Silicone elastomer use in medical devices continues to expand with more complex shapes and performance requirements. The physical properties of cured silicones make them potentially suitable for applications requiring not only flexibility and strength, but also the ability to be formed into intricate shapes and survive high temperatures and sterilization without deforming. Many applications for medical devices or disposable accessories made from silicone subject the part to cyclic force or stress. The frequency, stress and strain of the cycle is dependent upon the use and on the weight or load that is applied. Some examples include tubing in peristaltic drug delivery pumps, check valves, resuscitator bulbs, diaphragms and prosthesis suction cups for limb attachment. In these types of applications, the cyclical stress may be in a tensile, compressive, shear, flexural or torsional mode or, more likely, a combination of several modes.