MEMS structures deposited layer-by-layer during processing, are simulated using the “element birth-and-death” approach. The evaluated residual stresses for a simplified geometry using ANSYS three-dimensional FEA and analytical analysis employing three-dimensional laminate theory are presented along with their corresponding experimental results. A user-friendly software based on the 3-D laminate theory is developed and installed on the Internet. The “equivalent reference temperature” as well as residual stresses and strains can be determined using this software. The level of residual stresses and strains of P-MEMS depend upon various factors such as geometrical design, material selection, and process conditions.
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Yao, Ye, and Wai-Meng Quach. "Numerical Study on Residual Stresses and Plastic Strains in Cold-Formed High-Strength Steel Circular Hollow Sections." Materials 16, no. 18 (2023): 6337. http://dx.doi.org/10.3390/ma16186337.
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This paper presents a numerical investigation on the residual stresses and co-existent equivalent plastic strains in cold-formed high-strength steel (CFHSS) circular hollow sections (CHS) by using an advanced finite element (FE)-based method. In this method, the entire manufacturing process of the CFHSS CHS was modeled numerically. The accuracy of the numerical predictions of equivalent plastic strains and residual stresses in the CFHSS CHS was verified by comparing the predictions with the existing test results of both the residual stress measurement and load-end shortening response of the stub column. By using the FE-based method, the effects of high-frequency electric resistance welding on the residual stresses and the stub column response were investigated. The through-thickness variations of both the equivalent plastic strains and residual stresses in CFHSS CHS, which are difficult to measure in the laboratory, were explored numerically. Finally, the effect of cold work (which is quantified by the equivalent plastic strains and residual stresses) on the stub column response of CFHSS CHS tubes was evaluated. It can be found that the equivalent plastic strains and longitudinal residual stresses are generally uniform around the cross-section of CFHSS CHS. The transverse and longitudinal residual stresses are generally uniform across each half-thickness, with the inner half-thickness under compression and the outer half-thickness under tension. The results also demonstrate that both the plastic strains and residual stresses may significantly affect the cross-section capacities of CFHSS CHS.
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D. D’Lima, Darryl, Peter C. Chen, and Clifford W. Colwell Jr. "Osteochondral Grafting: Effect of Graft Alignment, Material Properties, and Articular Geometry." Open Orthopaedics Journal 3, no. 1 (2009): 61–68. http://dx.doi.org/10.2174/1874325000903010061.
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Osteochondral grafting for cartilage lesions is an attractive surgical procedure; however, the clinical results have not always been successful. Surgical recommendations differ with respect to donor site and graft placement technique. No clear biomechanical analysis of these surgical options has been reported. We hypothesized that differences in graft placement, graft biomechanical properties, and graft topography affect cartilage stresses and strains. A finite element model of articular cartilage and meniscus in a normal knee was constructed. The model was used to analyze the magnitude and the distribution of contact stresses, von Mises stresses, and compressive strains in the intact knee, after creation of an 8-mm diameter osteochondral defect, and after osteochondral grafting of the defect. The effects of graft placement, articular surface topography, and biomechanical properties were evaluated. The osteochondral defect generated minimal changes in peak contact stress (3.6 MPa) relative to the intact condition (3.4 MPa) but significantly increased peak von Mises stress (by 110%) and peak compressive strain (by 63%). A perfectly matched graft restored stresses and strains to near intact conditions. Leaving the graft proud by 0.5 mm generated the greatest increase in local stresses (peak contact stresses = 6.7 MPa). Reducing graft stiffness and curvature of articular surface had lesser effects on local stresses. Graft alignment, graft biomechanical properties, and graft topography all affected cartilage stresses and strains. Contact stresses, von Mises stresses, and compressive strains are biomechanical markers for potential tissue damage and cell death. Leaving the graft proud tends to jeopardize the graft by increasing the stresses and strains on the graft. From a biomechanical perspective, the ideal surgical procedure is a perfectly aligned graft with reasonably matched articular cartilage surface from a lower load-bearing region of the knee.
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Greenhalf, Jim. "Stresses and strains in city hall." Local Government Studies 11, no. 2 (1985): 1–7. http://dx.doi.org/10.1080/03003938508433189.
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Nowacki, Jerzy, and Michał Kawiak. "Stresses and strains in soldered joints." Welding International 27, no. 1 (2013): 42–47. http://dx.doi.org/10.1080/09507116.2011.600025.
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Comba, Peter. "Strains and stresses in coordination compounds." Coordination Chemistry Reviews 182, no. 1 (1999): 343–71. http://dx.doi.org/10.1016/s0010-8545(98)00199-4.
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Nichols, T. Richard. "The Stresses and Strains of Tensegrity." Journal of Motor Behavior 46, no. 3 (2014): 197–98. http://dx.doi.org/10.1080/00222895.2014.880308.
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Nicholson, D. W. "On stresses conjugate to Eulerian strains." Acta Mechanica 165, no. 1-2 (2003): 87–98. http://dx.doi.org/10.1007/s00707-003-0037-2.
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Ezendiokwere, Nnamdi E., Victor J. Aimikhe, Adewale Dosunmu, and Ogbonna F. Joel. "Influence of depth on induced geo-mechanical, chemical, and thermal poromechanical effects." Journal of Petroleum Exploration and Production Technology 11, no. 7 (2021): 2917–30. http://dx.doi.org/10.1007/s13202-021-01174-6.
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AbstractDelivering efficient and cost-effective drilled and excavated holes require effective prediction of instability along the hole profile. Most drilled and excavated hole stability analyses in the literature are performed for a given zone without considering the influence of depth. This study focused on determining the influence of depth on induced geo-mechanical, chemical, and thermal stresses and strains in drilled or excavated holes. To this end, a new porochemothermoelastic model was developed based on extended poroelastic theory, and the developed model was employed in determining induced strains and stresses for an oil and gas well case study, using data from the literature. The study delineated the different significance levels of geo-thermal-, chemical-, and thermal-induced strains and stresses as depth increased. From the results obtained, it was clear that at shallow depths, chemically induced strains and stress were the most significant formation perturbations responsible for instability of drilled and excavated holes. On the other hand, at deeper depths, geo-mechanical-induced strains and stress were the most predominant. Comparatively, thermally induced strains and stresses were found to be the least significant formation perturbations responsible for instability of drilled and excavated holes. For this case study, the results indicated that chemical strains and stresses were more prominent at depths below 170 m, accounting for more than 50% of the total stresses and strains. At 170 m, both chemical and geo-mechanical stress and strain had equal contributions to the overall stress and strain. However, as depth increased, the percentage contribution of the geo-mechanical component increased and accounted for about 80% of the total strains and stresses at 1000 m, which increased to 98.48% at depths of 6000 m and beyond. The findings of this study will provide guide for future studies on the application of extended poroelasticity theory in solving instability problems of drilled and excavated holes.
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Hyde, T. H., R. Sabesan, and S. B. Leen. "Approximate Prediction Methods For Multiaxial Notch Stresses and Strains Under Elastic-Plastic and Creep Conditions." Journal of Strain Analysis for Engineering Design 40, no. 6 (2005): 535–48. http://dx.doi.org/10.1243/030932405x16016.
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This paper describes general techniques for predicting multiaxial notch stresses and strains under elastic-plastic and creep conditions. The Neuber method, which is often used in elastic-plastic analysis, has been adapted and extended for predicting creep equivalent notch stresses and strains, based on a time-stepping integration scheme. A linear interpolation method, often used in creep analysis, is adapted and extended for predicting elastic-plastic equivalent stresses and strains. Then notch principal stresses and strains are obtained by applying plasticity theory in combination with assumptions concerning the ratios of the stress or strain components. The accuracy of the predicted equivalent and principal stress and strain values are assessed by comparing predictions based on them with results obtained from finite element analyses.
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Xing, Yufeng, Lingyu Meng, Zhiwei Huang, and Yahe Gao. "A Novel Efficient Prediction Method for Microscopic Stresses of Periodic Beam-like Structures." Aerospace 9, no. 10 (2022): 553. http://dx.doi.org/10.3390/aerospace9100553.
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This paper presents a novel superposition method for effectively predicting the microscopic stresses of heterogeneous periodic beam-like structures. The efficiency is attributed to using the microscopic stresses of the unit cell problem under six generalized strain states to construct the structural microscopic stresses. The six generalized strain states include one unit tension strain, two unit bending strains, one unit torsion strain, and two linear curvature strains of a Timoshenko beam. The six microscopic stress solutions of the unit cell problem under these six strain states have previously been used for the homogenization of composite beams to equivalent Timoshenko beams (Acta. Mech. Sin. 2022, 38, 421520), and they are employed in this work. In the first step of achieving structural stresses, two stress solutions concerning linear curvatures are transformed into two stress solutions concerning unit shear strains by linearly combining the stresses under two unit bending strains. Then, the six stress solutions corresponding to six generalized unit beam strains are combined together to predict the structural microscopic stresses, in which the six stress solutions serve as basic stresses. The last step is to determine the coefficients of these six basic stress solutions by the principle of the internal work equivalence. It is found that the six coefficients, in terms of the product of the inverse of the effective stiffness matrix and the macroscopic internal force column vector, are the actual generalized strains of the equivalent beam under real loads. The obtained coefficients are physically reasonable because the basic stress solutions are produced by the generalized unit strains. Several numerical examples show that the present method, combining the solutions of the microscopic unit cell problem with the solutions of the macroscopic equivalent beam problem, can accurately and effectively predict the microscopic stresses of whole composite beams. The present method is applicable to composite beams with arbitrary periodic microstructures and load conditions.
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PAVLOVA, I. P., and I. V. BELKINA. "PARAMETRIC RESEARCH OF RESTRAINED STRAINS AND STRESSES OF SELF-STRESSED FIBER-REINFORCED CONCRETE AT THE STAGE OF EXPANSION." Building and reconstruction 108, no. 4 (2023): 81–92. http://dx.doi.org/10.33979/2073-7416-2023-108-4-81-92.
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One of the main advantages of self-stressed concrete is its ability to compensate for one of the main disadvantages inherent in mineral binders – shrinkage strains. However, approaches to predicting the properties of self-stressed concrete are not universal, since they are based mainly on phenomenological approaches and empirical dependencies. The main approaches to predicting strains and stresses arising in expansive concrete are energy- and deformation approaches. A number of researchers confirm the effectiveness of applying the deformation approach to determine intrinsic strains and stresses. Modification of the model for determining its own stresses and strains made it possible to move from the case of uniaxial bar reinforcement to two- and three-axis-limited elements. Based on the provisions of the deformation approach, a deformation model was proposed to determine the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. The main prerequisites and assumptions of the proposed model are formulated. A block diagram of the algorithm of the iterative procedure is given, which makes it possible to calculate the intrinsic strains and stresses of self-stressed fiber-reinforced concrete. Parametric studies of self-strains and stresses of self-stressed fiber-reinforced concrete at the stage of expansion were carried out. The normalized dependences of the bounded strains on the varied parameters are presented. The area of effective use of steel fibers to achieve "binding" effect of free expansion in self-stressed concrete of different energy-activity has been determined. Influence of change of introduced fiber amount on development of bound strains of self-stressed concrete at different time intervals has been determined. The obtained results can be used in design, educational and research institutions.
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BONIFAZ, E. A., and N. L. RICHARDS. "STRESS–STRAIN EVOLUTION IN CAST IN-738 SUPERALLOY SINGLE FUSION WELDS." International Journal of Applied Mechanics 02, no. 04 (2010): 807–26. http://dx.doi.org/10.1142/s1758825110000767.
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A three-dimensional finite element elastic–plastic model was developed to study localized plastic strains and residual stresses that exist in a body that has previously been subjected to nonuniform temperature changes. The mechanical model was used to compute the evolution of plastic strains and residual stresses of welded material. The thermal gradient histories calculated during the GTA welding of cast IN-738LC alloys were imposed as load conditions on structural calculations. It can be clearly seen that at constant heat input, the level of plastic strains and the level of residual (Mises) stresses increase with welding speed. The model predicts highest residual stresses in regions of highest elastic strains, in agreement with conventional phenomenological material models where the macroscopic residual stress is always directly related to the macroscopic elastic strain. The highest residual stresses are located at the fusion line (where coarser dendrite secondary arm spacing exist); and the highest plastic strains are located at centerline (where finer dendrite secondary arm spacing exist). The calculations were performed using ABAQUS® FE code on the basis of a time-increment Lagrangian formulation.
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CHAUDHRY, H. R., B. BUKIET, T. FINDLEY, and A. B. RITTER. "STRESSES AND STRAINS IN THE PASSIVE LEFT VENTRICLE." Journal of Biological Systems 04, no. 04 (1996): 535–54. http://dx.doi.org/10.1142/s021833909600034x.
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In this paper, we estimate the stresses and strains from the equatorial region down to the apex of the heart by modeling the passive left ventricle as a frustrum of a thick hollow cone. Large deformation theory has been employed in this analysis. Furthermore, the effects of residual stresses and the anisotropy due to muscle fiber orientation have been included. It is observed that circumferential stress, which is the most important physiologically, decreases considerably at the endocardium and is more evenly distributed through the wall when residual stresses are taken into account. The stresses also decrease as we go from the equatorial region to the apex. Because heart muscles physically have residual stresses, the consequent lower stress gradient through the wall enhances the diastolic function of the left ventricle.
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Chang, Chia Lung, Yan Huo Kao, You Lung Jao, and Chih Laing Chang. "Residual Stress Measurements of Cylindrical Parts by Hole Drilling Strain Gage Method." Applied Mechanics and Materials 311 (February 2013): 462–66. http://dx.doi.org/10.4028/www.scientific.net/amm.311.462.
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Hole drilling strain gage method is a semi-destructive measurement. The method is most commonly used to measure residual stresses. The relieved strains are measured around the drilled hole, and the residual stresses are estimated by the mechanical relationship between relieved strains and residual stresses as well calibration coefficients. The calibration coefficients indicate the relieved strains due to unit stresses within the hole depth. Finite element method is always used to determine the calibration coefficients, and the analytical model is based on the infinite plate. But the geometrical shape and size of cylindrical part are different from the infinite plate. The relieved strains around the drilled hole are different too. Finite element model of the cylindrical part is constructed to obtain the hole drilling calibration coefficients. The measurement of residual stresses in a cylindrical part subject to axial loading calculated by calibration coefficients of both infinite plate and cylindrical part model are compared to show the difference.
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Safari, Maedeh, Shahrokh Shojaei, Pedram Tehrani, and Alireza Karimi. "A patient-specific finite element analysis of the anterior cruciate ligament under different flexion angles." Journal of Back and Musculoskeletal Rehabilitation 33, no. 5 (2020): 811–15. http://dx.doi.org/10.3233/bmr-191505.
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BACKGROUND: The main responsibility of the anterior cruciate ligament (ACL) is to restore normal knee kinematics and kinetics. Although so far different research has been carried out to measure or quantify the stresses and strains in the ACL experimentally or numerically, there is still a paucity of knowledge in this regard under different flexion angles of the tibiofemoral knee joint. OBJECTIVE: Understanding the stresses and strains within the ACL under various loading and boundary conditions may have a key asset for the development of an optimal surgical treatment of ACL injury that can better restore normal knee function. This study aimed to calculate the stresses and strains within the ACL under different flexion angles using a patient-specific finite element (FE) model of the human tibiofemoral knee joint. METHODS: A patient-specific FE model of the human tibiofemoral knee joint was established using computed tomography/magnetic resonance imaging data to calculate the stresses and strains in the ACL under different flexion angles of 0, 10, 20, 30, and 45∘. RESULTS: Although the role of the flexion angle in the induced stresses and strains of the ACL was insignificant, the highest stress and strain were observed at the flexion angle of 0∘. The concentration of the stresses and strains regardless of the flexion angles were also located at the proximal end of the ACL, where the clinical reports indicated that most ACL tearing occurs there at the femoral insertion site. CONCLUSIONS: The results have implications not only for understanding the stresses and strains within the ACL under different flexion angles, but also for providing preliminary data for the biomechanical and medical experts in regard of the injuries which may occur to the ACL at relatively higher flexion angles.
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Zhang, Min, and Xitian Tian. "Residual stresses and strains analysis in press-braking bending parts considering multi-step forming effect." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 234, no. 4 (2019): 788–800. http://dx.doi.org/10.1177/0954405419883053.
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Press-braking bending is a multi-step bending process and widely applied in the aerospace industry. Residual stresses and strains generated during the forming process play an important role in determining its forming parameters and bending path. This work aims to analyze the residual stresses and strains in press-braking bending parts using both the theoretical method and numerical method. First, the analytical model of residual stress and strain is established based on the elastic–plastic bending theory. Second, a fully finite element model of press-braking bending has been developed, and a procedure to simulate the multi-step bending process is presented by using the elastic–plastic large deformation finite element method. The simulation results are then compared with three-point bending experiments in terms of forming force and final shapes of the bent specimens, and excellent agreement is achieved. Finally, the results calculated from the analytical model are compared with the numerical results. The distributions of residual stresses and strains on the finished plate along the length and thickness direction, and particularly the multi-step forming effect on residual stresses and strains, are discussed. It is found that the residual stresses and strains decrease at the initial loading position along the thickness direction during the forming process of subsequent loading positions. With the same punch displacement, the residual stresses and strains at the initial loading position are less than those at the subsequent bending position.
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Al Ali, Mohamad, Michal Tomko, and Ivo Demjan. "Development of Plastic Zones during the Thermal Cycle of Welding." Key Engineering Materials 586 (September 2013): 11–14. http://dx.doi.org/10.4028/www.scientific.net/kem.586.11.
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The high temperatures induced during the welding process cause transient thermal stresses and non-continuous plastic strains around the weld. Uneven heating and cooling processes together with these plastic strains result in residual (welding) stresses, [1]. This paper deals with the development of plastic zones, related to welding stresses and their effects on the bearing capacity from a Civil-engineering perspective.
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Johnson, A. R., T. Chen, and J. L. Mead. "Modeling Step—Strain Relaxation and Cyclic Deformations of Elastomers." Rubber Chemistry and Technology 75, no. 2 (2002): 333–45. http://dx.doi.org/10.5254/1.3544982.
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Abstract Data for step—strain relaxation and cyclic compressive deformations of highly viscous short elastomer cylinders are modeled using a large strain rubber viscoelastic constitutive theory with a rate—independent friction stress term added. In the tests, both small and large amplitude cyclic compressive strains, in the range of 1% to 10%, were superimposed on steady state compressed strains, in the range of 5% to 20%, for frequencies of 1 and 10 Hz. The elastomer cylinders were conditioned prior to each test to soften them. The constants in the viscoelastic—friction constitutive theory are determined by employing a nonlinear least-squares method to fit the analytical stresses for a Maxwell model, which includes friction, to measured relaxation stresses obtained from a 20% step—strain compression test. The simulation of the relaxation data with the nonlinear model is successful at compressive strains of 5%, 10%, 15%, and 20%. Simulations of hysteresis stresses for enforced cyclic compressive strains of 20%±5% are made with the model calibrated by the relaxation data. The predicted hysteresis stresses are lower than the measured stresses.
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Kuo-Huang, Ling-Long, Yan-San Huang, Shin-Shin Chen, and Yi-Ru Huang. "GROWTH STRESSES AND RELATED ANATOMICAL CHARACTERISTICS IN COCONUT PALM TREES." IAWA Journal 25, no. 3 (2004): 297–310. http://dx.doi.org/10.1163/22941932-90000367.
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The surface growth strains and the distribution of internal stresses in woody palms, coconut (Cocos nucifera L.), were determined by measuring the strains released by the kerf method using strain gauges. Measurements of the surface strains showed that longitudinal tensile stresses existed at the cortex, while longitudinal compressive stresses existed at the periphery of the central cylinder. These stresses may be generated from the fibers located in the scattered fiber and vascular bundles. In the central cylinder of narrow and wide trunks, both positive and negative stresses were observed, indicating the existence of some tensile and compressive stresses in the trunks. The amount of stress varied from base to top and from periphery to core because of the variation in proportion of the vascular bundles and the fibers, and the cell wall layers of fibers along these points. Furthermore, changes in the angle of vascular bundles and of the fiber microfibrils were correlated with the various tensile and compressive stresses located in the central cylinder of the trunks.
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Lu, Yue Qing, and D. J. Laurie Kennedy. "Correction of residual strain for coupons that curve on sectioning." Canadian Journal of Civil Engineering 20, no. 4 (1993): 712–14. http://dx.doi.org/10.1139/l93-088.
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When coupons are cut from cross sections to determine the relaxation of residual strains by the method of sectioning, they frequently curve due to variations in the longitudinal residual stresses through the thickness. Relaxation strains measured on the chord will be in error. A method is presented to correct the errors using gauge holes drilled through the specimen to allow strains to be determined on both sides. Key words: correction, coupons, curve, residual, sectioning, strains, stresses.
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Li, Hong, and Hui Long Ren. "Welding Behavior Analysis of Stiffened Stainless Steel Structure." Key Engineering Materials 385-387 (July 2008): 413–16. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.413.
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Welding residual plastic strains and residual stresses are the product of complicated nonlinear behaviors of the structures during welding. The residual strains and stresses for stiffened stainless steel structure and welding fatigue analysis are studied in this paper. The three-dimensional transient temperature field is analyzed by FEM first. Doing the welding experiment for fundamental model is to verify the numerical results, the infrared thermograph is used to follow and record the whole process. The results of FEM are supported by experimental data. Then, the elastic-plastic-model is established to analyze the residual strains and stresses. Based on the stresses, loading and fatigue factors, according to Miner fatigue damage law, some fatigue behaviors such as fatigue life and remaining life are obtained.
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Shoykhet, B., M. A. Grinfeld, and P. M. Hazzledine. "Internal stresses and strains in coherent multilayers." Acta Materialia 46, no. 11 (1998): 3761–66. http://dx.doi.org/10.1016/s1359-6454(97)00244-9.
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Laforte, Caroline, and Jean-Louis Laforte. "Deicing Strains and Stresses of Iced Substrates." Journal of Adhesion Science and Technology 26, no. 4-5 (2012): 603–20. http://dx.doi.org/10.1163/016942411x574790.
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Chen, Youping, James Lee, and Liming Xiong. "Stresses and strains at nano/micro scales." Journal of Mechanics of Materials and Structures 1, no. 4 (2006): 705–23. http://dx.doi.org/10.2140/jomms.2006.1.705.
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Korsunsky, A. M. "Eigenstrain analysis of residual strains and stresses." Journal of Strain Analysis for Engineering Design 44, no. 1 (2008): 29–43. http://dx.doi.org/10.1243/03093247jsa423.
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Kaempf, Bernd. "Stresses and strains in two-phase materials." Computational Materials Science 5, no. 1-3 (1996): 151–56. http://dx.doi.org/10.1016/0927-0256(95)00066-6.
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VOGLER, FALKO, and PETER GROCHE. "CRITERIA FOR TOOL DESIGN IN HYDROFORMING." Journal of Advanced Manufacturing Systems 07, no. 01 (2008): 171–74. http://dx.doi.org/10.1142/s0219686708001309.
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Closing forces and internal pressure lead to stresses and strains in hydroforming dies. The deflection of the die influences the accuracy of the hydroformed products. The influence of the die geometry on stresses and strains in the die is being examined fundamentally. Additionally, the location of the closing force transmission is discovered to be crucial. The objectives of this research were to determine the demands on the hydroforming die and to reduce failure-critical stresses.
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Bobarikin, Yu L., and Yu V. Martyanov. "Research of the influence of highcarbon steel wire drawing speed on stresses and deformations on wire cross section." Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), no. 1 (April 10, 2019): 73–77. http://dx.doi.org/10.21122/1683-6065-2019-1-73-77.
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The parameters of wire production affecting the distribution of residual stresses and strains on the wire cross section are considered. It is determined that the modes of coarse drawing can affect the complex of mechanical properties of thin wire due to the uneven distribution of equivalent stresses and strains. The rough drawing speed is chosen as the investigated parameter.The effect of the coarse drawing rate of high-carbon steel wire on the distribution of equivalent residual stresses and strains over the wire cross section is studied by numerical simulation of wire drawing at different speeds by the finite element method. The values of equivalent residual stresses for the selected drawing route along the wire cross-section zones are determined. The analysis of the equivalent stress distribution over the wire cross section is made.It is shown that the increase in the speed of coarse drawing increases the uniformity of the distribution of equivalent residual stresses, does not have a negative effect on the deformed state of the wire, increases the absolute values of equivalent residual stresses, slightly reduces the absolute values of residual deformations.
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Ogawa, Masaru. "Proposal of an Eigen-Strain Estimation for Determination of Residual Stresses Considering the Influence of Machining." Advanced Materials Research 891-892 (March 2014): 1225–30. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1225.
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In order to assure structural integrity for mechanical structures, it is indispensable to estimate three-dimensional residual stresses quantitatively to asses a crack growth rate of an observed crack. Now, the neutron diffraction method and the DHD (Deep Hole Drilling) method have been proposed to evaluate stress gradient in the thickness direction. However, estimated stresses by these methods can not be input to the FEM (Finite Element Method) model that has been widely used at design time for the assessment of the structural integrity. Then, the eigen-strain method has been proposed. In this method, three-dimensional residual stresses are calculated by an elastic FEM analysis from eigen-strains those can be evaluated quantitatively by an inverse analysis from released strains measured by strain gauges while the geometric boundary condition or material properties of the object has been changed. However, inelastic strains are newly created on the machined surface, the estimation accuracy of this method becomes relatively poor because the eigen-strains before and after measurements have to be the same. In this study, a calculation technique to evaluate not only initial eigen-strains but also processing strains is shown, and effectiveness of this method is demonstrated numerically in the bead flush method based on the eigen-strain method. Although estimation accuracy of processing strains was poorer, three-dimensional residual stresses for whole region could be evaluated accurately from measured strains without measurement errors.
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Gu, Randy J., and Yung-Li Lee. "A New Method for Estimating Nonproportional Notch-Root Stresses and Strains." Journal of Engineering Materials and Technology 119, no. 1 (1997): 40–45. http://dx.doi.org/10.1115/1.2805971.
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This paper presents a generalized two-step endochronic approach for estimating notch stresses and strains based on elastic stress solutions. In the first stress-controlled step, notch root strains are calculated from elastic stresses using a conventional uniaxial method, such as Glinka’s energy density method and Neuber’s rule. In the second strain-controlled step notch root stresses corresponding to the estimated local strains are calculated from the given material properties. Both stress-controlled and strain-controlled algorithms based on endochronic plasticity theory are presented herein. The proposed method is used to calculate multiaxial strains under monotonie and nonproportional loads. Various geometric constraints (plane stress, plane strain, and intermediate level) are also examined. The results are compared with experimental measurements by other researchers and with predictions from other models.
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Gurevich, L. M., V. F. Danenko, A. A. Istrati, and V. A. Sonnova. "MODELING THE WORK OF THE HEAD OF A HYDROMECHANICAL EXPANDER FOR WELDED PIPES OF A LARGE DIAMETER." IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, no. 4(239) (April 22, 2020): 35–42. http://dx.doi.org/10.35211/1990-5297-2020-4-239-35-42.
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Finite element simulates of changing stresses and strains under loading by gradually increasing internal pressure of cylindrical welded vessels was carried out. The vessels had an annular mechanically inhomogeneous welded joint with different mechanical properties of the joint, heat-affected zone, and base metal. Maximum stresses developed in the caps of the vessels, and the annular joint are lightly loaded. The distribution of stresses and strains in joint at various design parameters of the vessels is investigated.