Material Selection Requirements

• Because of material fatigue, plastic parts exposed to cyclic loading often fail at substantially lower stress or strain levels than those under static loading.
  
  
• Fatigue can result from heavy vibrations or repeated loading and deflection.
  
  
• Performance of a part under fatigue depends on many factors such as the presence of notches, stress concentrators, loading frequency, environment conditions and material properties.
  
  
• It is important to know the fiber orientation within the material, since the material will exhibit better fatigue properties parallel to the fibers as opposed to perpendicular to the fibers.