抄録
A cyclic load testing device has been developed for examining structural strength of artificial legs. The device can trace the sinusoidal wave form of the load, and can apply any peak complex load on the test sample using only one linear push-pull type actuator. The principle of the loading method and some simple test dimensions to load on the test sample are shown. The actuator is an air cylinder controlled by pneumatic circuit. A pure pneumatic system is adopted because of its longevity up to 10^6〜10^7 cycles, which is impossible to realize with an electro-pneumatic system. The push-pull force is generated up to 2000N, and cyclic frequency can be set from 0.025Hz to 2.0Hz. The device is simple, its cost is low and it makes it possible to drive many devices at the same time and examine the mechanical properties of artificial limb parts in the shortest time, compared with conventional hydraulic devices. Some test results are shown. One is for a pylon tube used in the shank part of the lower limb prosthesis, and the other is for a knee joint with a swing aid mechanism, under the load values recommended by ISPO in 1977 and ISO/TC168/WG 3 in 1984. From the test results, it becomes clear that the load values of these recommendations are too severe for the cyclic load test of artificial legs for lightweight amputees.
