Deformation And Failure Mechanism Of Incremental Sheet Forming

Incremental sheet forming is gaining more and more interests from academic and industrial field because of its flexibility.Researchers have done a lot,including experiments,finite element simulation and theoretical models to analyze and improve incremental forming process.But still,they can not provide satisfactory answers to account for the fracture mechanism and the threshold value of fracture of incremental sheet forming process.In order to overcome the drawbacks,analytical models are established and experiments are conducted in this paper to explain the mechanism more clearly and efficiently:First of all,in this paper,an analytical stability model based on the force euquilibrium is established.The effects of bending and stretching on the stress variation are considered in this model.Then the influence of work-hardening and bending effects on the forming limit of incremental sheet forming is discussed in this model.And then in order to validate the model and further explore the fracture mechanism,uniaxial tension,bulge test and incremental forming of material aluminum ally AA1100 and AA5052 have been conducted,fracture forming limit of the two materials are established.By comparing the forming limit of conventional forming process,incremental sheet forming process and the instability model,the failure mechanism of incremental sheet forming of different materials are brought up.Materials with different mechanical property may have different failure mechanism.At last,in addition to the forming and failure mechanism of single point incremental sheet forming,an analytical model similar to that for single point incremental sheet forming is also established for double-side incremental sheet forming.In this model,the influence of the back force on the stability of the manufacturing process is also discussed.And experiments have been conducted to validate the theory.