A Note on the Determination of Relaxation and Creep Data from Ramp Tests

The response of (linearly) viscoelastic material is approximately the same for ramp and true step strain histories once an initial time interval of about ten times the ramp-up time has passed.Because the loss of relaxation data during that initial time can be a substantial portion of the total (logarithmically measured) time scale, a simple method is documented for exploiting data obtained from the initial ramp history via a recursion formula. Comparison of data obtained in ramp and relaxation histories are demonstrated to yield good results within the accuracy of the test method