Smart materials have drawn significant attention and interest in recent years. In particular, shape memory alloys (SMAs), a class of smart materials, are gaining importance in various fields: microsystems, biomedicine, robotics, aerospace and automotive. SMAs consist of two crystallographic phases, austenite and martensite. These types of materials can undergo large reversible deformations due to their capability of reversible phase transformation. One method utilised to exploit the exotic properties of SMAs is embedding such materials in the form of wires or continuous fibres, ribbons, or short fibres within a composite material, resulting in a hybrid smart composite. SMAs can present an attractive means for reducing stresses and deflections in the structures subjected to an impact, and they can generate significant tensile stresses. Furthermore, SMAs reinforced polymer composites have enormous potential as lightweight materials. In this direction, considering SMAs' superelastic effect, they are ideal candidates for energy-absorbing applications and the automotive industry. However, the integration of SMA composites for automotive structural components has not yet been fully explored and requires further investigation. The current study investigates innovative methods to incorporate SMAs within a composite material for an automotive structural component to enhance crashworthiness behaviour in the event of a collision. Numerical analysis of an SMA hybrid composite material, namely TiNi fibre-impregnated carbon fibre reinforced polymer (CFRP), for an automotive front structure crash box is considered. The materials' properties and the impact behaviours are simulated and verified by employing computational models discretised in LS-Dyna commercial explicit finite element analysis (FEA) software. The most relevant material models in Ls-Dyna are MAT_054/055 *MAT_ENHANCED_COMPOSITE_DAMAGE for composite materials and MAT_030 *MAT_SHAPE_MEMORY, which is ideal for the behaviour of the SMAs. Numerical results show the SMA's contribution in improving the specific energy absorption (SEA) and the stability of the crushing process progression in comparison to neat CFRP composites.

Dr. Ahmed Elmasry, Research Fellow and Academic Assistant, Northumbria University