Long Glass Fiber Reinforced Reaction Injection Molding Polyurethane Composite Bolt Connection Performance Study

With the Long Fiber Reinforced Polyurethane Reaction Injection Molding (LFI-RRIM PU) composite material was widely used in the automotive industry, its product used from auxiliary sub-bearing parts to the main load-bearing parts, and it connected with the metal material in more and more occasion. Due to the unevenness of LFI-RRIM PU composite materials in joints, it was very important to analysis the bolt connection performance. This paper did some research to find the way to ensure the connection strength and improve the connection efficiency of LFI-RRIM PU composite bolts.The paper was divided into four parts. Firstly, the mechanical properties and failure mechanisms of LFI-RRIM PU composite were analyzed by tensile properties test, and prediction equation of the tensile properties was established.in order to determine the appropriate failure criteria. Secondly, the single bolt connection performance of LFI-RRIM PU composite material was analyzed by orthogonal experiments as well as ABAQUS finite element analysis. The main factors included wide-diameter ratio, end diameter ratio, thickness to diameter ratio, as well as assembly preload, etc. In addition, the method of improving the LFI-RRIM PU composite bolted strength was analyzed by the finite element simulation of bolts connection local enhancement measures (such as additions boss and inlaid nuts, etc.)Thirdly, multi-bolt connection performance of LFI-RRIM composite material was analyzed by ABAQUS finite element analysis software. The main factors included end distance, line spacing, margins, line distance the thickness, assembly preload, thickness to diameter ratio and assembly preload of connecting plate, etc. At last, based on the multi-bolting simulation of LFI-RRIM PU composite, an optimization of those dimensional factors impacting on multi-bolting was completed to homogenize the load distribution, which satisfied the strength of multi-bolting and improved the joint efficiency. The result provides a basis for structural design of LFI-RRIM PU composite.