Automobile vehicle body structure fatigue life predicting system

Abstract

The invention relates to a fatigue life prediction system for a vehicle body structure of a vehicle in the technical field of vehicle design. The prediction system adopts a road spectrum fitting module to establish a combined road spectrum suitable for a field test; a vehicle body loading spectrum acquisition module is adopted to establish an entire vehicle multi-body rigid-flexible coupled model so as to extract the load-time-history at a connecting passage of the vehicle body and a chassis as the input of vehicle body excitation; an automobile body structure dynamic response analysis module is adopted to establish a finite element model of the vehicle body so as to obtain the static stress history generated by gravity and the dynamic stress history generated by road surface excitation of the vehicle body when the vehicle is under the excitation of the combined road spectrum; a dangerous position identifying module of low fatigue life of the vehicle body is adopted to quickly search dangerous positions of low fatigue life through an S-N method and a Miner linear accumulated damage model, and determine the multiaxial stress state of the dangerous positions by using 'biaxiality' analysis; and a fatigue life prediction module of the vehicle body structure is adopted to predict the fatigue lives of the dangerous positions accurately. The fatigue life prediction system for the vehicle body structure can improve the speed and the precision of the fatigue life prediction for the vehicle body structure so as to provide a reference for a real vehicle test.

Description

technical field [0001] The invention relates to a system in the technical field of automobile engineering, in particular to a system for predicting the fatigue life of an automobile body structure. Background technique [0002] With the continuous improvement of modern automobile research and development and manufacturing technology, automobile products are developing towards high speed and light weight, and the fatigue durability of automobile structures has become increasingly prominent. How to design a vehicle that can meet the durability requirements under the premise of ensuring vehicle safety, comfort, energy saving and environmental protection is an important challenge in today's automobile design. Fatigue damage occurs when a structure is subjected to a dynamic load much lower than the static load failure strength. According to statistics, in the damage of modern mechanical structures, accidents caused by fatigue damage caused by alternating loads account for 95% of...

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Problems solved by technology

In addition, the influence of the average stress is not considered, which will cause a large deviation in the fatigue life prediction value; in addition, in the fatigue life prediction, for the dangerous position where the two-way principal stress is in a non-proportional state, the "biaxial" analysis is not carried out. is the traditional S-N method, so its fatigue life cannot be accurately predicted

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