Mechanical properties of rabbit patellar tendon at high strain rate.

The tensile properties of the rabbit patellar tendon were determined at a very high extension rate (560 mm/s), and were compared to those obtained at lower rates (53 and 0.33 mm/s). A closed-loop servo-hydraulic material test machine was used for the tensile tests at the rates of 560 and 53 mm/s. Strain was determined using a high-speed video dimension analyzer consisting of a line sensor camera, control unit, and image processing board. For the tests at 0.33 mm/s, a conventional tensile tester and video dimension analyzer were utilized. The tensile strength and strain at failure of the tendon increased by 51 and 77%, respectively, with increase in the extension rate from 0.33 to 560 mm/s (from 0.566 to 1250% s(-1) in strain rate); these parameters increased by 35 and 42%, respectively, with the rate change from 0.33 to 53 mm/s (from 0.566 to 151% s(-1)). However, there were no significant differences in the tangent modulus among the three rates. These results indicate that tensile strength and strain at failure increase with increase in strain rate, with no change in tangent modulus.