应变率和骨密度对人下颌骨拉伸力学性能的影响

目的 探讨应变率和骨密度与下颌骨位伸力学性能的关系，建立下颌骨在拉伸载荷下的本构方程。方法 以５具新鲜男性青年尸体的下颌骨为材料，对每具标本进行骨密度测试，然后标准试件在Ｉｎｓｔｒｏｎ材料试验机上进行电子拉伸，应变率分别为０．０００３／ｓ、０．００３０／ｓ、０．０３００／ｓ、０．３０００／ｓ，获得不同载荷下相应的应力－应变曲线。利用模型Ｙ＝ａρｂεｃ，以极限强度、弹性模量及破坏应变为因变量（Ｙ），以应变率和骨密度为自变量（Ｘ）进行非线性回归分析，并建立与应变率和骨密度相关的下颌骨拉伸本构方程。结果 极限强度、弹性模量以及破坏应变相对于应变率和骨密度的非线性方程分别为σｕ＝１２６．３６ρ＾１．８８ε＾０．０４４（Ｐ〈０．０１）、Ｅ＝２５１７０．９７ρ＾０．９６ε＾０．０５６ε＾０．８０（Ｐ〈０．０１）。结论 应变

Relations of mechanical properties of human mandible to strain rate and density under tension load

OBJECTIVE: To study the biomechanical properties of human mandible under tension load and deduce the constitutive equation. METHODS: 100 specimens taken from five mandible of fresh human cadavers were examined on INSTRON by a group of tensile tests at different strain rates (0.0003/s, 0.0030/s, 0.0300/s, 0.3000/s). Bone mineral density of every individual mandible was measured. The effect of strain rate (epsilon), bone mineral density (rho) on young modulus (E), strength (sigma u) and ultimate strain (epsilon u) was studied and the constitutive equation was deduced using the following model: Y = a rho b epsilon c. RESULTS: (1) sigma u = 126.36 rho 1.88 x epsilon 0.044 (P < 0.01), (2) E = 25,170.97 rho 0.44 x epsilon 0.052 (P < 0.01), (3) epsilon u = 0.0088 rho 1.89 x epsilon -0.028 (P < 0.01), (4) sigma u = 6,309.57 rho 0.96 epsilon 0.056 x epsilon 0.80 (P < 0.01). CONCLUSIONS: Strain rate and bone mineral density are important factors for the biomechanical properties of human mandible under tension load. The results above may modelize and characterize the constitutive relation within small strain rates. From the constitutive equation, we could estimate the stress level of the mandible and assess the possibility and degree of mandible injury.