Fatigue Characterization of Laminated Composites used in Prosthetic Sockets Manufacturing

The below knee Prostheses sockets are subjected to varying loading conditions during the gait cycle. This will cause a fatigue in the sockets due to the induced tension and compression stresses developed during the gait cycle. Recently, the using of the laminated composites are widely used in the rehabilitation centers. The engineer should be based his design on the endurance stress level instead of the allowable stresses which are higher than the endurance level. The Prosthesis engineer should be given these levels of stresses for safe and durable product and cheap at the same time. In this work, five types of stacking sequence were chosen based upon a previous work of the authors. These are arranged (4 perlon+4 glass+ 4 perlon), (4 perlon+4 carbon+4 perlon) and three mixed samples (3perlon+2 kevlar+2 perlon+2 carbon+3 perlon), (3 perlon+2 kevlar+2 perlon+2 carbon+3 perlon), and (3 perlon+2 kevlar+2 perlon+3 carbon+2 perlon). The matrix which has been proved effective is the Ortocryl. A comprehensive program of fatigue experiments were achieved to predict the suitable type of laminate for the socket prostheses manufacturing which can sustain the dynamic fatigue during the gait cycle in addition to the finite element modeling. The experimental results have a good agreement with those obtained using the Finite Element Method with a maximum discrepancy not exceed 12%. It was found that the sample No. 2 has the maximum decay factor = −2.706 with a maximum number of cycles up to failure = 21.35 × 105 cycle for the constant amplitude test and the damage factor in the variable amplitude test is increased with the increasing the number of cycles at each test. The obtained results indicate that they can be used or manufacturing the socket prostheses depending upon the required sustainability, age of the patient and the daily work type.