We prepared an alumina-based ceramic ballistic protection armor sample consisting of hexagonal alumina tiles arranged in a honeycomb structure, glued with Kevlar (R), and covered with a polyurethane-based resin. The sample was shot with four projectiles, strongly hit from the back, and locally covered with water. The terahertz complex refractive index of the materials constituting the sample was measured. A terahertz time-domain spectroscopy (THz-TDS) setup in a reflection configuration was used to raster scan the XY sample. The results in the form of time signals, top views, and cross-sections enabled an understanding the internal structure of the sample. THz-TDS was proved to be suitable for non-destructive testing of the alumina-based armors with depthdiscriminant 3D imaging. Transfer matrix method (TMM) correctly simulated terahertz signals reflected from the sample, calculated the thickness of the sample layers, and help determine the type of hidden defects.

This research manuscript describes the process of degradation of an Armox 600 armour plate during the impact of a 5.56×45 mm SS109 projectile. The creation process of the numerical FEM model of the projectile is presented. The projectile impact angle is set between 15° and 90°, and this phenomenon is investigated via numerical and experimental approaches. The experiment is conducted under the same conditions as the numerical approach to validate the FEM model. The experiments are conducted using a high-speed camera. This research manuscript presents the influence of the projectile impact angle on the degradation of the armour plate and its protection capability for different angles. The results demonstrate the dependence of the transferred energy on the armour plate, speed of the particles after impact, and trace dimensions on the armour plate for different impact angles.

The paper presents a methodology and re-search results over propane-butane (P-B) gas cylinders hit by various projectiles fired with a firearm for assessing the susceptibility on initiation a fire (ability to initiate the fire) at the shooting. Cylinders were arranged in two configurations: the cylinder alone, or the cylinder with an armour plate behind it. During the tests, the projectile flight, a gas cylinder behaviour and the temperature released during the projectile impact to the P-B gas cylinder were measured using a high-speed camera (FASTCAM SA-Z 2100K 50.400 fps) and thermal cameras (FLIR X6580sc, FLIR X6901scSLS). The mass of liquid P-B gas in a cylinder at the tests was between 0.511.0 kg.

Methods used nowadays in forensic laboratories allow to stop some kinds of projectiles with degree of deformation which lets to use them for comparing traces to projectiles found on the crime scene. However they are not useful for every type of projectiles. Comparative physical tests are enough to indicate the best method for soft catching projectiles. For this aim point of view no modeling needed. The paper presents the results of ballistic tests of impact of chosen types of soft point projectiles into water. The behavior of projectiles of various shapes, with different kinetic energy, was analyzed. On the basis of the obtained results, the projectiles with the highest susceptibility to deformation were identified. Research works described in the paper were performed within the framework of the project Laboratory stand for stopping high-energy projectiles financed from the National Centre for Research and Development (Agreement no. DOB-BIO10/04/02/ 2019). The project is implemented in cooperation with Warsaw University of Technology, Military Institute of Armament Technology and Tebbex 2 since 2019 to 2022.

The article presents the results of tests on the temperature of propellant gases shortly after the bullet leaves the barrel. The temperature and movement of these gases were recorded with thermal cameras and a high-speed camera. Weapons with and without muzzle devices (flash suppressor, silencer) were used. The aim of the research was to check the capability to ignite flammable gases located in the vicinity of the propellant gases produced during firing. Comparison of the maximum temperature of the propellant gases and the ignition temperature of the flammable gases makes it possible to determine the probability of fire. The lowest temperature of propellant gases was in the case of shooting with 9 × 19 mm bullets with the lowest kinetic energy (518 J), and the highest temperature of these gases was during shooting with 5.56 × 45 mm HC (SS109) bullets with the highest kinetic energy (1,785 J).

This paper describes the process of creating a numerical FEM (finite element method) model of the 5.56 × 45 mm SS109 projectile. The model was used to calculate the temperatures occurring in the projectile materials during the impact on the steel plate at an angle of 45°. The purpose of the investigation is to estimate the ability of a ricocheting projectile to cause ignition. For the same projectile, experimental tests were also carried out under the conditions adopted for the numerical investigation in order to validate the FEM model. During the experiment, temperature was measured with a thermal camera; the phenomenon was also recorded with a colour high-speed camera.

Research works described in the paper, were performed within the framework of the project: Laboratory stand for stopping high-energy projectiles (Agreement no. DOBBIO10/ 04/02/2019). Methods used nowadays in forensic laboratories allow to stop some kinds of projectiles with degree of deformation which lets to use them for comparing traces to bullets found on the crime scene. However they are not useful for every type of projectiles. The aim of the research is to elaborate methods which allow to slow down and gently stop high-energy susceptible to deformation bullets in a way that does not cause their deformation or possibly limit it. The paper presents the results of ballistic tests of impact of various types of projectiles into water. The behavior of bullets of various calibers, with different kinetic energy and different construction was analyzed. On the basis of the obtained results, the projectiles with the highest susceptibility to deformation were identified.

The article presents results of research and analysis of the currently conducted project aiming at the development of a flexible impact protector. The need to carry out the work results from the necessity of the ever-wider and more frequent use of body armours, including those resistant to blunt impacts, by the army, police and other public security services as well as a demand for impact protective elements in the civilian market. In the first part, the assumptions regarding the protective coverage under development and the origin of the topic with reference to earlier work on the use of non-Newtonian fluids in body armours are indicated. Next, the requirements for impact protectors and a review of the state of the art in the scope of this type of protective elements are presented. Finally, the results of the impact tests of armour samples are shown.

Despite the intensive development of plastics and composite materials in the case of armours employed to protect vehicles, armour steel remains a material commonly and effectively used. This is especially evident in the base armour of armoured vehicles, where the body is made of welded armour steel plates. However, the area of joining both the weld and the heat affected zone are sensitive areas with the reduced protective capability. In the case of laser welding in comparison with methods such as shielded metal arc welding and gas metal arc welding, it is possible to narrow down the above mentioned areas. The paper presents the results of research on the protective capability of welded zone of armour steel plates with a hardness of 500 HB. In the first part of the work, in order to select the proper parameters for the bonding process, different connection variants were made and their microstructure and selected mechanical properties were analysed. After selecting the best variant of the welding process, samples (200 mm × 200 mm) consisting of two welded plates with dimensions 100 mm × 200 mm were made for testing. The thickness of the plates was selected in such a way that in the areas outside the bonding zone, the lack of complete perforation by the projectiles used in the tests is guaranteed. The samples were shot at the weld location and at different distances from the weld to verify, for the chosen method of joining steel plates, if the welded armour loses its protective capability and, possibly, how wide this area may be.

The article presents results of research and analysis of the currently conducted project aiming at the development of a flexible impact protector. The need to carry out the work results from the necessity of the ever-wider and more frequent use of body armours, including those resistant to blunt impacts, by the army, police and other public security services as well as a demand for impact protective elements in the civilian market. In the first part, the assumptions regarding the protective coverage under development and the origin of the topic with reference to earlier work on the use of non-Newtonian fluids in body armours are indicated. Next, the requirements for impact protectors and a review of the state of the art in the scope of this type of protective elements are presented. Finally, the results of the impact tests of armour samples are shown.

This paper describes rheological tests, drop tests and bulletproof tests of materials which are planned to be used as elements of bulletproof vests as well as in high impact protective equipment. Rheological tests of a homogenous composition of methyl-, phenyl-, borosiloxane polymers (KM material) performed for variable values of stress and strain at a fixed frequency of 1 Hz showed that the loss modulus exceeds the storage modulus throughout the whole tested range of shear stress so that the energy is more dissipated than stored. In the drop tests, same-mass samples of three materials, i.e. the KM material, the shear thickening fluid STF1 and the commercial shear thickening polymer ZB were tested. For a given impact energy (Ei = 35 J) and impact velocity (Vi = 1.9 m/s), the ZB material shows the best protective capability. In the ballistic tests, the sample with the KM material was tested with the use of .44 Magnum SJHP (semi-jacketed hollow-point) bullet following NIJ Standard-0101.04 for IIIA bulletproof class. The results were compared to the bulletproof tests of the ZB material from previous works. Better protective capability was achieved in the case of a commercial material. However, the tested KM material also exhibited the energy dissipation capability. Further work is needed to investigate the effectiveness of the KM material in a different type of casing.

The paper describes bulletproof tests of flexible armors containing different variants of modular interlayers. This elements were placed in the armor between the textile layers of the ultra high molecular weight polyethylene (UHMWPE). The interlayers were made of the rheological materials: the silicone elastomer (composition of methyl-, phenyl-, borosiloxane polymers with addition of fillers and lubricating mediums), the shear thickening fluid STF (silica nanoparticles dispersed in polypropylene glycol) and the commercial shear thickening polymer as well as the same polyethylene layers which were sewn or ultrasonically welded. Before performing the bulletproof tests in order to select the most appropriate process parameters and to compare the process to other ways of combining polyethylene layers the strength tests of ultrasonically welded joints were carried out. Different variants of ultrasonically welded protective layers were made. The samples with dimensions 400x400 mm were tested with the use of the 0.44 Magnum SJHP bullet.

The paper describes the rheological tests of three materials: the silicone elastomer, the shear thickening fluid STF and the commercial shear thickening polymer which are planned to be used as elements of the bulletproof vests as well as in the high impact protective equipment. In plate-plate configuration two kinds of tests were carried out. In the static mode the dependance of shear stress τ and viscosity η on shear rate 𝜸̇ was investigated wile in the dynamic mode storage modulus G’, loss modulus G’’ and complex modulus G* were determined. On the basis of the recorded values in the first test flow curves and viscosity curves for materials were drawn up. The dynamic tests defined what properties (elastic or viscous) are predominant in the materials for given loads and which material exhibits the most desirable characteristics with respect to the intended application.

In the article the possibility to increase capability of the ricochet of armour-piercing projectiles by application of a thin layer on the frontal surface of the armour with the Physical Vapour Deposition (PVD) method was carried out. The armours were made of the ARMOX 500T steel plates and were placed at various angles of inclination in relation to the initial flight path of the impacting projectile. The aim was to find the angle of inclination of the armour at which the penetration process changes from perforation to ricochet. Seven types of surface layers made of high-strength materials such as Ti, TiN, Al2O3, CrN were analysed. Results showed that the ricochet capability of the plates with and without the PVD coating is similar but the mechanisms of projectile-armour interaction are different.

The aim of research was to develop a new kind of flexible anti-trauma pads (including non-Newtonian materials) for the lightweight bulletproof vests which could decrease the behind armour blunt trauma (BABT) more effectively than present solutions. In the study shear thickening fluid (STF) based on silica nanoparticles dispersed in liquid polypropylene glycol and silicone elastomer based on homogeneous methyl-phenyl-borosiloxane polymer composition were tested for their energy dissipation capability. Different variants of the anti-trauma pads with non-Newtonian materials were designed and investigated: high performance polyurethane foams filled with STF and foams produced with addition of STF. The anti-trauma pads in samples were placed between the aramid or ultra-high molecular weight polyethylene layers. For comparison there were also investigated analogical samples with the commercial anti-trauma pads. The scope of research included ballistic tests (the .44 Magnum SJHP bullet) of armour samples fixed to a box with a clay backing material.

Essential aspects of numerical analysis for bullet hitting elastic layers of aramid fabric placed on a plastic substratum imitating the human body are presented in the paper. A review of results for bullet-proof vests tested on various substrata is included in the paper with justification of their use. It is explained why the ballistic plasticine is used as a substructure imitating the human body in most standards binding in the world for testing individual protections. Methods for modelling the fabrics with results of own numerical analyses are presented. As mutual reaction of yarns creating the interweaving of the fabric has an essential impact on its deformation then it is represented in simulations by a model that directly describes its mezzo-structure. Simulations were carried out by using an explicit procedure for integration of motion equations in program ANSYS AUTODYN v.16. The results of hitting by 9 mm bullet Parabellum FMJ (Full Metal Jacket) into the layers of Twaron® T750 fabric placed on ballistic plasticine are presented. Results of simulation and bulletproof resistance tests are compared.

The paper presents the results of the depth of penetration tests (DOP) and numerical simulations of the 5.56 x 45 mm SS109 projectile impact onto passive, layered armours placed on the armour backing material. Investigated passive layered armours (with dimensions 100 x 100 mm) were composed of polyester cover; soft ballistic aramid textile layers and Al[sub]2[/sub]O[sub]3[/sub] ceramic tile placed inside rubberized aramid bag. The 5.56 x 45 mm SS109 projectile was stopped for 7-mm thick ceramic tile. In the final armour modular interlayer will be used and each module will have common area near its edges with neighbouring modules. Considering that for 7-mm thick ceramic tile, the areal density of armour equals 42.1 kg/m2. To decrease the areal density of the modular armour to the value of 20÷30 kg/m2 the numerical simulations with the use of the Ansys Autodyn v15 program were performed as the base for further DOP tests. One and two-layer armours with two kinds of ceramic tiles (Al[sub]2[/sub]O[sub]3[/sub], SiC), armour steel plate (Armox 500) and titanium plate (Ti6Al4V) were investigated. The results of numerical simulation for the most effective armour for protection against the 5.56 x 45 mm SS109 projectile were presented.

The concept of using of shear thickening fluid (STF) in the insert of the lightweight bulletproof vest is presented in this paper. The design of the module of the armour containing STF was developed. This module is located in the special cover between layers of ballistic materials. All the mentioned elements create the flexible insert for bulletproof vest. Various variants of modules containing STF and the results of the inserts firing with the 9 mm Parabellum FMJ bullet are presented. On the basis of the ballistic tests results comparison of the behaviour of different variants of modules during the bullet impact was made, their protective capability was evaluated and the modules with the highest efficiency were selected. The designing, optimization and implementation process of a prototype of the cover for the armour modules containing STF, together with the preparation of the technology of production, were also presented.

The concept of using of magnetorheological fluid (MRF) as a part of the insert used in the lightweight, bulletproof vest is presented in this paper. For this purpose, a special design of the module of the armour containing MRF was developed. The modules with layers of ballistic materials placed in the cover, create a flexible insert for bulletproof vest. Ballistic performance of different variants of modules containing MRF was determined. On this basis, comparison of the behaviour of particular variants of modules during the projectile impact was made, their protective effectiveness was evaluated and the modules with the highest efficiency were selected. It was also presented the designing, optimization and implementation process of a prototype of the new construction of the cover for the armour modules containing MRF, together with the preparation of the technology of production.

The paper presents results of experimental research and numerical analysis (Ansys Autodyn v13 program) of penetration of 10 and 16 layers of the Twaron T750 aramid fabric with the 9 mm Parabellum projectile. As a boundary condition in the experiment and in the numerical simulations it was assumed that all the four edges of the fabric were fixed. In the numerical simulations the sample of 50x50 mm dimensions and the impact velocities V-i=448 m/s for 16 layers of the fabric and V-i =454 m/s for 10 layers of the fabric were adopted. In the paper the results of the numerical simulations for three material configurations with the same friction coefficients and for different values of yarn-yarn friction in case of one material configuration are presented. Residual velocity of the penetrator for the highest friction coefficient mu(s)=1 decreased of 13.1% in comparison to simulation with no friction (mu(s)=0).