Krzysztof Jamroziak

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• Professor
• Full Professor at Wrocław University of Science and Technology

The article presents an experimental and numerical study on the effectiveness of an additional shield mounted under the vehicles in reducing the penetration capability of the scattered mines, using the example of the MN-123 mine. For this purpose, the formation of the EFP (explosive formed penetrator) was analyzed for the classic scattered mine sys...

Dilatometric phenomena, mechanical and antifriction properties of a new high-temperature composite based on powder nickel alloy EP975 with additives (4.0− 8.0)% CaF 2 solid lubricant have been investigated. New composite has been manufactured using hot isostatic pressing (HIP) technology with subsequent hardening heat treatment. Antifriction proper...

The object of the research reported in this study was a welded joint of Hardox Extreme steel, made using submerged arc welding (SAW) and subjected to thermal treatments involving isothermal hardening in various temperature–time variants. This treatment serves as an alternative to conventional hardening, enabling the achievement of high mechanical i...

Among the materials used for components subjected to abrasive wear, chromium cast iron, hardfaced layers, martensitic steels and Hadfield steel should be singled out. Each of these types of materials exhibits a different morphology of structure and strength properties. Hadfield steel, characterized by an austenitic microstructure, shows the ability...

Horses have been companions of people for thousands of years. Areas in which humans use these animals include, for example, transport, participation in sports competitions, or during rehabilitation (hippotherapy). Unfortunately, injuries such as lower limb fracture very often require euthanasia due to the significant difficulties in conducting frac...

The object of the research reported in this study was a welded joint of Hardox Extreme steel, made using submerged arc welding (SAW) and subjected to thermal treatments involving isothermal hardening in various temperature-time variants. This treatment serves as an alternative to conventional hardening, enabling the achievement of high mechanical i...

The tests of resistance to dynamic impact with shaped charge (ŁK) were carried out on a homogeneous armor plate made of Armox 370T Class 1 steel, commonly used in the production of ballistic shields. The chemical composition of the steel was determined in spectrometric tests using a spark discharge spectrometer S1 MiniLab 150 by GNR INDIA and confi...

To design effective energy-absorbing shields made of modern composite materials (e.g., fibrous composite panels), it is necessary to use deformable materials whose important feature is the largest possible dissipation of impact energy. Rheological properties of these materials differ significantly from dissipative and elastic properties described b...

The shock wave resulting from the explosion process is the main burden on the technical infrastructure facilities or people in contact with the epicentre of the high explosive (HE). The article presents the tests of EN C45 steel pipe of 10 mm thickness buried beneath the earth as a result of the impulse load of the detonation wave of the explosive...

This paper presents the possibility of using additional ballistic shields based on composite materials, which are applied to the body of a passenger car. A ballistic laminate made of Twaron T 750 aramid fabric with 5 mm thick and 2 mm thick magnetic foil was used. In the first stage, the mechanical parameters of the tested ballistic laminate system...

This article analyzes the composition and distribution of chemical elements in friction films and their effect on the tribological properties of the self-lubricating, high-temperature antifriction composite based on EP975 powder nickel alloy with CaF 2 solid lubricant. Analysis of the chemical elements by energy-dispersive spectroscopy (EDS) showed...

In recent years, more and more emphasis has been placed on the use of home filtration systems as a coarse pre-filtration step. The PP (polypropylene) filter cartridge is one of the most common of these systems, with the role of retaining solid suspensions from drinking water. However, few studies have focused on the fouling analysis of PP cartridge...

The authors of this paper focused their attention on developing numerical models of mechanical wave propagation along human tissue as a result of the application of the measuring head of the FibroScan® elastograph. The FibroScan® diagnostic device is used for diagnostic testing of liver fibrosis and steatosis. This examination is carried out using...

Стаття представляє результати досліджень з впливу режимів тонкого боразонового шліфування на формування параметру шорсткості Ra циліндричних робочих поверхонь нових антифрикційних композитних деталей на основі утилізованих і регенерованих шліфувальних відходів швидкорізальної сталі Р6М5 з додаванням твердого мастила CaF2, що призначені для оснащенн...

Multi-layer fabrics are commonly used in ballistics shields with a lower bulletproof class to protect against pistol and revolver bullets. In order to additionally limit the dynamic deflection of the samples, layers reinforced with additional materials, including non-Newtonian fluids compacted by shear, are additionally used. Performing a wide rang...

This article is devoted to research of the tribosynthesis mechanism of antifriction films and their influence on the functional properties of antifriction composites based on copper alloyed with nickel and molybdenum with the CaF 2 solid lubricant additions for operation at rotation speeds of 3,000–7,000 rph and increased loads of 3.0–5.0 MPa in ai...

The main aim of the work was the experimental and numerical analysis of the energy absorption/dissipation capabilities and failure mechanisms of novel hyper-elastic target material intended for ballistic applications including layers of composite armors, projectile catching systems and anti-ricochet layers covering walls of shooting ranges, ballist...

This paper presents the results of a study of polyurethane rigid (PUR) elastomers in terms of the constitutive law identification, and analyses the effect of polyurethane elastomers’ hardness on fatigue properties. The research objects were PUR materials based on 4,4′-diphenylmethane diisocyanate (MDI) with the hardness of 80 ShA and 90 ShA, typica...

The paper is devoted to studying the chemical elements distribution in the material’s structure depending on the manufacturing technological parameters and their effect on properties of a new self-lubricating antifriction composite based on powder nickel alloy EP975 with CaF2 solid lubricant for operation at temperature 800 °C and loads up to 5.0 M...

Effectiveness of simplified modeling methods of ballistic inserts containing high-strength para-aramid fabrics under projectile impact condition was analyzed in the article. Various types of experimental tests including material characterization and ballistic impact were carried out in order to define and to validate numerical models of the individ...

The article studies the self-lubrication mechanism of new antifriction copper-based composites alloyed with Ni, Al, Si and Ti, with CaF2 solid lubricant for operation in the vehicles’ heavy loaded friction units. The developed manufacturing technology provided CaF2 uniform distribution throughout the material’s entire volume. The composite’s struct...

The main aim of the study was to define the static and dynamic properties of novel visco-hyperelastic material and its behavior under 7.62 × 25 mm Full Metal Jacket (FMJ) projectile impact condition. Mechanical tests were performed in both quasi-static and dynamic conditions. Uniaxial quasi-static compression tests were performed at different tempe...

The study aramid fabrics of Twaron T750 type loaded in quasi-static punching and impact loading tests were tested. The scope of these works was carried out in the form of piercing with a non-deformable steel penetrator with a semi-spherical tip, moving at a constant low speed and on the drop impact test and firing the aramid fabric with a 9 × 19 mm...

This article presents the tests of EN C45 steel as a result of the impulse load of the detonation wave of the explosive charge. This process was carried out on a specially prepared test stand using a 75 g Tri-Nitro-Toluene (TNT) drilling cartridge. Two series of tests were carried out with the explosive charge placed in direct contact with the samp...

This article presents an analysis of the effectiveness of available numerical techniques in mapping the characteristic behavior of ballistic ceramics under projectile impact conditions. As part of the work, the ballistic tests were performed on the layered ceramic/steel composite armor and tested with the 7.62 × 39 mm, armor-piercing incendiary (AP...

In recent years, hybrid composite materials are of increasing interest during the search for new materials to be used as ballistic barriers (shields) and kinetic energy absorbers. The main objective of this study is to test the energy absorption capacity of Zn-Al alloys filled with various polymer materials (epoxy resin, polyurethane resin and sili...

A simple and prompt method to determine the mechanical properties of industrial multilayer extrusion polypropylene pipes for a gravity sewer network is suggested. The engineering formulas included for calculating the permissible thickness and relative position of a foam core in the pipes are based on a linear-elastic approximation and the rule of m...

Titanium fixation plates and screws are commonly used in craniofacial fracture treatment and reconstructions. Depending on the design and clinical condition, they display better or worse clinical outcomes giving researchers space for improvement in this field. A model was designed by finite element method (FEM) to reconstruct a fractured human mand...

Finite element modeling of ballistic impact of inserts containing titanium structures were presented in the article. The inserts containing an additional layer made using additive manufacturing technology were analyzed. The layer was created from repetitive elements made without connections (adjacent cells were inseparable). Four variants of printe...

The article studies the tribological properties formation of new composite antifriction materials based on nickel with solid lubricant CaF2 for operation at temperatures 550–600 °C in air. It was shown the high antifriction properties are achieved due to the formation of homogeneous antiscoring friction films on contact surfaces under working condi...

This paper presents the results of research on ballistic panels made of polymer–matrix composites (PMCs). The analysis covers two types of composites produced by the authors based on high-density polyethylene (PEHD) and polypropylene (PP) reinforced with aramid fabric. Ballistic tests were carried out with the use of two types of projectile: 0.38 S...

In this paper, the authors presented an analysis of the strengthening of the cumulative jet by the appropriate formation of the detonation wave front acting under the influence of high pressure on the liner. The analysis of the Polish ŁK cumulative charge was carried out using numerical methods in the ABAQUS program. Simulation studies were carried...

Road traffic accidents involving coaches do not happen very often, but they are very dangerous because they affect a large number of passengers. Coaches (or intercity buses) are not equipped with safety belt harnesses. Valid regulations do not impose any obligation on coach manufacturers to provide intercity buses with either two- or three-point sa...

The friction behavior of the formed antifriction films and their effect on the functional properties of the composite based on the powder nickel alloy EI929 with solid lubricant CaF2 at high temperatures was investigated. An antifriction film was formed on the contact surfaces during the friction process. Such a film was the result of the interacti...

The paper presents the results of studies on the effects of shooting composite materials produced by pressure infiltration with the EN AW-7075 alloy as a matrix and reinforcement in the form of preforms made of α-Al2O3 particles. Composite materials were made with two reinforcement contents (i.e., 30% and 40% vol. of α-Al2O3 particles). The composi...

The paper presents a heat exchange model for the cooling system of any complex, physical system. Verification of the correctness of the theoretical model was carried out on the example of a vehicle with a combustion engine and additionally equipped with a hydraulic retarder. The results of laboratory tests, which were carried out on an engine test...

The aim of this work was to evaluate the influence of the matrix type and the number of reinforcement layers on the punch of the aramid laminates. The samples were tested under laboratory conditions and in a ballistic test. Two series of aramid laminates were produced with differing types of polymer matrix. The epoxy resin (EP) and the styrenebutad...

This paper discusses the general conditions relating to ballistic head protection, analyzing the risks that may occur on contemporary battlefields. A thorough literature review has enabled us to present development trends for helmets used in the largest armies in the world. The authors have focused on impacts to the helmet shell, overloading the en...

The work presents the concept of a gun barrel reinforced with the continuous filament. The barrel’s vulnerability to vibration and bending during shooting significantly affects the accuracy of fire. The phenomenon of vibrations of the barrel is compensated by its mass and such parameters as the maximum pressure acting in its front part, i.e. the ca...

The paper discusses the impact of explosively formed projectiles (EFP) on the process of penetration of armor elements. The protective abilities of homogeneous armor plates and their structure as a result of fast-changing phase transitions have been analyzed. The phenomenon of exposing the analyzed energy-absorbing shield to the EFP impact was also...

The article analyzes the structure and properties of the new composite antifriction materials based on the powder nickel alloy EI929 with solid lubricant CaF2 additives for exploitation at high temperature 650–700 °C and increased loads up to 5.0 MPa, in air. The article shows the mechanism of new materials’ structure formation after using the manu...

The authors simulated the piercing of a loose aramid fabric. The analysis was carried out in the ABAQUS environment with the use of the Explicit method. The fabric was modeled in two ways: the first one as a surface, with the parameters and nature of aramid fibers considered, while the second as single bands in the fabric. The qualitative and quant...

The phenomena found in the UKM-2000P machine gun barrel during the firing were investigated. The aim was to evaluate how the change in the center of the mass of the projectile being fired affects the occurring barrel vibrations. Numerical simulations were performed in the ABAQUS program, and then the results were compared with the experimental resu...

In this paper, the analysis of the possibility of regeneration the freight wagon body for transporting loose materials is presented. The proposed solution is based on increasing the stiffness of the load space walls by using the composite panels. Analysis of material behavior in a combination of steel sheet and glass-epoxy composite was carried out...

The analysis of selected methods useful in accelerated testing of systems and subsystems of high mobility vehicles has been presented. The paper contains information about a few methods applied in calculating the load signal in time and frequency domians: Constant Amplitude Loading – CAL, Peak Valley Extraction – PVE, Block Load Sequence – BLS, Sta...

ABSTRACT The article contains a comparison of selected numerical methods describing the structure of polymer composite. This work focuses on different FEM modeling methods using homogenization of composite material parameters. The estimation is based on comparing visual results of real ballistic test and numerical simulations. The main goal of this...

This work discusses the impact consequences of Explosively Formed Projectiles (EFP) on the process of armor penetration. Based on the example of piercing shields made of armor steel ARMOX 370T with anti-vehicle mine of MPB type to verify the effectiveness of EFP charge. The influence of the projectile on the armor wall was analyzed on the basis of...

The work presents the research conducted on the impact resistance of newly developed metal-ceramic composites with aluminum matrix on firing with 5.56 × 45 mm caliber intermediate ammunition. For this purpose, materials based on AC-44200 alloy reinforced with Al2O3 particles were made using the squeeze casting method. The ballistic resistance was c...

The results of structural periodicity in the antifriction composite parts based on copper alloyed with Ni, Mo, and W with solid lubricant CaF ⁠ 2 have been presented in paper. The periodicity of structure was studied using Fourier analysis. Analysis of the structural status complexity and friction surface's characteristics were executed by two-dime...

This paper presents numerical examination of cermet-type composite material subjected to impact loads. The base material was Aluminum 44200 matrix material, and materials with 20% and 40% digix trioxide as an additive. Using the ABAQUS software, homogenization of the Representative Volume Element material was performed and then subjected to dynamic...

Under loads of dynamic machine components made of composite materials an important role is played by their dissipative-elastic properties. The use of the traditional linear rheological model of the Kelvin type to describe these properties is often an oversimplification. In this paper the authors assume that the non-linear system is asymptotically s...

The paper analyzes the issues relating to the applicability of innovative material systems for flexible composite armors. The authors made several samplings of aramid fibers (Kevlar 49) by replacing the epoxy resin base, which is often described in the literature, with the thermoplastic matrix - polyethylene (HDPE) and polypropylene (PP). The sampl...

The paper presents the new way of identification of complex nonlinear dynamic systems. The method has been explained with the use of a dynamic structure (degenerated one) with 1.5 degrees-of-freedom and some nonlinear restitution force. The applied method allows for the assessment of the dynamic behavior of material in a wide range of dynamic loads...

For protection against projectiles with higher impact speed (up to 1000 m/s) a type of a ballistic sandwich shield can be used—which is a monolithic combination of ballistic laminates with additional materials, typically hard layers made of ceramic in the form of plates or spheres of oxides, carbides and nitrides. The authors of this paper, by usin...

This paper concerns the ballistic resistance of hybrid composite shields. The analysis covers three types of two-layer composites. The first shield layer were plates of tungsten carbide (WC), ceramic balls Al2O3 (aluminum oxide 92) or steel balls (100Cr6 steel) embedded in a polymer matrix. The second layer was a laminate consisting of 10 layers of...

Research for innovative composite material solutions for impact absorbers is focused on the analysis of their ability to absorb impact energy. For this purpose, aramid fiber laminate with DCPD resin matrix was prepared. Laminate samples were tested on the drop test and were subjected to ballistic loads. The laminate structure was modeled with ABAQU...

The paper presents a new way to determine some dynamical properties of materials modeled by the so-called degenerate system. The system is an element (subsystem) of any complex multidegree-of-freedom system. This subsystem follows from assumption of standard rheological model of stress-strain law of the materials. It is assumed that on the complex...

The paper presents the method to identify the dissipative properties of the materials with a clear hysteresis loop under the quasi-static loads. Because of the fact that for low values of velocity, the resisting forces related to the speed are minimal, it is not possible to determine these forces as the functions of velocity in the quasi-static def...

The article discusses the issues regarding the identification process of the ballistic impact on a shield of composite construction. Using a mathematical model of the phenomenon of piercing the material with a bullet fired from a firearm, it has been assumed that the resisting force F of the material is described by a non-linear function consisting...

The chosen problems of selection the basic chassis for special purpose body are presented in the paper. The technical data of chassis have to go through various tests, most often within the proving ground tests. The paper contains the analysis of chosen tests and their usefulness in the design process of special purpose vehicle.

Materials used for the construction of ballistic shields are characterized by a variety of behaviours under the influence of external loads. Ballistic impact (by a bullet) in armour (ballistic shield) is an example of the phenomena that could be considered in the category of a dynamic load caused by the strike of the mass. Computer simulations are...

The article presents an analysis of impact energy dissipation process with selected non-classical dynamic models. Identification of impact energy dissipation phenomena in layered mechanical systems (for example: composite ballistic shields) is a great challenge, because on the one hand a model with parameters responsible for the energy dissipation...

The paper presents the puncture resistance of the material, that is under the influence of highly deformable projectile, depending on changes of material’s yield strength. The simulation has been conducted using mobile cellular automata (MCA) with authors’ own software. The simulation took into account the elasto-plasto-viscous properties of the ma...

The analysis of literature and own research have showed that there are several important processes in metal pieces coated with plastic cover, which have significant influence on the strength of fatigue. Those processes are caused by generation of electricity in double layer (EDL), affecting the electrode potential shift in positive direction. The i...

The aim of conducted and presented in the paper experiment was to check if test rules and equipment to investigate fatigue behavior of a newly design composite panels were set properly. Information about fatigue phenomena of composite materials were shortly presented in the paper.

The dissipative properties of most structural materials are usually described by a viscous damping parameter determining the rate of energy dissipation. The parameter stem from the traditionally adopted rheological Kelvin model. However, the analytical description of the dynamic properties of modern structural materials, including biological materi...

The article discusses issues related to the process of piercing the material at high speed of ballistic impact. The analysis assumes the dynamic degenerate model that takes into account the dry friction. On the basis of the adopted parameters of the dynamical model of piercing the material, constants were identified, which value can strongly influe...

Purpose: The purpose of the series of research is drawing up an alternative armour plate with the composite structure, which would be resistant to 7.62 and 5.56 caliber bullets fired from the weapons the Polish army is equipped with. Design/methodology/approach: The research embraced the composite materials with epoxy matrix reinforced with the...

In modern engineering materials used for creating effective ballistic shields, the issues of evaluation of their energy consumption are extremely important. The paper presents a new way of solving this problem using a certain degenerate model with dry friction. This method involves the use of specially derived identification equations which describ...

The article discusses the issue of comfort, that should characterize a vehicle which has been designed to work under special conditions. If the criteria of ensuring the proper comfort of the passengers of special purpose vehicles are not met, it might lead to a serious disturbances in perception and in other factors that affect the logical behavior...

In the article the results description of punching into the composite ballistic shield with the use of sub-machine gun and 9mm Parabellum was presented. On the prepared measurement position using high-speed cameras and laser-vibrometer the process parameters of the ballistic shield and bullet deformation were recorded. An analyzed ballistic shield...

The paper presents the example of use of the operational modal analysis procedure (OMA) to set the torsional natural frequency of underframe of off-road vehicle. Determining the natural frequency for the object of this shape is possible with the output-only data and using the peak picking technique.

In the article the quality assessment method of the mechanical design of a Mine Resistant Ambush Protected Vehicle is presented. Based on the research of the High Mobility Multipurpose Wheeled Vehicle already in operation, the new design of a MRAP vehicle is evaluated in the context of the quality assessment of the designing process. The research a...

The article describes the development of design and construction guidelines (assumptions) for selected components of M-ATV G-10 vehicle. Based on these examples, a methodology of 3D model selection was presented and a technology demonstrator was built. An analysis and selection of material for building a technology demonstrator’s body was conducted...

The issues of driving comfort with regard to military vehicles transporting troops with their equipment are relatively new in available articles and published studies. This paper contains some information related to the driving comfort in high-mobility multipurpose military vehicles operated by the Polish Army. The authors used a daily exposure fac...

The paper focuses on the analysis of movement of a railway carriage on a curved track. The computer model was made in the Siemens PLM Software NX and the simulation process was performed in the ADAMS software. The investigation included the specification of track sections, by dividing the acceleration storage section to a specified speed and distan...

Critical to quality factors of engineering design process of armored vehicles includes establishing the effects that defects have on the quality of mechanical objects as per engineering assessment criteria. Determination of the factors is an original part of work known as the Optimal Design For Six Sigma [9], which defines a defect as an inconsiste...

Purpose: A development of methodology of adhesive force measuring, and at the same time an estimation of its value change in the specifically designated group of materials that are used in technical objects’ construction, requires defining the fatigue strength value changes. The one of the elements influencing adhesive force is electrode potential...

A determination of mechanical properties of the real material systems under dynamical excitations is a very complex problem. The real system can be described by continuous model as well as a discrete model with a finite number of degree-of-freedom. Some mechanical systems like beams, rods, strings, tow-lines etc. have so-called chain-like configura...

Purpose: Literature consists a lot of information concerning the issues of the fatigue endurance of metals coated with plastics. However few studies explicitly explain, what mechanisms decide on the increased fatigue endurance of metals coated with plastics. Therefore an expression is a purpose of the work on what a way increasing this fatigue endu...

The quality assurance method for the design and manufacturing process of armoured vehicles includes stablishing the effects that defects have on the quality of mechanical objects as per engineering assessment criteria. This method is an original work known as the Optimal Design For Six Sigma, which defi nes a defect as an inconsistency between param...

Purpose: The models come from complex rheological models that static and quasi-static loading analysis waspresented in the following publications. The main conception of the research is determination of the mechanicalproperties of ballistic shield materials with the use of the complex constitutive compounds.Design/methodology/approach: In the paper...

Purpose: The effect of penetration hydrogen into fatigue load metals is widely investigated by many researchers.Hydrogen is the chemical element which plays negative role in fatigue durability of structures. It decides on fatiguebrittle cracking. In the paper authors carry out an analysis of fatigue durability. Making use of naturally coming intoex...

Purpose: Composite materials on account of some their characteristics have application in a construction of ballistic shield. An example of the ballistic shield is laminate with the mix-structure materials such as layer pressed of aramid cloths on matrix polymer. Because of the shield’s assignment the aramid cloths are exposed to impact loads cause...

Purpose: The material piercing process is an extremely complex phenomenon for the theoretical analysis. This is connected with the fact that the materials used mainly for ballistic shields may not be treated as isotropic media. The description of piercing of ballistic shields made of light weight composite materials, on the basis of the Hooke’s mod...