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The controlled brittle failure of thermosetting fibre-reinforced polymer composites can provide a very efficient energy absorption mechanism. Consequently, the use of these materials in crashworthy vehicle designs has been the subject of considerable interest. In this respect, their more widespread application has been limited by the complexity of their collapse behavior. This article reviews the current level of understanding in this field, including the correlations between failure mode and energy absorption, the principal material, geometric, and physical parameters relevant to crashworthy design and methods for predicting the energy absorption capability of polymer composites. Areas which require further investigation are identified. This review article contains 70 references.

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With reduced operational energy consumption as the primary driver, a cross-industry consortium of vehicle manufacturers has explored some of the issues surrounding the introduction of lightweight materials into metro vehicles. Taking today's vehicles as the starting point, the aim of the study was to examine the current barriers that need to be removed or overcome in order to realize the economic and environmental benefits of lightweight materials. From a technical perspective, the use of a systematic approach to material selection is described that matches the design requirements and constraints of a given application to potentially suitable candidate materials within a large database. The approach is illustrated by a case study in which a 57 per cent mass saving is achieved for a metro vehicle interior grab rail. Estimates are also provided for the magnitude of the operational energy and cost savings that can be achieved through metro vehicle lightweighting. For the particular scenario considered in this article, a 10 per cent reduction in vehicle mass was estimated to equate to a 7 per cent saving in energy consumption and a corresponding 100 000 € annual operational cost saving per vehicle. Such data can now be used to support decision making with respect to the benefits of lightweighting.

This paper describes an investigation into the localized impact response of aluminium honeycombs and sandwich panels from the perspective of their use in occupant head protection applications. A programme of quasi-static and dynamic low-velocity impact testing using a hemispheric 'head form' impactor is described. From this, design data is presented in terms of acceleration histories and head injury criterion values. Furthermore, a simple analytical model is described for predicting acceleration histories for preliminary design purposes.

Three population-based optimization techniques -particle swarm optimization, ant colony optimization, and simulated annealing -are applied to the multi-objective design of sandwich materials. The formulation of the algorithms is described, along with metrics for quantifying their performance. For the case study considered of a sandwich beam in bending, it is shown that the ant colony technique out-performs the other two algorithms with respect to identifying optimal geometries, materials, and lay-ups for a stiff sandwich in which low mass and low cost are the design objectives. The particle swarm and simulated annealing algorithms were found to have particular difficulties in handling the optimization of multi-ply oriented fiber-reinforced polymer facing laminates.

Sandwich materials, consisting of two thin, stiff facings separated by a low density core, can be used to produce structures that are both light and flexurally rigid. However, the optimisation of sandwich materials is not straightforward. This is because there are typically multiple design variables and multiple design objectives. Particle swarm optimisation is a heuristic method that is capable of finding optimal solutions within complex design spaces. The application of particle swarm optimisation to multi-objective sandwich beam problems is described here. The free variables investigated include the facing thickness, and the facing and core materials. Furthermore, for the facings, multiply, oriented laminate constructions are considered. Based on these inputs, sandwich beams are optimised for stiffness, mass and cost. The results show that the particle swarm optimisation algorithm is effective at finding a range of optimal solutions for the given objectives.