[en] A systematic procedure is presented for comparing the relative performance of sandwich beams with various combinations of materials in three-point bending. Operative failure mechanisms are identified and failure maps are constructed. The geometry of sandwich beams is optimised to minimise the mass for a required load bearing capacity in three-point bending

[en] The elasto-plastic torsional response of a thin metal wire is analysed using the phenomenological flow theory of strain-gradient plasticity proposed by Fleck and Willis (2009 Part I J. Mech. Phys. Solids 57 161, 2009 Part II J. Mech. Phys. Solids 57 1045). Numerical results are obtained via minimum principles, and closed-form expressions are derived in the limit of vanishing elasticity. An elevation of both initial yield and hardening rate is predicted with decreasing wire diameter. The role of the stored energy of cold work is investigated, and its implications for kinematic hardening are discussed

[en] The effect of thermal dispersion upon heat transfer across a periodic array of parallel plates is studied. Three basic heat transfer problems are addressed, each for steady, fully-developed, laminar fluid flow: (a) transient heat transfer due to an arbitrary initial temperature distribution within the fluid, (b) steady heat transfer with constant heat flux on all plate surfaces, and (c) steady heat transfer with constant wall temperatures. For problems (a) and (b), the effective thermal dispersivity scales with the Peclet number Pe according to 1 + CPe², where the coefficient C is independent of Pe. For problem (c) the coefficient C is a function of Pe.

[en] Open-cell graphitic foams were fabricated by chemical vapor deposition using nickel templates and their compressive responses were measured over a range of relative densities. The mechanical response required an interpretation in terms of a hierarchical micromechanical model, spanning 3 distinct length scales. The power law scaling of elastic modulus and yield strength versus relative density suggests that the cell walls of the graphitic foam deform by bending. The length scale of the unit cell of the foam is set by the length of the struts comprising the cell wall, and is termed level I. The cell walls comprise hollow triangular tubes, and bending of these strut-like tubes involves axial stretching of the tube walls. This length scale is termed level II. In turn, the tube walls form a wavy stack of graphitic layers, and this waviness induces interlayer shear of the graphitic layers when the tube walls are subjected to axial stretch. The thickness of the tube wall defines the third length scale, termed level III. We show that the addition of a thin, flexible ceramic Al₂O₃ scaffold stiffens and strengthens the foam, yet preserves the power law scaling. The hierarchical model gives fresh insight into the mechanical properties of foams with cell walls made from emergent 2D layered solids.