ghua Qin

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.

A YIELD CRITERION AND PLASTIC ANALYSIS FOR PHYSICALLY ASYMMETRIC SANDWICH BEAM WITH METAL FOAM CORE

A yield criterion for physically asymmetric sandwich cross-sections is proposed in this paper. Using the yield criterion, analytical solutions for the large deflections of fully clamped asymmetric slender sandwich beams transversely loaded by a flat punch at the midspan are derived considering the core strength effect and interaction of bending and axial stretching. Finite element (FE) method is employed to predict the large deflection behavior of the sandwich beams. Good agreement is achieved between the analytical predictions and FE results. Effects of asymmetric factor, core strength and loading punch size are also discussed. It is demonstrated that core strength and loading punch size have significant influences on the load-carrying and energy absorption capacities of physically asymmetric metal sandwich beams while the asymmetry effect could be neglected when the deflection exceeds sandwich beam depth.

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.

Indentation of sandwich beams with metal foam core

Abstract The quasi-static indentation behavior of sandwich beams with a metal foam core was investigated. An analytical model was developed to predict the large deflections of indention of the sandwich beams with a metal foam core subjected to a concentrated loading. The interaction of plastic bending and stretching in the local deformation regions of the face sheet was considered in the analytical model. Moreover, the effects of the shear strength of the foam core on the indentation behavior were discussed in detail. The finite element simulations were preformed to validate the theoretical model. Comparisons between the analytical predictions and finite element results were conducted and good agreement was achieved. The results show that the membrane force dominates indentation behavior of the sandwich beams when the maximum deflection exceeds the thickness of the face sheet.

Analytical Solution for the Large Deflection of Fully Clamped Metallic Foam Sandwich Beam

A unified yield criterion is proposed in this paper, which is valid for the metallic sandwich sections with various core strength and geometrical dimensions and can reduce to the classical yield criteria for solid monolithic section and sandwich section with weak core, respectively. Then, the unified yield criterion is used to derive the analytical solution for the large deflection of fully clamped metallic sandwich beam subject to a transversely concentrated load, in which the interaction of bending and stretching is considered. Comparisons of the present solutions with experimental results are carried out and good agreements are found. It is seen that the axial stretching induced by large deflection has a significant effect on the deflection of sandwich structure in the post-yield regime, and the load carrying capacity of metallic foam core sandwich beam may be underestimated as the core strength is neglected in analysis.

A Yield Criterion for Hybrid Asymmetric Metal Sandwich Structures and its Application

In this paper, a yield criterion for hybrid asymmetric metal sandwich structure is proposed including the combined effects of geometrical and physical asymmetries. Taking account of the interaction of bending and axial stretching and using the yield criterion, we obtain an analytical solution for large deflections of fully clamped hybrid asymmetric sandwich beam transversely loaded by a flat punch at mid-span. Moreover, finite element analysis is performed and good agreement is achieved between numerical results and analytical predictions. It is shown that the well-designed hybrid asymmetric sandwich beam may have higher load-carrying capacity than the conventional geometrically or physically asymmetric counterpart in large deflections.

Resistance of metallic foam-filled trapezoidal plate core sandwich plate to blast loading

Abstract The resistance of metallic foam‐filled sandwich plate with trapezoidal plate core under blast loading is studied. The role of metal foam filling the interstice of metal sandwich plate is investigated to ascertain the effect of foam on the structural performance. The results are compared with those of unfilled trapezoidal plate core sandwich plate having the same weight. Large deflection and resistance of metallic sandwich plate to blast loading is analytically and numerically analysed. The impulsive blast loading is applied to the sandwich plate with infinite length and fully clamped along the sides. Additionally, the normal and longitudinal compressive stresses in the foam‐filled trapezoidal plate core are analytically obtained.

Large-Deflection Bending of Clamped Metal Foam-Filled Rectangular Tubes

Large-deflection bending of fully clamped slender metal foam-filled rectangular tubes is investigated theoretically, experimentally and numerically. A plastic yield criterion for the foam-filled rectangular tube is proposed. Considering the filled foam strength effect and the interaction of bending and stretching, an analytical solution is proposed to predict the structural response of the foam-filled rectangular tubes transversely loaded by a flat punch. Clamped bending tests of aluminium alloy foam-filled rectangular tubes are conducted. The analytical model captures experimental results reasonably. Numerical calculations are carried out to predict the large-deflection behavior of the foam-filled tubes, and good agreement is achieved between the analytical solutions and numerical results. The effects of wall thickness of tube, punch size and filled foam strength are discussed in detail. It is demonstrated that the present analytical model can reasonably predict the post-yield behavior of the foam-filled rectangular tube.

Quasi-Static Crush Behavior of Aluminum Hexagonal Honeycomb with Perforated Cell Walls

The crush behavior of aluminum hexagonal honeycomb with perforated cell walls under out-of-plane quasi-static loadings was experimentally investigated. The honeycomb specimens with different heights were compressed in axial direction under displacement control. There are four sequential deformation stages during compression: linear elasticity, buckling, crushing and densification state. The performances of hexagonal honeycombs with perforated cell walls were compared with those of imperforated hexagonal honeycombs with the same sizes. The results show that the perforated holes weaken the strength of honeycombs markedly and the strength of honeycomb decreases with the specimen height.

Low velocity impact response of lightweight metal sandwich panel with corrugated core

Abstract Low velocity impact resistance of a lightweight metal sandwich panel with a corrugated core struck by a heavy mass is investigated. Face sheets and the corrugated core are made of the same material. Large energy impact is considered that is sufficient to produce lateral deflection. Fracture is not included in analysis and it is assumed that the sandwich panel has sufficient ductility to sustain the large deformation. It is shown that the metal sandwich panel with a corrugated core possesses higher impact resistance compared to monolithic solid plate of the same mass. In addition, analytical predictions are obtained and agree well with finite element results.