Calculating Impact Force and oil well tree

[Fuller]

I was wondering if anybody could help me. I need to calculate the impact force exerted on an rov if it collides with a oil well tree. The information I have are the mass of the rov = 500 kg, initial velocity othe rov is 1.5 m/s and the oil well tree is a fixed body. I am unsure how to calculate the final velocity of the rov ( do I assume this to be 0?) and on how to calculate the duration of the impact.

 

[stewartcs]

I was wondering if anybody could help me. I need to calculate the impact force exerted on an rov if it collides with a oil well tree. The information I have are the mass of the rov = 500 kg, initial velocity othe rov is 1.5 m/s and the oil well tree is a fixed body. I am unsure how to calculate the final velocity of the rov ( do I assume this to be 0?) and on how to calculate the duration of the impact.

You are looking for the Impulse of the ROV on the tree, so you'll have to estimate how long the contact time is. Mathematically stated...

$$J = \frac{mv}{t}$$

where,

J = the impulse or impact force
m = the mass of the ROV
v = the velocity of the ROV
t = the time of contact between the ROV and the tree

A typical estimate for the time of contact would be $$\frac{A}{v}$$

where,

A = the area of contact

Make sure your units are correct.

CS

 

[minger]

We often cannot get these theoretical values. A couple of years ago, I had a problem where I was to determine if a pipe fell onto a platform, if the platform would break. Obviously this was not something we could test, and I looked all over to try to get something that would help. My boss gave me a couple of copied pages from a 1940 textbook, that looked handwritten, that gave:

They use impact factors which mulitiply the static force, and the impact factor is based on static deflection, which I can find. Here are the equations (sorry, haven't mastered the laxtype thing yet)
Impact Factors for Loads on Members
Static Load: 1.0
Suddenly Applied: 2.0
Suddenly Applied and Reversed: 3.0
Dropped from a height h: k
where
$$k = 1 + \frac{\sqrt{(d^2 + dv^2)}}{d}$$
and v = velocity and d=static deflection

Perhaps you could use something like this.