Józef Wysocki

The Researches of Effectiveness of Road Restraint Systems

The Researches of Effectiveness of Road Restraint Systems The work describes model and experimental tests on the road restraint systems with particular attention to vehicle collisions with a concrete protective barrier. Vehicle and protective barrier crash tests include the experiment results in three basic fields: intensity of influence of the collision effects on vehicle passengers, collision impact on a vehicle and the road restraint system. It presents a test track concept as well as criteria for performing and evaluating the crash tests with a passenger vehicle and a safety barrier. The experimental tests were performed according to the test methodology recommended by the standard [2]. Examples of model test results were compared with experimental test results obtained on the test track. Badania skuteczności drogowych systemów zabezpieczających W pracy opisano badania modelowe i eksperymentalne drogowych systemów zabezpieczających ze szczególnym uwzględnieniem zderzeń pojazdu, ze sztywną barierą zabezpieczającą. Badania zderzeniowe pojazdu z barierą ochronną obejmują wyniki eksperymentu w trzech podstawowych obszarach: intensywność oddziaływania skutków zderzenia na osoby znajdujące się w pojeśdzie, skutki oddziaływania zderzenia na pojazd oraz odkształcenie drogowego sytemu zabezpieczającego. Przedstawiono koncepcję toru badawczego oraz kryteria przeprowadzenia i oceny próby zderzeniowej samochodu osobowego z betonową barierą zabezpieczającą. Badania eksperymentalne zrealizowano zgodnie z metodyką badań zalecaną przez normę [2]. Przykładowe wyniki badań modelowych porównano z wynikami badań eksperymentalnymi uzyskanymi na poligonowym torze badawczym.

Experimental investigations of double multi - leaf spring subjected to impact load

The article deals with experimental investigations of a prototype double multi-leaf spring, compound of a fourleaf main spring and a double-leaf supporting spring subjected to an impact test. In real conditions of car movement (e.g. curb, bump), dynamic oscillating loads, which generate dynamic stress in a car suspension affecting other elements of the car, occur. Consequently, effects of coupled oscillations having a great impact on comfort of a driver and passengers can be observed. The research was conducted in the Laboratory of Material and Construction Strength Department of Mechanics and Applied Computer Science (DMACS) in the Faculty of Mechanical Engineering of Military University of Technology. The experiment was carried out on an original construction of a spring impact hammer developed in DMACS. Energy of the impact was set up by changing mass of a beam with beater and beam dropping height. The results were presented in the form of table summaries, time-dependent load and displacement graphs. The methodology of the research presented in the paper and a set of measuring equipment can be utilized to evaluate load and vibrations of any multi-leaf spring under impact load with given energy. The experimental results obtained from the test are supposed to be used to verify and develop FEM model describing a spring under impact load and oscillations.

Combat Vehicle Dynamic Load Tests in the Aspect of the Operation Safety

Combat Vehicle Dynamic Load Tests in the Aspect of the Operation Safety The scientific team, working in the Mechanical Vehicle and Transport Institute of the Mechanical Department of the Military Technical Academy since the 90s, has been dealing with the analysis of dynamic loads of combat vehicles (tanks, infantry combat vehicles and wheeled armoured carriers). The work presents the combat vehicle tasks and operation tasks and conditions. Possible threats and possible effects of their influence were described on the basis of available information. The results of own model and experimental tests of dynamic loads affecting the aforementioned vehicles were presented. Selected analysis results were presented in a form of characteristics, diagrams and tables. Due to a type of analysed vehicles, the results are of qualitative nature rather than the quantitative one. Badanie obciążeń dynamicznych wozów bojowych w aspekcie bezpieczeństwa ich użytkowania Pracujący, w Instytucie Pojazdów Mechanicznych i Transportu Wydziału Mechanicznego WAT, od początku lat 90-tych zespół naukowy zajmuje się badaniem oraz analizą obciążeń dynamicznych wozów bojowych (czołgów, bojowych wozów piechoty oraz kołowych transporterów opancerzonych). W pracy przedstawiono zadania oraz warunki eksploatacji wozów bojowych. Opisano potencjalne zagrożenia oraz, na podstawie dostępnych informacji, ewentualne skutki ich oddziaływania. Zamieszczono wyniki własnych badań modelowych oraz eksperymentalnych obciążeń dynamicznych działających na w/w pojazdy. Wybrane rezultaty analiz zaprezentowano w postaci charakterystyk, wykresów i tabel. Z uwagi na rodzaj analizowanych pojazdów rezultaty mają głównie charakter jakościowy a nie ilościowy.

Influence of the shape of the explosive charge on blast profile

When an explosive charge is fired, the nature and mass of the explosive are the only parameters of importance usually considered. The shape however, also plays a major role in the effect of an explosive charge. Knowledge of shape effect can be important before the use of the explosive (in order to create a maximum effect with a given mass of explosive), or in post-explosion damage assessment. The shape effect however is only significant within a certain range from the charge. At longer distance, the produced blast wave tends to be spherical. The shock wave parameters studied in this work are the peak overpressure and the first positive impulse. A series of numerical test has been performed in order to determine the range of influence of the charge shape. Different locations of initiation were compared. A hemispherical charge was point detonated at its centre whereas a cylindrical shape was detonated at the centre of an upper or lower plane. Numerical simulations of near field burst were conducted using LS-DYNA software. During numerical tests a pressure fields were determined for different shapes of explosive charges as well as the pressure waveforms at points located 1000 mm from a centre. Additionally, reference pressure history curves from LOAD_BLAST_ENHANCED procedure were calculated.

NUMERICAL TESTS OF THE DOUBLE SPRING WITH HANGERS

Subject of the work include selected numerical models of the test stand intended for testing a prototype double multi-leaf spring of bi-linear nature. Basic design assumptions of the stand were as follows: provide laboratory tests of multi-leaf (single and double) springs designed for dependent suspensions of passenger cars of permissible weight up to 3,5 tones. The stand should allow for testing basic spring and strength characteristics in the quasi-static conditions and dynamic conditions with the impact of the force impulse or a set variable load characterized by a particular force amplitude (displacement) and frequency of its variations. Considered stand models include the tested spring, base, support and the hanger. This paper presents two types of FEM models of the spring element (beam and 3D). In the first element, components of the spring-hanger system were mapped by means of beam elements, in the second one by means of definite solid elements. The spring was loaded with a vertical force from 0 to 10000 N. A nonlinear analysis of the bi-linear spring was carried out including clearance as well as the elastic analysis of the stand. The results of the numerical tests are presented in a form of tabular specifications, diagrams of displacements, and reduced stresses of selected components of the stand.

The research on dynamic loads and traction properties of military vehicles in the aspect of improvement of their structures

Since the beginning of the 90’s, a scientific team in the Motor Vehicle and Transport Institute of the Mechanical Department in the Military University of Technology, has been involved in the model and experimental tests of the existing structures of the military vehicles (tanks, combat infantry vehicles and wheeled armoured carriers) in the aspect of their modernization. A part of works is related to the military vehicles included in the army’s equipment and the other parts are related to newly designed vehicles. In both cases issues related to the behaviour of selected assemblies and the whole vehicle, structure during threats posed by the reality of contemporary battlefield or armed symmetric or asymmetric conflicts are analysed. Selected effects of the tests and analyses will be presented mostly within the qualitative scope due to the data sensitivity. Contemporary design of military vehicles requires involvement of various research methods and specialized calculation software. The results obtained during performed various experimental tests make a valuable basis for verification of numerical models used in design process and multi-option simulation calculations.

Mathematical model of stabilising and tracking control system in main battle tank

The T-72 battle tank (and its’ derivative PT-91 Twardy) are equipped with 2E28M two-axis stabilisation system and monoaxially (in elevation) stabilised gunner’s sight system. The stabilisation system compensates the velocities of the vehicle. The stabilisation system automatically maintains a position of the gun at a fixed bearing in space. In spite of any motion of the vehicle in roll (LK-rotation round axis yK), in pitch (. K-rotation round axis xK) or in yaw (B K-rotation round axis zK), the tank gun stabiliser minimises the effects of vehicle motion on the main armament of the tank under typical conditions of tank operation over rough ground (see Fig. 1) [1, 2, 4, 7, 14, 21, 25]. The gun is rotated in pitch (. A) relative to the turret by an elevation drive system. A hydraulic servo-motor (actuator), fixed to the gun and turret drives the gun (see Fig. 2) [3, 10, 19]. The turret is rotated in yaw (B W) relative to the hull by an azimuth drive system. A hydraulic servo-motor, fixed to the hull drives the turret. The power for the drive is taken from the onboard 24V system. The power is taken from the generator buffered over a set of batteries. It is fed to the electric motor. This electric motor is turn drives a pump. The electric power is thus converted into hydraulic power. The flow of hydraulic fluid through to the drive unit is controlled by a servo valve. An electronic control unit compares the actual speed of the drive with the speed specified by the gunner and regulates the valve setting accordingly to compensate for any discrepancy between the two (the advantage of such a servo control lies in the precision that it affords, its disadvantage is the loss of power at the servo valve, The tank gun stabiliser is an electro-hydraulic control system which makes possible aiming at a target, tracking of a target and stabilise of a given gun angular position. The two-axial stabiliser consists of two separate control systems to stabilise the gun in elevation and the turret (with gun) in azimuth. The aim of researches was to identify all functional blocks of tank gun elevation stabiliser 2E28M (installed in tanks T-72 and PT-91 Twardy) in order to build mathematical model of the system. After detailed analysis of construction and work principles, schematic of 2E28M hydro-mechanical powered mounting, showing number of energy conversion were worked out. Stabiliser has been divided into appropriate functional parts and functional scheme of investigated system were build. Afterwards, static and dynamic characteristics of functional parts of the system were determined. On the basis of obtained characteristics and based on the knowledge about the system feedbacks, structural scheme and mathematical model of foregoing stabiliser were derived. On the basis of the mathematical model, the algorithm and the computer program were worked out. Making use of the Matlab-Simulink program, one worked-up the scheme for numerical computation. The mathematical model and its numerical implementation have been experimentally verified.

STUDIES ON POSSIBILITIES OF INCREASING THE IMPACT RESISTANCE OF KTO ROSOMAK

Military vehicles are mostly designed in order to provide effective execution of tasks in regions of expected actions and operation conditions. During execution of projects, resulting from participation in peace making and stabilization missions, military vehicles are subject to the impact of various mines and improvised explosives. In many cases, the explosive material mass included in the explosive charges affecting the vehicles significantly exceeds the values specified in standards defining the required protection levels assumed at the design stage. The above determines the search for additional shields or energy-absorbing elements reducing the effects of such influence. Information concerning design solutions is usually classified or very limited. Majority of companies dealing with that issue provides information concerning the scope of their business, highlighting the military area thus high efficiency of their protective solutions, possibly presenting a general outline of a particular solution. This paper presents selected results of analyses and studies being carried out and obtained results of solutions to problems included in the study tasks covering a considered subject. Proposed solutions of protective shields against mines and IED for the KTO Rosomak are presented.

STUDIES ON THE EFFECTIVENESS OF THE INNOVATIVE ROAD SAFETY SYSTEM

The paper evaluates the effectiveness of the innovative road safety system equipped with prototype component segments composed of a body made of a plastic filled with reinforced concrete. Main advantages of the new safety barrier include increased resistance to corrosion as well as easy transport and assembly directly on a road section being secured. Model tests were performed on a car of 900 kg weight allowing for carrying out the TB11 tests according to the EN 1317-2 standard. LS-DYNA software was applied for modelling, using the finite element method. The work presents the numerical test results, trajectory of vehicle movement after collision as well as the concrete barrier displacement. It also includes examples of stress in steel bars and joint coupling. Detailed assessing of simulation test results were made on the basis of ASI, THIV and PHD index. They were calculated on the basis of velocity and acceleration courses of selected car bodywork points. Numerical test results confirm the fact that this system meets the normative requirements. They allow for qualifying that system for B impact severity level and W4 working width. The results presented in the paper make the initial stage of the study and further calculations will be oriented towards a possibility of meeting the requirements for higher restraint levels.