抄録
Effects of fluid properties on stress relaxation behavior in a liver of a pig were investigated. First, compression and relaxation tests were carried out for various liquid viscosities and fluid pressures using liver of a pig. In the compression tests, the fracture strain was dramatically increased with increasing viscosity of liquid while the fracture strain decreases with increasing viscosity. The hardening ratio increases with increasing pressure of fluid. In contrast, Young's modulus for zero-load decreases with fluid pressure. In the relaxation tests, the change in relaxation ratio with time became gradual with increasing viscosity of liquid. However, it rapidly decreased with increasing pressure of fluid. Two-step compression tests were then conducted to clarify the effects of primary and final tightening of a plastic tourniquet. The values of stress gradient and stress for the final tightening in the normal compression tests were almost the same as those in the two-step compression tests. However, stress gradient in the second compression exhibited only a linear behavior. The second relaxation behavior became gradual with increasing the first relaxation time. It was found that movement and outflow of liquid end at around 300 seconds after the start of the first relaxation.
