人下颌骨在压缩载荷下的生物力学性质

摘要

Objective:To study the biomechanical characters of human mandible under compression load and to deduce the constitutive equation.Methods: Specimens taken from five mandible of fresh human cadavers were examined on INSTRON by a group of tensile tests at different strain rates (0.000　5,0.005,0.05 and 0.5 s-1).Bone mineral density of every individual mandible was measured.The effects of strain rate(**),bone mineral density (ρ) on Young'Modulus (E),strength(σu)and ultimate strain(εu) were studied and the constitutive equations were deduced using the following model:Y=aρb**c.Results:(1)σu=216.27ρ1.23**0.055（P<0.01），(2)E(Pa)=5　604.024**0.083（P<0.01）,(3)εu =0.045**-0.045（P<0.01）,(4)σu=1　798.87ρ-1.17**0.083ε0.82（P<0.01).Conclusions:Strain rate and bone mineral density are important factors for the biomechanical characters of human mandible under compression load.Based on the constitutive equations,the stress level,the possibility and degree of mandible injury may be estimated.%目的：研究下颌骨在不同压缩载荷下的生物力学性质，建立下颌骨在压缩载荷下的本构方程。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定，然后制成标准试件在INSTRON材料试验机上进行电子压缩，应变率分别为0.000　5、0.005、0.05、0.5 s-1，获得不同载荷下相应的应力-应变曲线。利用模型Y=aρb**c，以极限强度、弹性模量以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压缩本构方程。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(N/mm2)=216.27ρ1.23**0.055（P<0.01）、E(Pa)=5　604.024**0.083（P<0.01）和εu =0.045**-0.045（P<0.01）。下颌骨在压缩载荷下的本构方程为σu=1　798.87ρ-1.17**0.083ε0.82（P<0.01）。结论：应变率和骨密度是影响下颌骨压缩生物力学性质的重要因素。在较低应变率下可用获取的本构方程模拟下颌骨材料的生物力学特性。根据本构关系可以计算下颌骨在一定外载作用下的应力大小，为损伤评判提供参考依据。