This paper investigates the behaviour of aluminium alloy plates with and without initial cracks under repeated impacts. Three series of impact tests were conducted to study the behaviour of circular plate that do not have any cracks (series B), have surface cracks with varying length (series L), and have cracks varying depths (series D). A hammer was dropped from the same height with a constant initial striking energy 60J for all tests. It was observed that plates with larger cracks carried smaller impact forces and assumed larger deformations. With the increase in impact number, the effects of crack lengths and depths on the dynamic behaviour became much more significant. Predictions using a rigid-plastic theoretical model were compared with these test results. With the stresses determined based on the true strain-stress curve obtained by standard tension test, the refined analytical formula provides better predictions that agree well with the lab tests.

Composite double-arrow auxetic structures were designed and fabricated. The local impact experiments were carried out on the auxetic structures to explore the dynamic responses and failure modes. The effects of relative density and impulse level on the impact properties were analyzed and discussed. As the relative density increased, the local deformation of the auxetic structures and the damage of the core layer decreased, and the overall response of the auxetic structure increased. The finite element model was used to simulate the impact responses of the auxetic structures, and the numerical simulation results were in good agreement with the experimental results.

High long-term stress on the plantar fascia (PF) is the main cause of plantar fasciitis. Changes in the midsole hardness (MH) of running shoes are an important factor leading to the alteration of the PF. This study aims to establish a finite-element (FE) model of the foot–shoe, and investigates the effects of midsole hardness on PF stress and strain. The FE foot–shoe model was built in ANSYS using computed-tomography imaging data. Static structural analysis was used to simulate the moment of running push and stretch. Plantar stress and strain under different MH levels were quantitatively analyzed. A complete and valid 3D FE model was established. With an increase in MH from 10 to 50 Shore A, the overall stress and strain of the PF were decreased by approximately 1.62%, and the metatarsophalangeal (MTP) joint flexion angle was decreased by approximately 26.2%. The height of the arch descent decreased by approximately 24.7%, but the peak pressure of the outsole increased by approximately 26.6%. The established model in this study was effective. For running shoes, increasing the MH reduces the stress and strain of PF, but also imposes a higher load on the foot.

This paper addresses a study on the resistance of a clamped rectangular plate quasi-statically punched at the mid-span by a rigid indenter with a knife and a flat edge shape, through simplified analytical method. A new membrane stretching pattern is proposed and the resistancepenetration response is obtained. To validate this analytical method, a series of quasi-static tests on specimens with three lengthwidth ratios and indenters with six different scantlings are conducted. The well-matching of the resistance–penetration curves from analytical calculations and those from experiments proves the validity of the proposed simplified analytical method. Based on the analytical method, the influences of the indenter size and the plate scantlings on the resistance are evaluated. Moreover, the analytical method proposed in this paper is proved to be able to predict the quasi-static response for a wide range of plate lengthwidth ratios as well as to forecast low-velocity impact dynamic responses.