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IE 552 Mechanics of Musculoskeletal System Dr. Andris Freivalds Class #14. Tension Buildup (con’t). Step: 1-e -at. Ramp: e -at /a -1/a + t. K SE =100, K PE =400, B=5 a=100, Τ =.01sec → 100 Hz. Time Constant in Muscle Response. Time Constant Corresponds to Tetanic Frequency.
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IE 552 Mechanics of Musculoskeletal System Dr. Andris Freivalds Class #14 IE 552
Tension Buildup (con’t) Step: 1-e-at Ramp: e-at/a -1/a + t KSE=100, KPE=400, B=5 a=100, Τ =.01sec → 100 Hz IE 552
Summary of Muscle Model Parameter DeterminationDashpot B – Initial slope KSE – Slope from Quick Stretch IE 552
Summary of Muscle Model Parameter Determination (con’t) KPE from time constant (τ): • Stress relaxation • Strain relaxation (creep) IE 552
Frequency Analysis of Muscle TCE = -(Bs + KPE)ε + (Bs + KPE + KSE)/KSE T T = (Bs + KPE)ε (Bs+KPE+KSE) IE 552
General Frequency Analysis For complex variable: X(ω) + jY(ω), where j =√-1 M(ω) = [X2(ω) + Y2(ω)]½ (magnitude) Φ(ω) = tan-1Y(ω)/X(ω) (argument) IE 552
H(s) = 1/(s+1) (substitute s = jω) Manipulation (Frequency Domain) IE 552