Study Of Composite On Pinned-joint Strength

Along with the composite materials application expansion, the composite materials integral forming already could not satisfy the need of he actual situation, therefore it needs the partial formation, and used the glued joint or the mechanical joint assembles.Regarding the large-scale component, it often uses the mechanical joint, so it must carry on punch processing to the composite materials product, because the composite materials are composed by two heterogeneity material:resin substrates and the enhancement material,punch processing can shut off the textile fiber, creates the stress concentration, and in the system hole process, the resin and the textile fiber can have the stratification. The study found that the destruction of composite materials mainly in the joint parts, so the composite connection has the vital significance.Many scholars have done a lot of work about influence factors of mechanical connection of composites, including the size of holes, sample thickness, fiber layer order, clamping force, assembling clearance etc.But they did little work about the influence of the way of opening hole. Composite with open hole often require reinforcing,it is very important to do research on the effect of reinforcement to connection. Different preparation process, the properties of materials also will be different, it is also important to study the influence of Preparation Technology to composites connection.This paper studies the influence of different layer order to pin connection strength. Additionally this article through preparation interlaminar shear samples and made holes by two ways,study the influence of Preparation Technology to interlaminar shear strength.,and then study the influence of Preparation Technology to composites connection. This paper also studied the influence of reinforcing area to composites connection.By changing forming technology,we also study the influence of vacuum infusion processes and hand lay-up process to composite connection strength.Results showed that the damage form is different to different layer samples, the damage form in happen at the same time with other forms of destruction.,this was due to the different Angle layer caused by the differences,45°layer in outer help composite pin connection strength improved.Specimens'interlaminar shear strength by mechanical milling hole is higher than the mechanical borehole samples'interlaminar shear strength by 14%,showed the damage to composites by mechanical milling is bigger;the hole wall is scanned by scanning electron microscope,the hole wall by mechanical drilling can be observed obviously statified phenomenon,but the hole wall by mechanical milling is not apparent,further proved its pin connection strength of mechanical milling hole is higher than another by 13%.Research also found that reinforcing near the hole can help composite connection strength increase 20%～50%,but the strength is not better as the reinforcing area is bigger.The reinforcement should be the area of stress concentration, ensure area damage occurred in reinforcing area.The strength changes little when reinforcing ouer the area of stress concentration. In the same layer conditions the pin connection strength of composites made by hand is higher than the strength of samples made by vacuum infusion processes by 2.6%.