Dissertations / Theses: 'Stiffened plates'

1

Sheikh, Imtiaz Ali. "Stiffener tripping in stiffened steel plates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ60496.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Bellur, Ramaswamy Ravi Shankar. "Optimal design of stiffened plates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0017/MQ45871.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Hildrum, Hilde Giæver. "Stiffened Aluminium Plates Subjected to Impact Loading." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-130.

Full text

Abstract:

An experimental investigation has been carried out to study the behaviour of stiffened aluminium plates subjected to large mass (55 kg) projectiles in the low velocity regime. The stiffened aluminium plates were fabricated from aluminium alloy AA6082 temper T6 extrusions MIG-welded together to form flat stiffened plates. The study was made on the variation of failure mode and the energy-absorbing capacity with various combinations of projectile nose shape (blunt and hemispherical) and load application point (between two stiffeners, on a stiffener and next to a stiffener).

The estimated incipient fracture velocity (giving cracks in the target) was significant less for the hemispherical ended nose than the blunt ended nose. The impact between the stiffeners gave lowest incipient fracture velocity followed by impact next to the stiffener and impact on a stiffener in that order. The estimated ballistic limit velocity was almost equal for impact between two stiffeners using both nose shapes and for impact next to a stiffener with the blunt ended projectile. The hemispherical ended projectile impacting next to a stiffener lead to significant higher ballistic limit.

The observed differences in the ballistic limit velocity and incipient fracture velocity were mainly attributed to the change in failure mode (and energy absorption). The blunt projectile caused failure by plugging, while petaling fracture modes were observed for impact with a hemispherical ended projectile.

In addition to impact tests, static punch tests were carries out to study any possible relationships between the dynamic and quasi-static capacity before fracture occurs. In the studied velocity range and for the blunt ended projectile, it seems that the static tests may give a conservative estimate of the incipient fracture impact energy. For the hemispherical ended projectile this method may lead to non-conservative results.

A metallurgical examination of cross sections of the target at the impact point was carried out to reveal details of internal changes of configuration such as deformations and changes of microstructure, and the generation of fractures. The fracture was initiated on the rear side impacting next to a stiffener or between the stiffeners (on the weld) with both nose shapes. Ductile fracture was observed in all test specimens except for fracture in the welds. No evidence of temperature effects and no pronounced shear localisation through the thickness of the plate where seen.

Numerical simulation of perforation of a stiffened plate impacted with a hemispherical ended projectile between two stiffeners (on the weld) has been performed using the non-linear finite element code LS-DYNA. Inverse modelling of tensile test specimens was performed to identify the material parameters. The weld and heat affected were modelled with reduced strength compared to the parent material. The main objective with these numerical simulations was to study whether the Lemaitre damage material model could predict the response of the impacted plate when taking failure into account. The numerical simulation described the maximum force quite well. Furthermore, the model predicts the instability phenomenon and fracture process as observed in the experiments reasonably well.

APA, Harvard, Vancouver, ISO, and other styles

4

Lim, B. S. "Buckling behaviour of asymmetric edge stiffened plates." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371363.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Farsi, Maryam. "Localized and cellular buckling in stiffened plates." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24998.

Full text

Abstract:

Nonlinear buckling behaviour of a thin-walled simply-supported stiffened panel that has uniformly spaced longitudinal stiffeners is studied. The structure is made from a linear elastic, isotropic and homogeneous material. The panel is subjected to pure compression applied at the centroid of whole cross-section. In such structures, the nonlinear interaction can occur between a global (Euler) buckling and local plate ( i.e. the stiffener or the main plate) buckling modes. The interactive buckling behaviour is usually more unstable than when the modes are triggered individually. This can lead to a significant reduction of the load-carrying capacity. The current work focuses on the case where the stiffening is only on one side of the main plate. An analytical model of a perfect thin-walled stiffened plate is formulated based on variational principles by minimizing the total potential energy. The equations of equilibrium are then solved numerically using the continuation and bifurcation software Auto to determine the post-buckling behaviour. Cellular buckling (or snaking) is revealed analytically in such a component arising from nonlinear local global interactive buckling, perhaps for the first time. In addition, the effect of varying the rigidity at the main plate -stiffener junction is studied; a rapid erosion of the cellular buckling response is revealed by increasing the joint rigidity. The initial model is then developed by including more degrees of freedom within the stiffened panel and the introduction of global and local imperfections. The results from the analytical model are validated by the finite element (FE) method using the commercial software Abaqus as well as by comparing against some experimental results taken from the literature. To obtain a greater understanding of the drivers of the structural behaviour, parametric studies are conducted for a variety of different plate and stiffener geometries as well as an investigation into the heightened sensitivity to geometric imperfections. The worst forms of local imperfection are identified in terms of the initial amplitude, number of waves and the degree of localization. The imperfection sensitivity and the parametric studies are conducted for two limiting cases, where the main plate- stiffener joint is assumed to be fully pinned or fully rigid. A framework for establishing the zone where structural designers need to consider mode interaction carefully is presented.

APA, Harvard, Vancouver, ISO, and other styles

6

Afifi, Amal Afifi Mohamed. "Buckling of stiffened pultruded GRP plates and columns." Thesis, Lancaster University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497222.

Full text

Abstract:

The research work presented in this thesis is focused or investigating the buckling behaviour of wide range pultruded structural GRP profiles. Investigations of both global and local buckling of GRP profiles have been carried out to determine the buckling capacities. An investigation on improving the buckling capacity of plates and columns was carried out. The program of research undertaken to enhance column buckling capacity included analytical and finite element modelling of the buckling of GRP plates and columns and experimental work on the buckling of GRP columns.

APA, Harvard, Vancouver, ISO, and other styles

7

Bardell, N. S. "Wave propagation in periodically stiffened plates and shells." Thesis, University of Southampton, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256281.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Dwire, Heather B. "RISK BASED ANALYSIS AND DESIGN OF STIFFENED PLATES." Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1208453129.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Ozdamar, Huseyin Hasan. "A Stiffened Dkt Shell Element." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/2/12605741/index.pdf.

Full text

Abstract:

A stiffened DKT shell element is formulated for the linear static analysis of stiffened plates and shells. Three-noded triangular shell elements and two-noded beam elements with 18 and 12 degrees of freedom are used respectively in the formulation. The stiffeners follow the nodal lines of the shell element. Eccentricity of the stiffener is taken into account. The dynamic and stability characteristic of the element is also investigated. With the developed computer program, the results obtained by the proposed element agrees fairly well with the existing literature.

APA, Harvard, Vancouver, ISO, and other styles

10

Sawicki, Adam John. "Damage tolerance of integrally stiffened composite plates and cylinders." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13615.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Salomon, Ami 1972. "An evaluation of finite element models of stiffened plates." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91329.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Yaman, Yavuz. "Wave receptance analysis of vibrating beams and stiffened plates." Thesis, University of Southampton, 1989. https://eprints.soton.ac.uk/425888/.

Full text

Abstract:

This study develops analytical methods for the analysis of harmonically forced vibrations of multi-supported beams and stiffened plates. The methods are based on the response of infinite, uninterrupted structures to a single external excitation from which families of waves propagate outwards in all directions. The structures considered are uniform in thickness. The beams have a single-point force. The plates are finite in width with the two opposite parallel edges being simply-supported along the length. A line forcing varies sinusoidally between those edges. The first part of the thesis analyses the dynamics of infinite, uninterrupted structures. Special attention is subsequently paid to three-layered sandwich structures and their dispersion characteristics are also investigated. The second part considers finite structures. An analytical approach is presented for single-bay and multi-bay structures with arbitrary support spacing. Influences of support elastic/inertial characteristics are investigated in detail. Effects of end reflections are fully dealt with. The third part deals with the free and forced vibrations of infinite, periodic structures. Particular attention is focused on the effects of stiffness characteristics and cross-sectional distortion of the stiffeners. Part four outlines experimental work undertaken to validate the above theories. The experimental and theoretical results are compared.

APA, Harvard, Vancouver, ISO, and other styles

13

Ahmad, Naveed. "Passive Damping in Stiffened Structures Using Viscoelastic Polymers." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/79566.

Full text

Abstract:

Noise and vibration suppression is an important aspect in the design process of structures and machines. Undesirable vibrations can cause fatigue in a structure and are, therefore, a risk to the safety of a structure. One of the most effective and widely used methods of mitigating these unwanted vibrations from a system is passive damping, by using a viscoelastic material. This dissertation will primarily focus on constrained layer passive damping treatments in structures and the investigation of associated complex modes. The key idea behind constrained damping treatment is to increase damping as affected by the presence of a highly damped core layer vibrating mainly in shear. Our main goal was to incorporate viscoelastic material in a thick stiffened panel with plate-strip stiffeners, to enhance the damping characteristics of the structure. First, we investigated complex damped modes in beams in the presence of a viscoelastic layer sandwiched between two elastic layers. The problem was solved using two approaches, (1) Rayleigh beam theory and analyzed using the principle of virtual work, and (2) by using 2D plane stress elasticity based finite-element method. The damping in the viscoelastic material was modeled using the complex modulus approach. We used FEM without any kinematic assumptions for the transverse shear in both the core and elastic layers. Moreover, numerical examples were studied, by including complex modulus in the base and constraining layers. The loss factor was calculated by modal strain energy method, and by solving a complex eigenvalue problem. The efficiency of the modal strain energy method was tested for different loss factors in the core layer. Complex mode shapes of the beam were also examined in the study, and a comparison was made between viscoelastically damped and non-proportionally damped structures. Secondly, we studied the free vibration response of an integrally stiffened and/or stepped plate. The stiffeners used here were plate-strip stiffeners, unlike the rib stiffeners often investigated by researchers. Both plate and stiffeners were analyzed using the first-order shear deformation theory. The deflections and rotations were assumed as a product of Timoshenko beam functions, chosen appropriately according to the given boundary conditions. Unlike Navier and Levy solution techniques, the approach used here can also be applied to fully clamped, free and cantilever supported stiffened plates. The governing differential equations were solved using the Rayleigh-Ritz method. The development of the stiffness and the mass matrices in the Ritz analysis was found to consume a huge amount of CPU time due to the recursive integration of Timoshenko beam functions. An approach is suggested to greatly decrease this amount of CPU time, by replacing the recursive integration in a loop structure in the computer program, with the analytical integration of the integrand in the loop. The numerical results were compared with the exact solutions available in the literature and the commercially available finite-element software ABAQUS. Some parametric studies were carried out to show the influence of certain important parameters on the overall natural frequencies of the stiffened plate. Finally, we investigated the damped response of an adhesively bonded plate employing plate-strip stiffeners, using FSDT for both the plate and stiffeners. The problem was analyzed using the principle of virtual work. At first, we did not consider damping in the adhesive in order to validate our code, by comparing our results with those available in the literature as well as with the results obtained using ABAQUS 3D model. The results were found to be highly satisfactory. We also considered the effect of changing the stiffness of the adhesive layer on the vibration of the bonded system. As a second step, we included damping in the stiffened structure using complex modulus approach, a widely used technique to represent the rheology of the viscoelastic material. We observed an overall increase in the natural frequencies of the system, due to the damping provided by the viscoelastic material. Moreover, it was noticed that when the thickness of the adhesive layer is increased, the natural frequencies and loss factor of the stiffened structure decrease. A viscoelastic material with high loss factor and small thickness will be a perfect design variable to obtain overall high damping in the structure.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

14

Lumpp, Dirk Manfred. "An experimental investigation of circular plates, beams and stiffened circular plates subjected to impulsive loading." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/9658.

Full text

Abstract:

Bibliography: leaves 94-96.
This primarily experimental investigation describes a series of experiments on fully-clamped circular plates, rectangular beams and stiffened circular plates. These test specimens were subjected to a uniformly distributed impulse. The impulse was provided by plastic explosive. This was arranged in such a way that a uniformly distributed impulse was imparted to the test specimens. The impulse was measured by means of a ballistic pendulum to which the test specimens were attached. The final mid-point deflections of the plates and beams were measured. The plate and beam results were compared to previous experimental work. A non-dimensional number for plates was modified to include an experimental mass scaling factor due to the ballistic pendulum mass. A non-dimensional number for rectangular beams was developed, including a similar experimental mass scaling factor. Comparing the beam and plate results from this study with those of previous work, using the respective non-dimensional numbers, showed good correlation. The results for the stiffened plates are compared with the plate results.

APA, Harvard, Vancouver, ISO, and other styles

15

Yuen, Steeve Chung Kim. "Deformation and tearing of uniformly blast-loaded quadrangular stiffened plates." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/14952.

Full text

Abstract:

Includes bibliographical references (leaves 131-134).
An investigation into the deformation and tearing of stiffened quadrangular plates subjected to a uniform blast load is presented. A series of experimental results and numerical modelling using the finite element package; ABAQUS, on built-in quadrangular mild steel plates of different stiffener configurations and sizes subjected to a uniform blast load are reported. The main objectives of this investigation are to determine the dynamic response of stiffened quadrangular plates subjected to uniform blast loads, to assess the effect of the stiffener configuration and size on plate failure and to use a new approach that uses material properties that include temperature dependency to model the plate response. The experimental procedure consists of creating an impulsive load with the use of plastic explosive and measuring the resulting impulse using a ballistic pendulum. Explosive is centrally laid out in two concentric rectangular annuli on quadrangular plates of thickness 1.6mm with stiffeners of sizes; 3x3mm, 3x7mm, 4x3mm and 4x7mm; and configurations; none, single, double, cross and double cross; to provide the impulse required to give deformations up to plate tearing. In all the tests of Mode I category of large inelastic deformation, the plate profiles are characterised by a uniform global dome. The results of mid-point deflection versus impulse for the various stiffener sizes and configurations for Mode I show a generally linear relationship. In all the experiments, thinning mechanisms at the boundary are observed for all plates despite different stiffener sizes and configurations. Thinning, however, is not consistent all around the boundary. Thinning is also observed at the stiffener side closest to the boundary for double and double cross stiffened plates. There is, furthermore, a reduction in the stiffener width where two stiffeners cross each other perpendicularly.

APA, Harvard, Vancouver, ISO, and other styles

16

Schubak, Robert Brian. "Nonlinear rigid-plastic analysis of stiffened plates under blast loads." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/31482.

Full text

Abstract:

The large ductile deformation response of stiffened plates subjected to blast loads is investigated and simplified methods of analysis of such response are developed. Simplification is derived from modelling stiffened plates as singly symmetric beams or as grillages thereof. These beams are further assumed to behave in a rigid, perfectly plastic manner and to have piecewise linear bending moment-axial force capacity interaction relations, otherwise known as yield curves. A blast loaded, one-way stiffened plate is modelled as a singly symmetric beam comprised of one stiffener and its tributary plating, and subjected to a uniformly distributed line load. For a stiffened plate having edges fully restrained against rotations and translations, both transverse and in-plane, use of the piecewise linear yield curve divides the response of the beam model into two distinct phases: an initial small displacement phase wherein the beam responds as a plastic hinge mechanism, and a final large displacement phase wherein the beam responds as a plastic string. If the line load is restricted to be a blast-type pulse, such response is governed by linear differential equations and so may be solved in closed form. Examples of a one-way stiffened plate subjected to various blast-type pulses demonstrate good agreement between the present rigid-plastic formulation and elastic-plastic beam finite element and finite strip solutions. The response of a one-way stiffened plate is alternatively analysed by approximating it as a sequence of instantaneous mode responses. An instantaneous mode is analogous to a normal mode of linear vibration, but because of system nonlinearity exists for only the instant and deformed configuration considered. The instantaneous mode shapes are determined by an extremum principle which maximizes the rate of change of the stiffened plate's kinetic energy. This approximate rigid-plastic response is not solved in closed form but rather by a semi-analytical time-stepping algorithm. Instantaneous mode solutions compare very well with the closed-form results. The instantaneous mode analysis is extended to the case of two-way stiffened plates, which are modelled by grillages of singly symmetric beams. For two examples of blast loaded two-way stiffened plates, instantaneous mode solutions are compared to results from super finite element analyses. In one of these examples the comparison between analyses is extremely good; in the other, although the magnitudes of displacement response differ between the analyses, the predicted durations and mechanisms of response are in agreement. Incomplete fixity of a stiffened plate's edges is accounted for in the beam and grillage models by way of rigid-plastic links connecting the beams to their rigid supports. Like the beams, these links are assumed to have piecewise linear yield curves, but with reduced bending moment and axial force capacities. The instantaneous mode solution is modified accordingly, and its results again compare well with those of beam finite element analyses. Modifications to the closed-form and instantaneous mode solutions to account for strain rate sensitivity of the panel material are presented. In the closed-form solution, such modification takes the form of an effective dynamic yield stress to be used throughout the rigid-plastic analysis. In the time-stepping instantaneous mode solution, a dynamic yield stress is calculated at each time step and used within that time step only. With these modifications in place, the responses of rate-sensitive one-way stiffened plates predicted by the present analyses once again compare well with finite element and finite strip solutions.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

17

Attaf, Brahim. "Vibration and stability analyses of unstiffened and stiffened composite plates." Thesis, University of Surrey, 1990. http://epubs.surrey.ac.uk/842974/.

Full text

Abstract:

Vibration and stability studies have been undertaken on glass fibre reinforced polymer composite unstiffened and stiffened plates to optimise their dynamic properties. Boundary conditions, stiffeners and orthotropy of the material add to the complexity of a mathematical solution and to overcome this problem experimental and analytical studies were undertaken. The former method was carried out by impact hammer and an FFT digital signal analyser and the latter method was undertaken using finite element computer software. The current research concentrated upon the procedures and possible techniques available to optimise the dynamic properties of the plate without introducing weight penalty with the object of achieving an efficient structural performance coupled with an economic design. It has been shown that most of the increase in frequency and critical buckling load was directly related to the increase in stiffness of the stiffener and its position on the plate structure. The mode shapes have provided information regarding the most advantageous position for the setting of the stiffeners; they must be positioned away from nodal lines. The effect of the stiffener was significant for the fully clamped and clamped/free plates where only bending modes of vibration are present. However, for the completely free plates, where both bending and torsional modes of vibration could occur, the effect that the stiffeners have on the torsional modes was minimal. To locate precisely the position of the stiffener may be difficult when the plates are subjected to in-plane compressive loads, because higher order mode shapes may interchange. The mass-saving advantage which has been obtained in this research has shown that the stiffened plates with top-hat stiffeners were seen to have higher natural frequencies, within a specific vibration mode, compared to stiffened plates with rectangular stiffeners (blade).

APA, Harvard, Vancouver, ISO, and other styles

18

Kassegne, Samuel Kinde. "Layerwise theory for discretely stiffened laminated cylindrical shells." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07282008-134249/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Koko, Tamunoiyala Stanley. "Super finite elements for nonlinear static and dynamic analysis of stiffened plate structures." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30723.

Full text

Abstract:

The analysis of stiffened plate structures subject to complex loads such as air-blast pressure waves from external or internal explosions, water waves, collisions or simply large static loads is still considered a difficult task. The associated response is highly nonlinear and although it can be solved with currently available commercial finite element programs, the modelling requires many elements with a huge amount of input data and very expensive computer runs. Hence this type of analysis is impractical at the preliminary design stage. The present work is aimed at improving this situation by introducing a new philosophy. That is, a new formulation is developed which is capable of representing the overall response of the complete structure with reasonable accuracy but with a sacrifice in local detailed accuracy. The resulting modelling is relatively simple thereby requiring much reduced data input and run times. It now becomes feasible to carry out design oriented response analyses. Based on the above philosophy, new plate and stiffener beam finite elements are developed for the nonlinear static and dynamic analysis of stiffened plate structures. The elements are specially designed to contain all the basic modes of deformation response which occur in stiffened plates and are called super finite elements since only one plate element per bay or one beam element per span is needed to achieve engineering design level accuracy at minimum cost. Rectangular plate elements are used so that orthogonally stiffened plates can be modelled. The von Karman large deflection theory is used to model the nonlinear geometric behaviour. Material nonlinearities are modelled by von Mises yield criterion and associated flow rule using a bi-linear stress-strain law. The finite element equations are derived using the virtual work principle and the matrix quantities are evaluated by Gauss quadrature. Temporal integration is carried out using the Newmark-β method with Newton-Raphson iteration for the nonlinear equations at each time step. A computer code has been written to implement the theory and this has been applied to the static, vibration and transient analysis of unstiffened plates, beams and plates stiffened in one or two orthogonal directions. Good approximations have been obtained for both linear and nonlinear problems with only one element representations for each plate bay or beam span with significant savings in computing time and costs. The displacement and stress responses obtained from the present analysis compare well with experimental, analytical or other numerical results.
Applied Science, Faculty of
Civil Engineering, Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

20

Hsu, Sin Sin. "Response of stiffened and unstiffened mild steel plates to blast loading." Thesis, University of Liverpool, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399140.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Jhita, P. S. "The stability and post-buckling behaviour of stiffened plates in compression." Thesis, Cranfield University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276166.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Phillips, John L. "Structural analysis and optimum design of geodesically stiffened composite panels." Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-03122009-040802/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Young, Andrew J. "Active control of vibration in stiffened structures." Title page, contents and abstract only, 1995. http://hdl.handle.net/2440/37722.

Full text

Abstract:

Active control of vibration in structures has been investigated by an increasing number of researchers in recent years. There has been a great deal of theoretical work and some experiment examining the use of point forces for vibration control, and more recently, the use of thin piezoelectric crystals laminated to the surfaces of structures. However, control by point forces is impractical, requiring large reaction masses, and the forces generated by laminated piezoelectric crystals are not sufficient to control vibration in large and heavy structures. The control of flexural vibrations in stiffened structures using piezoceramic stack actuators placed between stiffener flanges and the structure is examined theoretically and experimentally in this thesis. Used in this way, piezoceramic actuators are capable of developing much higher forces than laminated piezoelectric crystals, and no reaction mass is required. This thesis aims to show the feasibility of active vibration control using piezoceramic actuators and angle stiffeners in a variety of fundamental structures. The work is divided into three parts. In the first, the simple case of a single actuator used to control vibration in a beam is examined. In the second, vibration in stiffened plates is controlled using multiple actuators, and in the third, the control of vibration in a ring-stiffened cylinder is investigated. In each section, the classical equations of motion are used to develop theoretical models describing the vibration of the structures with and without active vibration control. The effects of the angle stiffener(s) are included in the analysis. The models are used to establish the quantitative effects of variation in frequency, the location of control source(s) and the location of the error sensor(s) on the achievable attenuation and the control forces required for optimal control. Comparison is also made between the results for the cases with multiple control sources driven by the same signal and with multiple independently driven control sources. Both finite and semi-finite structures are examined to enable comparison between the results for travelling waves and standing waves in each of the three structure types. This thesis attempts to provide physical explanations for all the observed variations in achievable attenuation and control force(s) with varied frequency, control source location and error sensor location. The analysis of the simpler cases aids in interpreting the results for the more complicated cases. Experimental results are given to demonstrate the accuracy of the theoretical models in each section. Trials are performed on a stiffened beam with a single control source and a single error sensor, a stiffened plate with three control sources and a line of error sensors and a ring-stiffened cylinder with six control sources and a ring of error sensors. The experimental results are compared with theory for each structure for the two cases with and without active vibration control.
Thesis (Ph.D.)--Mechanical Engineering, 1995.

APA, Harvard, Vancouver, ISO, and other styles

24

Achenbach, Mark R. "Design optimization of blade stiffened laminated composite plates for maximum buckling load." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA241651.

Full text

Abstract:

Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Shin, Phillip Y. "December 1990." Description based on title screen as viewed on March 28, 2010. DTIC Descriptor(s): Thickness, optimization, layers, laminates, finite element analysis, height, stiffening, orientation(direction), blades, solutions(general), buckling, equations, fibers, loads(forces) DTIC Identifier(s): Design optimization, laminates, blade stiffened plate, buckling Author(s) subject terms: Design optimization, blade stiffened plate, buckling Includes bibliographical references (p. 81-84). Also available in print.

APA, Harvard, Vancouver, ISO, and other styles

25

Bajaj, Srikanth. "EVALUATION OF RESIDUAL STRENGTH OF CORRODED STRUCTURAL STEEL PLATES AND STIFFENED PANELS." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1543570329693244.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Wilmer, Archie. "Analytic expression of the buckling loads for stiffened plates with bulb-flat flanges." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FWilmer%5FPhD.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Pedatzur, Omri. "An evaluation of finite element models of stiffened plates subjected to impulsive loading." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/33436.

Full text

Abstract:

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2004.
Includes bibliographical references (leaves 88-89).
Different finite element models are evaluated for two very common structures, a cantilever beam and a stiffened plate, subjected to impulsive loading. For the cantilever beam case, the finite element models are one, two or three dimensional models. Various results from the finite element analyses are compared including with analytical solution and a closed-form approximate solution. For the stiffened plate, the models differ from each other by the way the plate and the stiffeners are modeled. Some of the models are very accurate but require much computational resource, while other models are considerably more economic. The purpose of this study was to decide which model is most appropriate for analyzing a ship deck under slamming conditions. The plate modeled with 4-node shell elements and the stiffeners modeled with 2- node iso-beam elements are shown to yield excellent results while requiring reasonable computational resources. In addition to the evaluation of the finite element models, the thesis presents closed- form approximate solutions for both the cantilever beam and the stiffened panel.
(cont.) These simplified solutions can be used to check and validate finite element analyses of similar structures. Furthermore, the analytical solutions can be very useful in understanding the basic physical behavior and the main parameters governing the dynamic response of these structures.
by Omri Pedatzur.
S.M.

APA, Harvard, Vancouver, ISO, and other styles

28

Stanway, Graeme Scott. "The behaviour and design of transversely stiffened plates subject to in-plane shear forces." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46562.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Salehi, Manouchehr. "Elasto-plastic large deflection response of radially stiffened circular, sector and annular sector plates." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306022.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Cil, Kursad. "Free Flexural (or Bending) Vibrations Analysis Of Doubly Stiffened, Composite, Orthotropic And/or Isotropic Base Plates And Panels (in Aero-structural Systems)." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/2/1062256/index.pdf.

Full text

Abstract:

In this Thesis, the problem of the Free Vibrations Analysis of Doubly Stiffened Composite, Orthotropic and/or Isotropic, Base Plates or Panels (with Orthotropic Stiffening Plate Strips) is investigated. The composite plate or panel system is made of an Orthotropic and/or Isotropic Base Plate stiffened or reinforced by adhesively bonded Upper and Lower Orthotropic Stiffening Plate Strips. The plates are assumed to be the Mindlin Plates connected by relatively very thin adhesive layers. The general problem under study is considered in terms of three problems, namely Main PROBLEM I Main PROBLEM II and Main PROBLEM III. The theoretical formulation of the Main PROBLEMS is based on a First Order Shear Deformation Plate Theory (FSDPT) that is, in this case, the Mindlin Plate Theory. The entire composite system is assumed to have simple supports along the two opposite edges so that the Classical Levy'
s Solutions can be applied in that direction. Thus, the transverse shear deformations and the rotary moments of inertia of plates are included in the formulation. The very thin, yet elastic deformable adhesive layers are considered as continua with transverse normal and shear stresses. The damping effects in the plates and the adhesive layers are neglected. The sets of the systems of equations of the Mindlin Plate Theory are reduced to a set of the Governing System of First Order Ordinary Differential Equations in the state vector form. The sets of the Governing System for each Main PROBLEM constitute a Two-Point Boundary Value Problem in the y-direction which is taken along the length of the plates. Then, the system is solved by the Modified Transfer Matrix Method (with Interpolation Polynomials and/or Chebyshev Polynomials)which is a relatively semi-analytical and numerical technique. The numerical results and important parametric studies of the natural modes and the corresponding frequencies of the composite system are presented.

APA, Harvard, Vancouver, ISO, and other styles

31

Petri, Steven Walter. "The response of line-stiffened fluid-loaded infinite elastic plates to convecting pressure fields." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14347.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Mesquita, Luis Clemente. "Structural optimization for control of stiffened laminated composite plates using nonlinear mixed integer programming." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/52309.

Full text

Abstract:

The effect of structural optimization on control of stiffened laminated composite structures is considered. The structural optimization considered here, is the maximization of structural frequencies of the structure subject to maximum weight and frequency separation constraints and an upper bound on weight. The number of plies with a given orientation and the stiffener areas form the two sets of design variables. As the number of plies is restricted to integer values, the optimization problem considered belongs to the class of nonlinear mixed integer problems (NMIP). Several efficiency measures are proposed to reduce the computational cost for solution of the optimization problem. Savings in computer time due to each of the measures is discussed. The control problem is solved using the independent modal space control technique. This technique greatly simplifies the evaluation of the sensitivity of the performance index with respect to the individual frequencies. The effect of different optimization schemes on the control performance is considered. To reduce the probability, that conclusions drawn from numerical results, are purely coincidental, a large number of cases has been studied. It has been concluded that sufficient improvement in control performance can be achieved through structural optimization.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

33

Sun, Liecheng. "ANALYTICAL STRIP METHOD TO ANTISYMMETRIC LAMINATED PLATES." UKnowledge, 2009. http://uknowledge.uky.edu/gradschool_diss/715.

Full text

Abstract:

An Analytical Strip Method (ASM) for the analysis of stiffened and non-stiffened antisymmetric laminated composite plates is derived by considering the bending-extension coupling effect for bending, free vibration and buckling. A system of three equations of equilibrium, governing the general response of arbitrarily laminated composite plates, is reduced to a single eighth order partial differential equation in terms of a displacement function. The displacement function is solved in a single series form to determine the displacement, fundamental frequency, and buckling load of antisymmetric cross-ply and angle-ply laminated composite plates. The solution is applicable to rectangular plates with two opposite edges simply supported, while the other edges are simply supported, clamped, free, beam supported, or any combinations of these boundary conditions. This method overcomes the limitations of other analytical methods (Navier’s and Lévy’s), and provides an alternative to numerical, semi-numerical, and approximate methods of analysis. Numerical examples of bending, free vibration, and buckling of antisymmetric laminated composite plates are presented in tabular and graphical form. Whenever possible, the results of the present study are compared with those published in the literature and/or ANSYS solutions. The comparison firmly establishes that this method could be used for the analysis of antisymmetric laminated composite plates. Future research needs are identified for the aspects that have not been reached by the present study and others.

APA, Harvard, Vancouver, ISO, and other styles

34

Javanshir, Hasbestan Jaber. "Free Flexural (or Bending) Vibration Analysis Of Certain Of Stiffened Composite Plates Or Panels In Flight Vehicle Structures." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12611489/index.pdf.

Full text

Abstract:

In this study, the &ldquo
Free Flexural (or Bending) Vibrations of Stiffened Plates or Panels&rdquo
are investigated in detail. Two different Groups of &ldquo
Stiffened Plates&rdquo
will be considered. In the first group, the &ldquo
Type 4&rdquo
and the &ldquo
Type 6&rdquo
of &ldquo
Group I&rdquo
of the &ldquo
Integrally-Stiffened and/or Stepped-Thickness Plate or Panel Systems&rdquo
are theoretically analyzed and numerically solved by making use of the &ldquo
Mindlin Plate Theory&rdquo
. Here, the natural frequencies and the corresponding mode shapes, up to the sixth mode, are obtained for each &ldquo
Dynamic System&rdquo
. Some important parametric studies are also presented for each case. In the second group, the &ldquo
Class 2&rdquo
and the &ldquo
Class 3&rdquo
of the &ldquo
Bonded and Stiffened Plate or Panel Systems&rdquo
are also analyzed and solved in terms of the natural frequencies with their corresponding mode shapes. In this case, the &ldquo
Plate Assembly&rdquo
is constructed by bonding &ldquo
Stiffening Plate Strips&rdquo
to a &ldquo
Base Plate or Panel&rdquo
by dissimilar relatively thin adhesive layers. This is done with the purpose of reinforcing the &ldquo
Base Plate or Panel&rdquo
by these &ldquo
Stiffening Strips&rdquo
in the appropriate locations, so that the &ldquo
Base Plate or Panel&rdquo
will exhibit satisfactory dynamic response. The forementioned &ldquo
Bonded and Stiffened Systems&rdquo
may also be used to repair a damaged (or rather cracked) &ldquo
Base Plate or Panel&rdquo
. Here in the analysis, the &ldquo
Base Plate or Panel&rdquo
, the &ldquo
Stiffening Plate Strips&rdquo
as well as the in- between &ldquo
adhesive layers&rdquo
are assumed to be linearly elastic continua. They are assumed to be dissimilar &ldquo
Orthotropic Mindlin Plates&rdquo
. Therefore, the effects of shear deformations and rotary moments of inertia are considered in the theoretical formulation. In each case of the &ldquo
Group I&rdquo
and &ldquo
Group II&rdquo
problems, the &ldquo
Governing System of Dynamic Equations&rdquo
for every problem is reduced to the &ldquo
First Order Ordinary Differential Equations&rdquo
. In other words the &ldquo
Free Vibrations Problem&rdquo
, in both cases, is an &ldquo
Initial and Boundary Value Problem&rdquo
is reduced to a &ldquo
Two- Point or Multi-Point Boundary Value Problem&rdquo
by using the present &ldquo
Solution Technique&rdquo
. For this purpose, these &ldquo
Governing Equations&rdquo
are expressed in &ldquo
compact forms&rdquo
or &ldquo
state vector&rdquo
forms. These equations are numerically integrated by the so-called &ldquo
Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)&rdquo
. In the numerical results, the mode shapes together with their corresponding non-dimensional natural frequencies are presented up to the sixth mode and for various sets of &ldquo
Boundary Conditions&rdquo
for each structural &ldquo
System&rdquo
. The effects of several important parameters on the natural frequencies of the aforementioned &ldquo
Systems&rdquo
are also investigated and are graphically presented for each &ldquo
Stiffened and Stiffened and Bonded Plate or Panel System&rdquo
. Additionally, in the case of the &ldquo
Bonded and Stiffened System&rdquo
, the significant effects of the &ldquo
adhesive material properties&rdquo
(i.e. the &ldquo
Hard&rdquo
adhesive and the &ldquo
Soft&rdquo
adhesive cases) on the dynamic response of the &ldquo
plate assembly&rdquo
are also presented.

APA, Harvard, Vancouver, ISO, and other styles

35

Xie, Min. "Behaviour and design of transversely stiffened plates subjected to combined shear and direct in-plane loading." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/7657.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Zizza, Antonio [Verfasser], and Ulrike [Akademischer Betreuer] Kuhlmann. "Buckling behaviour of unstiffened and stiffened steel plates under multiaxial stress states / Antonio Zizza ; Betreuer: Ulrike Kuhlmann." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1124000046/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Little, Patrick E. (Patrick Edward). "A study of the wedge cutting force through transversely stiffened plates : an application to ship grounding resistance." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37522.

Full text

Abstract:

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994.
Includes bibliographical references (leaves 115-117).
by Patrick E. Little.
M.S.

APA, Harvard, Vancouver, ISO, and other styles

38

Hall, Benjamin L. "Finite element and analytical analysis of cracks in thick stiffened plates repaired with a single–sided composite patch." Thesis, Monterey, California: Naval Postgraduate School, 2014. http://hdl.handle.net/10945/42638.

Full text

Abstract:

Approved for public release; distribution is unlimited
The purpose of this thesis was to investigate crack growth behavior in thick stiffened aluminum plates repaired with a single-sided composite patch. A model was developed using finite element analysis that extracted the mode I strain energy release rate (SERR) with use of the Virtual Crack Closure Technique. The dimensions and spacing of the stiffeners were varied to determine their effect on reducing the SERR. This model was also compared to an unstiffened model and one without a composite patch. A tensile load and a bending moment were both applied to the model for various configurations. These results were then used to develop an analytical model that can be used to predict the effectiveness of a patched surface.

APA, Harvard, Vancouver, ISO, and other styles

39

Bracco, Mark Douglas. "A study of the wedge cutting force through longitudinally stiffened plates : an application to grounding resistance of single and double hull ships." Thesis, Monterey, California. Naval Postgraduate School, 1994. http://hdl.handle.net/10945/26279.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Tschakert, Roman [Verfasser], B. A. T. [Akademischer Betreuer] Petersson, Michael [Akademischer Betreuer] Möser, and Michael [Akademischer Betreuer] Vorländer. "Structure-borne sound propagation in cross-stiffened plates : a two-dimensional analytic method / Roman Tschakert. Gutachter: Michael Möser ; Michael Vorländer. Betreuer: B.A.T. Petersson ; Michael Möser." Berlin : Technische Universität Berlin, 2014. http://d-nb.info/1065666047/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Orozco, Juan Carlos Galindo. "Contribuição ao estudo de painéis reforçados: comparação entre o método da chapa ortotrópica e o método dos elementos finitos." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3135/tde-09022009-170059/.

Full text

Abstract:

Métodos convencionais, tais como o método da chapa ortotrópica, têm sido aplicados por muitos anos no estudo de painéis reforçados pela sua simplicidade e facilidade de aplicação na determinação de tensões agentes nas fases iniciais da espiral projeto. Não estão disponíveis na literatura, porém, análises comparativas do método da chapa ortotrópica com procedimentos numéricos utilizando elementos finitos (MEF) que permitam a determinação da acurácia ou da ordem de grandeza dos desvios inerentes à aplicação desta metodologia. O presente trabalho apresenta análises comparativas entre estas duas metodologias na solução de painéis reforçados submetidos a carga lateral uniforme, tipicamente aplicados a estruturas navais (chapa em apenas um dos lados com reforçadores em T). Com este objetivo foram construídos modelos de painéis simplesmente apoiados e engastados (modelagem com elementos de viga e casca) com diferentes espaçamentos e diferentes inércias de reforçadores, configurando uma ampla matriz de análise paramétrica. Os resultados de deflexões e tensões nas vigas e chapas obtidos dos modelos MEF foram parametrizados em função das variáveis da chapa ortotrópica (razão de aspecto virtual), (coeficiente de torção) e K (parâmetro adimensional de tensões e de deflexão). Esta parametrização permite gerar curvas numéricas de tensão e deflexão dos modelos em estudo. As curvas numéricas assim geradas são comparadas com as curvas propostas pelo método da chapa ortotrópica para painéis reforçados simplesmente apoiados, de tal maneira que sua comparação permita, além de determinar a sensibilidade dos resultados numéricos em função das mudanças de inércia e espaçamento entre reforçadores, aferir o nível de desvio oriundo do uso da metodologia da chapa ortotrópica em relação ao método dos elementos finitos. Resultados mostram que as curvas derivadas da metodologia da chapa ortotrópica fornecem bons resultados para as deflexões e tensões transversais nas vigas no centro do painel reforçado. Para as tensões longitudinais nas vigas, uma curva corrigida de tensões longitudinais máximas é fornecida. No caso das curvas de tensões longitudinais e transversais na chapa, as curvas da chapa ortotrópica fornecem valores conservadores de tensão no centro do painel em relação aos valores obtidos dos modelos MEF. Adicionalmente, uma vez que o método da chapa ortotrópica só fornece curvas para chapa sem reforçadores no caso de condição de engaste, curvas numéricas das diferentes variáveis são fornecidas para esta condição. Analogias são feitas com a solução fornecida pelo método da chapa ortotrópica para painéis reforçados com razão de aspecto =, borda longitudinal engastada e borda transversal apoiada. Adicionalmente, resultados analíticos baseados na teoria de grelhas são comparados com os valores fornecidos pelas curvas numéricas para painel engastado obtendo-se resultados consistentes. Com esta análise foi possível determinar a aplicabilidade e limitações do método da chapa ortotrópica no estudo de painéis reforçados simplesmente apoiados. O estudo também fornece novas curvas numéricas para painéis reforçados engastados.
Conventional methods, such as the orthotropic plate, have been applied for many years in the study of stiffened plates to obtain the stresses acting on the structure in the early stages of the structural design, because of its simplicity and easy application. However, comparative analyses of the orthotropic plate method with numerical methods using finite element analyses (FEM) to determine its accuracy or inherent errors are not available in the literature. This study presents comparative analyses between the solutions of the two methodologies for reinforced panels subjected to lateral uniform load, typically applied to marine structures (plate only on one side with T beams). Models of reinforced panels were implemented for a simply supported and clamped boundary conditions with different spacing between stiffeners and different stiffeners`s inertia, setting up a broad array of parametric analysis. The deflections and stresses in beams and plate derived from the MEF analyses were parameterized as function of the orthotropic plate parameters: (virtual aspect ratio), (torsion coefficient) and K (dimensionless parameter of stress and deflection). This enables the generation of parametric numerical curves of stresses and deflections for the models under study. The numerical curves generated in this way were compared with the analytic curves proposed by the orthotropic plate theory for reinforced panels with simply supported boundary conditions. The comparisons allow, in addition to a sensitivity analysis of the numerical curves as a function of inertia and spacing between stiffeners, the assessment of inherent deviation for the orthotropic plate theory when compared with the finite element analyses. From the comparative analyses, it is possible to conclude that the curves proposed for the orthotropic theory for deflection and stresses of the transverse beam at the center of the reinforced panels have a good correlation with the numeric curves and provide accurate results. For the stresses on longitudinal beam, a revised curved for maximum stresses is provided. For the curves of plate stresses in the longitudinal and transverse directions at the center of the panels, the orthotropic plate theory provides conservative values when compared with the values of FEM models. The orthotropic plate method only provides curves for unstiffened plate under clamped boundary condition. Numerical curves for reinforced panels with clamped boundary condition are provided. Analogies are made between the solution provided by the orthotropic theory for a reinforced panel with an infinite virtual aspect ratio = , longitudinal edges clamped and transverse edges simply supported. Additionally, analytical results based on grillage theory were compared with the values provided by the numerical curves for clamped reinforced panels, obtaining a consistent results and a good correlation. This analysis provides a critic overview of the applicability and limitations of the orthotropic plate method for the analyses of reinforced panels with simply supported boundary condition. The study also provides new numerical solutions for reinforced panels with clamped boundary condition.

APA, Harvard, Vancouver, ISO, and other styles

42

Li, Tianyu. "On the Formulation of a Hybrid Discontinuous Galerkin Finite Element Method (DG-FEM) for Multi-layered Shell Structures." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/82962.

Full text

Abstract:

A high-order hybrid discontinuous Galerkin finite element method (DG-FEM) is developed for multi-layered curved panels having large deformation and finite strain. The kinematics of the multi-layered shells is presented at first. The Jacobian matrix and its determinant are also calculated. The weak form of the DG-FEM is next presented. In this case, the discontinuous basis functions can be employed for the displacement basis functions. The implementation details of the nonlinear FEM are next presented. Then, the Consistent Orthogonal Basis Function Space is developed. Given the boundary conditions and structure configurations, there will be a unique basis function space, such that the mass matrix is an accurate diagonal matrix. Moreover, the Consistent Orthogonal Basis Functions are very similar to mode shape functions. Based on the DG-FEM, three dedicated finite elements are developed for the multi-layered pipes, curved stiffeners and multi-layered stiffened hydrofoils. The kinematics of these three structures are presented. The smooth configuration is also obtained, which is very important for the buckling analysis with large deformation and finite strain. Finally, five problems are solved, including sandwich plates, 2-D multi-layered pipes, 3-D multi-layered pipes, stiffened plates and stiffened multi-layered hydrofoils. Material and geometric nonlinearities are both considered. The results are verified by other papers' results or ANSYS.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

43

Palamadai, Subramanian Lakshmi Priya. "Flexural resistance of longitudinally stiffened plate girders." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54436.

Full text

Abstract:

AASHTO LRFD requires the use of longitudinal stiffeners in plate girder webs when the web slenderness D/tw is greater than 150. This practice is intended to limit the lateral flexing of the web plate during construction and at service conditions. AASHTO accounts for an increase in the web bend buckling resistance due to the presence of a longitudinal stiffener. However, when the theoretical bend buckling capacity of the stiffened web is exceeded under strength load conditions, the Specifications do not consider any contribution from the longitudinal stiffener to the girder resistance. That is, the AASHTO LRFD web bend buckling strength reduction factor Rb applied in these cases is based on an idealization of the web neglecting the longitudinal stiffener. This deficiency can have significant impact on girder resistance in regions of negative flexure. This research is aimed at evaluating the improvements that may be achieved by fully considering the contribution of web longitudinal stiffeners to the girder flexural resistance. Based on refined FE test simulations, this research establishes that minimum size longitudinal stiffeners, per current AASHTO LRFD requirements, contribute significantly to the post buckling flexural resistance of plate girders, and can bring as much as a 60% increase in the flexural strength of the girder. A simple cross-section Rb model is proposed that can be used to calculate the girder flexural resistance at the yield limit state. This model is developed based on test simulations of straight homogenous girders subjected to pure bending, and is tested extensively and validated for hybrid girders and other limit states. It is found that there is a substantial deviation between the AISC/AASHTO LTB resistance equations and common FE test simulations. Research is conducted to determine the appropriate parameters to use in FE test simulations. Recommended parameters are identified that provide a best fit to the mean of experimental data. Based on FE simulations on unstiffened girders using these recommended parameters, a modified LTB resistance equation is proposed. This equation, used in conjunction with the proposed Rb model also provides an improved handling of combined web buckling and LTB of longitudinally stiffened plate girders. It is observed that the noncompact web slenderness limit in the Specifications, which is an approximation based on nearly rigid edge conditions for the buckling of the web plate in flexure is optimistic for certain cross-sections with narrow flanges. This research establishes that the degree of restraint at the edges of the web depend largely on the relative areas of the adjoining flanges and the area of the web. An improved equation for the noncompact web slenderness limit is proposed which leads to a better understanding and representation of the behavior of these types of members.

APA, Harvard, Vancouver, ISO, and other styles

44

Hoon, K. H. "Buckling behaviour of intermediately stiffened plate elements." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Nast, Trina E. "Cyclic behavior of stiffened gusset plate-brace member assemblies." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/MQ47076.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Ma, Ming. "Elastic and inelastic analysis of panel collapse by stiffener buckling." Diss., This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06062008-170150/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Yeilaghi, Tamijani Ali. "Vibration and Buckling Analysis of Unitized Structure Using Meshfree Method and Kriging Model." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/37817.

Full text

Abstract:

The Element Free Galerkin (EFG) method, which is based on the Moving Least Squares (MLS) approximation, is developed here for vibration, buckling and static analysis of homogenous and FGM plate with curvilinear stiffeners. Numerical results for different stiffeners configurations and boundary conditions are presented. All results are verified using the commercial finite element software ANSYSÂ® and other available results in literature. In addition, the vibration analysis of plates with curvilinear stiffeners is carried out using Ritz method. A 24 by 28 in. curvilinear stiffened panel was machined from 2219-T851 aluminum for experimental validation of the Ritz and meshfree methods of vibration mode shape predictions. Results were obtained for this panel mounted vertically to a steel clamping bracket using acoustic excitation and a laser vibrometer. Experimental results appear to correlate well with the meshfree and Ritz method results. In reality, many engineering structures are subjected to random pressure loads in nature and cannot be assumed to be deterministic. Typical engineering structures include buildings and towers, offshore structures, vehicles and ships, are subjected to random pressure. The vibrations induced from gust loads, engine noise, and other auxiliary electrical system can also produce noise inside aircraft. Consequently, all flight vehicles operate in random vibration environment. These random loads can be modeled by using their statistical properties. The dynamical responses of the structures which are subjected to random excitations are very complicated. To investigate their dynamic responses under random loads, the meshfree method is developed for random vibration analysis of curvilinearly-stiffened plates . Since extensive efforts have been devoted to study the buckling and vibration analysis of stiffened panel to maximize their natural frequencies and critical buckling loads, these structures are subjected to in-plane loading while the vibration analysis is considered. In these cases the natural frequencies calculated by neglecting the in-plane compression are usually over predicted. In order to have more accurate results it might be necessary to take into account the effects of in-plane load since it can change the natural frequency of plate considerably. To provide a better view of the free vibration behavior of the plate with curvilinear stiffeners subjected to axial/biaxial or shear stresses several numerical examples are studied. The FEM analysis of curvilinearly stiffened plate is quite computationally expensive, and the meshfree method seems to be a proper substitution to reduce the CPU time. However it will still require many simulations. Because of the number of simulations may be required in the solution of an engineering optimization problem, many researchers have tried to find approaches and techniques in optimization which can reduce the number of function evaluations. In these problems, surrogate models for analysis and optimization can be very efficient. The basic idea in surrogate model is to reduce computational cost and giving a better understanding of the influence of the design variables on the different objectives and constrains. To use the advantage of both meshfree method and surrogate model in reducing CPU time, the meshfree method is used to generate the sample points and combination of Kriging (a surrogate model) and Genetic Algorithms is used for design of curvilinearly stiffened plate. The meshfree and kriging results and CPU time were compared with those obtained using EBF3PanelOpt.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

48

Morel, Osman Fuat. "Earthquake Performance Of Un-stiffened Thin Steel Plate Shear Walls." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/1260427/index.pdf.

Full text

Abstract:

In this study two dimensional steel frames, reinforced with un-stiffened thin steel panels, are investigated. In the first part of the study, the strip model, a method for analyzing un-stiffened thin steel plate shear walls, was investigated. Sensitivity studies to investigate the influence of the number of strip members to be used to in the strip model and their angle of inclination were conducted. In the second part, responses of various un-stiffened steel plate shear wall systems to lateral loads were investigated. The influences of three major parameters were studied. These are the beam-to-column connection type, the boundary frame stiffness and the plate slenderness ratio (the ratio of the centerline column spacing to the thickness of the plate). In both parts nonlinear pushover analysis were performed with SAP2000 structural analysis program. In this study, the history of development, theory and advantages of un-stiffened thin steel plate shear walls and recommendations for this lateral load resisting system are presented.

APA, Harvard, Vancouver, ISO, and other styles

49

Parthasarathi, N. "A parametric study of shear provisions for stiffened plate girders." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/MQ49701.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Hopkins, Thomas Andrew. "Optimization of stiffener placement for thin plate buckling." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43892.

Full text

Abstract:

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.
Includes bibliographical references (leaf 67).
Stiffened plates are a common component in many structures, from plate girders and box girder bridges to ships and offshore structures. Plates and stiffened plates buckle into doubly curved surfaces, substantially complicating the mathematics for an analytic solution. Finite element methods allow direct analysis of stiffened plates without requiring the solving of complicated differential equations. This analysis considers stiffened plates from the buoy of a tension leg platform designed to support a 5 megawatt wind turbine. The interior plates were stiffened using conventional, large, triangular, diamond and truss type stiffener arrangements. The truss scheme was designed or "tuned" specifically to the suppress the first buckling mode of the particular plate, and compared to other more arbitrary forms of material placement. The results showed that the truss stiffener that was tuned to the first mode was the most effective in increasing the critical buckling load. The truss arrangement increased the critical load by 7, 269 kips compared to 4, 180 for conventional, 2, 912 for large, 911 for triangular and 2,562 kips for a diamond stiffener arrangement.
by Thomas Andrew Hopkins.
M.Eng.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Stiffened plates'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles