Experimental Research And Finite Stimulation On Composite Bolt Joint Structure

During the last decades, the advancement in performance of reinforced fiber and matrix resin were achieved, and its categories became more various.The development in raw materials has helped the development and application of Fiber Reinforced Plastics(FRP), by introducing rapid advancement of FRP molding processes and manufacture skilles, and promoting wide use of high performance FRP. Large capacity ship and high power wind blade have comed forth, advanced composte material,which can withstand serious conditions, is the first choice in the aerial field.The trend is obvious that FRP will replace metal materials, FRP have been used more widely in hypo-structures or secondary structures and primary structures.The mechanical connection between FRPs or FRP to metal materials were used , Details design and analysis became vital important in the weak joint region because of sophisticated and vigor application condition and material discontinuity.The details of joint structure have been generally omitted in the analysis of the whole large-scale structure, therefore, the real stress distribution of simulation can't be exposed clearly.Sometimes,strength of the whole model, when omitting the joint, can meet the requirements, but the joint region is destroyed due to extreme stress concentration, which results in the destruction or disfunction of the structure. This thesis emphasizes on contact analysis of bolt joint between FRP to metal materials in uniform bending load. Experimental investigation was conducted on the single bolted joint structure in average displacemental load, the strain data on the surface of FRP is collected continuously, then the relationship between load and strain is examined.The analysis shows the continuous process of the initiation, extension and failure of FRP. The load when damage starts is taken as the final load used in finite analysis, the equivalent stress shows good agreement with that reported in document, and the validity of this method is proved.And then linear analysis for simplified model and nonlinear contact analysis for full model are carried out. Displacement, strain and stress are contrastively analyzed. The stress details in contact region can't be revealed in linear analysis of simplified model, and limitation is evident in application. Single row bolts and few ribs FRP structure is lack of stiffness, large displacement and local stress is extremely large and can't meet the requirements. The method of locating more ribs and using multi-row bolts are adapted to upgrade stiffness and reduce local stress, and the results of strain and stress can meet design requirements. At the same time, the influence of friction coefficient and±45 degree stack ply versus load distribution in X,Y and Z directionare studied.