Experimental investigation on the characteristics of temporary cavity in BABT with 9 mm projectiles.

Temporary cavity, one physical phenomenon in BABT reflects the dynamic response of biological tissues and is used to evaluate the trauma. To clarify the characteristics of cavity evolution during 9 mm Luger penetration, we obtain the deformation profiles by using an experimental method with a high-speed camera and thereby visualize the cavity formation and development. According to the dynamic impact experiments at the velocity from 220 to 420 m/s, the temporary cavity profile can be approximately regarded as a semi-ellipsoid. The maximum depth increases as a quadratic function of velocity. Additionally, the maximum volume of the temporary cavity is attained significantly after the maximum depth. The change rate of cavity volume in the expansion stage is larger than that in the contraction stage.

Study on nonlinear constitutive model of skin under compression load over a wide range of strain rates.

PURPOSE: In wound ballistics, skin has obvious blocking effect in the biological target penetration of projectiles. An analytical description of skin mechanical properties under compression can set the basis for the numerical simulation and the evaluation of blocking effect. METHODS: In this study, an improved three-parameter solid visco-elastic model was proposed to describe the skin creep phenomenon. And then combined with Maxwell and Ogden model, a new nonlinear skin constitutive model, consisting of hyper-elastic unit, creep unit and relaxation unit in parallel, was established. Here, we examine the material properties of freshly harvested porcine skin in compression at strain rates from 0.01/s to 4000/s. RESULTS: The model is verified by comparison with the experimental results by our test and that in the literature at different strain rates. CONCLUSIONS: It shows that calculated results of the constitutive model agree well with the experiment data at extremely low to high strain rates, which is useful for the description of the heterogeneous, nonlinear viscoelastic, relaxation and creep mechanical response of skin under compression.

Transient pressure wave in the behind armor blunt trauma: experimental and computational investigation.

In the last few decades, various researches focus on the transient pressure in the behind armor blunt trauma. This paper presented a investigation on the transient pressure in the ballistic gelatin behind a soft body armor subjected to the impacting from three ammunitions. Experimental results show that three peaks appear on the pressure-time curves without taking into account the ammunition type and the impact velocity. Furthermore, numerical models of the test were created to compare modelling results to the pressure from the pressure gauges buried in the gelatin block. The main features on the pressure-time cure were discussed to analyze the wave formation and propagation. With the verified model, the effect of the boundary was also investigated to explain the wave reflection which appeared after two peaks.

Experimental investigation of the response of gelatine behind the soft body armor.

Understanding the transient cavity formation and transient pressure in the behind armor blunt trauma (BABT) is of fundamental importance in various research fields. In this paper, the transient response of ballistic gelatine behind the soft body armor subjected to the impacting of pistol bullets was studied. The profiles of the transient cavity in real time were captured by a high-speed camera, while the transient pressures were simultaneously recorded by pressure gauges. We find the cavity expansion-contraction movement is self-similar and can be expressed as a semi-ellipse. The gauges-recorded pressures reveal that three peaks on the pressure-time curve.

The experimental and numerical study of indirect effect of a rifle bullet on the bone.

We study the transient indirect effect of a rifle bullet on bone in the gelatin-bone composite target experimentally and computationally. The process of a 56 type 7.62-mm rifle bullet penetrating the composite target has been simulated using numerical method. The experiment provided the criteria for verifying the correctness of the numerical model. We have obtained tomographic data of bone by CT scans, and also defined the bone as different layers by the gray scale to simulate its heterogeneity. The computed results are in good agreement with the experimental data. Effects of the impact velocity and bone location on damage caused to the composite target have also been studied. The numerical results imply the follows: When the velocity of bullet increases, the stress on bone also increases with the earlier pressure peak; When the bone is located in a certain distance from the trajectory, it will not be fractured, although it is affected by the stress wave.