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Experiments were carried out to examine the behaviour of aluminium foams under quasistatic shear loading. Special fixtures were designed to clamp the both ends of a beam-like specimen while the load was applied via a punch, which led to failure by shearing along the clearance near the fixed end. Specimens were made of CYMAT foams with two nominal relative densities (12% and 17%) and several values of width. This study focuses on the maximum strength under shear and the essential energy in fracture. It has been found that the ultimate shear force increases linearly with the width of the beam, so does the total energy absorbed. Two empirical formulae have been obtained which relates to the relative density, respectively, the ultimate shear strength and energy absorbed in shearing.

Summary In principle, wave propagation in porous media can simultaneously trigger macroscopic fluid flow and thermal flow, which can be described by Biot's poroelasticity and Lord-Shulman thermoelasticity, respectively. The physical processes of those effects are significantly different, but phenomenologically, they can lead to identical wave attenuation and dispersion and are hard to be distinguished. By using Biot's virtual concept entropy flow, the Biot-consistent General Linear Solid (the GLS) framework and matrix notation, a rigorous and convenient tool is provided to reveal the similarities and disparities between poroelasticity and thermoelasticity. By using the same framework, a Biot-consistent thermo-poroelastic model is proposed to consider macroscopic effects of fluid and thermal flows simultaneously in an elegant way. These similarities allow us to directly translate many of the available results in poroelasticity to thermoelasticity and vice versa by a simple change of notation. The disparities indicate a fundamental difference in physical mechanisms. Plane-wave analysis shows that the primary P-wave modes of thermoelasticity and poroelasticity are all GSLS-equivalent (Generalized Standard Linear Solid) and can be identical if the model parameters are selected properly. However, the corresponding slow-wave modes have significantly different phase velocity dispersion although the attenuation spectra of which are identical. Such a surprising result can be explained by the GSLS-nonequivalence of the slow-wave modes and the fundamentally different mechanisms. As expected, the thermo-poroelastic model predicts four wave modes, which are the fast-P wave, slow-P wave, temperature wave (T-wave) and S-wave. Two attenuation peaks due to, respectively, the thermal- and fluid flow effects are predicted for the fast-P wave. The slow-P wave mode due to fluid flow is influenced by the thermal effects, but the T-wave seems unaffected by the fluid flow. The thermo-poroelastic model is then applied to laboratory observations at 200∼106 Hz for the brine-saturated tight sandstone under 35 MPa effective pressure. The unified model provides a convenient framework for studying geothermal exploration, thermal-enhanced oil recovery, and other applications involving temperature variations within the porous rock.

This paper is concerned with the load-carrying capacities of a circular sandwich panel with metallic foam core subjected to quasi-static pressure loading. The analysis is performed with a newly developed yield criterion for the sandwich cross section. The large deflection response is estimated by assuming a velocity field, which is defined based on the initial velocity field and the boundary condition. A finite element simulation has been performed to validate the analytical solution for the simply supported cases. Good agreement is found between the theoretical and finite element predictions for the load-deflection response.