Fatigue Test Design Of Grid Structure Joints And Analysis Of Data

With the popularization and application of grid structure with bolt-sphere joints and welded hollow spherical joints in industrial factory with suspended crane, the fatigue performance becomes the hot problem to be solved for many years in the engineering field. Fatigue test is well-known as the direct and reliable method to reveal the fatigue performance of joints and components. However, fatigue test costs so much time, money and is influenced by so many factors that it develops relatively slowly at home and abroad.Based on fatigue test of grid structure joints, the paper carrys out the following research work:1,A highly efficient, stable, reliable test loading device has been designed to complete the fatigue test of all the specimens.2,The author has designed bolt-sphere joints and welded hollow spherical joints, and witnesses the processing of the specimen production. The quality and accuracy of Specimen processing met requirements of the test.3,Through a comprehensive and systematic regression analysis on constant amplitude and variable amplitude ,the paper has come to the following conclusions:1) The S-N curves of five kinds of different diameter high-strength bolts have been obtained.2) Changing rule of the fatigue strength of high-strength bolts with the changes of different bolt diameter has been finished. 3 ) Analysis on the impact of the loading sequence to fatigue has been done.4,This paper has introduced the "hot spot stress amplitude",and obtained the method of fatigue design for grid structure with bolt-sphere joints.5,This paper has analysed some uncertain factors that have the greater impact on the fatigue test data.Through the study and analysis of this paper, it will offer the important basis for revising the codes and supplementing clauses; Promote the development of the fatigue test and the wide application of the grid structure with bolt-sphere joints at the same time.