Liu Li, Fan Yurun, Li Wei
State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, P.R. China.
State Key Lab of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, P.R. China.
J Mech Behav Biomed Mater. 2014 Jun;34:199-207. doi: 10.1016/j.jmbbm.2014.02.011. Epub 2014 Feb 18.
Ballistic gelatins are widely used as a surrogate of biological tissue in blunt trauma tests. Non-penetration impact tests of handgun bullets on the 10wt% ballistic gelatin block behind soft armor were carried out in which a high-speed camera recorded the crater׳s movement and pressure sensors imbedded in the gelatin block recorded the pressure waves at different locations. The observed shock wave attenuation indicates the necessity of considering the gelatin׳s viscoelasticity. A three-element viscoelastic constitutive model was adopted, in which the relevant parameters were obtained via fitting the damping free oscillations at the beginning of the creep-mode of rheological measurement, and by examining the data of published split Hopkinson pressure bar (SHPB) experiments. The viscoelastic model is determined by a retardation time of 5.5×10(-5)s for high oscillation frequencies and a stress relaxation time of 2.0-4.5×10(-7)s for shock wave attenuation. Using the characteristic-line method and the spherical wave assumption, the propagation of impact pressure wave front and the subsequent unloading profile can be simulated using the experimental velocity boundary condition. The established viscoelastic model considerably improves the prediction of shock wave attenuation in the ballistic gelatin.
弹道明胶在钝器创伤试验中被广泛用作生物组织的替代品。对手枪子弹在软质防弹衣后的10wt%弹道明胶块上进行了非穿透冲击试验，试验中用高速摄像机记录弹坑的运动情况，并用嵌入明胶块中的压力传感器记录不同位置的压力波。观察到的冲击波衰减表明有必要考虑明胶的粘弹性。采用了三元粘弹性本构模型，其中相关参数通过拟合流变测量蠕变模式开始时的阻尼自由振荡，并参考已发表的分离式霍普金森压杆（SHPB）实验数据获得。粘弹性模型由高振荡频率下5.5×10(-5)s的延迟时间和冲击波衰减下2.0 - 4.5×10(-7)s的应力松弛时间确定。利用特征线法和球面波假设，结合实验速度边界条件，可以模拟冲击压力波前的传播以及随后的卸载剖面。所建立的粘弹性模型显著改善了对弹道明胶中冲击波衰减的预测。
