Tensile Properties Of Composite Multi-nail Hybrid Joints And Fatigue Life Research

With the widespread application of composite materials in the aerospace,automotive and shipbuilding industries,the connection between composite materials and metals has become increasingly prominent.In this paper,numerical simulation and test methods are used to study the tensile properties and fatigue life of CFRP laminates and titanium alloy multi-bolt hybrid joints.Focus on the influence of the number of bolts,bolt arrangement,lap width and other parameters on the tensile and fatigue properties of the hybrid joint,aiming to further improve the bearing capacity and fatigue life of the hybrid bonded-bolted joint,and provide a theoretical reference for the engineering application of the structure.First,the tensile test and numerical simulation of the tandem multi-nail hybrid joint are carried out to explore the difference in the tensile properties of the hybrid joint under different bolt numbers and different lap widths.The results show that the double-nail hybrid joint can effectively improve the single nail.Low load-carrying capacity of hybrid joints and end warping problems;when the lap width is 25 mm,the load-carrying capacity of the three-nail hybrid joint is 20.9% higher than that of the double-nail,and when the width is 30 mm,the load-carrying capacity of the three-nail hybrid joint is 43.2% higher than that of the double-nail.;When the lap width is30 mm,it is best to increase the number of bolts to increase the bearing capacity of the joint,which can give full play to the tensile performance of the composite plate;when the lap width is 25 mm and 30 mm,the ultimate failure load of the double-nail hybrid joint Both gradually increase with the increase of the inter-bolt distance.Secondly,taking the horizontal multi-nail hybrid joint as the research object,through experiments and numerical simulation methods,the tensile behavior of the horizontal double-nail hybrid joint under different lap lengths is explored,and further analyze the influence of the number and arrangement of bolts on the bearing capacity of the hybrid joint.The results show that increasing the lap length of the horizontal double-nail hybrid joint can increase the ultimate failure load.at the same time,compared with the horizontal double-nail joint,the two arrangements of the horizontal three-nail structure A and B can greatly improve the bearing capacity of the structure;although A The area of the bonding area and the number of bolts of the two joints are the same,but the different bolt arrangement methods cause the failure modes and load-bearing capacity of the two joints to be different.Compared with the3bolt-A joint,the bearing capacity of the 3bolt-B joint is increased by 16.1%,that is,the B type of arrangement can better improve the tensile performance of the hybrid joint.Finally,use the test method to explore the fatigue life and failure modes of the longitudinal double-nail,horizontal double-nail,and three-nail hybrid joints under different stress levels,and compare and analyze the fatigue life of the hybrid joint under different bolt arrangements and different bolt numbers.The difference.The results show that the fatigue resistance of the 30 mm tandem double-nailed joint is better than that of the horizontal double-nailed 30 mm joint.Compared with the 30 mm tandem double-nailed joint,the 3bolt-B hybrid joint not only improves the static tensile load,but also greatly improves the fatigue resistance.Improve the fatigue resistance of hybrid joints.