A size 4-0 (0.15mm diameter) monofilament nylon suture was tested for its stress relaxation properties using a micro-mechanical tester at room temperature. A 20 mm sample was stretched 2 mm over a 20 second period; the force-displacement curve for the suture was linear during this initial stretching and its slope was reported as 2.15 N/mm. Consequently, the load was then recorded over a period of 10 minutes. The relaxation ratio is defined as the force from the initial 2mm displacement divided by the force after the 10 minutes stress-relaxation period and was determined to be 1.61. Assume that the Maxwell model applies.
A) What is the elastic modulus of the suture?
B) What is the relaxation time?
C) How long will it take for the force to reach 15% of its original value?