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1.
Yu Xie Mukherjee Zhicheng Xie Anthony R. Ingraffea 《International journal for numerical methods in engineering》1991,32(6):1321-1337
The subject of this paper is the buckling of laminated plates, with a pre-existing delamination, subjected to in-plane loading. Each laminate is modelled as an orthotropic Mindlin plate. The analysis is carried out by a combination of the finite element and asymptotic expansion methods. By applying the finite element method, plates with general delamination regions can be studied. The asymptotic expansion method reduces the number of unknown variables of the eigenvalue equation to that of the equation for a single Kirchhoff plate. Numerical results for the critical buckling load are presented for several examples. The effects of the shape, size and position of the delamination on the buckling load are studied through these examples. 相似文献
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Thermal buckling behavior of composite laminated plates 总被引:1,自引:0,他引:1
Thermal buckling behavior of composite laminated plates was studied by making the use of finite element method. The thermal buckling mode shapes of cross-ply and angle-ply laminates with various E1/E2 ratios, aspect ratios, fiber angle, stacking sequence and boundary condition were studied in detail. The results indicate that the high E1/E2 and α2/α1 ratios of AS4/3501-6 and T 300/5208 laminates produce higher bending rigidity along the fiber direction and higher in-plane compressive force in a direction perpendicular to the fiber direction. Therefore, the higher thermal buckling mode shapes are formed. The thermal buckling mode that composite laminated plate will buckle into is mainly dependent on the E1/E2 ratio, α2/α1 ratio, fiber orientation and aspect ratio of the plate. 相似文献
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Mehdi Bohlooly 《Advanced Composite Materials》2017,26(5):407-426
A thermomechanical buckling analysis is presented for simply supported rectangular symmetric cross-ply laminated composite plates that are integrated with surface-mounted piezoelectric actuators and are subjected to the combined action of in-plane compressive edge loads, two types of thermal loads, and constant applied actuator voltage. The formulation of equations is based on the classical laminated plate theory and the von-Karman non-linear kinematic relations. The analysis uses an exact method to obtain closed-form solutions for the buckling load. The effects of applied actuator voltage, thermal and mechanical loads, plate geometry, and lay-up configuration of the laminated plates are investigated. The novelty of the present work is to obtain closed-form solutions for electro-thermomechanical buckling of hybrid composite plates, and to cover non-uniform temperature distribution loading. The results for various states are verified with known data in the literature. 相似文献
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The effects of moisture and temperature on the static instability of laminated composite plates are investigated. The analysis is carried out by the finite element method using a quadratic isoparametric element which takes transverse shear deformation into account. The conventional finite element formulation is modified to include hygrothermal effects. The stiffness matrix, geometric stiffness matrix due to residual stresses, geometric stiffness matrix due to applied in-plane loads and load vector of the element are derived based upon the principle of minimum potential energy. The analysis accounts for reduced lamina material properties at elevated moisture concentrations and temperatures. Critical loads are obtained for symmetric and anti-symmetric laminates with simply-supported and clamped boundary conditions at different moisture concentrations and temperatures. Their dependence on moisture and temperature is studied. The effects of aspect ratio and side-to-thickness ratio on the critical loads are also considered. Mode shapes are verified in a few cases for anti-symmetric cross-ply laminate. 相似文献
6.
Elastic buckling strength of corroded steel plates 总被引:1,自引:0,他引:1
AHMAD RAHBAR-RANJI 《Sadhana》2013,38(1):89-99
Corrosion makes structures more vulnerable to buckling and yielding failures. It is common practice to assume a uniform thickness reduction for general corrosion. To estimate the remaining strength of corroded structures, typically a much higher level of accuracy is required, since the actual corroded structures have irregular surfaces. Elastic buckling of simply supported rectangular corroded plates are studied with one- and both-sided irregular surfaces. Eigenvalue analysis by using finite element method (FEM) is employed for computing Euler stress. The influence of various geometric and corrosion characteristics are investigated and it is found that the aspect ratio of the plate, the average thickness diminution, the standard deviation of thickness diminution and the amount of corrosion loss have influence on the reduction of buckling strength of the corroded plates. Buckling strength of one- and both-sided corroded plates are the same. In plates with low value of aspect ratio, reduction of buckling strength is negligible. Reduction of buckling strength is more prominent in plates with higher aspect ratio. Reduction of buckling strength is very sensitive to the amount of corrosion loss; the higher the amount of corrosion loss, the more reduction of buckling strength. Reduction of buckling strength is less sensitive to the standard deviation of thickness diminution. 相似文献
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A. G. Kolpakov 《Strength of Materials》1990,22(2):263-267
The article explains the method of designing laminated plates with a specified set of rigidity and strength characteristics on the basis of the use of a finite number of materials. An algorithm is presented for solving problems of designing which yields partial solutions of the corresponding inverse problem. Examples are discussed.Translated from Problemy Prochnosti, No. 2, pp. 85–88, February, 1990. 相似文献
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Thermal buckling behavior of laminated composite plates with temperature-dependent properties 总被引:1,自引:0,他引:1
The thermal buckling behavior of composite laminated plates subjected to a uniform temperature field is investigated by the finite element method. Temperature-dependent elastic and thermal properties are considered. The stiffness and geometry matrices are derived based on the principle of minimum potential energy. The assumed displacement state over the middle surface of the plate element is expressed as the product of one-dimensional, first-order Hermitian polynomials. An iterative method is employed to determine the thermal buckling load. It is shown by numerical results that the influence of temperature-dependent mechanical properties on the thermal buckling behavior is significant. 相似文献
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Buckling of composite annular plates under uniform internal and external radial edge loads have been investigated using energy method. Trefftez rule is used in the stability equations. The symmetric buckling of symmetric cross-ply laminates is considered. In this paper, buckling behavior for the three laminates (90/0)2s, (90/02/90)s and (902/02)s are studied. Influence of some parameters such as thickness, stacking sequence, type of supports and the ratio of hole to sheet radius on buckling loads and modes are investigated. The results of the energy method are compared with the results of numerical method. Based on the results, in the plates with clamped boundary conditions the symmetric buckling assumption is not accurate, contrary to other boundary conditions. 相似文献
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A study of residual compressive strength in delaminated laminates is presented. A methodology is proposed for simulating the whole compressive failure responses, such as initial buckling, postbuckling, contact of delamination front region, delamination propagation, fiber breakage, and matrix cracking etc. An finite element analysis (FEA) of the residual compressive strength is conducted on the basis of the Von Karman's nonlinearity assumption and the first-order shear deformation plate theory, combined with a stiffness degradation scheme. The numerical analysis models and methods are briefly introduced in this paper and some numerical examples are presented to illustrate it. From numerical results and discussion, it is clear that the compressive failure response involves complex multi-failure modes during compressive process. The method and numerical conclusions provide in this paper should of great value to engineers dealing with composite structures. 相似文献
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Thermal buckling of antisymmetric cross-ply laminates having central circular holes subjected to uniform or non-uniform temperature distribution are analysed by the finite element method. To account for the transverse shear deformation, the thermo-elastic Mindlin plate theory is used. Numerical results show that significant reduction of the critical buckling temperature occurs for laminates having a central hole. 相似文献
14.
C. V. Srinivasa W. P. Prema Kumar M. T. Prathap Kumar Ashok R. Bangar Pavan Kumar M. S. Rudresh 《先进材料力学与结构力学》2017,24(4):304-317
This article deals with experimental and finite element studies on the buckling of isotropic and laminated composite skew plates with circular holes subjected to uniaxial compression. The influence of skew angle, fiber orientation angle, laminate stacking sequence, and aspect ratio on critical buckling load are evaluated using the experimental method (using Methods I through V) and finite element method using MSC/NASTRAN. Method I yields the highest experimental value and Method IV the lowest experimental value for critical buckling load in the case of isotropic skew plates with circular holes. For all laminate stacking sequences considered, Method V yields the highest experimental value for critical buckling load for skew angle = 0° and Method IV yields the highest experimental value for critical buckling load for skew angles = 15° and 30°. For all laminate stacking sequences and skew angles considered, Method II yields the lowest experimental value for critical buckling load. The maximum discrepancy between the experimental values given by Method IV and the finite element solution is about 10% in the case of isotropic skew plates. The maximum discrepancy between the experimental values given by Method II and the finite element solution is about 21% in the case of laminated composite skew plates considered. The percentage of discrepancy between the numerical or finite element solution and experimental value increases as the skew angle increases. The critical buckling load decreases as the aspect ratio increases. 相似文献
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A design approach is presented for dealing with multiple (six or even more) object functions in the optimal design problem of laminated composite plates. The proposed approach is divided into some steps. First, the design variables are discretized with a certain increment that depends on the required accuracy, and all the values of physical parameters (used as object functions) are calculated for the discrete values of design variables. The second step is based on statistical treatment of the data. The calculated values of each physical parameter for discrete design variables are normalized and modified to be the deviated values on the assumption that the values are subjected to the Gaussian distribution with the prescribed standard deviation and average. At the last step, the best design in global sense is determined by considering the weighted sum of the deviated object functions and also graphical presentations. In the application, a three-layered rectangular plate with angle-ply stacking sequence [θ/−θ/θ] is considered where a representative fiber orientation angle θ is a single design variable. The object functions are taken to be six physical parameters of vibration and various buckling problems. 相似文献
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A new stiffened plate element for stability analysis of laminated stiffened plates has been presented. The basic plate element is a combination of Allman's plane stress triangular element and a Discrete Kirchhoff–Mindlin plate bending element. The element includes transverse shear effects. The model accommodates any number of arbitrarily oriented stiffeners within the plate element and eliminates constraints on the mesh division of the plate. The element has no problem associated with shear locking – a phenomenon usually encountered in isoparametric elements. The stability analysis of laminated stiffened plates has been carried out under different loading conditions with the present element. 相似文献
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Optimal design of composite laminates under buckling load uncertainty is presented. The laminates are subjected to biaxial compressive loads and the buckling load is maximized under worst case in-plane loading which is computed using an anti-optimization approach. The magnitudes of the in-plane loads are not known a priori resulting in load uncertainty subject to the only constraint that the loads belong to a given uncertainty domain. Results are given for continuous and discrete fibre orientations which constitute the optimization problem coupled to load anti-optimization problem leading to a nested solution method. It is observed that the stacking sequence of a laminate designed for a deterministic load case only differs considerably from that of a robust laminate designed taking load uncertainties into account. Consequently the buckling load carried by a deterministic design is considerably less than the one carried by a robust design when both are subjected to uncertain loads. 相似文献
18.
Bodo Geier Klaus Rohwer 《International journal for numerical methods in engineering》1989,27(2):403-427
In general, plates and shells out of composite laminates are more susceptible to transverse shear than those out of homogeneous isotropic material. By means of different shear flexible theories the effect on buckling and postbuckling behaviour is studied. It turns out that there is a rather limited range of plates where the transverse shear is of considerable influence. Results obtained with Mindlin- or Reissner-type theories prove almost as adequate as those obtained with Reddy's theory. For the buckling analysis of shells the Kirchhoff–Love theory is precise enough. Snap-through buckling and imperfection sensitivity appear in composite shells, too, especially if they are optimized with respect to high bifurcation buckling loads. 相似文献
19.
Alexander Humer 《Acta Mechanica》2013,224(7):1493-1525
The buckling and postbuckling of beams is revisited taking into account both the influence of axial compressibility and shear deformation. A theory based on Reissner’s geometrically exact relations for the plane deformation of beams is adopted, in which the stress resultants depend linearly on the generalized strain measures. The equilibrium equation is derived in a general form that holds for the statically determinate and indeterminate combinations of boundary conditions representing the four fundamental buckling cases. The eigenvalue problem is recovered by consistent linearization of the governing equations, the critical loads at which the trivial solution bifurcates are determined, and the influence of shear on the buckling behavior is investigated. By a series of transformations, the equilibrium equation is rearranged such that it allows a representation of the solution in terms of elliptic integrals. Additionally, closed-form relations are provided for the displacement of the axis, from which buckled shapes are eventually obtained. Even for slender beams, for which shear deformation can usually be neglected, both the buckling and the postbuckling behavior turn out to be affected by shear not only quantitatively, but also qualitatively. 相似文献
20.
Summary The frequency and buckling equations of rectangular plates with various boundary conditions are developed within the third-order and the first-order shear deformation plate theories. The third-order theories account for a quadratic distribution of the transverse shear strains through the thickness of the plate. In the first part of this paper, Levinson's third-order theory, derived as a special case from Reddy's third-order theory, is used to study a plate laminated of transversely isotropic layers. The relationship between the original form of the governing equations and the interior and the edge-zone equations of the plate is closely examined and the physical insights from the latter equations are established. In the second part of the paper, the first-order shear deformation theory and the third-order theory of Reddy are studied for vibration and buckling. 相似文献