Su Peng, Lu D A, Deng Shijing, Zhang Leiyu, Hao Yuxin, Yang Yang
School of Electromechanical Engineering, Beijing Information Science and Technology University, Beijing, China.
Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs, National Research Center for Rehabilitation Technical Aids, Beijing, China.
Acta Bioeng Biomech. 2018;20(2):23-33.
Trephination is one of the basic operations of keratoplasty, and the biomechanical mechanism of the operation can be revealed based on three-dimensional modeling and simulation of trephine cutting cornea.
Based on the analysis of the physical and biomechanical characteristics of corneal trephination, a three-dimensional numerical model of corneal trephination is built, where the cornea can be simplified to two layers structure including stroma and epithelium, and the trephine cuts the cornea under the vertical motion load and the rotational motion load. A three-dimensional failure criterion of corneal material is proposed based on the yield strength theory. On this basis, trephination simulation is carried out, and the units of corneal material are removed from the model when they meet the defined failure criterion.
Under the given parameters including the velocity, the angle and the angular velocity, the trephine force curves, include the linear cutting force and the rotary cutting force are obtained, and show the change of the forces with displacement during the process of trephination simulation. The maps of the equivalent stress show the destruction and deformation of the cornea. Then, the experiment of robotic trephination is carried out under the same parameters and the effectiveness of the simulation is evaluated.
Based on mechanics theory and finite element method, the process of trephine cutting cornea has been reproduced, and the interaction mechanism is revealed, which lays the foundation for the development of real-time simulation and virtual system of the corneal surgery.
环钻术是角膜移植术的基本操作之一，基于环钻切割角膜的三维建模与模拟可揭示该手术的生物力学机制。
在分析角膜环钻术物理和生物力学特性的基础上，构建角膜环钻术的三维数值模型，其中角膜可简化为包括基质层和上皮层的两层结构，环钻在垂直运动载荷和旋转运动载荷作用下切割角膜。基于屈服强度理论提出角膜材料的三维失效准则。在此基础上进行环钻模拟，当角膜材料单元满足定义的失效准则时，将其从模型中移除。
在给定速度、角度和角速度等参数下，获得了包括直线切割力和旋转切割力的环钻力曲线，展示了环钻模拟过程中力随位移的变化。等效应力图显示了角膜的破坏和变形情况。然后，在相同参数下进行机器人环钻实验并评估模拟的有效性。
基于力学理论和有限元方法，再现了环钻切割角膜的过程，揭示了其相互作用机制，为角膜手术实时模拟和虚拟系统的开发奠定了基础。
