Metal Foam Core Sandwich Beams Research Articles

Three-point bending of physically asymmetric metal sandwich beams with aluminum foam core: Failure behavior and optimal design

The failure behavior of physically asymmetric metal foam core sandwich beams under three-point bending is studied experimentally and analytically. Five failure modes including indentation, face yield, core shear (Type A), core shear (Type AB) and core shear (Type A-AB) were observed in the three-point bending tests. Analytical formulae for the critical loads of different failure modes are presented, and failure mechanism maps are constructed based on the formulae. There is a reasonable agreement between the analytical predictions and the experimental results. The effects of face material strain hardening and exchanging two faces, on the failure behavior of physically asymmetric metal sandwich beams are studied. Optimal designs are performed for the load-carrying capacity of physically asymmetric sandwich beams under three-point bending. Based on the optimization results, a method to compare the performances of physically asymmetric sandwich beams with various material combinations is proposed.

Free vibration analysis of metal foam core sandwich beams on elastic foundation using Chebyshev collocation method

In this paper, free vibration of a metal foam core sandwich (MFCS) beam embedded in Winkler–Pasternak elastic foundation is studied using the Chebyshev collocation method (CCM). This method can achieve high precision within the range allowed by the effective number of bits of computers. Three foam distribution types along the thickness direction are considered for the core. The Timoshenko beam theory is adopted and Hamilton’s principle is utilized to derive the boundary conditions and governing equations of the model. The numerical results show that natural frequencies of the sandwich beam initially increase and then decrease with the rise in thickness of metal foam core. By arranging the foam distribution in the core, natural frequencies of the sandwich beam can be significantly changed. Moreover, natural frequencies of the uniform foam distribution beam are insensitive to the foam coefficient. For the beam with non-uniform foam distribution, however, the natural frequencies increase or decrease with the foam coefficient, depending closely on the foam type. In addition, the present method is validated by comparing with the published ones for special cases.

On low-velocity impact response of metal foam core sandwich beam: A dual beam model

A theoretical procedure for dynamic response of metal foam core sandwich beams struck by a heavy mass with low-velocity is developed to consider the combined local denting and global deformation. Analysis focuses on effect of local denting on global deformation and inertial effect of the structure. Large deflection effects are determined by using the membrane factor method. A set of finite element simulations is carried out to validate the model predictions. It is demonstrated that the model predictions are in good agreement with the finite element computations. The sandwich beam is strengthened with the deflection increasing.

Indentation of Metal Foam Core Sandwich Beams: Experimental and Theoretical Investigations

Indentation behavior of metal foam core sandwich beams is investigated experimentally and theoretically. The deformation mechanisms of indentation are explored. The interaction of plastic bending and stretching in the local deformation regions of the top face sheet is considered. An analytical model is developed to predict large deflections of indentation of the sandwich beams transversely loaded at any location of the span. The analytical predictions are in good agreement with experiment results. Effects of the punch shape, the face sheet thickness and loading location on the indentation are discussed. It is shown that the loading location drives various deformation mechanisms of indentation for a given sandwich beam. The membrane force plays an important role in the large deflection of indentation of sandwich beams when the loading point exceeds the face sheet thickness.

The initial plastic failure of fully clamped geometrical asymmetric metal foam core sandwich beams

The initial plastic failure of fully clamped geometrical asymmetric metal foam core sandwich beams is analytically and experimentally investigated. Initial failure modes of the clamped asymmetric sandwich beams are observed, i.e. face yield, core shear and indentation. The analytical formulae for the initial failure loads are developed and used to construct the initial failure mechanism maps for the fully clamped geometrical asymmetric sandwich beams. It is shown that the initial failure modes of the sandwich beams depend on geometry and material properties of the sandwich beams. The predicted failure mechanisms of fully clamped asymmetrical sandwich beams are consistent with the experimental results and obviously different from those of simply supported ones. Finally, the minimum weight designs are presented by using the analytical formulae.

The Failure Behavior of Geometrically Asymmetric Metal Foam Core Sandwich Beams Under Three-Point Bending

The failure behavior of geometrically asymmetric sandwich beams with a metal foam core is analytically and experimentally investigated. New initial failure modes of the asymmetric sandwich beams are observed under three-point bending, i.e., face yield, face wrinkling, core shear A, core shear AB, core shear A-AB, and indentation. It is shown that the initial failure modes of sandwich beams depend on the span of the beam, the thicknesses of top and bottom face sheets, core height and material properties. We derived the analytical formulae for the initial failure loads and then constructed the initial failure mechanism maps for the geometrically asymmetric sandwich beams. It is shown that the analytically predicted initial failure mechanism maps are in good agreement with the experimental results, which are clearly different from the symmetric sandwich beams. As a preliminary application, the minimum weight designs are presented for asymmetric metal sandwich beams.

Effects of material uncertainty in the structural response of metal foam core sandwich beams

The present study is concerned with a numerical analysis of the uncertainties in the response of foam core sandwich structures caused by the uncertain microstructure of the core material. In the sense of an integrated computational materials engineering type approach, a three-step procedure is proposed. In the first step, the effective material properties of the core material are computed. For this purpose, a probabilistic homogenization procedure is adopted for the prediction of all elastic constants together with their probability distributions as well as all spatial correlations and interrelations between the individual parameters. In the second step, a random field model for the core material is derived, based on the homogenization results obtained in the first step. The random fields are found to reproduce all stochastic features of the uncertain core material in a proper manner. Using the random field description as an input for a Monte-Carlo-type structural analysis, the uncertainties in the stiffness and strength of sandwich structures are computed in the third step. The capabilities of the proposed procedure are demonstrated using the example of a single edge clamped sandwich beam under transverse loads.

Large Deflection of a Pin-Supported Slender Geometrically Asymmetric Sandwich Beam under Transverse Loading

The objective of this work is to study the large deflection of a pin-supported slender geometrically asymmetric metal foam core sandwich beam under transverse loading by a flat punch. Based on the yield criterion for geometrically asymmetric metal foam core sandwich structure, analytical solution for the large deflection of a pin-supported slender sandwich beam is obtained, in which the interaction of bending and stretching induced by large deflection is considered. The finite element results confirm the accuracy of the analytical solutions. The effects of asymmetric factor and boundary condition on the structural response of the asymmetric sandwich beam are discussed in detail. It is shown that the axial stretching induced by large deflection plays an important role in the load-carrying and energy absorption capacities of geometrically asymmetric sandwich structure.

Numerical assessment of disorder effects in metal foam core sandwich beams based on a local homogenization procedure

AbstractThe present study is concerned with a numerical procedure for prediction of uncertainty effects in sandwich structures with disordered cores. The approach is based on probability distributions of different material properties and their spatial correlation which are the results of the multiple homogenization analysis of testing volume elements. In order to illustrate the essential difference in the results of material uncertainties between computations using random fields and a deterministic approach both methods are applied to a single edge clamped sandwich beam with a metal foam core which is loaded by a force at the free end. (© 2012 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low-velocity impact response of geometrically asymmetric slender sandwich beams with metal foam core

The low-velocity impact response of fully clamped slender metal foam core sandwich beams with geometrically asymmetric cross-section struck by a heavy mass at midspan is investigated. The exact and approximate yield criteria for metal sandwich cross-section are presented considering the effect of core strength. Using the yield criteria, the analytical solutions for large deflection of the fully clamped slender sandwich beams, including dynamic and quasi-static solutions, are derived respectively. Also, finite element (FE) calculations are carried out to validate the analytical model. Moreover, the effects of material elasticity and strain hardening of face sheets are considered in FE analysis. Comparisons of the FE results and analytical solutions reveal that the present analytical model enables the acceptable predictions of the low-velocity impact response of fully clamped asymmetric slender sandwich beams. Material elasticity and strain hardening of face sheets have minor effects on dynamic response.

Low-velocity impact response of fully clamped metal foam core sandwich beam incorporating local denting effect

Local denting caused by low-velocity heavy mass impact is one of the active failure mechanisms of sandwich structures, which is important for the structural integrity assessment of sandwich structures. The objective of this work is to investigate the low-velocity impact response of metal foam core sandwich beams incorporating local denting effect. Analytical and numerical solutions are obtained for the structural response of fully clamped sandwich beams struck by a heavy mass with low velocity. The effects of local denting and foam core strength on the overall deformation of the sandwich beams are considered in theoretical analysis. Comparisons of the analytical and numerical results are presented and good agreement is achieved between the predictions and numerical results. It is seen that the load-carrying capacity of sandwich structures may be overestimated if the effect of local denting is neglected in theoretical analysis.

Plastic Analysis of Metal Foam Core Sandwich Beam Transversely Loaded by a Flat Punch: Combined Local Denting and Overall Deformation

The objective of this work is to investigate the quasi-static plastic behavior of a fully clamped metal foam core sandwich beam transversely loaded by a flat punch. A rigid-plastic beam-on-foundation model is extended to study the local denting deformation of a metal foam core sandwich beam. The effects of local denting and core strength on the overall deformation are incorporated in the analysis. Analytical solutions are derived for three different regimes of post-yield deformation mechanisms. Additionally, finite element results are obtained. Comparisons of the present analytical predictions with numerical, previous experimental, and analytical results are presented, respectively. It is shown that local denting has a significant effect on the finite deflection response of the metal foam core sandwich structure. The load-carrying and energy absorption capacities of sandwich beams may be overestimated if the effect of local denting is neglected in analysis. It is demonstrated that the present analytial model can reasonably predict the behaviors of post-yield deformation of sandwich beams. Moreover, the present analytical method can be extended to predict the low velocity/energy impact problems of sandwich structures.

Large Deflection of Geometrically Asymmetric Metal Foam Core Sandwich Beam Transversely Loaded by a Flat Punch

The objective of this work is to study the large deflection of geometrically asymmetric metal foam core sandwich beam under transverse loading by a fiat punch. A yield criterion is proposed for geometrically asymmetric metal foam core sandwich structures, and then analytical solution for the large deflection of a fully clamped slender sandwich beam is obtained, in which the interaction of bending and stretching induced by large deflection is considered. Also, finite element (FE) analysis is carried out. Comparisons of the analytical solution with numerical results are presented and good agreements are found. The effects of asymmetric factor, core strength and loading punch size on the structural response of asymmetric sandwich beam are discussed in detail. It is shown that the axial stretching induced by large deflection has significant effect on the load-carrying and energy absorption capacities of geometrically asymmetric sandwich structure, but the effect of asymmetry is negligible as the deflection is larger than the depth of the sandwich beam.

Analytical Solution for Pin-Supported Metal Foam Core Sandwich Beam with Local Denting

Structural response of pin-supported metallic foam core sandwich beam is theoretically investigated. Effects of local denting and core strength and interaction of bending and axial stretching are considered in analysis. A rigid-plastic beam-on-foundation is employed to consider local denting deformation. The local denting continues during the overall deformation of sandwich beam. It is shown that upon neglecting the effect of local denting, the load-carrying capacity and energy absorption of sandwich beam may be overestimated, and the normal axial (membrane) force associated with plastic stretching substantially stiffens the sandwich beams.

Low-velocity heavy-mass impact response of slender metal foam core sandwich beam

Abstract The objective of this work is to investigate the dynamic large deflection response of fully clamped metal foam core sandwich beam struck by a low-velocity heavy mass. Analytical solution and ‘bounds’ of dynamic solutions are derived, respectively. Also, finite element analysis is carried out to obtain the numerical solution of the problem. Comparisons of the dynamic, the quasi-static and numerical solutions for the non-dimensional maximum deflection of the sandwich beam with non-dimensional initial kinetic energy of the striker are presented for different cases of mass ratio, impact velocity and location. It is seen that the dynamic solution approaches the quasi-static one as the mass ratio of the striker to the beam is large enough, the quasi-static solution is in good agreement with the numerical results and both solutions lie in the ‘bounds’ of dynamic solutions. The quasi-static and numerical results for the impact force against the maximum deflection of the sandwich beam are obtained. It shows that the quasi-static solution can offer adequate accuracy to predict the low-velocity heavy-mass impact response of fully clamped sandwich beam.