Study On Stress Concentration And Related Mechanical Properties Of Shear Connection In Mechanical Structures

There is a large number of tight firmware in mechanical connection structure. A crack will firstly appear near the nail holes due to the significant stress concentration nearby, and then lead to a fatigue or fracture structure, makes the connection structure ineffective. So the fatigue problem of fastening connection structure has received widely attention, especially in the field of civil aircraft structure design and analysis. At present, the domestic and foreign countries mainly use the methods of fatigue analysis and detail fatigue rating (DFR) to evaluate the structure durability of civil aircraft. Stress serious factor (SSF) can be supplement to DFR while the structure is tensile, but the SSF which is widely used in the engineer field for estimating the fatigue life of structure parts can be only applied in tensile connection structure, it has limitations in shear connection structure. SSF can’t be directly applied in tensile connection structure, so the DFR needs to be improved, and the most important problems in improve the DFR are the pin load distribution and stress concentration problem. Based on the classical elastic mechanic, this paper uses a method of 3D finite element to analysis the pin load distribution and stress concentration nearby the hole edges of a double row multi fastener structure which is under shearing force, and studies the main factors which influence the pin load distribution and stress concentration nearby the hole edges including thickness, material properties,component size and connection technology etc, focus on the stress concentration and other related mechanical property problems in structures under shearing force, and provide computing method of pin load distribution and stress concentration in structures under shearing force, and test the correctness of the computing method with experiments,and achieve satisfactory results with the comparison results of theoretical analysis and 3D finite element simulation analysis and experiments test, it indicate the analysis and calculation of this paper is correct and the analysis and calculation process is reasonable.The main content of this paper including:(1) Investigate the load transfer rules and solve load distribution problems of fastening pieces according to analysis the connection status, distribution status and deformation of the fastening pieces in the structure under shearing force.(2) After getting a results of the load of fastening pieces, solve the stress concentration problems nearby the nail hole in connection structure under shearing force according to the stress distribution in the zone of action of nail hole.And this paper lay a solid foundation for raising up new analysis method of stress concentration in engineering structure under shearing force in the following days and completely solving this kind of problems,and lay a theoretical foundation for the fatigue analysis in connection structures under shearing force.