Analysis And Regulation On The Principle Of Welding-induced Distortion Of Bus Framework

Welding is considered to be significant in the field of material processing.Due to the highly localization and instantaneity of welding heat process,it would inevitably produce welding distortion,which seriously decrease the precision and service ability of the welding structure and component.Therefore,the analysis and action of the welding distortion,have been a crucial theoretical and engineering topic.Now with the rapid development of the analysis about welding distortion and computer technics,numerical simulation is known as an effective method to analyze the welding distortion.In which the inherent strain finite element method is faster and more efficient,now is widely used in bus,ship and aerospace industry.Bus framework is a typical large and complex structure,considering less computer resource and more efficiency,inherent strain method is introduced in this paper to analyze the welding distortion.Based on the characteristic of the bus framework structure,the whole structure is dissembled into five parts and welded separately,and then welded together into one complete structure.By changing the welding sequence and adjusting the clap orientation,the welding distortion is analyzed and regulated on the whole and five parts bus frameworks.The thermoelastic finite element method is introduced to simulate the two typical welded joint,butt and T type,and in post treatment module,the inherent strain is taken and integrated to the equivalent force and moment.Finally,inherent strain method based on elastic finite element theory is used to calculate the welding deformation.By verifying with the measurement data,it is accurate to analyze the welding distortion for inherent strain method.The result is testified that the welding distortion is mainly controlled by the clap orientation,welding distortion can be controlled within 2.0mm by adjusting the clapping orientation on five parts of bus framework,Based on adjusting the clapping orientation,the welding sequence is further changed to find less distortion,unfortunately,the magnitude and orientation of welding distortion are almost no change,that means the adjustment of the clapping orientation can control the welding distortion utmostly.Based on the adjustment of the clapping orientation,five parts of bus frame are welded separately,and then welded into one complete bus framework.Furthermore,the welding sequence is changed to find less distortion.The distortion can be controlled within 1.0mm infour welding sequence,and center to end is less compared with other sequences.In the end the lifting process is optimized,number and orientation of listing are changed to find less distortion.Big distortion is 506 mm and distribute in the area of driver room,front wheel and passenger door.After optimization,big distortion is 445 mm and distribute in the area of front pillar of driver room.Significantly,the latter is more reasonable to decrease the distortion.