I found this white paper by Weaver Engineering especially useful when considering weld FEA as it connects hand calculations with FEA results that is mesh independent (sans singularities). There is sufficient details in it for the results to be replicated using FEA software of your choice. A good...
I suspect it is because of the shape of the PWM Link. As the speed increases, the pulse length increases, thus reducing the period. I'm guessing the harmonics in general are caused by the square waves Link.
Perhaps try creating a fake PWM signal and do an FFT on it?
Hi Vladimir,
There are many FEA codes out there but if you're starting out, I would suggest looking at commercial codes (such as Nastran) that is used by your desired company. Try contacting the sales people for a student version. For example, you could download Ansys student and use it (with...
There is one official one on notepad++:
http://notepad-plus.sourceforge.net/commun/userDefinedLang/userDefineLang_ANSYS.xml.
I've made a few changes to it. Here's the linkhttps://drive.google.com/open?id=1ORdqhUQV-6yAz-uq3X5ncHQtgk9-azuG
Best,
Jason
Hi Lee.Conti,
Fundamentally speaking, random vibration and harmonic analysis both uses the same equations of motion. Where they differ is how the modes are scaled and added as well as how the stresses from different modes are 'added'. But yes, I agree with you. Smartly substructuring should...
An alternative is to export it out in market matrix file format maintained by NIST:
*dmat, exportmatrix, D, import, APDL, c ! export to matrix file
*export, exportmatrix, mmf, mytemp.mtx
You can then read it in Matlab (and Octave?) using mmread.m found here.
After you have the function in...
I like your attitude Greg [thumbsup2]
Depending on the tip of the hammer, more than 1 mode can be excited. An example time domain output in this paper on a simple reinforced concrete beam on Figure 3 shows log decrement method is difficult to apply.
Kind regards,
Jason
PLMKY,
Logarithmic decrement method works nicely for SDOF textbook problems. For your beam test with multiple modes getting excited simultaneously, a half power method should work better. See this simple writeup on how to apply it.
If the cross section of your beam has similar width and...
You could try mesh decomposition. For your problem, perhaps have 4 quarters of the rod and 4 quarters of the orange body. You could then put hard size controls to force the sizing that you want. An approximate example can be found here.
Kind regards,
Jason
Hi Rana,
You could try looking into acoustic elements to model water instead of approximating it with artificial mass and springs. Note the sloshing surface must be parallel to the coordinate plane of the global Cartesian system and can be flagged via the FREE surface load label
Kind regards...
L_K's proposed hydrostatic fluid elements looks more promising than acoustic elements for tires.
karachun- Yes, while my intuition is the tire air pressure could increase as the car takes on heavy passengers and cargo. My assumption may be incorrect.
Kind regards,
Jason
Hi Shahril,
It may be worthwhile to look at acoustic elements to represent air. That way, the pressure is directly coupled to the deformed volume without need for looping. The element does make some assumptions such as small density change so it's worth understanding the limitations to see if...
Hi Sachin46,
Sorry, I should have added that the above script may be used as an APDL command snippet in Ansys Workbench. Example animation below:
Kind regards,
Jason
Hi Erica,
From what I gather, the solver attempts to negotiate and resolve the overconstraint conditions while it issues that warning message. Overconstrained models most often result in nonconvergence of the solution with small solver pivot warnings. Is that the error message you see in the...
Raphael,
It sounds like an interesting project. Perhaps a way forward is to fine tune your parameters with narrowly focused experiments. For example, you could try calibrating the piezoelectric properties by testing it in air with a laser vibrometer orienting it in multiple directions.
Kind...
