DEFINING THE AGING OF KNEELING MATS

1. DEFINING THE AGING OF KNEELING MATS • This study is intended to evaluate the effect of aging and long-term use on the protective effectiveness of the kneeling mats • The rate at which the mat recovers from cyclic loading is proposed as a measure of aging and usage deterioration • The effect of repeated cyclic loading on the recovery characteristics of kneeling mats was investigated in this phase of this research • After long-term usage, kneeling mat can show visible signs of aging and deterioration, but the effects of these changes on the protective properties are unknown Jeremy Sosa Naira Campbell-Kyureghyan Ph.D.

2. Methods • New and used kneeling mats were provided for testing by an industry partner (Figure 1) • Two loading phases were used repetitively in sequence (Figure 2) • 0-500N compression for 500 cycles to simulate one month of industrial usage, followed by • constant loading to measure deformation recovery • The new mat is not labeled • The mat labeled 1 is the lightly used mat • The mat labeled 3 is the heavily used mat

3. Results • The new mat recovered at a higher rate than did the used mats • For the two used mats • There was little difference in the rate of recovery after the first cyclic load set • The lightly used mat recovered at a higher rate than the heavily used mat after subsequent cyclic load sets • With usage, the mats did not recover as quickly, indicating that they have lost some of their resilience • The loss of resilience with use may indicate a reduction in effectiveness at providing protection to the knee. Questions? • The rate of recovery for the three kneeling mats was 0.0053mm/s, 0.0038mm/s, and 0.0036mm/s respectively • The new mat began to recover sooner than the used mats. Lightly used mat recovered slightly quicker than the heavily used mat.