| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 90 === In this study, a 5-12MHz linear array transducer was used to compress the soft tissue, and four kinds of loading frequency, 0.5Hz，1Hz，2Hz，and loading with 0.5second and recover with 2 seconds was adopted. The changes in front plantar soft-tissue thickness and the compression force were recorded simultaneously, and the stress-strain could be derived directly. In this study, energy dissipation ratio(EDR) , recover ratio, E1, and two mathematical model, time constant τand quasi-linear viscoelastic model were used to discuss the differences between the diabetes and age control adult.
From the stress-strain curves, we can get the EDRs (%) at various loading frequencies ; 0.5Hz, 46.7±7.6 vs. 53.9±5.9，(p=0.001)；1Hz，57.0±6.3 vs. 62.5±6.6，(p=0.006)；in 2Hz，67.6±6.4 vs. 70.9±7.8，(p=0.126) ,for respectively age control group and diabetic patients. With the increase in loading frequency, the difference between the two group decreased. The recover ratio that quantify the level of relaxation of the soft tissue after compression, were 0.924±0.053 vs. 0.835±0.072, (p<0.01), for age control group and diabetic patients respectively. It appears that the recover of soft-tissue of diabetic patients is worse than age control. The E1, for various loading frequency were 0.5Hz: 89.3±21.4 vs. 70.6±13.9, (p=0.03)； 1Hz: 109.9±34.9 vs. 83.6±17.6(p=0.07)； 2Hz: 120.3±47.1 vs. 107.7±43.9，(p=0.43), for age control group and diabetes respectively. The difference between the two groups decreased with the increase in frequency. The relaxation time constants τ in relaxation model were 0.168±0.141 vs. 1.152±0.948，(p<0.01), for age control group and diabetic patients respectively. The hysteresis and the stress relaxation coefficients in the QLV mathematical model , “a” and “te”, were 0.0041±0.0009 vs. 0.017±0.010，(p=0.01)；0.090±0.078 vs.0.014±0.0068，(p=0.01) respectively, for age control group and diabetic patients. Generally, diabetes caused worse dynamic response of the soft tissue and more energy dissipated.
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