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KevinEldridge

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  1. I had something like this happen a few years back, and the "fix" (discovered quite by accident) ended up being to change the color of the system collector. Seems like a long shot here but may be worth a try.
  2. I'm assuming you want to define the optional contact thickness in LS-Dyna, which is found on the *PART_CONTACT card. If so, try this: 1. click on the component in the Entity Browser 2. in the Entity Editor (located below the browser) click next to "Options" to get a list of options for the *PART card. Select "Contact" 3. OPTT should now show as one of the options.
  3. Two control cards are needed to run modal simulation in LS-Dyna: *CONTROL_IMPLICIT_GENERAL with IMFLAG=1 (tells Dyna it's an implicit simulation); and *CONTROL_IMPLICIT_EIGENVALUE with NEIG set to the number of modes you want extracted.
  4. An Abaqus .odb file can be read using HyperWorks 14 if the latest hotfix is installed (HyperWorks Desktop 14.0.132). I have done this on Windows workstations but there is a comment in the release notes saying, "Abaqus 2017 ODB reader is not supported on Red Hat Enterprise Linux 5.9 and prior versions."
  5. Stresses are calculated (via the material model) using the calculated strains. The strains are calculated using the relative displacements of the nodes, along with the initial element size. Consider a simple example of a 1D element that is 10 mm long. If the left end displaces 1,000,000,000 mm and the right end displaces 1,000,000,001 mm the relative displacement is only 1 mm. The strain would then be (change in length)/(initial length) = (1mm)/(10mm) = 0.1. As long as the strains can be accurately calculated the stresses should be OK. For your example it sounds like OptiStruct was able to get the correct strains and subsequent stresses despite the lack of constraint.
  6. Rahul, The standard equation for calculating head injury criteria (HIC) is based on the acceleration of the head form and the time interval of the impact. If you Google "Head Injury Criterion" you can find a number of references for it. See also this posting for more info:
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