Impulse and Impact time of a collision

AI Thread Summary
The discussion focuses on calculating the force exerted on road safety barriers during vehicle collisions, specifically the impact time (delta t). The user is analyzing Road Restraint Systems using Finite Element Analysis but lacks an assumed value for delta t, which is crucial for their calculations. They have derived equations related to energy and momentum but are struggling to find relevant past studies or tests that provide delta t values. The user requests assistance in obtaining this data or alternative methods for calculating the force. The inquiry highlights a gap in available research on collision impact times for safety barriers.
frostie
Messages
3
Reaction score
0
Hi there,

For my Final Year Project at University I am analysing Road Restraint Systems/Safety Barriers in a Finite Element Analysis package.

My problem is calculating the force exerted onto the barrier by a vehicle during a collision, more specifically the time over which this impact occurs.

Using d (this distance over which the impact occurs) isn't an option as this is an unknown that is calculated during the analysis.

What I've got so far...

E=1/2mv2
Momentum = mv=2E/v
Momentum = F. delta t = 2E/v

Therefore, F = 2E/v.delta t

What I really need is an assumed value of delta t from past numerical or field tests. I've searched for journals with such information with no luck. Failing that a method or idea how else to calculate the force exerted on the barrier from a vehicle.


Any help would be greatly appreciated.

Regards,

Frostie
 
Physics news on Phys.org
Sorry...Looking at the sub-forum descriptions and the general topics of the posts in this forum...I think I may have posted this in the wrong section. I saw PhD help and posted...but I think this is probably more for help on choosing a PhD?

Could a moderator possibly move this to a more appropriate place.

Thanks,

Frostie
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top