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M
MW_96549111-Visitor
1-Visitor
February 3, 2021
Question

Dynamic shock analysis results

  • February 3, 2021
  • 1 reply
  • 5002 views

Dear Creo user,

i have question regarding interpretation of my results i got from a Dynamic Shock analysis in Creo 4.0 m120. I was also getting sth similar in Creo 5. Can anybody tell me from where such "corrugated" results may be coming? I am using here shell elements for each component. The modal analysis shows some modes and everything is ok (photo, right side). When i run the shock analysis with a defined by me spectral acceleration, modal combination SRSS, the result is as in the left part of the photo. 

so far my observations are as follow:

- when i use the default Uniform spectral values the result is "smooth"

- when i run this assembly with its parent everything is ok

- tried once to run with the supports having solid elements and the results were ok.

I don't think it is a matter of shell/solids. It looks like the flat areas would be getting some extra waves as mode for the area itself, but it doesnt make sense as the modal analysis doesnt show such modes. 

 

Any hint will be appreciated highly, thx

BR,

Marek

1 reply

J
JXBWk14-Alexandrite
14-Alexandrite
February 8, 2021

image 1. disp =  3675mm !! It this from you dynamic analysis right? so are these peak values? or at a given time

what is your "spectral acceleration" ?

the right picture is an eigenvector?

applying the correct results file? May not be applicable to software like simulate but with a proper FEM tool if you attach the wrong result file something you get that pattern (node ID "conflict)

 

    M
    MW_96549111-VisitorAuthor
    1-Visitor
    February 8, 2021

    my spectral acceleration is max 1,5g. it is not much. (file Spectral.png attached). THe units i have are mmKgSec and i was checking already if the value i type for spectral acceleration is 1000 bigger. FIrst of all, when i have a full assembly, not only this barrell i am getting proper results with this input. i played with units and spectral acceleration 1000smaller and the results are also nonsense. Small displacement looking relatively ok but the stresses are at the level of Pascals, not MPa. Extremely small - that is impossible.

    The right photo shows displacement for all modal nodes combined. 

    The results file is taken directly from the analysis. No mistake here possible from my side. 

      J
      JXBWk14-Alexandrite
      14-Alexandrite
      February 8, 2021

      this is not a shock profile! some sort of sine sweep I guess

      What is the lowest eigenvalue (1st natural frequency) you are getting for your assy?

      If one uses mm then usually one has the mass in tonne to be unit consistent

      What does the "all modes combined" suppose to show?

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