Freezing needle preventing epidural puncture

为了验证冷冻黄韧带（LF）变形减小的假设，采用了冷冻室拉伸试验和非线性有限元分析。猪LF的拉伸试验分别在-40℃的冷冻室和室温的实验室进行。得到了应力应变图。采用非线性有限元分析方法，从拉伸试验的应力应变图中确定了猪LF的一阶奥格登系数。假设当Mises应力达到一定值时，尖杆刺穿LF，冻结LF所需的变形缩短了73%。

In order to test the hypothesis about reduction in the deformation of the freeze ligamentum flavum (LF), tensile test in a freezing room and nonlinear finite element (FE) analysis were employed. Tensile test of the porcine LF was conducted both in a freezing room at -40 degrees Celsius and a laboratory at room temperature. Stress-strain diagram was obtained. To apply nonlinear FE analysis for the porcine LF, the 1st order Ogden coefficient of the porcine LF was identified from the stress-strain diagram from the tensile test. Assuming that the sharp bar pierced the LF when the Mises stress reached a constant value, the required deformation became shorter by 73% by freezing the LF.