Forces on an object being run over?

[andy_padgett]

Hello All,

I'm currently trying to complete a Finite Element Analysis of a design i have made at uni.
Put simply I have designed a new 'Stinger' type device for the police to use to stop pursuits with.
I am trying to calculate the force that will be placed on my design when placed in the road and run over by cars etc.. - Obviously it must be strong enough to withstand these forces.
The profile of the design is triangular, 35mm high and 75mm wide, with pretty much a 45 degree angle.
I have tried to work out the force using basic impact equations, but obviously the force will not be hitting the object head on e.g. only the bottom 35mm of the tyre will hit it, the profile of the object will have some effect, etc..
Is there any way to make this more accurate?

With my calculations the impact force is about 2000N at a speed of 60mph.
This does not take into account the weight of the car, should i add 1/4 of this to the impact force (to account for the 4 wheels) to get the final force so i can complete the FEA?

Any help or pointers would be very appreciated!

Many thanks,

Andy

 

[Aaron Bex]

Hi Andy,

It sounds like you are trying to do a difficult calculation and I am sure you will appreciate any help you can get. The impact force that you are calculating is just an estimate and it might be useful to utilize a finite element analysis to work out the actual force on your design when it is placed in the road. You could also consider other factors such as the weight of the car and the profile of the object that could affect the force. It might make sense to add 1/4 of the weight of the car to the impact force in order to get a more accurate result. Good luck with your project and I hope you find a solution.

 

[GSXR750]

Hello Andy,

It sounds like you are working on a very interesting project! When it comes to calculating forces on an object being run over, there are a few different factors to consider. One important factor is the distribution of the force on the object. As you mentioned, the force will not be hitting the object head on, so it's important to take into account the angle of impact and the surface area of the object that will be in contact with the car. This will affect the magnitude and direction of the force on your design.

Another factor to consider is the weight of the car. As you mentioned, adding 1/4 of the car's weight to the impact force could be a good estimate to account for the weight of all four wheels. However, the weight distribution of the car can also play a role in the force exerted on your design. For example, a heavier car with more weight concentrated on the front wheels may exert more force on your design compared to a lighter car with more weight on the back wheels.

In terms of making your calculations more accurate, you may want to consider using more advanced equations or simulations, such as Finite Element Analysis, to take into account all the different factors at play. You can also consult with a mechanical engineer or an expert in FEA to get a more accurate estimate of the forces on your design.

Overall, it's important to consider all the different factors and variables that can affect the forces on your design when being run over by a car. Good luck with your project!