6 Replies Latest reply on May 5, 2014 12:49 AM by Jared Conway

Drop test with Nonlinear Material

Zhemin CAI May 2, 2014 1:33 AM

Hi All:

I am trying to simulate a 4inch drop for our product. The module layout is shown in the attached picture.

Three rubber pads are used in the module to absorb the contact shock.

As a result, the linear drop test cannot give me an accurate predication.

I have two questions for this nonlinear simulation:

1. How to model the ground for the object to hit. It should be similar to the

"virtual wall" option in static analysis but the nonlinear package doesn't provide this option.

2. How to calculate the Rayleigh damping coefficient for this system.

I understand I should calculate these values according to the system natural frequency.

However, I should calculate the natural frequency of the drop piece only or the drop piece with

ground?

Can anyone give me some suggestions on these questions?

Thanks a lot.

Zhemin

Model Layout.bmp 538.2 KB

Re: Drop test with Nonlinear Material

Jared Conway May 2, 2014 1:56 AM (in response to Zhemin CAI)

Drop test has some nonlinear materials, did you try selecting something other than linear?

In no lie at dynamic you would need to model the ground.

Rayleigh damping will require testing or an estimation. Check help and kb for some estimates.
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- Re: Drop test with Nonlinear Material
  
  Zhemin CAI May 2, 2014 2:05 AM (in response to Jared Conway)
  
  Thanks Jared.
  
  To simulate the rubber behavior, I need to input the stress-strain curve in three directions but the linear material only allow me to input one curve, this is why I think I might need to move to nonlinear.
  
  Another question is to model the rigid wall similar to linear drop test, is that I need to set a dummy matrial with high elastic module but low poission ratio?
  
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  - Re: Drop test with Nonlinear Material
    
    Jared Conway May 2, 2014 2:12 AM (in response to Zhemin CAI)
    
    Is the material really that nonlinear that you need that?
    
    I Thibk linear would be enough and if you needed more, you could use platixity
    
    http://help.solidworks.com/2010/english/SolidWorks/cworks/legacyhelp/simulation/Materials/Material_models/von_Mises_Plasticity_Model_(Kinematic_Isotropic).htm
    
    Model the ground the way it actually exists.
    
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    - Re: Drop test with Nonlinear Material
      
      Zhemin CAI May 2, 2014 2:19 AM (in response to Jared Conway)
      
      Thanks Jared, I will run the linear drop test at the meantime.
      
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- Re: Drop test with Nonlinear Material
  
  Qinghai Jin May 5, 2014 12:47 AM (in response to Jared Conway)
  
  Dear Jared,
  
  why it is necessary to create the model of ground? how about just treating the top plane as 'rigid ground'? it is applicable to set it in other software, but I am newbie to SW Simulation.
  
  by the way, could you introduce any document/resources of FEM with SW Simulation? Thanks first!
  
  Regards,
  
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  - Re: Drop test with Nonlinear Material
    
    Jared Conway May 5, 2014 12:49 AM (in response to Qinghai Jin)
    
    that can be done with drop test
    
    the help is very good with solidworks simulation, the solidworks kb has some great info as well, and your reseller should also offer training
    
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