A brief analysis is presented of how heat transfer takes place in porous materials of various types. The emphasis is on materials able to withstand extremes of temperature, gas pressure, irradiation, etc., i.e. metals and ceramics, rather than polymers. A primary aim is commonly to maximize either the thermal resistance (i.e. provide insulation) or the rate of thermal equilibration between the material and a fluid passing through it (i.e. to facilitate heat exchange). The main structural characteristics concern porosity (void content), anisotropy, pore connectivity and scale. The effect of scale is complex, since the permeability decreases as the structure is refined, but the interfacial area for fluid–solid heat exchange is, thereby, raised. The durability of the pore structure may also be an issue, with a possible disadvantage of finer scale structures being poor microstructural stability under service conditions. Finally, good mechanical properties may be required, since the development of thermal gradients, high fluid fluxes, etc. can generate substantial levels of stress. There are, thus, some complex interplays between service conditions, pore architecture/scale, fluid permeation characteristics, convective heat flow, thermal conduction and radiative heat transfer. Such interplays are illustrated with reference to three examples: (i) a thermal barrier coating in a gas turbine engine; (ii) a Space Shuttle tile; and (iii) a Stirling engine heat exchanger. Highly porous, permeable materials are often made by bonding fibres together into a network structure and much of the analysis presented here is oriented towards such materials.

This is a review of the current state‐of‐the‐art regarding a particular approach to extraction of the (quasistatic) stress–strain relationship of a metallic sample from an indentation experiment. It is based on the application of a relatively high load (kN range) to the sample via a large spherical indenter (≈1 mm radius), followed by measurement of the indent profile. This profile is then used as the target outcome for inverse finite element method (FEM) modeling of the test, aimed at converging on the best fit set of parameter values in a constitutive plasticity law (true stress–true strain relationship). This can then be used to simulate any specified loading configuration, including a conventional tensile test. Commercial products are now available in which the indentation, profilometry, and convergence operations are all automated and completed within a few minutes. The review covers the various conceptual and practical issues involved in implementation and optimization of these procedures, including both those related to the measurement system (experimental and FEM simulation) and those associated with the sample (such as anisotropy, inhomogeneities, and residual stresses). An attempt is made to convey an impression of the expected levels of reliability and also the scope for obtaining insights that are not readily obtainable using other types of test.