Deformation behaviors of four-layered U-shaped metallic bellows in hydroforming  

作　　者：Jing LIU Zhiyong LV Yang LIU Lanyun LI 

机构地区：[1]Key Laboratory of Materials Processing Engineering,School of Material Science and Engineering,Xi'an Shiyou University,Xi'an 710065,China [2]Key Laboratory of Advanced Manufacture Technology for Automobile Parts(Chongqing University of Technology),Ministry of Education,Chongqing 400054,China [3]Bime,Bremen Institute of Mechanical Engineering,MAPEX Center for Materials and Processing,University of Bremen,Bremen 28359,Germany

出　　处：《Chinese Journal of Aeronautics》2020年第12期3479-3494,共16页中国航空学报（英文版）

基　　金：the funds of the National Natural Science Foundation of China(No.51875456);the Natural Science Basic Research Plan in Shaanxi Province of China(No.2019JM-450);the Young Talent fund of University Association for Science and Technology in Shaanxi,China(No.20170518);the Key Laboratory of Advanced Manufacture Technology for Automobile Parts(Chongqing University of Technology),Ministry of Education(No.2018KLMT03);Materials Science and Engineering provincial-level superior discipline funding project of Xi'an Shiyou University;the Program for Young Innovative Research Team in Xi'an Shiyou University(No.2015QNKYCXTD02)。

摘　　要：Because of the complex constraint effects among layers in multi-layered metallic bellows hydroforming,the stress concentration and defects such as wrinkling and fracture may easily occur.It is a key to reveal the deformation behaviors in order to obtain a sound product.Based on the ABAQUS platform,a 3 D-FE model of the four-layered U-shaped metallic bellow hydroforming process is established and validated by experiment.The stress and strain distributions,wall thickness variations and bellow profiles of each layer in the whole process,including bulging,folding and springback stages,are studied.Then deformation behaviors of bellows under different forming conditions are discussed.It is found that the wall thinning degrees of different layer vary after hydroforming,and is the largest for the inner layer and smallest for the outer layer.At folding stage,the wall thinning degree of the crown point increases lineally,and the difference among layers increases as the process going.The displacements of the crown point decrease from the inner layer to the outer layer.After springback,the U-shaped cross section changes to a tongue shape,the change of convolution pitch is much larger than the change of convolution height,and the springback values of the inner layer are smaller than the outer layer.An increase in the internal pressure and die spacing cause the maximum wall thinning degree and springback increase.With changing of process parameters,bellows with deep convolution are easily encountered wall thinning during hydroforming and convolution distortion after springback.This research is helpful for precision forming of multi-layered bellows.

关 键 词：Deformation behaviors Four-layered U-shaped bellow HYDROFORMING Numerical simulation Springback 

分 类 号：TG306[金属学及工艺—金属压力加工]