Crash test of chassis shows 1000 hours

I'm performing a chassis crash test analysis on ANSYS Explicit dynamics. I'm using a chassis model, along with a wall. I have meshed both the geometries, and given the velocity of chassis, along with fixed support for the wall. When I start to solve, it shows me about 1200 hours remaining. I have specified the end time as 0.001s, and default number of cycles. What can be done? Thanks in advance.

The mesh size I have applied is 4 mm near nodes, and 6 mm at tubes with no trim. Errors occur in meshing when I increase the mesh element size. I have applied tetrahedrons to the chassis members.

Best Answer

  • peteroznewmanpeteroznewman Member
    edited December 2020 Accepted Answer

    @sankarsuresh01

    Please plot the Characteristic Length (CL) element quality metric. Show the statistics. Show the graph, show the minimum element. If most of the elements have a CL that is 10 or 100 times larger than the minimum CL, then when you remove those tiny elements, you can easily cut the wait time by a factor of 10 or more.

    Explicit Dynamics models take a long time to optimize and a long time to run. Don't use Explicit Dynamics if you only have 1 day. Use Static Structural with some hand calculations like I have shown before.

Answers

  • @sankarsuresh01

    You can wait 1200 hours = 50 days = 7 weeks. Make sure you have a Uninterruptable Power Supply on that computer!

    You can run the model on a computer with a CPU clock speed that is 2 times faster and cut the wait time in half.

    You can locate the elements that have the minimum Characteristic Length and remesh to double the Characteristic Length, which will cut the wait time in half.

    Characteristic Length is in the Mesh Quality Metrics at the bottom of the list.

    If the minimum Characteristic Length is in the wall, increase the density of the material in the wall until the minimum CL is in the chassis.

  • edited December 2020

    Is there any way where I could do the analysis in like 1 day ? I really dont have that much time to finish this tho.... If I make some changes in the mesh, meshing gives me errors.

    @peteroznewman I had tried by importing sketch of the chassis and going forward with 1D meshing too, if you remember. I had asked many doubts in that too. Any way where I could do this in like a day? Thanks in advance

    My geometry contains a lot of Trim/Extend feature from solidworks, and I have also used Slice in DesignModeler for slicing out some bodies which were intersecting with each other. I have then applied Boolean to all the chassis member, and then meshed it.

  • peteroznewmanpeteroznewman Member
    edited December 2020 Accepted Answer

    @sankarsuresh01

    Please plot the Characteristic Length (CL) element quality metric. Show the statistics. Show the graph, show the minimum element. If most of the elements have a CL that is 10 or 100 times larger than the minimum CL, then when you remove those tiny elements, you can easily cut the wait time by a factor of 10 or more.

    Explicit Dynamics models take a long time to optimize and a long time to run. Don't use Explicit Dynamics if you only have 1 day. Use Static Structural with some hand calculations like I have shown before.

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