The work deals with the problem a straight beam of a rectangular cross-section pivoted at both ends and loaded with a lengthwise compressive force. The beam is made of an isotropic porous material. Its properties vary through thickness of the beam. The modulus of elasticity is minimal on the beam axis and assumes maximum values at its top and bottom surfaces. The principle of stationarity of the total potential energy enables one to define a system of differential equations that govern the beam stability. The system is analytically solved, which leads to an explicit expression for the critical load of the compressed beam. Results of the solution are verified on an example beam by means of the Finite Element Method (COSMOS).

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Elastic buckling of a porous beam

Bending behavior of corrugated-core sandwich plates

A numerical analysis approach for evaluating elastic constants of sandwich structures with various cores

termsA44 andA55 werecalculatedusinganenergyapproach.Usingtheshear-deformableplatetheory,aclosed-form solution of the plate response was derived. The variation of plate stiffness and maximum plate deflection due to changing the web angle are discussed. The calculated results, which require significantly less computational effort and time, agree well with the three-dimensional finite element analysis. This study indicates that panels with rectangular webs resulted in a weak extensional, bending, and A55 stiffness and that the center plate deflection was minimum for a triangular corrugated core. The micromechanical analysis procedures developed in this study were used to determine the stresses in each component of the sandwich panel (face and web) due to a uniform pressure load.

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Micromechanical Analysis of Composite Corrugated-Core Sandwich Panels for Integral Thermal Protection Systems

Gives a bibliographical review of the finite element analyses of sandwich structures from the theoretical as well as practical points of view. Both isotropic and composite materials are considered. Topics include: material and mechanical properties of sandwich structures; vibration, dynamic response and impact problems; heat transfer and thermomechanical responses; contact problems; fracture mechanics, fatigue and damage; stability problems; special finite elements developed for the analysis of sandwich structures; analysis of sandwich beams, plates, panels and shells; specific applications in various fields of engineering; other topics. The analysis of cellular solids is also included. The bibliography at the end of this paper contains 655 references to papers, conference proceedings and theses/dissertations dealing with presented subjects that were published between 1980 and 2001.

Finite element analyses of sandwich structures: a bibliography (1980–2001)

In this paper, a truss-core sandwich panel is introduced and its elastic properties are presented. Two thin flat sheets, separated by two inclined plates acting as the core and rigidly jointed at their ends, characterize the sandwich section. This construction form eliminates most of the attendant problems of conventional spot-welded or rivet-fastened sandwich panel construction. Advantages of the truss-core panel are discussed. The 3D sandwich panel is idealized as an equivalent 2D orthotropic thick plate continuum. Equivalent bending, twisting, and transverse shear stiffness are derived, and the influence of the relatively weak shear stiffness on the behavior is discussed. By integrating these elastic stiffness constants into closed-form solution, panel response is calculated. The calculated results, which requires significantly less computational effort, agree well with 3D finite-element analysis. Comparisons of stiffnesses and deflections with the corresponding responses of conventional sandwich construction are provided. This study indicates that the truss-core sandwich panel performs better due to its inherently higher flexural resistance per unit weight.

Tat-Seng Lok

Papers

Elastic Stiffness Properties and Behavior of Truss-Core Sandwich Panel