Astronauts who are exposed to weightless environment in long-term spaceflight might encounter bone density and mass loss for the mechanical stimulus is smaller than normal value. This study built a three dimensional model of human femur to simulate the remodeling process of human femur during bed rest experiment based on finite element analysis (FEA). The remodeling parameters of this finite element model was validated after comparing experimental and numerical results. Then, the remodeling process of human femur in weightless environment was simulated, and the remodeling function of time was derived. The loading magnitude and loading cycle on human femur during weightless environment were increased to simulate the exercise against bone loss. Simulation results showed that increasing loading magnitude is more effective in diminishing bone loss than increasing loading cycles, which demonstrated that exercise of certain intensity could help resist bone loss during long-term spaceflight. At the end, this study simulated the bone recovery process after spaceflight. It was found that the bone absorption rate is larger than bone formation rate. We advise that astronauts should take exercise during spaceflight to resist bone loss.
进行长期空间飞行的航天员处于失重环境，所受力学激励小于正常值，会面临骨密度减小和骨丢失的问题。为了探究失重环境下股骨密度和质量的变化趋势，本文建立了人体股骨的三维模型，进行了卧床条件下基于有限元的人体股骨重建的仿真分析。通过对比卧床实验数据与仿真数据，验证了人体股骨有限元模型与重建参数的有效性。继而进行人体股骨在空间失重条件下的重建仿真，建立关于时间的骨重建速率函数。增大载荷大小和增加载荷循环都能减少骨丢失，仿真结果表明增大载荷大小更能有效减少骨丢失。对股骨骨量恢复的重建速率作出讨论，结果表明骨量恢复的重建速率小于骨丢失的重建速率。本文为航天员阻力锻炼方法及后期恢复训练提供了理论依据，航天员在空间飞行期间可以通过增大阻力锻炼强度减少骨量丢失。.
Keywords: bone remodeling; finite element analysis; human femur; remodeling rate; space weightlessness.