I am trying to run a post-buckle analysis using Riks method available in abaqus. Now I need to add imperfection at the mid height of steel column model. Could you please let me know how can I define imperfection directly? I read abaqus manual and found that I need to add following keywords into input file:
*IMPREFECTION, SYSTEM=name, INPUT=input file
My questions are:
1. what does it mean by SYSTEM?
2. how to prepare ainput file?
1. Set SYSTEM=R (default) to specify the imperfection as perturbation values of Cartesian coordinates. Set SYSTEM=C to specify the imperfection as perturbation values of cylindrical coordinates. Set SYSTEM=S to specify the imperfection as perturbation values of spherical coordinates. See Figure 9.3-1 of Abaqus Keywords Reference manual.
2. The input file contains the imperfection data, in general, as the node number and imperfection values in the global coordinate system. See “Input syntax rules,” Section 1.2.1 of the Abaqus Analysis User's Manual, for the syntax of the file.