The bending and spring back behaviors of DP780 and DP980 were
investigated using experiments, analytical models, and PEA. An PEA study using
3D shells was first performed of the work by Queener and DeAngelis (1968) and
demonstrated that the 3D shell element behavior in bending and springback, is
similar to that from simple bending theory.
Experimental and FE studies were then performed using DP780 and
DP980 steels under simple and general bending conditions. Simple bending
conditions were studied in V -die bending. General bending was studied for
DP780 using a commercial bending machine. The PEA examined the effect of
element formulation and material hardening assumptions on springback, bending
stresses, and the residual stress distributions after springback. Corresponding
simple and general bending analytical models were also compared. The simple
bending model was from Queener and DeAngelis ( 1968), and the general bending
model was from Tan et al. ( 1995), modified for Ludwig hardening.
Overall, the PEA predicted the springback magnitude in the order; 2D
continuum >3D continuum> 3D shells, and kinematic hardening> mixed
hardening> isotropic hardening.
In the V -die bending study the 3D shell PEA, using a calibrated mixed
hardening assumption, produced the most accurate results. The PEA using pure
isotropic hardening demonstrated that bending and springback behaviors for both steels were consistent with that described by simple bending theory. The
behaviors demonstrated by the FEA using mixed or pure kinematic hardening
were not.
In the general bending study, the 3D continuum element FEA using pure
kinematic hardening was the most accurate. The 3D continuum element FEA
captured the bending stress interaction with the hardening assumption as well as
thinning deformation, in agreement with the analytical model and thinning
measured experimentally. 3D Shell elements could not capture these behaviors
and significantly under-predicted springback under the pure isotropic hardening
assumption. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/29411 |
| Date | 06 1900 |
| Creators | Lim, Timothy |
| Contributors | Jain, Mukesh, Mechanical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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