| Ballistic gelatin is usually used as a substitute for simulating damage to human body,but it is hard to be numerically simulated,the main reason is the lack of materials mechanical parameters of ballistic gelatin and suitable constitutive model.In this paper,the material parameters of ballistic gelatin are obtained by experiment,and a suitable constitutive model is established.First of all,the ballistic gelatin specimen for quasi static and dynamic tests is prepared by a strict test piece preparation method.Then,the quasi-static mechanical properties of ballistic gelatin were systematically measured by universal material testing machine.Quasi-static tensile tests of 20%ballistic gelatin at 10℃ is carried out.The matching of different material bar’s and ballistic gelatin’s wave impedance is studied.Three kinds of signal acquisition methods are compared and analyzed for the resistance strain gauge,the semiconductor strain gauge and the PVDF piezoelectric film sensor.The plastic effect of different material and shape shaper on the incident wave is studied.The results show that the perfect loading wave can be obtained by using hard paper as shaper,and the dynamic mechanical properties data of ballistic gelatin at strain rate 5800/s-13000/s are obtained by combining aluminum bar and semiconductor strain gauge test.The experimental results show that the ballistic gelatin has an obvious strain rate effect in the range of low strain rate and high strain rate.When strain is 0.5,the stress of seven groups of strain rates(0.001/s,0.01/s,0.1/s,5800/s,7900/s,10400/s and 13000/s)are 48.53KPa、103.1KPa、182.0KPa、20723KPa、57443KPa、87265KPa and 165590KPa.The propagation characteristics of shock wave in a long cylindrical ballistic gelatin sample are studied by a high-speed camera.To Improve the Hopkinson pressure bar experiment technology,The dynamic mechanical properties of ballistic gelatin under high strain rate were investigated and studied,and the stress-strain curves under high strain rate were obtained,and compared with the quasi-static experimental results,it is found that the ballistic gelatin has a significant strain rate effect.Finally,according to the existing super elastic constitutive model,the experimental data are fitted one by one,and finally established a constitutive model with strain rate for quasi-static and two constitutive models with strain rate for dynamic. |
