Contact Characteristic Analysis Method And Experimental Study Of Bolted Connection Structure

Bolted connection is one of the most commonly used assembly connections,with the advantages of uniform standard,simple structure and easy assembly and maintenance.There are many contact surfaces in the bolted connection structure and the characteristics of the contact surface are important factors affecting the characteristics of the overall structure.Therefore,it is of great significance to study the contact surface of bolted connection structure This paper aims at exploring the contact stiffness of bolted connection structure,the influence of bolt connection contact stiffness on dynamic characteristics of overall structure and contact stiffness of special contact surfaces were explored by establishing a bolted connection structure with a lock washer.In order to study the contact stiffness between the lock washer and the connected parts in the bolted connection structure,the bolted connection structure with the actual thread structure was simulated and analyzed.The three-dimensional model of the bolted connection structure was established,and the material properties,contact relationships and other parameters of the model were set up in the finite element simulation software.The change of bolt preload was simulated by applying different torques to the nuts.The tightening process of the bolt was analyzed by the explicit dynamics method,and then the contact stiffness between the lock washer and the connected parts under different bolt preload was calculated by the relationship between pretension force and deformation.And the results show that the contact stiffness varies nonlinearly.In order to study the influence of contact characteristics of the bolted connection structure on the natural frequency of the whole structure,a test bench of cantilever beam bolted connection structure with lock washer was established.The natural frequencies of the first six bending modes of the structure were tested by changing the bolt preload,the size of the lock washer,and the number of tests.The influence of the above factors on the natural frequencies of the bolted connection structure was qualitatively studied by analyzing the experimental data.The resonance data measured in the experiment were analyzed by signal analysis and processing method,and the eigenvalues of the resonance data were extracted.It is found that the eigenvalues obtained by signal analysis are basically consistent with the natural frequencies read in the test process.In order to simulate and analyze the natural characteristics of the first six bending modes of the cantilever beam bolted connection structure,the finite element model of the cantilever beam bolted connection structure was established based on the finite element analysis software.The bolted connection structure was modeled by the actual finite element method and the layer element method,respectively.The simulation results show that the natural frequencies of the structure increase with the increase of the bolt preload.And by comparing with the experimental results,it was proved that the equivalent model established by layer element method is feasible to solve the natural frequencies of the bolted connection structure.