Mechanical impact

1. May 30, 2004

Michael777

Hello there,
I got this little project I am working on, it maybe simple to you , but I have a hard time getting some useful results.
I have an assembly, it looks like a square box(section) 6 inches long, with a cylinder attached to one end.
On the end I have the possibility to attach a sleeve made of a rubbery material (I use relatively soft , Shore 80 A Santoprene) . The measured weight of the assembly is 3.77 lbs.
In my experiment I attached this assembly to an arm (67 inch long), which can swing like a pendulum.
The arm is rotating on a pin with a bearing on it
I bring the arm horizontally, and let the assembly swing in the gravity field, initial speed 0.
At 90 degree (arm vertical) the assembly impacts a concrete wall and bounces back.
The impact area of the assembly is the ream of the sleeve.
In reality, the contact is not a cylindrical ring because the contact is not always centric.
I have instances when the contact is a segment of a ring, since the initial wall-ring contact is an edge of the ring ; under impact forces the edge deforms and at times folds (changing the area of contact) and changing the bounce speed of the assembly.
To complicate the things, I have some small masses attached to the assembly through some miniature connectors.
The fashion these masses are attached to the assembly is in such a way that the inertial forces generated at impact pulls them out of the connectors, overcoming the retaining forces. The connecting pins are parallel with the impact force vector.
I did my homework and I’ve drawn my conclusions regarding this experiment (I don’t mind sharing my thinking about how to solve this problem with any of you).
Below, I will formulated the questions I want answered as a reality check:

I need to find out;
1/ the impact speed of the assembly
2./ the max deceleration at impact
3./ the maximum kinetic energy developed along the trajectory.

TIA,
Michael