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Must I use a non-linear study?

Question asked by 1-L5M1MV on Sep 3, 2009
Latest reply on Sep 4, 2009 by Stefan Wozniak

Some background:  I'm studying mostly sheet metal brackets that mount to large military vehicles and hold all sorts of different government furnished equipment (GFE).  The studies I'm running are shock tests straight out of MIL-STD-810 (sawtooth pulse loading).


The biggest concern that I have is that SolidWorks doesn't have the option to create "no penetration" contact sets (or bolted connectors, but there are ways around that) in Time History Linear Dynamic studies.  I understand why this isn't an option for Random Vibration or Frequency studies, but I'm not completely sure about the Time History study.


The loading is exactly the same between Non-Linear Dynamic and Linear Dynamic studies, and I'm not interested in anything after the material reaches the yield stress, so the Linear Dynamic study would seem to meet my needs.  However, the inability to create No Penetration contact sets is really limiting the accuracy of the analysis.  Much of our equipment (our brackets as well as the GFE) is mounted on a vertical plane, which almost always creates problems when unable to use No Penetration.  I don't want to bond the flanges to the bracket or the ground, since that isn't an accurate representation of the force distribution, especially as the component CG moves away from the mounting points.  I also don't want to allow the flanges to move freely, since interaction between the flanges can introduce additional stresses.


I've included an example of what I'm dealing with.  I'm only interested in the stresses in the green part (all else is simplified modeling for GFE) and the fasteners.  We are dealing with explosive blasts from any direction, so 6 studies must be run, with the acceleration applied in the positive and negative direction for each axis.


Must I use a Non-Linear Dynamic study, even though there is no geometric or material non-linearity?