Stretching a rubber tube

[Enrg54321]

If a rubber tube of length L and outside diameter OD and inside diameter ID is stretched along the long axis, the OD and ID will shrink correspondingly.

The question is how can the shrinkage be calculated from the material properties of the rubber and the applied stress?

My sense is that the shrinkage is a function of the distance from either end of the tube. In other words, the OD and ID necks down.

 

[Dtuck]

If the ends are properly retained and open to the outside atmosphere, the main shrinkage will be in the thickness of the wall as the length increases. The inside size will shrink only if the inside is isolated fron the outside atmosphere.

 

[Enrg54321]

Thanks for your reply.

You are saying that stretching an open tube, the length of the tube will grow and the wall thickness of the tube will shrink.

However, if the tube is sealed on both ends, similar to a pressure vessel, the stretching will cause the internal pressure to drop (gas law) causing the OD to shrink due to the pressure difference. This is interesting. Have you seen this happen?

 

[Compositepro]

When you stretch a rubber tube the diameter will shrink as well as the wall thickness, whether or not the ends are sealed.It is called "necking".