Set control parameters for springback analysis, as illustrated in Figure 8.3.107.
GENERAL
SHELL WARPING STIFFNESS (BWC): Default is set as 2, i.e. Belytschko-Tsay
ADVANCED: Advanced parameter setting.
Figure 8.3.107 Springback control parameters interface
IMPLICIT ANALYSIS
Allow to user to select approach of springback analysis: single step
springback or multiple step springback analysis. Multiple step springback is
set as default option. Single step springback analysis usually leads to good
result. However, converged result may not be obtained using single step
springback analysis for relatively flexible part. The user is recommended to
conduct springback analysis using multiple step approach. Detailed descriptions
for setting up single or multiple step springback analysis is described in
LS-DYNA Keyword User’s Manual.
INITIAL TIME STEP SIZE (DT0): Initial
time step size of springback analysis. Default value is 0.001.
NUMBER OF IMPLICIT STEP (NSBS): Number
of implicit step. Set to 1 if single step implicit analysis is performed. If
the value is greater than 1, multiple implicit analysis is used.
ADVANCED: Sets
advanced parameter of implicit analysis. See Figure 8.3.108 for the list of
parameters.
Figure 8.3.108 Advanced parameter for Implicit Analysis
COARSENING MESH
Allow the user to use coarsening mesh technique during springback analysis.
During drawing simulation, adaptive mesh is adopted to refine blank mesh to
capture details on tooling. Adaptive meshing increases model size and poses a
challenge to convergence in springback analysis. This option merges the refined
mesh in flat regions to reduce model size. It reduces the rate of incidence of
convergence problems and shorten the computing time.
ANGLE: Sets the angle
criteria for merging neighboring elements. If the angular difference of element
normals between adjacent elements is less than the given criteria, these
elements are merged. Default angle is 8°.
CHECKING MESH
This function allows the user to check mesh quality during Springback
analysis. The user can check adaptive constraints, minimum aspect ratio,
minimum and maximum allowable interior angle and minimum element size.
FIXING BAD ELEMENT
This function enables the solver to automatically repair distorted
elements and output the relevant information into text file. It helps to
increase precision of springback analysis, as well as improving convergence.