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  • Users: rh142
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  1. rh142

    PEEQ Explanation

    To All, I know that equivalent plastic strain that you output using PEEQ command is cumulative, positive, scaler quatity but does it increase everytime the strain goes above yield or when it exceeds the previous max value. Assume you have a cyclic compressive load on an element. The load stays...
  2. rh142

    Digital Filter Software

    Noway2, I am more interested in the wave shape, which is why I was wondering about backwards filtering to reduce the effects of time delay and phase shift. I created a filter in octave using the butter (generates the b and a arrays) and filtfilt (which does forward and backwards filtering). I...
  3. rh142

    Digital Filter Software

    Skogsgurra, FFT or filter? Assuming filter, I should flip the filtered response then filter again. Then flip it back? Is this my final filtered response or do I need to add it to the first filtered response and average. Thanks, rh142
  4. rh142

    Digital Filter Software

    Greglocok, Thanks, Octave was already available on our system since we have red hat. So I was able to use it. I am following a published paper for the analysis and filter they used is an 8th order butterworth filter, so I want to use an 8th order butterworth filter. The paper also states...
  5. rh142

    Digital Filter Software

    macgyvers2000, To clarify a little more. I am a structural engineer and the "signal" I want to filter is from a numerical analysis which is giving time vs acceleration data. The data is in two columns with sampling rate of 10,000 Hz and the cutoff frequency I want to use is 180 Hz. Thanks...
  6. rh142

    Digital Filter Software

    What is the best software to do filter. I need create an 8th order low pass butterworth filter. Also from what I remember from by signal processing class (which was a long time ago) that filtering causes a time delay and phase shift. What is the best way of eliminating it or reduce the...
  7. rh142

    Thin Shells vs Thick Shells

    GBor, I am using LS DYNA, I was thinking about using the TSHELL (Thick shell) option for this. At one end the tube is supporting a much larger plate (100x100x2)and it will probably by fillet welded on the outside. At the other end it will be supported on a plate again fillet welded, so the...
  8. rh142

    Thin Shells vs Thick Shells

    rb1957, The tube is 1 inch thick and 1 inch long. So its a short, stubby tube.
  9. rh142

    Thin Shells vs Thick Shells

    I have sqare tube that is 9 inch wide x 1 inch long x 1 inch thick. It is going to get loaded in compression along 1 inch length. Is it ok to model it as a shell element? Thanks in advance rh142
  10. rh142

    Non linear material models

    Which material model would be best suitable if I wanted to model a material which will have to strength in tension but have some strength in compression and after yield in compression let it behave perfectly plastic. Thanks in advance
  11. rh142

    Non-linear buckling analysis in ANSYS

    Yugabalan, Thanks for the input, I agree that initial imperfections also need to be taken into account. My question is relating to steps e and f. When calculating the ultimate buckling load the switches in the program do make a difference where you final converged load step is. If I turn...
  12. rh142

    Non-linear buckling analysis in ANSYS

    YGK, Thanks for the response. I am looking under ANSYS help section 7.3 Performing a Nonlinear buckling analysis of ANSYS10 help. Specfically in section 7.3.2 for automatic time stepping. I am trying to calculate the buckling of a flexible composite plate structure. I need to take into...
  13. rh142

    Non-linear buckling analysis in ANSYS

    ANSYS help recomends that if SSTIFF is used for non-linear buckling analysis adaptive decent should be turned off to get a lower bound. What if SSTIFF is turned off? I have found that adaptive descent is helpfull when doing elastic-plastic analysis, turning it off will give an unrealistic low...
  14. rh142

    Non-linear buckling analysis

    ANSYS help recomends that if SSTIFF is used for non-linear buckling analysis adaptive decent should be turned off to get a lower bound. What if SSTIFF is turned off? I have found that adaptive descent is helpfull when doing elastic-plastic analysis, turning it off will give an unrealistic low...
  15. rh142

    Transient convergence issue

    I am running a transient dynamic analysis in ansys, at some time point it is failing to converge and the MAX DOF INC bounces back and forth between two point. I am including a sample. It bisects soon and converges but the same bouncing happens again and again. Eventually it reaches the limit and...
  16. rh142

    Engineering Stress or True Stress

    Should engineering or tru stress-strain curve be input for material properties. Thanks,
  17. rh142

    Ansys_ load case combination-basic query

    Word of caution, I don't believe you can do load case combination on nonlinear analysis, only linear analysis.
  18. rh142

    Combining Participation factors

    To All, After running a modal analysis in ANSYS, you get participation factors in all DOFs. Can you combine these directional participation factor by SRSS and get a one value. Thanks in advance
  19. rh142

    Smearing rebar material properties

    thanks for all your responses, for the orthotropic material will the shear modulus change the same way? What about poisson's ratio? GregLocock, I don't understand the neutral axis if its being modeled with solid elements Thanks,
  20. rh142

    Smearing rebar material properties

    Is there an equation to smear the modulus of elasticity of rebar on a solid element. I have a 3D model of a concrete structure and only the concrete is modeled as an isotropic material. The natural frequency is coming out to be too low. I wanted to smear the stiffness of rebar without...

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