Study on low-velocity impact and residual strength at high temperatures of composite laminates

Abstract

In this paper, low-velocity impact characteristics and residual tensile/compressive strength of composite laminates at high temperatures are experimentally and analytically investigated. Low-velocity impact tests at room temperature were performed using a drop-weight apparatus, and residual strength tests at high temperatures were performed using a hydraulic MTS machine. The experimental results show that both residual tensile and compressive strength decrease monotonically with the increase of impact energy, while the variation trend of residual tensile/compressive strength of composite laminates keeps the same with longitudinal tensile/compressive strength with the increase of temperature. In addition, a new stress-based delamination failure criterion was established, in which the delamination is considered to be controlled by the difference between through-thickness stresses of adjacent layers. Once delamination occurs, only the elements below the interface are marked with delamination, whereas the material properties of the elements on both sides of the interface are reduced simultaneously. In this way, delamination can be defined more precisely without cohesive elements, and a considerable reduction in CPU time can be achieved. Combined with extended Hashin failure criteria, an integrated finite element model was established to simulate low-velocity impact damage and to predict residual tensile and compressive strength of composite laminates. The numerical results show good agreements with experimental data.