How do you perform a multiple step analysis?

There are two ways to do multiple steps analysis:

a) Including all the parts from different steps in one input file, and specifying the loading and boundary conditions in each stage. In the mean time, specify the birth time and death time for each contact (in *CONTACT_xxxx, the seventh and eighth parameters on the second line). This methodology can result in a very complicated input deck, and can lead to user errors. Accordingly, this method is only suggested for experienced users who like to keep everything in one file.

b) The second method to perform a multiple steps analysis is to generate a “dynain” file upon successful completion of each individual step. After one simulation process, LSDYNA can generate a “dynain” file; this file can contains all the necessary information related to the deformed parts including the deformed mesh, thickness, stress, and strain components. This information can be used for the subsequent analysis. With this method, only the parts that are used for this specific process need to be included in the input deck, and all the other parts can be in any subsequent analysis.

c) The advantage of the second method is that a simple and compact input can be used which is easy to debug and effective when iterative step solutions are to be considered.

d) If a multiple stage forming analysis is required it may be prudent to perform a springback analysis between each step when the blank is transferred between physical dies similar to a transfer press operation..