model of a seesaw

Rahul_P1

Hello,

I want to modelling ur torsional stiffness test bench for formula student frame. I´ve a problem with modelling the lower structure. This part should work like a seesaw from a playground. The basic support of the frame is at the back suspension (not pointed in the drafting).

The principal model is drafted in the picture 01 and 02. The lower beam is centrically supported. The intersection points of A & C are simply supported (just like intersection point of B & D). The line of C & D is in every situation stiff.

I need help with the modelling of the pin joints.

Thanks in advance!

Anton

Rahul_P1

Maybe I should split the problem in two parts.

First 'seesaw-problem': I need a beam (line of C/D) with centric support and one load at the left. The reaction should by a converse motion on the right. The important aspect is, that the beam is stiff and can commit the reaction of the force.

Second 'vertical beam': The vertical beams A & B moving on a plane not only on the vertical axes. But while moving they still in a vertical position. So I need a simply support between A/C respectively B/D.

Thanks in advance!
Anton

Rahul_P1

Anton,

If I understand your problem correctly you need to model the test bench so that the displacement of A in the negative Y direction is the same as the displacement of B in the positive y direction resulting in a see saw effect that will hence induce torsion in the structure under test.

I see in a simple model here that a constraint at the centre alone produces this kind of a see saw effect with the same displacement in either direction. simply supported joints on either end will distort the results ending with an effect that is not like a rigid see saw.

 

So I see that constraining the node at the joint is how you would model the pin joints for Optistruct or RADIOSS bulk,
You can model joints in an MBD analysis,