تصميم وتصنيع مفصل كاحل خامل جديد لقدم مبتوري الطرف السفلي
Design and Manufacturing of Novel Foot Passive Ankle Joint for Lower Limb Amputation
- الباحث
- محمد صفاء الدين طاهر
- المشرف
- شاكر سكران حسن - جمعة سلمان جياد
- الجامعة
- الجامعة التكنولوجية
- الكلية / القسم
- قسم الهندسة الميكانيكية / الهندسة الميكانيكية
- الشهادة
- دكتوراه
- السنة
- 2022
- لغة الرسالة
- انكليزي
- الكلمات المفتاحية
- Prosthetic foot;Passive ankle joint;Lower limb amputation;Biomechanics
Abstract
The work carried out in this thesis aims to design and manufacture a prosthetic foot with a passive ankle joint, which mimics the biological foot functions and performance. In addition to the high degree of similarity to the biological foot, the designed foot is aimed to be effortless to install with low manufacturing and maintenance costs. This thesis is carried out in three parts. In the first part, the SOLIDWORKS program is exploited to draw the design of the foot and ankle. Also, in this stage, the mechanical properties of the used materials are tested and investigated through several experiments. The second part concerns conducting a numerical mechanical analysis by simulating the working conditions of each piece according to the drawn model and the material mechanical properties in order to determine the best design. Moreover, this part contains the derivation of the lateral stiffness equation of the conical spring when a moment is applied on its large side, which has been verified through simulation and experiment. The lateral stiffness equation and biomechanical tests must meet two targets: First, the foot must return to the zero position of the ankle in the swing phase. Second, the spring should not limit ankle-free movement. The third part of this work is to conduct biomechanical tests (kinetic and kinematic) on the manufactured prosthesis to determine the degree of similarity of the designed foot with the biological foot. These tests are conducted on a patient who has transtibial amputation by walking on a specially made platform to simulate different walking conditions (ascent ramp, descent ramp, flat road, right-rise, and left-rise). The results manifested that the safety factors of the large, small leaf springs and the holder are 1.5, 2.29, 1.57, respectively. The lateral stiffness of 6.96 – 12.433 Nm/rad can be achieved using a conical spring wire of 4.5 mm diameter. However, this result is the maximum Von-Mises stress of 138 MPa at the highest inclination angle of 60o which is lower than the yield stress of the spring wire (820 MPa). The kinetic results evinced a strong similarity in the ground reaction force between the designed and biological feet with a similarity percentage of 87.8% when the patient descents the ramp and 98.5% at ascents the ramp. The kinematic results elucidated a high degree of similarity between the designed and the biological feet of the gait cycle, such as length and width of the step which can be clearly seen during the walk on the inclined roads. This similarity indicated a high degree of performance of the designed ankle joint which is verified by KINOVEA test. This test showed a very small difference in movement angles between the prosthetic and biological feet, where a maximum angle difference is recorded at 2o for all movements on different kinds of roads. The designed prosthesis is able to be used for different patients due to a length reduction technique of the conical spring, through which increases the lateral stiffness.
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