Research On Strength Checking Method Of Connecting Bolts For Rolling Stock

VDI 2230 is the calculation criteria for high-strength bolts issued by the German Association of Mechanical Engineers.The evaluation process involves many parameters that affect bolt selection and safety.However,by consulting the standard,it is found that the standard only applies to the bolt structure of the connected parts with circular holes,and does not describe the connected parts with long round holes.Therefore,in order to conduct a more in-depth study of the VDI 2230 theory,this paper,based on the VDI 2230 standard,studies the influence of the oblong hole on the bolt evaluation results,and selects the hoisting structure under the vehicle as the research object.The bolt strength of the connector bolt group is checked,the two results are compared and studied,and the correctness of the derivation of the relevant formula is verified by an example.The main contents of this paper are as follows:First,the bolt strength evaluation process is expounded,and the research significance and research background of bolt strength verification,the origin of the VDI 2230 standard and the limitations in the standard,the development history of foreign high-strength bolts(research/strength assessment),The development status of domestic high-strength bolts(research/strength assessment),and the main research content of this paper is proposed.Second,the finite element theory and the bolt connection principle are expounded,and the relevant theories and calculation methods of the finite element are summarized.At the same time,the bolt types,material mechanical properties,tightening and loosening,strength characteristics and pre-tightening force are introduced.Third,the calculation of the springback of the connected piece with non-circular holes is expounded,the VDI 2230 standard evaluation process is introduced,and the calculation formula of the springback of the connected piece with long round holes is deduced and verified.Calculate the springback amount with the structural example of the bolt group of the connected parts with long round holes,compare the results,and find out the key parameters that affect the springback of the connected parts through the comparison results.Finally,based on MATLAB software and Excel software,write Bolt strength check program to realize the automation of bolt strength check.Fourth,taking the battery hoisting structure under a vehicle as the object and the connecting bolts on the hoisting as the research object,the Hyper Mesh software is used for modeling,and the ANSYS software is used for finite element analysisFifth,through the bolt strength check system,the connected parts of the battery hoisted to the bolt group are calculated according to the oval and circular bolt holes respectively,and the springback of the connected parts is studied according to the two different results output by the system.The impact on the entire evaluation process and the impact of different shapes of bolt holes on the safety factor of the evaluation results.