Load Balance in FMVSS 207/210 Simulations for MPP

Analyses involving automotive seat designs for loadcases such as FMVSS 207/210 has shown some poor load balance on compute nodes when using the default decomposition in MPP LS-DYNA. In FMVSS 207/210 type simulations, the computationally expensive portion of the model lies at the seat and its immediate viscinity while the rest of the model involves relatively less computations as they are not in contact or remains elastic saving contact and plasticity treatments. In such cases, the region based domain decomposition, available from LS-DYNA 971 onwards, seems very promising to help achieve improved load balance which significantly improves job turnaround time. A sample region based domain decomposition is shown below where the seat and its immediate environment is defined as a region using a box definition and is first distributed equally to all processors. Subsequent regions are defined at the front and rear portions of the seat to again distribute them equally to all processors.

(Click image to enlarge)

decomposition {
/* Seats and immediate regions around it
region { box 2420.4485 3402.3416 -728.05231 778.30634 466.34595 2058.3201 sy 0.0001 sx 1000}
/* Rear of the vehicle
region { box 4253.3398 6208.3799 -959.01001 959.01001 700.54901 1219.0830 sy 0.0001 sx 1000}
/* Front of the vehicle
region { box 340.63901 2091.1599 -1010.8800 1010.8800 717.90198 2111.4448 sy 0.0001 sx 1000}
/* Rest of the vehicle
sy 0.00001 sx 1000

  • Respected Sir, your blog is very helpful for me to understands various concepts in Ls Dyna. I am Mechanical Enginnering Student and I am doing a Project on Seating System. I am performing a test on seat for FMVSS 207/210 Standard. I need your help regarding hand calculations. Can you please give guidance for the project. Please reply me .Regards.

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