Special Issue on Stability of Composite Structures

Abstract

The increased use of composites in aerospace and civil engineering has resulted in growing demand for engineers versed in the advanced design of composite structures. Composite structures are understood in the wide sense, including microstructured materials, composite structural shapes, composite members built up by subelements of various materials, laminate or sandwich members, small-scale composite structures, etc. Compositelike structural elements are increasingly used in traditional engineeringfields, such as civil engineering, mechanical engineering, or aeronautical engineering, and they have also found some new applications with some recent developments, such as biomedical engineering or biomechanics, nanotechnology, etc. This special issue is primarily based on the presentations given in the symposium on the stability of composite structures organized by the EngineeringMechanics Institute (EMI) Stability Committee during the ASCE EMI Annual Conference held in Boston on June 2–4, 2011. This symposium has provided a forum to discuss recent advances and address the future prospects in the area of the stability of composite structures. The symposium has covered a large number of topics related to the stability of composite structures including the following: • Buckling of composite members; • Plate buckling; • Buckling and vibration of thin-walled structures; • Shear and large displacement analysis; • Interactive buckling and nonlocal mechanics; • Shear effects for in-plane and out-of-plane analyses; • Inelastic buckling; • Anisotropic effects, microstructured materials, and stability problems; • Buckling of sandwich structures; • Stability of partially composite members and delamination effects; • Postbuckling; and • Dynamic buckling. After going through an external review process, the following papers have been accepted and are included in this special issue on the stability of composite structures. As indicated by the title of this special issue, most of the presented papers uniquely deal with the challenges in stability analysis brought by the complexity of composite materials and structures. Their specific advances by these contributions are briefly summarized as follows: 1. In “Local Buckling Analysis of Restrained Orthotropic Plates under Generic In-Plane Loading,” Qiao et al. investigated analytically and numerically the local buckling of composite orthotropic plates under generic in-plane loading and with rotationally restrained boundary conditions. They used both semianalytical and finite-element method (FEM) numerical approaches to characterize the stability behavior of laminated plates or panels of fiber-reinforced plastic structural shapes. The approximated semianalytical solution is obtained from the variationally based Rayleigh-Ritz method, and it is successively compared with available results published in the literature. 2. In “Modeling of Interactive Buckling in Sandwich Struts with Functionally Graded Cores,” Yiatros et al. studied the interactive buckling in sandwich struts with functionally graded cores. The postbuckling behavior is analyzed for this sandwich column composed of two Euler-Bernoulli extensible columns connected with a shear functionally graded core. Linearized and nonlinear analyses are presented for this nonlinear elastic structural problem, and the possibility of capturing secondary bifurcations for such nonlinear systems is numerically shown. This nonlinear model is compared successively to some FEM results based on two-dimensional analyses for the core behavior. 3. In “Buckling Loads of Two-Layer Composite Columns with Interlayer Slip and Stochastic Material Properties,” Schnabl et al. presented an efficient stochastic buckling model for studying the structural reliability of layered composite columns with interlayer slip between the layers and random material and loading parameters. The deterministic model is composed of two connected elastic columns with the shear effect neglected for each column. The nonderterministic approach is based on the exact buckling model, response surface method, and Monte Carlo simulations. The probability of failure for this stochastic buckling problem is computed, and it is shown to be very sensitive to loading and material distribution parameters. 4. In “Effect of Fiber Orientation on Buckling and First-Ply Failures of Cylindrical Shear-Deformable Laminates,” Cagdas and Adali investigated the effect of fiber orientation on buckling and first-ply failures of cylindrical shear-deformable laminates using an 8-node shell finite element (FE). The best ply angle is optimized for each stacking sequence to maximize the failure load. They identified that the rotational restraints at the curved edges have a pronounced effect on the failure load. 5. In “Thermal Postbuckling of Shear Deformable FGM Cylindrical Shells Surrounded by an Elastic Medium,” Shen incorporated the additional effect of an elastic medium on the thermal postbuckling of shear deformable functionally graded material (FGM) cylindrical shells. The surrounding elastic medium is modeled as a Pasternak foundation. The nonlinear governing equations are solved using a singular perturbation technique. The numerical results show that in some cases the FGM cylindrical shell with an intermediate volume fraction index does not have an intermediate buckling temperature and thermal postbuckling strength. In the case of heat conduction, the nonlinear equilibrium path for geometrically perfect FGM shells with simply supported boundary conditions is no longer of the bifurcation type. 6. In “Generalized Beam Theory to Analyze the Vibration of Open-Section Thin-Walled Composite Members,” Silvestre