The paper presents some questions of designing and testing for modern ballistic protecting screens and applied materials especially such as ceramics. Continuous development of present ballistic composite materials enforces the optimisation of existing solutions for ballistic protections in respect to the mass, thickness and costs of material. In times of technological arm race a reduction of armour weight by 5% is a success. It may be achieved by development of new solutions of armour systems applying the newest materials. Ballistic ceramics both enhances the resistance of the armour against armour piercing projectiles and reduces its areal dencity in relation to traditional steel armours due to high mechanical properties, low density, high hardness and dissipation of energy at the mechanism of breaking. The paper illustrates the development of ceramic based armours and the structure of a multilayer ballistic protection, and finally the meaning of its particular layers in fighting the projectile. Moreover the impact of mechanical properties of some ceramic materials used for designing a protection system into its ballistic resistance is discussed.
The paper presents results of thermal decomposition analysis of selected solid rocket propellants. Homogeneous propellant PAC and heterogeneous propellant H2 were subjected to simultaneous thermal analysis with the use of NETZSCH STA 2500 Regulus device with five heating rates of 2.5, 5, 7.5, 10 and 15 K/min. The method combines TG, DTG and DTA analytical techniques in a single measurement. The aim of the conducted experiments was to study thermal decomposition of these energetic materials as well as to determine activation energy of the decomposition process and the preconditioning factor from the TG curves.
The tested materials properties and chemical composition along with a brief description of the experimental procedure are described. The inverse procedure of calculating the activation energy, based on the Ozawa-Flynn-Wall model is described. Finally, the results of thermal decomposition of two tested solid rocket propellants are presented along with maximum decomposition rates and percentage of mass loss.
Analyses of the human bones failure mechanisms under projectile impact conditions can be made through performing of a large number of ballistic trials. But the amount of data that can be collected during ballistic experiments is limited due to the high dynamics of the process and its destructive character. Numerical analyses may support experimental methodologies allowing to better understand the principles of the phenomenon. Therefore, the main aim of the study was to create and to verify a numerical model of commercially available synthetic bone material-Synbone ® . The model could be used in the future as a supporting tool facilitating forensic studies or designing processes of personal protection systems (helmets, bulletproof vests, etc.). Although Synbone ® is commonly used in the ballistic experiments, the literature lacks reliable numerical models of this material. In order to define a numerical model of Synbone ® , mechanical experiments characterizing the response of the material to the applied loads in a wide range of strains and strain rates were carried out. Based on the mechanical tests results, an appropriate material model was selected for the Synbone ® composite and the values of constants in its equations were determined. Material characterization experiments were subsequently reproduced with numerical simulations and a high correlation of the results was obtained. The final validation of the material model was based on the comparison of the ballistic impact experiments and simulation results. High similarity obtained (relative error lower than 10%) demonstrates that the numerical model of Synbone ® material was properly defined.ballistic impact, beveling effect, numerical modeling, projectile, Synbone ® , synthetic bone
| INTRODUCTIONWhen human bone is perforated with small caliber projectiles, characteristic fracture patterns are generated in the internal structure of the bone. A nearly circular hole in the proximal cortical layer (with a diameter slightly larger than
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