I use Ansys to perform random vibration analysis. But I have a doubt about the input load spectrum. Is the amplitude of the input load spectrum force fitted in the normal distribution model such that the maximum load recorded ( from road load data acquired) equal to the 3-sigma load?
Yes, you are correct but with 99.8% probability !, provided that the input load has perfectly normal distribution.
I have verified it numerically in MATLAB by generating the signal with normal distribution and obtaining its probability distribution.
For normal distribution, about 99.7% are within three standard deviations, hence, some values may be greater with 0.3% probability. Even +/- 6 sigma will not give 100% of probability.
Hi Mr. Chandrashekhar Dharankar and Mr.Pavel V. Krot . Thanks for your answers. I am interested in knowing how the input PSD profile for testing is decided on basis of the road load data.
Mr. Mir, go through my publications for more details-
Article Performance improvement of passive suspension of vehicles us...
Article Numerical generation of road profile through spectral descri...
Regards
With reference to the paper:
Article Performance improvement of passive suspension of vehicles us...
it is important to note that the equations of motion Equation (22) and (23) are applicable only when the tire is in contact with the road i.e. when Rhd < Rhs at any instant of time and it must be ensured during simulation.
It can be ensured by observing the non-dimensional parameter RHRMS, which is defined in the Section 5 (para 3) to measure road holding ability. RHRMS is defined as the ratio of RMS of dynamic road holding force Rhd to static road holding force Rhs. When vehicle is stationary, the static road holding force Rhs is equal to combined weight of sprung and unsprung mass and it fluctuates when vehicle vibrates.
At any instant the tire and road are in positive contact when the condition Rhd < Rhs or Rhd / Rhs
- Badges
- Science topic
- Similar topics
- Chemistry
- Pharmacology
- Pharmaceuticals
- Drugs