Numerical simulation of incremental sheet forming based on GTN damage model

Abstract

An attempt was made to analyze the damage evolution and ductile fracture of incremental forming at the microscopic level. Firstly, an extended Gurson-TvergaardNeedleman (GTN) model integrating with Hill'48 anisotropic yield criterion was established and numerically implemented by User-defined Material Subroutine (VUMAT) in the commercial finite element software ABAQUS. Then, the VUMAT program was verified via a single element test, and its damage parameters were determined through the combination of the simulation and the experiment of a tensile test. Afterwards, based on the extended GTN model, a finite element model of incremental forming was established and experimentally verified. And the influence of different values of two damage parameters, the volume fraction of void nucleating particles f N and the mean plastic strain value when voids nucleate ε N , on the damage evolution of incremental forming was explored. It shows that there is almost no connection between the microscopic equivalent strain ε pl m and the values of f N and ε N . However, the maximum value of void volume fraction will increase significantly with the increase of f N or with the decrease of ε N . Finally, void volume fraction was proved to be an effective index to predict crack occurrence of incremental forming.

Determination of Forming Limit Diagrams Based on Ductile Damage Models and Necking Criteria

“…(1)) is modified by introducing the Hill (1948) equivalent stress instead of the von Mises one (see, e.g., Chen and Butcher, 2013;Kami et al, 2015;Li et al, 2015). The corresponding expression of equivalent stress is given by…”

Experimental and Finite Element Analysis of Single Stage Single Point Incremental Forming

“…Blaga and Oleksik [17] have tried 3 different forming paths to create a frustum of a cone using DC04 steel sheet and concluded that the spiral path is the best among used strategies due to the occurrence of homogenous distribution of strains. Similar spiral path was used in both experimentation and FEA to produce truncated cone in Stainless steel 304, DC06 and aluminum alloy AL5052 by Golabi and Khazaali [18], Li et al [19] and Wang et al [20]. Experiment and FEA was carried out by Neto et al [21] using circular path and found that stress and strain FEA results are in good agreement with experimental results.…”

Study on Deformation Force of Hard Aluminum Alloy Incremental Forming

“…Therefore, the plastic deformation of the material is caused by the deviatoric stress. It can be seen from Equation (7) that the deformation of the contact zone meets the condition of plane pure shear deformation. That is, the principal stresses in two opposite directions have the same size, and those in the other direction are null.…”

“…This new market demand can be met using digital incremental forming [1][2][3], which is a new sheet metal flexible rapid prototyping technology [4][5][6]. In contrast to the traditional stamping forming, this technology can produce sheet metal parts with large forming limits and complex shapes without the use of a special die, or by simply using model support, which makes it ideal for rapid prototyping and small batch production [7][8][9][10][11].…”