Hi,
In the version I’m currently using (v2.1.11) SPRING2 and SPRINGA elements can not be added in the UI. And these are needed to connect two or more bodies/nodes/remote points not to the ground but to one another.
@FEAnalyst explained briefly what are these spring element types in this post.. Thanks a lot.
I tried to make it more clear.
2_DOF_MASS_SPRING : 2 Degree of Freedom Mass-Spring System with PrePoMax & CalculiX
What’s that?
\\01_2_dof_mass_spring_system.inp
Solver deck file is in this folder.
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Model Explanation
There are 2 cubes represent masses and 2 spring elements attached to these cubes.
SPRING1 element can be defined in PrePoMax UI. SPRING2 and SPRINGA elements can not be defined in UI so you have to add them as CalculiX Keyword. Yellow spring element that named as k1 here is SPRING1 which is defined in PPM UI.
Other Spring element which has SPRING2 or SPRINGA element type will be added as CalculiX keywords.
1) Model-->Edit CalculiX Keywords
2) You need to add 3 things here:
2.1) Define Spring Element as Additional Element with elementID, node1_ID, node2_ID:
Also adding code text:
*Element,TYPE=SPRINGA,ELSET=ESPRING
999999,18525,18527
2.2) Define your spring as Additional Element Set with elementID.
Also adding code text:
*Elset, Elset = ESPRING
999999
2.3) Define your spring as Additional Section with Stiffness Value.
Also adding code text:
*Spring,ELSET=ESPRING
0.003
IMPORTANT!
Let’s say your spring stiffness is 5 N/mm. When you add this 5 value as a keyword YOU HAVE TO ADD A GODDAMN POINT AT THE END OF VALUE. Like 5. My value already has a decimal here, it’s 0.003 N/mm but if it was 100 N/mm so i would write 100. there.
3) That’s it. Run your model…
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By the way, the inp file i add here has 2 steps.
- NORMAL_MODES analysis that calculates
undamped natural frequenciesof mass-spring system. - MODAL_DYNAMICS analysis that uses results of NORMAL_MODES analysis as input and calculates time domain response of cubes.
- There is a time domain force applied to the right cube. It’s applied like a shock force in a short duration. like ultra dummy version of hammer test force application
