Research On Bearing Strength Of Thick Composite Laminates Single Bolted Joint

With the increase of composite structures' thickness, the load non-uniformity existed in the thickness direction lead to the occurrence of the bending of bolt and non-uniformity of hole-edge stress distribution in thickness direction, which result in some deviations in the analysis for thick laminates based on theoretical analysis for the original thin laminates. Therefore, researches on the joint strength of bolted joints between thick composite laminates have theoretical significance and practical value.Based on the experimental study, literature reference and numerical simulation, the main contents are as follows:(1) T300/5405 composite open-hole laminate has been chose to do the experiment. The 3D finite element model for predicting strengths of open-hole composite laminate specimens was established based on the ABAQUS software. The type and evolution of different damage modes were simulated by UMAT user-defined subroutine based on three-dimensional Hashin failure criteria and global stiffness degradation scheme. The reasonability and effectiveness of the model were validated by the comparison between numerical simulations and experimental data. The impacts that thickness?layer sequence and w/d have on the structure have been studied.(2) T800S/BA9918 composite single bolt double lap composite joint has been chose to do the experiment. The 3D finite element model for predicting joint strengths of the structure was established based on the ABAQUS software with the three-dimensional Hashin failure criteria and global stiffness degradation scheme. The impacts that thickness?layer sequence and w/d has on the structure have been studied.(3) The 3D finite element model for predicting joint strengths of the single bolt single lap composite joint was established based on the ABAQUS software with the three-dimensional Hashin failure criteria. By comparing the simulation results based on the global degradation scheme and partition degradation scheme it show that the global degradation scheme can't correctly simulate the joint strength of the structure and the result of partition degradation scheme is more accuracy. The impacts that thickness?clearance have and t/d?layer sequence ?clearance?pre-tightening load?friction fore and w/d on the structure have been analyzed and studied.