[Design and support performance evaluation of medical multi-position auxiliary support exoskeleton mechanism].

Aiming at the status of muscle and joint damage caused on surgeons keeping surgical posture for a long time, this paper designs a medical multi-position auxiliary support exoskeleton with multi-joint mechanism by analyzing the surgical postures and conducting conformational studies on different joints respectively. Then by establishing a human-machine static model, this study obtains the joint torque and joint force before and after the human body wears the exoskeleton, and calibrates the strength of the exoskeleton with finite element analysis software. The results show that the maximum stress of the exoskeleton is less than the material strength requirements, the overall deformation is small, and the structural strength of the exoskeleton meets the use requirements. Finally, in this study, subjects were selected to participate in the plantar pressure test and biomechanical simulation with the man-machine static model, and the results were analyzed in terms of plantar pressure, joint torque and joint force, muscle force and overall muscle metabolism to assess the exoskeleton support performance. The results show that the exoskeleton has better support for the whole body and can reduce the musculoskeletal burden. The exoskeleton mechanism in this study better matches the actual working needs of surgeons and provides a new paradigm for the design of medical support exoskeleton mechanism.

Numerical Simulation on Support Performance of NiTi Alloy Thoracic Aortic Stent / 医用生物力学

Objective To study the influence of different support heights, support numbers and cross-sectional dimensions on support performance of NiTi thoracic aortic stents. Methods Twenty-seven scaffold models with different parameters were established by using AutoCAD 2016 and SoildWorks 2014 software. HyperMesh 14.0 was used for tetrahedral mesh division, and ABAQUS 2017 was used for support performance simulation analysis. Results With the decrease of support height, the support stiffness would increase; a larger cross-section size would lead to a larger support stiffness; with the increase of support numbers, the support stiffness would increase. Among the influencing factors of support performance, the order of influence degree was support height＞section size＞support numbers. Conclusions The research findings have certain guiding significance for the development and research of thoracic aortic stents, and provide theoretical basis for the selection and optimization of clinical stents.

Analysis and Optimization for Support Performance of Magnesium Alloy Stent / 医用生物力学

Objective To conduct simulation analysis on support performance of the stent by using finite element method, and optimize structure parameters of the stent by using Kriging surrogate model, so as to provide more scientific guidance for clinical treatment with design and development of the stent. Methods The contact model was established by penalty function method. The generalized variational principle was selected as theoretical basis of the numerical simulation, and the theory of Kriging surrogate model was used for finite element optimization on support stiffness of the stent, so as to study the effect from the number of circumferential support, the length of the support and the initial diameter on support performance of the stent. Results With the increase of the number of circumferential support or the length of the support, the support performance showed the decreasing tendency; with the increase of the initial diameter, the support performance showed the increasing tendency. From seven stents by using the theory of Kriging surrogate model, it was concluded that structural parameters of the optimal stent were: the number of circumferential support was six, the length of the support was 1.15 mm, and the initial diameter was 1.65 mm. Conclusions The numerical result agreed well with the experimental data and the error was smaller than 5%, and the error rate of experimental repeatability was within 0.5%, which verified effectiveness and rationality of the finite element analysis. The optimization of support performance provides an important reference for design and exploration of new magnesium alloy stent.