Strength Analysis And Optimization Of Mechanical Joints In Composite Laminates And Development Of Software

Composite materials are increasingly applied in various fields because of their outstanding features. However, it is unavoidable for composites to be joined with other components like metals due to the limitations of various factors, and the mechanical joint is the most popular type, which is normally the weak position. Thus, it is necessary to have investigations on related theoretical methods, numerical simulations and experiments. From the perspective of convenience for engineering application, some researches and analysis work are carried out in this thesis.First of all, aiming at the single bolted joint in composite laminates, three methods, which are empirical formulas, numerical simulation and test methods, are used to do damage and failure analysis and the results are compared. The progressive damage model of mechanical joints in composite materials with Hashin failure criterion and degradation criteria is verified, which is available to simulate the failure process of composites. Then the influence on the carrying capacity and bearing strength of composite laminates with single bolted joint of different edge distance ratio, diameter to thickness ratio, etc. is also considered. According to similar models, composite laminates structure with three bolted joints including single-row model with three-column and single-column model with three-row is applied to investigate the influence of the stacking sequence, stacking proportion, materials of connectors on strength and pin-load distribution, and then the recommended geometric parameters are proposed for design.Apart from that, aiming at the multi-blot joints in composite laminates, numerical analysis is carried out with the parameterized modeling method. The evaluating indice for connection efficiency are offered in this thesis and the enumeration method is utilized to optimize the pin arrays. After summarizing the pin arrays’law of some structures with high connection efficiency, one conclusion for improving connection efficiency is found, that is, the row distance, column distance and their summation should meet the design requirements together.Finally, the mechanical joints composite laminates software for strength analysis is developed, based on the commercial software ABAQUS. The software is available to achieve the work automatically, including modeling, damage analysis and post-processing for mechanical joints composite laminates. The software can save the time for numerical simulation and integrate empirical method for finite element analysis. Meanwhile, it is convenient for analyzing the influence factors of connection efficiency in composite laminates with multi-blot joints.