Pre-Stresses in LS-DYNA

Dynamic Relaxation ::

Dynamic Relaxation is method to implement pre-stresses in LS-Dyna
some applications are bolt pre-load, gravity loading , interference fit etc .
It is applicable to both Implicit and Explicit analysis .
its a solution method to perform quasi static simulation in a psuedo time before the actual transient analysis
Stresses and geometry at the end of this "psuedo" analysis are automatically used in transient analysis , thus including the desired Pre-stress efeect in the simulation .

Dynamic relaxation can be activated by setting the SIDR a non zero (1/2) value in *DEFINE_CURVE keyword

SIDR can take three values :

• 0:load curve used in transient analysis only
• 1: load curve used in only stress initialization (DR) phase 
• 2:load curve is used in both DR and transient analysis phase 

References:

1. http://www.feapublications.com/pdf/StressInitialization.pdf
2. LS-DYNA_manual_Vol_I_R7.1

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