Contact stiffness of bolted joint with different material combination in machine tools

Bolted joint is a commonly used complex flexible interface in machine tools. The stiffness influential factors-based dynamic model provides a high accuracy modeling method of bolted joints in machine tools. The key of wide application of this method is the database of the stiffness matrices of bolted joints under different conditions. This paper mainly concerns the contact stiffness of bolted joints with different material combination in machine tools and tries to establish the relationship of them. Using the stiffness influential factors-based dynamic modeling method, the contact stiffness of bolted joint is expressed as the stiffness matrix of the connection finite element. After impact modal tests were carried on the specimens, stiffness matrices of bolted joints with different material combinations are identified from the frequency response functions. The ratio of the stiffness matrices validates the effectiveness of the conclusion that the contact stiffness of bolted joints with different material combination is proportional to the corresponding equivalent elastic modulus deduced from Hertz contact theory. The reliable proportional relationship provides a great convenience to the wide application of the stiffness influential factors-based dynamic modeling method of bolted joint.