No!  I'm not talking about the dork who sits behind you in biology class.  I am labeling the mechanical property of stretching in a composite material.  If we were to pull on the dork in biology class from his head and feet outwards, would we get any stretching?  Would he be able to return to his original shape?  Not if we Broke something or Ripped him apart.  Polymers and composites have the ability to both resist deformation upon tension and be elastic (return to original form) after having their shape changes.  A polymer which is fiber reinforced has its creep ability greatly reduced due to the strong hardness of the fibers.
      There are several different types of creep tests.  In a creep test the deformation increases with time.  If the strain is divided by the applied stress, one obtains a quantity known as the compliance.  The compliance is a time dependent reciprocal modulus.  If load is removed from a creep specimen after some time, there is a tendency for the specimen to reform its original shape.  A recovery curve can be obtained if the deformation is plotted as a function of time after removal of load.

Back to Mechanical Tests

Back to Physical Tests

Back to Characterization Mainpage