记忆加压接骨器在肱骨骨折治疗中的生物力学分析

目的 分析接骨器对于肱骨骨折的愈合提供的应力环境 ,分折接骨器在骨折愈合过程中的应力遮挡效应 ,同时应用骨重建理论分析接骨器加压支提供的应力环境对于骨折愈合的影响。方法 运用三维有限单元法 ,对新型记忆加压接骨器以及肱骨分别进行三维有限元计算。结果 肱骨骨折段始终处于三向压应力状态 ,剪应力不会引起骨内部的剪切破坏 ,同时接骨器固定后肱骨产生的变形很小。接骨器在环抱支的腕部产生大的弯矩 ,产生的应力较大。结论 加压支提供的持续压应力使接骨器产生的应力遮挡效应消失 ,肱骨的压应力刺激在骨折愈合过程中不断得到改善。

Machining distortion prediction of aerospace monolithic components

To predict the distortion of aerospace monolithic components, a model is established to simulate the numerical control (NC) milling process using 3D finite element method (FEM). In this model, the cutting layer is simplified firstly. Then, the models of cutting force and cutting temperature are established to gain the cutting loads, which are applied to the mesh model of the part. Finally, a prototype of machining simulation environment is developed to simulate the milling process of a spar. Key factors influencing the distortion, such as initial residual stress, cutting loads, fixture layout, cutting sequence, and tool path are considered all together. The total distortion of the spar is predicted and an experiment is conducted to validate the numerical results. It is found that the maximum discrepancy between the simulation results and experiment values is 19.0%