How do i simulate this situation in catia Structural analysis?

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Discussion Overview

The discussion revolves around simulating the impact of a car crash on a rotor supported by bearings, specifically focusing on how to model the shock load in CATIA Structural Analysis. Participants explore the effects of crash forces on the rotor and the bearings' ability to withstand such impacts.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant describes a scenario where a rotor is spinning perpendicular to a car's direction of travel and asks how to simulate the crash force of approximately 672kN as a shock load.
  • Another participant suggests that the first step is to determine how much of the crash force is transmitted to the rotor, which depends on the relative masses of the car and rotor, as well as the flexibility of the car's structure.
  • It is proposed that a good initial approach is to model the bearings as rigid and apply an acceleration to the rotor opposite to that of the car during the crash.
  • Participants discuss the significance of rotordynamic effects and suggest starting with a non-spinning rotor model for sensible results before including these effects.
  • One participant questions the definition of "survive" in terms of the rotor's stability post-crash, clarifying that they mean the rotor should not detach from the bearings.
  • Another participant points out that knowing the force allows for estimating the mass of the car using the equation Force = mass x acceleration, even without exact figures for the crash duration.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best approach to simulate the crash impact or the specifics of how to calculate the relevant parameters. Multiple competing views on modeling techniques and definitions of survival remain present.

Contextual Notes

Limitations include the lack of specific figures for the mass of the car and the time duration of the crash, which may affect the calculations and assumptions made by participants.

Webbd050
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I have a rotor spinning perpendicular to the direction of travel of a car. Its supported at either end of its axle by bearings. The car crashes and I've calculated the force of the crash to be approximately 672kN. How would i simulate this on the rotor as a shock load? I could do it as a static load would that give the same results? Also how do i know if the bearings would survive the impact? Thanks
 
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The first step is to find how much of your "crash force" is actually felt by the rotor. That depends on the relative masses of the car and the rotor, and how flexible the car structure is.

A fairly straightforward approach would be to assume the bearings are rigid and apply an acceleration to the rotor, opposite to the acceleration of the car as it crashes, Rotordynamic effects like gyroscopic forces may or may not be significant, depending on the design of the rotor and its speed, but in any case it would be a good idea to get the model giving sensible results with the rotor not spinning before you include the rotordynamics.
Also how do i know if the bearings would survive the impact?
First define "survive". Do you mean the rotor doesn't fall out of the car, or that it will still do whatever it is supposed to do after the crash?
 
Ahhh okay so what equation would i use to calculate the acceleration? I haven't got a figure for the time of the crash. By survive i mean the rotor isn't going to fly off the bearings and embed itself in someones head. Thanks
 
You know the force. You should be able to guess the mass of the car even if you don't know it exactly. Force = mass x acceleration.
 

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