3D打印连续纤维复合假肢接受腔Z向强化制造策略

Z-direction Enhancing Manufacturing Strategy for 3D Printing Prosthetic Socket of Continuous Fiber Composite

假肢是截肢者恢复行动能力所必须的康复辅具,假肢接受腔作为连接残肢与假肢系统之间重要的生机界面,具有包容残肢、支撑体重、传递运动载荷的重要作用。与传统工艺制备的假肢接受腔相比,MEX(Material Extrusion,材料挤出成形)3D打印接受腔具有加工周期短,成本低等优势,能够满足接受腔快速低成本制造的需求,但该工艺制备的接受腔以Z向力学性能较差为突出劣势,应用也因此受到限制。之前的研究针对该问题提出了一系列的策略对MEX打印工艺的Z向力学性能进行提升,但受到材料与工艺限制,优化后的打印策略制备接受腔的Z向力学性能依然不足。为解决该问题,本研究首先基于假肢接受腔的打印需求,自主研发了可控制挤出头姿态变换的多自由度MEX打印设备。随后,本研究系统地研究了多自由度打印工况下纤维方向和打印层厚对芳纶纤维增强复合材料打印件Z向力学性能的影响。最后,本研究根据多步态下假肢接受腔的力学分析结果,将纤维方向和接受腔厚度等参数和接受腔受力状态进行关联,提出了接受腔Z向强化打印策略。结果表明,与传统3D打印工艺相比,Z向强化制造策略可显著提升接受腔的力学性能,所制备的假肢接受腔可满足穿戴疲劳要求。

The prosthetic socket is a necessary rehabilitation-aid equipment for lower limb amputees. As an important kind of human-machine interface between the residual limb and the prosthesis, the prosthetic socket plays an important role in containing the residual limb, supporting the body weight and transmitting the motion load. Compared with the prosthetic socket by conventional process, MEX-printing(material extrusion) prosthetic socket has the advantages of short processing period and low cost, which can meet the needs of rapid and low-cost manufacturing of prosthetic socket. However, the socket prepared by this process has a prominent disadvantage of poor Z-direction mechanical performance, which limited its application. To solve this problem, a series of strategies are proposed by previous studies to improve the Z-direction mechanical performance of MEX-printing process. Due to the limitations of materials and processes, the Z-direction mechanical performance of the sample prepared by the optimized printing strategy is still insufficient. In order to solve this problem, a multiaxial MEX printing equipment which can change the angle of extrusion head is developed based on the print requirements of the prosthetic socket. Then, the effect of fiber orthogonal-laying direction and the printing layer height on Z-direction mechanical properties of aramid fiber reinforced composites are systemically studied. Finally, parameters such as fiber direction and the thickness are correlated with the stress conditions of the prosthetic socket based on the mechanical analysis results of prosthetic socket during multi gait, then the Z-direction enhanced printing strategy of the prosthetic socket is proposed. The results showed that compared with the traditional 3D printing process, the Z-direction enhancing manufacturing strategy can significantly improve the mechanical properties of the prosthetic socket, which can meet the requirements of wearing fatigue property.