Numerical and experimental study of the residual strength of CFRP laminate single-lap joint after transverse impact

Abstract

The adhesive joint is one of the efficient joining method in the composite structures, and it is important to comprehend the behavior of adhesive joints during impact in order to design stronger and safer structures. This paper investigates the residual strength of CFRP single-lap joints (SLJs) after transverse impact using both finite element analysis (FEA) and experimental methods. The impact damage FEA model and static tensile strength FEA model are established using the Hashin failure criterion and cohesive zone model. The impact damage results of the SLJs are transferred to static tensile strength FEA model using the restart analysis method. The CFRP single-lap joint models with different impact energies and lap lengths are analyzed. According to the research requirements, a total of 24 SLJ specimens with [45/0/-45/90]s lamination are manufactured, and the impact test and tensile strength test are conducted sequentially. For the SLJs with a 20 mm overlap length but different impact energies (1 J, 2 J, and 4 J), the maximum and minimum residual strength errors are 12.6 % and 6.2 % respectively. The results show that the tensile strength of the joint decreases significantly after impact. Specifically, the residual strength of the SLJ after a 4 J impact is 2902 N, whereas the strength of the non-impact SLJ is 4088 N. When considering the 20 mm, 30 mm, and 40 mm overlap length SLJs with a 4 J impact energy, the errors in the residual strength coefficients between FEA and experiment are all within 3 %. Additionally, the residual strength coefficient of a 40 mm overlap length increases by approximately 10 % compared to a 20 mm overlap length. These results demonstrate that the proposed FEA model can accurately simulate the impact and residual strength of SLJs with reasonable accuracy.