Table 3.

Estimated Conversion of Sinusoidal Frequencies From the Compression Test Data of the Present Study to Loading-, Stress-, Displacement-, and Strain-Rates Used for Comparison With Other Studies

Freq. (Hz)	Average Max. Applied Compressive Load (N)	Average Max. Applied Stress (MPa)	Average Modulus (MPa)	Loading Rate (N/s)	Stress Rate (kPa/s)	RMS Displ. Rate (mm/s)	RMS Strain Rate (strain/s)
0.001	878	0.59	23.6	3.5	2.3	0.0011	0.00011
0.01	1077	0.72	28.8	43.1	29	0.011	0.0011
0.1	1184	0.78	31.2	474	316	0.111	0.011
1	1285	0.86	34.4	5140	3430	1.11	0.111

Compressive stiffnesses from Table 1 were used to estimate the average maximum applied compressive load at a compressive displacement of 0.25 mm. An average disc area of 1500 mm² was assumed for average maximum applied stress calculations, and an average disc height of 10 mm after overnight preload equilibration was used for strain calculations. Root mean square (RMS) values are presented as approximations for displacement and strain rates because the strain rate for a sine wave is not constant.