Influence of spherical triggers on axial collapse of tapered tubes

Abstract

Thin-walled structures are widely used in the design of energy absorbers due to their excellent performance on crashworthiness. Various designs and optimisations on the internal and external structures, materials, and fillers of thin-walled structures are intensively studied. However, traditional thin-walled structures often exhibit excessive initial peak crushing force (IPCF) and large fluctuations in the force-displacement curve under axial load. This paper optimises the traditional thin-walled structure from the perspective of biological structure and proposes a new tapered structure that mimics the shape of a conch shell, named ‘Conch tube’ (CT), which aims to stabilise the crushing process and improve energy absorption capacity. Numerical simulations are used to study the effects of thread pitch and groove width on the deformation mode and performance on crashworthiness of the CT. The results show that the deformation mode of the CTs can be changed from the spiral groove trigger mode to the progressive mode by controlling the thread pitch and groove width. Therefore, by controlling the pitch and groove width, the CT can obtain a lower IPCF. Finally, multi-objective optimisation based on active learning is used to obtain the best CT structure. Compared with the traditional conical tube, the CT has an excellent crashworthiness performance. The effectiveness of the spiral groove structure in enhancing energy absorption and reducing IPCF is confirmed.