Low-velocity impact and residual flexural behaviors of 2.5-D woven composite under accelerated thermal ageing: Experiment and numerical modelling

This paper aims to investigate the thermal ageing effect on the impact and post-impact behaviors of 2.5-D woven composites. A combined experimental and numerical study is carried out over a range of impact energies with the subsequent residual flexural tests on both aged (in the air for 32 days at 180℃) and pristine samples. Low-velocity impact tests are performed to assess the degradation of impact-resistant ability in terms of energy absorption mechanism and failure modes. Subsequently, three-point bending tests are conducted to determine the post-impact behaviors with respect to strain concentration, stress transfer and damage evolution process. The strain fields in the finite element model are compared with experimental results obtained by the DIC method. A larger strain concentration area could be found at higher energy levels and longer ageing time. Extended impact damage, such as fiber breakage and delamination, plays an important role in load transfer process in post-impact behavior, thus leading to the decrease of residual stress in aged samples.