Lightweight weft-knitted tubular lattice composite for energy absorption applications: An experimental and numerical study

Strong, lightweight structures are increasingly in demand for various engineering applications. Here we present a method to produce a lightweight lattice composite tube with hexagonal unit cells using a high production rate, textile-based method. A weft knitting process was employed for the first time to produce lattice preforms made of a common high-performance E-glass yarn. The lattice preforms were impregnated with epoxy resin to create lattice composite tubes of various sizes. The crashworthiness performance of the as-fabricated lattice composite tubes was evaluated experimentally and numerically in quasi-static axial compression tests. Based on the findings and the results of comparisons made with expanded metal tubes, the proposed lattice composite system exhibited comparable energy absorption properties. Finite element simulations provided insight into the failure mechanism of the proposed structure for predicting the energy absorption behavior of the composite lattice. The simulations revealed that further improvement was possible if global buckling could be controlled, which was carried out in the current study via polyurethane foam injection into the tube and using a concentric placement of multiple tubes of various sizes. Overall, the proposed lightweight, knitted lattice composite tube showed enhanced performance in its strength.