The boundary conditions are:

1. The left edge of the outer can is restrained in the axial direction and free to expand in the radial direction. 
2. The right surface of the inner member is deflected axially which shears the elastomeric layers.

The deformation changes the volume available for the gas, therefore the gas pressure changes. The gas pressure is trying to move the elastomer towards the right, while the deflection of the inner member is trying to move the elastomer towards the right or left. This combination of loading on the elastomer results in a reversal in the direction the elastomer is moving within the layers.

An analysis had to be performed by applying alternating portions of the pressure and deflection due to the high distortion. The actual component had folds in the elastomer when loaded, in the same regions of the high distortion.

The following video shows results from the analysis.

Video of Gas Spring Analysis

• Uncompressed AVI file: Gas Spring AVI (1.35 MB)
  
• Compressed ZIP version: Gas Spring ZIP (226 KB)  
  

Note: the ZIP files download faster than the AVI file. After downloading, you must unzip the file with a program, such as WinZip or PKzip. Then choose "File | Open" from your web browser's menu. Find the unzipped file and open it with the web browser. Click on the image to see the video.