| With the development of aircraft structures, composite materials have been widely used in mainload-bearing components in which bolted joints between thick composite laminates are indispensable.Due to the load non-uniformity existed in the thickness direction, the bending of bolt andnonuniformity of hole-edge stress distribution in the thickness direction occur, which results in somedeviations in the analysis for thick laminates based on the2D finite element and theoricatical analysisfor the traditional thin laminates. Therefore, researches on the bearing strength of bolted jointsbetween thick composite laminates have theoretical significance and practical value.Based on the experimental study and numerical simulation, the main contents are as follows:(1) The bearing strengths of bolted joints between T800S/BA9918thick composite laminatespecies with different layers, connecting styles and geometrical sizes were tested by using the fixturefor single-lap bolted jointed specimen which was designed by referring to the testing standard.Experimental phenomenon and failure mode of jointed specimen were investigated, and some resultswere finally obtained.(2) The3D finite element modelling for predicting bearing strengths of single-bolt, single-lapand single-bolt, double-lap and double-bolt, single-lap thick composite laminate specimens wasestablished based on the ABAQUS software. The type and evolution of different damage modes weresimulated by UMAT user-defined subroutine based on three-dimensional Hashin failure criteria andcorresponding stiffness degradation scheme. The reasonability and effectiveness of the model werevalidated by the comparison between numerical simulations and experimental data.(3) The2D finite element model was established for predicting the bearing strength of single-bolt,single-lap thin composite laminates based on ABAQUS software. As increasing the laminatethicknesses, calculation deviations of the2D model were analysed and the application scope oflaminate thickness for2D model was obtained. Influences of different bolt models and frictioncoefficients on the compression strength were discussed. And effects of the increase of laminatethickness on the compression strength were mainly studied.(4) According to the testing results, the Hart-Smith engineering algorithm was modified to applyto areas of thick laminates. |
