General Mechanical

General Mechanical

Model Check Parameters – MAXRATIO and EPSILON

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    • Peter_Mur
      Subscriber
      I am doing certain model checks of my Ansys 2019 R1 setup and I would like to know how can I extract the following (NASTRAN) parameters:n1)The maximum ratiowhich represents the ratio between the highest and the lowest term of the stiffness matrix. The value of the model shall be less than 1.0E7. (Modal Analysis) n2) The EPSILONvalue corresponds to the ratio of work done by residual loads vs. work done by external applied loads. The EPSILON ratio computed shall be less than 1.E-8. (Structural Analysis) nIs there a command I can add to extract these ratios? nThank you! n
    • Aniket
      Ansys Employee
      for 1 you should see something like in the solver output:nRange of element maximum matrix coefficients in global coordinatesn Maximum = 4661594.26 at element 3090. n Minimum = 42327.3155 at element 187. nratio of these two terms should give you the required max ratio. nFor second question you can compare stabilization energy (https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v201/en/wb_sim/ds_stabil_energy.html) and strain energy (https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v201/en/wb_sim/ds_Strain_Energy.html) perhaps?.-AniketnHow to access Ansys help linksnGuidelines for Posting on Ansys Learning Forumn
    • peteroznewman
      Subscriber
      nHere is the definition of Nastran's Epsilon check, also known as...nTo calculate this in ANSYS, you have to do the matrix math to calculate deltaP, then divide by the system energy to normalize it to get epsilon. I don't know how to do that.n
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