Doable analysis?

[peterbrown77]

Let me preface this by saying that I am the most casual of casual Mechanica users. We have a Structure license and I am trying to figure out what is happening in one of my designs.

The situation is this: I have a bandsaw with a 12" drive wheel. The bandsaw blade is .030 thick and .65 wide. The blade passes through a guide that twists it 90deg about 10" away from the center of the wheel. Imagine the side of the blade being perp to the centerline of the wheel.

I'm trying to determine where the top of the blade is relative to the centerline of the wheel after it passes through the guide.

At first I assumed that the blade simply twisted about its neutral axis, starting out at 0deg and ending up at 90deg 10" away. Therefore, the top of the blade would be 6.015 (the wheel rad plus 1/2 blade thickness) - (.65/2) or 5.690 from center. However, this is not the case.

The blade is not clamped to the wheel at the tangency point, and in reality it starts to lift off the wheel at a point before the tangency for the edge that is moving away from centerline as it is twisted. The opposite edge cannot move a commensurate amount towards centerline because the wheel is in the way. This means that the top of the blade is a greater distance from wheel centerline than 5.690.....I just don't know how much.

I tried modelling this in Structure and applying a rotation deformation to the end of the blade of 90deg but the analysis keeps failing.

Is a deformation of this magnitude too much to ask of Mechanica? Will it even give me an accurate result? I can do this empiracally, but with all this wonderful software at my disposal.....

TIA
Peter Brown
Edited by: peterbrown77

 

[mch]

Peter,


What you are describing would require a contact analysis with large deformation. Mechanica will do either of these types of analysis, butnot both. Just because the problem is simple to describe doesn't mean that it's easy to solve. Bolted joints are a classic example of this.


For your problem I would start by doing a contact analysis of the blade as it passes over the wheel. You will need to define the shape of the blade as it is bent over the wheel in the flat state, then in Mechanica assign a contact region between the underside of the blade and the wheel. Apply a twisting load to the belt to simulate the guide, then you will see in the results the blade lifting off on one side of the wheel and pressing down on the other. Good Luck, this is not the easiest analysis for the novice analyst!


Regerds,


Rod