Mechanical Properties Analysis Of Carbon Fiber Composites Bolted Joints

Carbon fiber composite materials are popular with people for some of their good properties such as excellent high strength,light weight,stable thermal physical and so on.With the improvement of the production process of composite materials,the application of carbon fiber composite materials has gradually expanded to civilian use,which is widely used in automobile frame,sports equipment and building reinforcement,not just for aerospace application.In the large-scale structure design,the joint is inevitable and the weak link of the structure,so it is certainly necessary to study the mechanical properties of carbon fiber composite materials.The anisotropy of the mechanical properties of the carbon fiber composites,the diversity and complexity of the failure modes,and the non-linearity of the contact problems in the joint structure increase the difficulty of analyzing the joint structure.In order to obtain the failure mechanism of the carbon fiber composite structure under static tensile and impact loading,the content of this paper is determined.The acoustic emission detection technology was used to study the static tensile properties and damage form of its joint structure,the influence factors of mechanical properties in the mechanical joint structure under static tensile load and the characteristics of the structural damage acoustic emission signal are analyzed by the combination of test and numerical simulation.The impact properties of the metal-composite structure were studied by experimental method.The main work is as follows:The tensile mechanical properties of the single shear bolt joint structure of the carbon fiber composite were studied,and the influence laws of different geometrical dimensions on the bearing capacity and failure mode of the jointing structure was obtained.The damage form of the composites joint under different geometric dimensions is analyzed by acoustic emission technique.The acoustic emission signals of the joint structures in different failure modes are obtained,also the development rules of different damage forms in the process of structural failure are obtained,which reveals the failure mechanism of the joint structure.The failure model of carbon fiber composites under static tensile load is established,and the accuracy of the numerical model is proved according to the experimental results,which provides a reliable model for further analyzing the influence of structure type on its mechanical properties.The impact properties of the metal-composite bolted joint were studyed.The effects of laying sequence,metal-composite material matching,bolt spacing,gasket type,interface and other factors on the impact properties of the joint structure were analyzed.The influence degree of different factors on the impact properties of the structure is obtained,and provide reference for the structural design of carbon fiber composite materials and metal joint structure under impact load.