Showing papers in "Thin-walled Structures in 1997"
TL;DR: The rotated stress field method was used in Eurocode 3, Part 1.1, version April 1992, for steel plate girders as mentioned in this paper, and it was adopted for plated structures in EuroCode 3, part 1.5, draft July 1996.
Abstract: During the development of Eurocode 9 for aluminium alloy structures a number of design methods for the shear buckling resistance of plate girders were appraised, by comparison with experimental data. Among studied methods the so-called rotated stress field method [Hoglund, T., Design of thin plate I girders in shear and bending with special reference to web buckling. Royal Institute of Technology, Department of Building Statics & Structural Engineering, Stockholm, 1972], with some modifications, was found to give the best agreement with 366 tests on steel plate girders as well as 93 tests on aluminium alloy plate girders in shear. The method is simple to use and is applicable to unstiffened, transversally and longitudinally stiffened and trapezoidally corrugated webs. This paper presents the rotated stress field method and summarizes the result of the comparisons, including the design methods in Eurocode 3, Part 1.1, version April 1992, for steel plate girders. The rotated stress field method is also adopted in Eurocode 3, Part 1.5: plated structures, draft July 1996.
137 citations
TL;DR: In this paper, the authors present a design method for distortional buckling of flexural members recently drafted for use in the Australian/New Zealand Standard for Cold formed Steel Structures.
Abstract: For thin-walled flexural members composed of high-strength steel and/or slender elements in the section, a mode of buckling at half-wavelengths intermediate between local buckling and flexural—torsional or flexural buckling can occur. The mode is most common for edge-stiffened sections such as C- and Z-purlins, and involves rotation of the flange and lip about the flange—web junction. The mode is commonly called distortional buckling. This paper presents a design method for distortional buckling of flexural members recently drafted for use in the Australian/New Zealand Standard for Cold formed Steel Structures. Methods for computing the elastic buckling stress, and design curves for determining the distortional buckling strength are presented. Comparisons of different methods for computing the elastic distortional buckling stress are made with accurate solutions based on the finite strip method of structural analysis.
121 citations
TL;DR: In this article, the Martinet analysis is reinterpreted and reproduced in terms of the buckling of a simple clamped column and this approach is then extended to provide an alternative conceptual understanding of the mechanics for, and a more direct and simplified analysis of, the upheaval bucking of systems containing initially imperfect geometries.
Abstract: That very close relationships exist between the thermal buckling of components such as continuously welded rail-tracks, concrete road pavements or subsea and buried pipelines, and the simple buckling of columns has long been recognized. It is surprising, therefore, that greater use has not been made of this relationship to provide both simplified design analysis and a more direct physical interpretation of behaviour. In the following the “classical” Martinet analysis is first reinterpreted and reproduced in terms of the buckling of the simple clamped column. This approach is then extended to provide an alternative conceptual understanding of the mechanics for, and a more direct and simplified analysis of, the upheaval buckling of systems containing initially imperfect geometries. It is suggested that the simple, closed form, solutions for both initial lift-off and the maximum upheaval buckling loads make this alternative approach particularly suited to future design to prevent potentially damaging upheaval buckling.
84 citations
TL;DR: In this paper, the authors present an appraisal of commercially available beam end connectors and attempt to classify the connectors based on their special features, as well as their deformation modes using stress-sensitive lacquer.
Abstract: Boltless semi-rigid connections are used in the storage rack industry. The connectors consist of end plates welded to each end of a beam and an interlocking arrangement to engage with perforated columns, hence supporting the beams and restraining the columns. There are a variety of types and designs in use, characteristic of different rack manufacturers. In the absence of theoretical approaches, currently the only way to determine the properties of such joints is by testing. The aim of this paper is to determine the parameters governing an efficient beam end connector design. The paper includes an appraisal of commercially available beam end connectors and attempts to classify the connectors based on their special features. The paper presents the results of the tests carried out on a selected number of connectors and compares their moment-rotation characteristics, as well as their deformation modes using stress-sensitive lacquer. A theoretical investigation is carried out to estimate the influence of the flexibility of the beam and the column used in the tests on the stiffnesses determined experimentally. The effects of dimensional changes on moment-rotation characteristics are considered, and the main parameters controlling the behaviour of beam end connectors are discussed.
70 citations
TL;DR: In this paper, an experimental investigation has been carried out to study the local buckling behaviour of square thin-walled aluminium extrusions in alloy AA6060 and the Stowell theory for plates has been modified to take postbuckling strength into account.
Abstract: An experimental investigation has been carried out to study the local buckling behaviour of square thin-walled aluminium extrusions in alloy AA6060. The primary variables have been the temper and wall thickness of the extrusions. Furthermore, the classical Stowell theory for plates has been modified to take postbuckling strength into account. Good correlation between theory and the present test results and results from the literature has been found.
56 citations
TL;DR: In this article, a non-linear elasto-plastic finite element model is proposed to predict the behavior of purlin-sheeting systems without the need for either experimental input or over simplifying assumptions.
Abstract: Purlin-sheeting systems used for roofs and walls commonly take the form of cold-formed channel or zed section purlins, screw-connected to corrugated sheeting. These purlin-sheeting systems have been the subject of numerous theoretical and experimental investigations over the past three decades, but the complexity of the systems has led to great difficulty in developing a sound and general model. This paper presents a non-linear elasto-plastic finite element model, capable of predicting the behaviour of purlin-sheeting systems without the need for either experimental input or over simplifying assumptions. The model incorporates both the sheeting and the purlin, and is able to account for cross-sectional distortion of the purlin, the flexural and membrane restraining effects of the sheeting, and failure of the purlin by local buckling or yielding. The validity of the model is shown by its good correlation with experimental results. A simplified version of this model, which is more suitable for use in a design environment, is presented in a companion paper.
52 citations
TL;DR: In this article, a comprehensive set of test results on upright sections in compression is presented, in which the load position was varied along the axis of symmetry, and longer columns were analysed using both finite elements and a version of generalized beam theory.
Abstract: The uprights in a typical pallet rack are typically singly-symmetrical cold-formed sections subject to axial load together with bending about both axes. They usually contain arrays of holes in order to enable beams to be clipped into position at heights that are not pre-determined prior to manufacture. Their slenderness is such that their behaviour may be influenced by the three generic forms of buckling, namely local, distortional and global (lateral torsional). In practice, these members have generally been designed on the basis of expensive test programmes. This paper addresses the problem of how they might be designed analytically. The basis of the investigation is a comprehensive set of test results on upright sections in compression which embraces both stub column tests, in which the load position was varied along the axis of symmetry, and longer columns. The test results were analysed using both finite elements and a version of “Generalized Beam Theory” (GBT) which incorporated systematic imperfections. Consideration was also given to the design procedures proposed by the “Federation Europeene de la Manutention” (FEM) and recent research into the influence of perforations on the performance of cold formed steel sections. It is shown that GBT can be modified to take account of perforations so that the lower bound results give a sufficiently accurate column design curve, which takes account of local, distortional and global buckling, thus making extensive testing unnecessary.
49 citations
TL;DR: In this paper, a finite element model is proposed to simulate single lap screw connections in steel sheeting of different thicknesses, under static shear, which can be used to predict the ultimate resistance, deformation, screw rotation and stress distribution of the connections.
Abstract: The behaviour of sheeting connections is important in thin walled structures, especially when diaphragm skin action is considered for these structures. Thousands of tests have been carried out in many countries but the study results are still not satisfactory. We felt that it would be very helpful to do more studies on this subject not only by experimental analysis but numerically, as well. Therefore, a finite element model is proposed, in this study, to simulate single lap screw connections in steel sheeting of different thicknesses, under static shear. This model can be used to predict the ultimate resistance, deformation, screw rotation and stress distribution of the connections. The results show a good correlation with the test results. This model can therefore be used in further relevant parametric studies and with little change adapted to model the connections with other types of fasteners.
48 citations
TL;DR: In this paper, a simplified version of the first model is presented, which has considerably decreased requirements in terms of computer memory, running time and data preparation, and is able to account for the cross-sectional distortion of the purlin, the shear and rotational restraining effects of the sheeting, and failure of a purlin by local buckling or yielding.
Abstract: A number of theoretical and experimental investigations have been made into the nature of purlin-sheeting systems over the past 30 years. These systems commonly consist of cold-formed zed or channel section purlins, connected to corrugated sheeting. They have proven difficult to model due to the complexity of both the purlin deformation and the restraint provided to the purlin by the sheeting. Part 1 of this paper presented a non-linear elasto plastic finite element model which, by incorporating both the purlin and the sheeting in the analysis, allowed the interaction between the two components of the system to be modelled. This paper presents a simplified version of the first model which has considerably decreased requirements in terms of computer memory, running time and data preparation. The Simplified Model includes only the purlin but allows for the sheeting's shear and rotational restraints by modelling these effects as springs located at the purlin-sheeting connections. Two accompanying programs determine the stiffness of these springs numerically. As in the Full Model, the Simplified Model is able to account for the cross-sectional distortion of the purlin, the shear and rotational restraining effects of the sheeting, and failure of the purlin by local buckling or yielding. The model requires no experimental or empirical input and its validity is shown by its goon con elation with experimental results. (C) 1997 Elsevier Science Ltd.
43 citations
TL;DR: A review of the research work that has been carried out to date to account for the effects of openings on the behaviour of thin-walled elements in steel structures is presented in this paper.
Abstract: A review is made of the research work that has been carried out to date to account for the effects of openings on the behaviour of thin-walled elements in steel structures. Attention is directed to relatively thin steel plate elements typical of those that occur in plated structures. Plate elements that are subjected to uniaxial compression or biaxial compression or shear loading, stiffened plates, shear webs and cold formed steel sections are considered separately. Analytical and experimental work carried out on centrally or eccentrically placed, reinforced or unreinforced circular or rectangular openings are considered in the review. Design methods of thin-walled steel structural elements that account for the presence of openings are highlighted.
41 citations
TL;DR: In this article, the fundamental behavior of restrained roof purlins under both downward and uplift load can be best understood with the aid of generalized beam theory (GBT) and an improvement is proposed.
Abstract: Roof purlins and sheeting rails are generally loaded through the cladding members that they support and this provides both rotational and translational restraint. This restraint reduces the tendency to lateral torsional buckling and thus increases the importance of distortional buckling in the design procedure. This paper shows that the fundamental behaviour of restrained purlins under both downward and uplift load can be best understood with the aid of ‘Generalized Beam Theory’ (GBT). GBT also provides a yardstick by which approximate design methods can be assessed. The existing approximate methods are evaluated and an improvement is proposed. The proposed design approach is then validated by comparison with test results.
TL;DR: In this article, the theoretical steps of a semi-empirical method for evaluating the rotation capacity of aluminium alloy members subjected to non-uniform bending are outlined, and both the preliminary test results and the planned activity are presented.
Abstract: In this paper the theoretical steps of a semi-empirical method for evaluating the rotation capacity of aluminium alloy members subjected to non-uniform bending are outlined. The approach is represented by the extension to aluminium alloy members of the semi-empirical methods proposed for evaluating the rotation capacity of steel members. The moment-curvature relationship of aluminium alloy members can be conveniently represented by means of a Ramberg-Osgood type relation. This allows, with reference to the classical three-point bending test, the derivation in closed form of the curvature diagram. Furthermore, a closed-form integration of the curvature diagram can be performed, providing a relation for evaluating the rotation corresponding to the occurrence of local buckling. The rotation capacity is then computed. The final ring of this link is represented by the experimental evaluation of the non-dimensional stress corresponding to the attainment of the local buckling. The testing needs for this evaluation are outlined, and both the preliminary test results and the planned activity are presented.
TL;DR: In this article, the reliability of finite element analyses in predictions of the ultimate strength of aluminium plates subjected to in-plane compression is presented. But the accuracy of the predictions was evaluated by comparison with existing experimental results.
Abstract: A study with the objective of assessing the reliability of non-linear finite element analyses in predictions of the ultimate strength of aluminium plates subjected to in-plane compression is presented. Outstand elements of alloy AA6082 in tempers T4 and T6 and internal elements of alloys 5083 M and 6082 TF were analysed for a range of b/t-ratios. For the latter class both non-welded and welded plates were studied, the non-welded plates having two levels of geometric imperfections. The accuracy of the predictions was evaluated by comparison with existing experimental results. It was found that the overall correlation between the experimental and predicted ultimate compressive strengths was good. The finite element analyses reproduced the main effects of slenderness, stress-strain curve (i.e. alloy and temper), geometric imperfections and welding (i.e. residual stresses and heat-affected zones) that were observed in the experiments
TL;DR: In this paper, a general bifurcation analysis of members that are locally buckled in the fundamental state is presented, where the members are assumed to be geometrically perfect.
Abstract: The paper presents a general bifurcation analysis of members that are locally buckled in the fundamental state. The members are assumed to be geometrically perfect in the overall sense such that bifurcation of the locally buckled member in an overall mode may occur. The analysis applies to arbitrary types of loads and support conditions. The cross-section, which may be arbitrary in shape, is assumed to be composed of flat plates. The paper derives the general variational equations expressing equilibrium of the fundamental and bifurcated states. The variational equations are applied to doubly symmetric columns and doubly symmetric beam-columns. The differential equations and boundary conditions are derived from the variational equations and solved for the fundamental and bifurcated states, thus providing the bifurcation loads of the members.
TL;DR: In this article, an elastic analysis using Galerkin's method to solve Marguerre's equations was first used to determine the first yield point, based on which the local plastic mechanism/imperfection tolerance tables have been developed which give the type of mechanism as a function of b/t ratio, imperfection level and yield stress of steel.
Abstract: Thin-walled steel plates subjected to in plane compression develop two types of local plastic mechanism, namely the roof-shaped mechanism and the so-called flip-disc mechanism, but the intriguing question of why two mechanisms should develop was not answered until recently. It was considered that the location of first yield point shifted from the centre of the plate to the midpoint of the longitudinal edge depending on the b/t ratio, imperfection level, and yield stress of steel, which then decided the type of mechanism. This paper has verified this hypothesis using analysis and laboratory experiments. An elastic analysis using Galerkin's method to solve Marguerre's equations was first used to determine the first yield point, based on which the local plastic mechanism/imperfection tolerance tables have been developed which give the type of mechanism as a function of b/t ratio, imperfection level and yield stress of steel. Laboratory experiments of thin-walled columns verified the imperfection tolerance tables and thus indirectly the hypothesis. Elastic and rigid-plastic curves were then used to predict the effect on the ultimate load due to the change of mechanism. A finite element analysis of selected cases also confirmed the results from simple analyses and experiments.
TL;DR: In this paper, the authors used the modified Lau and Hancock 2 model to predict the moment resistance of cold-formed steel C-and Z-sections in bending and compared with the applicable test data.
Abstract: Recent experimental tests of cold-formed steel C- and Z-sections in bending have revealed unconservative results in the prediction of the bending moment resistance, using the current North American Design Standards. The failure mode of these tests was identified as flange/web distortional buckling. This mode of failure initially involves a rotation of the lip/flange component about the flange/web corner, which typically occurs for short half-wavelength distortional buckling. Near ultimate failure, an apparent lateral movement of the flange/web corner, which includes transverse bending of the web, is experienced. Various analytical methods that predict the moment resistance of sections which experience short half-wavelength distortional buckling were investigated and compared with the applicable test data. The modified Lau and Hancock 2 Model, with S136-94 Standard calculated effective section modulus, is recommended for use as the North American predictor model for the flange/web distortional buckling moment resistance of cold-formed steel sections in bending.
TL;DR: In this article, the vibration, buckling and parameterc instability behavior of a plate with internal opening subjected to in-plane compressive or tensile periodic edge loading are studied.
Abstract: The vibration, buckling and parameterc instability behaviour of a plate with internal opening subjected to in-plane compressive or tensile periodic edge loading are studied. Different shapes and sizes of the cutout are considered. Compression and tension buckling results are discussed. The vibration analysis for this problem shows that for certain parameters of tensile loading and the opening, the frequency of the plate initially rises' with the load, but then begins to decrease with increasing tension showing the onset of tension buckling. Dynamic instability behaviour of the plate under compressive and tensile loading shows that the instability regions are affected by the size, shape of the opening and the loading parameters. Instability behaviour due to all the parameters are discussed.
TL;DR: In this article, the authors describe the behavior of profiled steel sheeting under inplane shear and its application in building frames and validate the results by small scale model tests and finite element analyses.
Abstract: This paper will describe the behaviour of profiled steel sheeting under inplane shear and its application in building frames. Analytical models for shear strength and stiffness of the profiled steel sheeting are developed and validated by small scale model tests and finite element analyses. The strength, stiffness, failure modes and strain conditions are found to be greatly influenced by the boundary condition of the sheeting. The values of several factors related to the mode of attachment of the sheeting to practical building frames are studied to verify the suitability of design equations.
TL;DR: Based on a 3-year study that focused on the behavior of cold-formed steel beams with web openings, researchers at the University of Missouri Rolla have developed simple, easy, to apply design recommendations.
Abstract: Based on a 3-year study that focused on the behavior of cold-formed steel beams with web openings, researchers at the University of Missouri Rolla have developed simple, easy, to apply design recommendations. The design recommendations address the limit states of web buckling resulting from bending, shear, web crippling, combined bending and shear, and combined bending and web crippling. The recommendations were developed based on the results of experimental and analytical studies of C-section beams. The C-sections, which are commonly used for wall studs and floor joists, are manufactured with web openings. Common web opening sizes are 38 × 102 mm and 19 × 51 mm. All web openings are located at mid-depth of the web and spaced 61 cm on center along the length of the C-section.
TL;DR: In this article, the authors investigated the postbuckling behavior of isotropic sandwiches, with different combinations of nonlinear material combinations, under compressive and/or bending loading, and experimental studies were performed to verify the analytical and numerical results, respectively.
Abstract: Wrinkling of the face layers is one of the typical failure modes in sandwich structures. Different aspects of this phenomenon are investigated in this paper: analytical considerations concern the determination of wrinkling loads for anisotropic elastic sandwiches under uniaxial as well as biaxial loading. Finite element calculations are carried out to investigate the postbuckling behaviour of isotropic sandwiches, with different combinations of nonlinear material combinations, under compressive and/or bending loading, and experimental studies are performed to verify the analytical and numerical results, respectively.
TL;DR: In this article, the fundamental and bifurcated states of members with singly symmetric cross-sections that locally buckle in the fundamental state were derived and the results were shown to be sensitive to the magnitudes of local and overall geometric imperfections.
Abstract: The paper derives the governing equations for the fundamental and bifurcated states of members with singly symmetric cross-sections that locally buckle in the fundamental state. The members are subject to pure compression and assumed to be geometrically perfect in the overall sense. It is shown using the fundamental state equations that fixed-ended columns exhibit overall bifurcation behaviour while pin-ended columns do not. The bifurcation equation is applied to plain channel sections and the results are compared with tests of fixed-ended columns. The variation of the bifurcation loads with the length is shown to be in good agreement with the tests. The results are shown to be sensitive to the magnitudes of local and overall geometric imperfections.
TL;DR: In this article, the elastic behavior of multi-stiffened plates under uniform compression was investigated, in which the structure was idealized as assembled plate and beam elements and rigidity connected at their junctions.
Abstract: The paper investigates the elastic behaviour of multi-stiffened plates under uniform compression. An energy formulation is first presented, in which the structure is idealized as assembled plate and beam elements and rigidity connected at their junctions. The strain energy components for the plate and the stiffener elements are then derived in terms of the out and in-plane displacement functions. Sequential Quadratic Programming (SQP) technique is then used to determine the critical buckling load for given plate% stiffener geometric properties. Results are then presented showing the transition from the overall to local mode by increasing the stiffener depth for various concentric and eccentric stiffening configurations. Finally, a design example is presented to compare the efficiency of various stiffening configurations.
TL;DR: In this article, an experimental research program aiming to evaluate the semi-rigid behaviour of some typical bolted connections, that are used in cold formed steel plane truss joints, was carried out in the Laboratory of CMMC Department of The ‘Politehnica’ University of Timisoara.
Abstract: An experimental research program aiming to evaluate the semi-rigid behaviour of some typical bolted connections, that are used in cold formed steel plane truss joints, was carried out in the Laboratory of CMMC Department of The ‘Politehnica’ University of Timisoara. From the experimental values of the resistant moment and initial stiffness of the joints, the semi-rigid character of tested joints were established via the Eurocode 3 provisions. A numerical analysis of this type of truss, in which this semi-rigid behaviour is taken into account using the experimental results, is performed in order to demonstrate the improvement of load capacity in comparison with the classical assumptions. Finally, a semianalytical method combined with FEM simulations, calibrated via some experimental results, is proposed, in order to carry out a parametric study on the local behaviour of this type of connection.
TL;DR: In this article, the possibility of local buckling in members classified as slender is kept into account in the most up-to-date codes by replacing the true section with an effective one.
Abstract: The possibility of local buckling in members classified as slender is kept into account in the most up-to-date codes by replacing the true section with an effective one This can be done via several approaches In order to compare these approaches a comprehensive parametric analysis is presented in this paper, applying different design criteria to a set of sections which adequately represent the most important types of slender aluminium alloy sections The obtained results allow one to check the reliability of the procedures proposed by the codes considering also the different computational cost required by each method
TL;DR: In this article, two types of quadrilateral transition elements based on the Mindlin-Reissner plate theory are presented for the adaptive mesh refinement in the plate bending problem, and both of the transition elements can be effectively used for the mesh refinement and the discretization error by nonconforming model reduces more rapidly than the conforming model.
Abstract: Two types of quadrilateral transition elements based on the Mindlin-Reissner plate theory are presented for the adaptive mesh refinement in the plate bending problem. The first type of transition element, designated as the conforming transition element, has piecewise linear folded side(s) which preserves the interelement compatibility when connected to refined four-node elements, and has been improved by construction of the substitute shear strain fields. The other type of elements, designated as the nonconforming transition element, can have curved side(s) and has been improved by the selective addition of nonconforming displacement modes. Numerical examples are presented to evaluate the performance of proposed elements. It was shown that the nonconforming model produces a smoother stress distribution than the conforming model does, even though the nonconforming model is not compatible along the interelement boundaries. It was also shown that both of the transition elements can be effectively used for the adaptive mesh refinement and the discretization error by nonconforming model reduces more rapidly than the conforming model.
TL;DR: In this article, a simple analytical procedure for determining the constrained torsional response of a specific class of carbon fiber composite box-beams is detailed, where the analysis approach essentially makes use of the existing theories of torsion appropriate to isotropic construction and these are then suitably modified to account for the nonisotropic nature of typical carbon fibre composite material.
Abstract: A simple analytical procedure for determining the constrained torsional response of a specific class of carbon fibre composite box-beams is detailed in this paper. The analysis approach essentially makes use of the existing theories of torsion appropriate to isotropic construction and these are then suitably modified to account for the non-isotropic nature of typical carbon fibre composite material. The composite box-beams are devoid of overall elastic couplings through the use of constituent laminates which are symmetrically laid-up about their own mid-planes and which possess in-plane orthotropy. The thin walls of the box-sections can have different lay-up configurations provided the stiffness distribution around the sections is of a symmetrically disposed nature. The flanges of a box-section can thus have a different lay-up configuration to that of the section webs. The constrained condition considered in the paper is that of the cantilevered box-beam with torque applied at the free end and the torsional and warping rigidities of the composite box-sections are determined through the use of the appropriate equivalent engineering elastic constants of the individual thin composite walls. Comparisons between theory and finite element solutions are given in the paper and these are shown to give close agreement. It is also clear that the use of the appropriate equivalent engineering elastic material constants in the theory is able to closely predict actual behaviour.
TL;DR: In this article, the natural frequencies and elastic buckling loads of square plates, containing reinforced square holes and subjected to inplane loads, are determined using the finite element method using a rectangular non-conforming bending element with three degrees of freedom at each of its four corner nodes.
Abstract: The natural frequencies and the elastic buckling loads of square plates, containing reinforced square holes and subjected to inplane loads, are determined using the finite element method. The reinforcing beams which are located at the four edges of the hole are either square or rectangular in cross section. To determine the appropriate out-of-plane stiffness and mass matrices, a rectangular non-conforming bending element is employed. This element has three degrees of freedom at each of its four corner nodes. The finite element method is also used to calculate the inplane stress distribution prior to buckling. This inplane element is rectangular and is based on strain assumptions. The element also includes the inplane rotation as well as the two translational displacements as the three degrees of freedom at each of its four corner nodes. To model the behaviour of the reinforcement, a three-dimensional exact beam element is used. For this element, the degrees of freedom for out-of-plane displacement are consistent with the non-conforming bending element, and the inplane degrees of freedom are consistent with the inplane strain-based element. In the present paper the natural frequencies and the corresponding modes of vibration are investigated when the reinforced plates are subjected to uniform uniaxial, biaxial and shear loads. The variation of the natural frequencies with various sizes of reinforcement is obtained for plates subjected to a range of magnitude of inplane loading.
TL;DR: In this paper, the main points of the long-term engineering experience at Cranfield Impact Centre Ltd in the field of crashworthiness of thin-walled beams and joints in vehicle structures are summarized.
Abstract: The paper summarises the main points of the long-term engineering experience at Cranfield Impact Centre Ltd in the field of crashworthiness of thin-walled beams and joints in vehicle structures. Subjects covered are: the ‘hybrid’ approach to crashworthiness design/analysis (where beams and joints are treated separately from complete structures), the deep bending collapse of beams and joints from the points of view of static and dynamic testing and analytical prediction (models of hinge mechanisms, regression analysis, finite element analysis and from experimental databases). Use of the component properties in the simplified finite element analysis of complete structures is also presented. Illustrations are shown during the oral presentation.
TL;DR: In this article, a series of eight mild steel domes subjected to internal pressure were tested up to burst in order to verify optimal solutions obtained by a zero order optimisation subroutine and a stress analysis code.
Abstract: A series of eight mild steel domes subjected to internal pressure were tested up to burst in order to verify optimal solutions obtained by a zero order optimisation subroutine and a stress analysis code. Four classes of minimum weight domes were obtained. The first one was sought within torispherical shells of constant wall thickness. The second case corresponded to a variable meridional profile described by a generalised ellipse and a given wall thickness. In the third case, the uniform wall thickness became an additional design variable. In the fourth case both the meridional shape and variable wall thickness along the meridian were used as design variables. The plastic load was greater than 20 MPa in all four cases. The weight reduction obtained for the above mentioned four cases was 18, 19, 27 and 31%, respectively. Comparison with the fully stressed design is also provided.
TL;DR: In this paper, the performance at the internal support can be predicted by finite element analysis and that continuing the analysis into the drooping post-yield range allows a relatively simple pseudo-plastic design method to be developed.
Abstract: When designing profiled metal sheeting and decking at the ultimate limit state, the conditions at the internal supports, where the bending moment interacts with the support reaction force, are critical. Design code provisions for estimating the moment of resistance over an internal support are known to be inadequate and the problem is aggravated if account is taken of the redistribution of bending moment accompanied by post-yield buckling. This paper shows that the performance at the internal support can be predicted by finite element analysis and that continuing the analysis into the drooping post-yield range allows a relatively simple pseudo-plastic design method to be developed.