I’ve discovered a minor bug that occurs when working with multi-step analysis and using the new Point Mass Section type added in PrePoMax V2.1 in combination with Gravity (acceleration) loading.
Here is a link to a minimal .pmx file to demonstrate the issue. There is no geometry or mesh defined in this file but it is not required. All that is defined is the Reference Point for the Point Mass, the Point Mass Section, and two identical steps with Gravity loads applied to the Point Mass: Point Mass 2 Step Analysis
If you check the Calculix input file using the keyword editor (or check the .inp directly) and check the Step 1 gravity load, you can see that the gravity load is applied to the automatically generated Element Set “Point_Mass-1_RP_Reference_Point-1”.
If you check the Step 2 gravity load there is no Element or Element Set definition applied, despite the settings in the PrePoMax GUI being the same as Step 1 (the gravity component defitions are different but that is irrelevant).
The major difficulty with this is that Calculix will not throw an error due to the lack of Element/Element Set definition for this load. It will simply exit “successfully” without analyzing Step 2, and no Step 2 results will be produced. It will not continue solving further steps (ie. 3, 4, 5…) if they are defined, regardless of whether they contain another invalid Gravity load definition or not.
I have tried all manner of order of operations in defining the loads to determine if there is a workaround. If the Gravity load is defined in Step 2 before it is defined in Step 1, then the Element Set definition will show up properly in Step 2. But as soon as a Gravity load is defined in Step 1 and assigned to the Point Mass, it will only assign the Element Set correctly in Step 1 (and no assignment in Step 2). It seems as if it can only assign that Element Set once, and any reuse after that results in this issue.
The workaround for me was to simply use the keyword editor to add the Gravity loads to steps after Step 1 using the correct Point Mass Element Set definition.
