Mechanical Connection Strength Of The Composite Analysis And Influencing Factors,

With the extensive use of composite materials in aircraft structures, bolting and riveting are extensively used as a primary method of forming structural joints. However, designing bolted joints in composite structures is more complex than in metallic structures due to anisotropic material properties, complex failure modes and the inability of the composite to yield and a lot of expansive experiments are needed. Advanced numerical design methods for bolted joints in composite aircraft structures are expected by joints designers. To increase the efficiency of whole structures, the author performed the research on the composite bolted joints.According to different intention 2D and 3D FEM model were built respectively. Clamping force, countersunk head bolts, different distance between the fasteners and lap modes were considered to analyze the load distribution on the bolts. For the purpose of determining the load distribution on each bolt a computer program was developed. The results were compared with available experimental data and good correlation observed.Hashin criteria was improved based on damage mechanics, the experimental data and simulation results obtained from foreign thesis. The related material property reduction rules were proposed and cumulative damage was taken into account. Parametric studies were carried out to evaluate the effect of the new method.The obtained results were compared with experimental data and comparison showed good agreement between numerical and experimental method.In the last part, strength prediction for multi-bolted joints was discussed, and stack sequence, clamping force, countersunk head bolt, fastener material, distance between bolts and effect of secondary bending were taken into account.Except bolt-hole clearance, wash size etc. a major of parameters related to joints were considered, and some of them were validated by experimental data.