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Found 17 results

  1. I am trying to simulate the influence of an unbalanced tyre on the structure using an FRF. Because it is rotating in the XZ-plane I have made two inputs, one excitation in X and one in Z. I combine these inputs in a DLOAD through 2 RLOAD load collectors. The thing I am struggling with is implying a 90 degree phase delay for one of the 2 RLOAD collectors. I have expirimented with the delay option and dphase option but I have not obtained the result I wanted. How do I apply this delay in my model? Is there a tutorial for this?
  2. Hi I am performing a modal frequency response analysis with OptiStruct. The model I have gives the displacement as output. However, I am interested in the acceleration as output. I tried obtaining this by checking the acceleration box under load steps => load case => subcase options output, but I could not access the acceleration result when in hyperview. Am I missing something? I can calculate the acceleration from the displacements but I feel like I should be able to get the acceleration results directly from the model. Thx
  3. Hi, I'm doing a frequency response analysis (NASTRAN SOL 111) asking stress in both plate and solid elements. The concern is that when I plot Von Mises conour in Hyperview, the calculated value derive only from the combination of the real part of the stress tensor components and not from the magnitude ones. Moreover I am not able to plot corner results in plate elements, but only in solid ones. Why? Can someone help me? Thanks!
  4. Hi, I would perform an Impact Hammer Test on a panel and plot acceleration in some points of that. I don't know if i'm right following the frequency response tutorial (i'm not sure if use modal or direct method), so i have 2 question: 1. How can i model (if possible) the load as an impulse? 2. I have the damping loss factor function the frequency of the material. How can I input this on the model? Thanks for answering.
  5. Hello everyone, A frequency response analysis was done, and I want to get the reaction force frequency response at the SPC nodes. The following control cards were used. However, I cannot get the reaction force frequency response. FORMAT OPTI FORMAT H3D OUTPUT,HGFREQ,ALL SPCFORCE(H3D,REAL) = 1 Which output control should be used to get the reaction force frequency response?
  6. Hi, does Hypermesh use a default damping factor for harmonic analysis if I don't manually set one? I need to compare another frequency response without damping and I need to know if the response obtained with Optistruct has or hasn't damping in it. Thank you
  7. Hi, I need to carry out frequency response analysis with operating speed. There is no force and I have only speed in rpm as input. How to specify this in Optistruct instead of using SPCD/DAREA card?
  8. I am new to frequnecy response analysis and have some queries regrding the same 1. I referred the OS- 1300 module for frquency response and I am not sure about how the values of COUPMASS and WTMASS was taken. 2. I want to apply the base excitation of 1g to my model. How can I do that? 3. In the tutorial the DAREA is applied and dof3 is given value of 20. Does that mean the application of frequnecy with amplitude 20? 4. How can I give the damping of 1% to my system? Thank You.
  9. want to perform frequency response analysis of a component with the Base excitation of 1g over 10 to 1000Hz, Damping 1% over 10 to 1000Hz. How can get the damping?
  10. want to perform frequency response analysis of a component with the Base excitation of 1g over 10 to 1000Hz, Damping 1% over 10 to 1000Hz. How can get the damping?
  11. Hi , Can anyone explain how to calculate / Plot dynamic stiffness from frequency response analysis in Optistruct?
  12. Hello Everyone! I am doing a response spectrum analysis an like to retrieve a eigenvalues and vectors from normal modes analysis which has already done. I hav saved the eigen value using EIGVNAME = modes and EIGVSAVE = 100. The file is has saved as modes.100.eigv. While doing RSPEC, I retreived the eigv using EIGVRETRIEVE = 100 and same EIGVNAME. But Solving throws an error as, *** ERROR # 372 *** Number of MPC constraints in file modes.100.eigv 474 does not match current value 0. Can Someone figure it out . Thanks in Advance -RathinaVel
  13. Hi, What is the significance or reason of plotting input curve and output response curve in same plot in Frequency response analysis ?
  14. Hello, First of all i want to explain what i did so far. I performed a frequency response modal Analysis to investigate the dynamic stiffness of my component in Hypermesh/Optistruct. I performed an Analysis with Optistruct and my results are the frequency-depended Displacement (s) and SPC-Force (F). Then i plotted the dynamic stiffness by calculating Cdyn=F/s. The results are exactly what i expected. After that i changed the structure of my component using Mesh Morphing and recalculated the dynamic stiffness of the changed component. This had a huge effect on the dynamic stiffness. I saved the morph-changes as shapes and created a shape design variable. I want to do a shape optimization to reduce (minimize) the dynamic stiffness. Now my questions: 1. Is it possible to do a shape-optimization to reduce the dynamic stiffness (reduce the quotient F/s) with optistruct? 2. When it is possible, can you give me a hint, how i have to proceed with the Responses, constraints and objectives for the optimization? Regards, Fatih Uysal
  15. Hi, What is the significance or reason of plotting Gin (PSD) curve and Gout ( Response) curve in same plot in Random response analysis ? Is there any theory behinds?
  16. Hi, What is the significance or reason of plotting Gin (PSD) curve and Gout ( Response) curve in same plot in Random response analysis ? Is there any theory behinds?
  17. Dear All, I have a structure for which i have carried out frequency response analysis using Hypermesh as preprocessor and NASTRAN as solver. I have the following queries: 1) In the .f06 output file, the principal stresses are not printed. 2) I have used hex hedral meshing for the entire structure. After carrying out the meshing and frequency response analysis only Normal shear stress are printed. When i use the formula(see attachment) to calculate 3d principal stresses, at some points, i am unable to calculate the angle due to incorrect value? Is this due to inaccurate meshing? Please advise.
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