DEVELOPMENTAL TENDENCY OF LANDMINE PROTECTION IN VEHICLE

Transcription

1 MODELLING AND OPTIMIZATION OF PHYSICAL SYSTEMS 8, pp , Gliwice 2009 DEVELOPMENTAL TENDENCY OF LANDMINE PROTECTION IN VEHICLE EDYTA KANIA Department of Applied Mechanics, Silesian University of Technology Abstract The aim of this paper is to provide an overview of developmental tendency of vehicle landmine protection. The background of the mine detonation process as well as its consequence on military vehicle and there occupant are presented. Analysis of requirements of armoured vehicle is described. Based on the current status, recommendations for future work are given 1. INDTRODUCTION Military vehicle moving in a armed conflict have to fulfill suitable ballistic requirements independently verified in accordance with an internationally accepted test standard [1] [2] Currently a document which determines ballistic protection requirements in vehicle is NATO Standardization Agreement STANAG 4569 Protection Levels for Occupants of Logistic and Light Armored Vehicles. The aim of the STANAG document is standardization of occupant threat level [3]. The essence of this issue is an assessment of live threating of occupant of military vehicle depending on vehicle construction and selected material structures. The standard for the future construction of military vehicle is an assurance of landmine protection [3]. The existing open test standards for vehicle landmine protection is a RSA-MIL-STD-37 Issue 3 including validation of the wheeled landmine protection threat as well as details concerning equipment and test methodology [2]. The main security measure of military vehicle is there armour [4]. The construction of vehicle made of certified material is not enough, that ballistic requirement will fulfill [3]. There is a need of complex, effective vehicle protection that means the protection assurance of their occupant especially from landmine detonation. In this paper, the background of the mine detonation process as well as its consequence on human and analysis of requirements of armoured vehicle are presented. 2. BACKGROUD OF A LANDMINE DETONATION PROBLEM 2.1 Types of landmine Landmines pose a significant threat for military vehicles and their occupants [5]. They can be classified according to target and to damage mechanism. We can distinguish the following kind of mine: - Anti-Personnel (AP) mines, which are devided into: blast mines and fragmenting mines; - Anti-Tank (AT) mines devided into: blast mines, shaped charge mines [6]

2 68 E. KANIA Fig. 1 Examples of landmines a) Anti Vehicle, b) Anti Vehicle, c)anti Personal [7] Anti-vehicle mines are designed for the destruction and damage of armored and other vehicles, usually by creating mine-fields on the roads used by tanks. These mines, with great range, a huge amount of strong explosive, and great destructive force, can be buried in all types of ground, on railroad lines, in coastal areas and river approaches, and they can be buried in groups to form minefields or separately [5] [6]. The first antitank mines appeared in World War I as a weapon against the first armored vehicles. During World War II, technological progress in the production of antitank mines enabled their widespread tactical application. Nowadays, there are several hundred different types of antitank mines in the world [5]. Fig. 1 Examples of mines under a vehicle [8] [9] [10] Mine detonation under a vehicle can result in effects like fragments, fire, gases, blast overpressure as well as the mechanical shock and a vertical impulse load [5]. An Anti Vehicle mine detonation causes structural deformations. Besides, sometimes it causes a vehicle rapture, which affected the occupant. In the same case, but without structural rupture, the occupants might still be affected by the mechanical effects like shock, structural deformation and the vertical impulse load. After a blast mine detonation, a shock wave goes through the vehicle [6]. 2.2 The effect of mine detonation Mine detonation under a vehicle (fig. 2) caused following results: local effect, global effect, drop down effect and subsequent effects. A local effect occurs after initiation of the blast mine under a vehicle. A shock wave is formed by the detonating of explosive and hits

3 DEVELOPMENTAL TENDENCY OF LANDMINE PROTECTION IN VEHICLE 69 the bottom plate of the vehicle within approximately 0.5 ms. After that is subsequently reflected causing an extremely large peak pressure resulting in a local acceleration of the bottom plate. Within approximately 5 ms after the detonation the bottom plate bends in both the elastic and plastic regions depending on the shape, thickness, material and additional stiffeners. The shock wave causes a mechanical shock in the material of the vehicle structure, which travels goes through the whole structure and causes strong vibrations in all vehicle parts. In case of global effects, reflecting blast wave under the vehicle and pressure force briefly acts on the complete bottom section of a vehicle. The total impulse load of this pressure force is a measure of the initial vertical velocity causing a jump of the complete vehicle. The jump height depends on the total mass and the moments of inertia around the centre of gravity. After reaching its maximum jump height the vehicle will fall due to gravity. In actual incidents the vehicle is driving and will not drop down on the original place, whereas in an experimental set-up, the vehicles are tested in a static situation. Therefore, it is possible that the vehicle drops down into its own crater, which can result in higher vertical loadings than in an actual incident. By a subsequent effect we mean incidents like roll over and frontal crashes after the mine detonation but they have to be considered in crashworthiness investigations [6] ms MINE DETONATION LOCAL STRUCTURAL RESPONSE OCCUPANT RESPONSE 2.3 Occupant loading Fig. 2 Mine loading process [6] [9] GLOBAL VEHICLE RESPONSE The response of the occupant inside the vehicle is influenced by both the local effect (shock and deformation) and the global effect (vehicle motion) of the vehicle mine detonation process (Fig. 2). The human body or parts of the body can be loaded directly by the shock (primary effect) or by the local deformation (secondary effect) or indirectly by the relative body motion and resulting impacts to the vehicle structure (tertiary effect) [6]. The severity of the threat, and therefore, the severity of the loads on the occupant, depend on the distance between the casualty and the detonation point as well as on the vehicle structure, the interior structure, like seat and seat mountings, and the foot plate configurations [5]. When a seat or a footrest is mounted on or close to the deforming bottom plate large loads are most likely transferred to respectively the feet, the ankles, the legs and the lumbar spine. Additionally, the chance of injury depends on initial body posture, the presence and use of personal protection equipment and restraint systems. Age, gender, health, training may influence the injury probability as well [6]. In general, the leg and foot/ankle complex are loaded first because there are usually in the closest position to the detonation point and the deforming structure [6].

4 70 E. KANIA Due to the acceleration force, the legs move upwards with the risk of hitting other vehicle parts. The leg motion may also have its influence on the lumbar spine and other body parts. The pelvis can be loaded through either the lower extremities or the seat of the vehicle. The pelvis acceleration and motion will also load the upper body parts, including the neck and the head. The whole body will be launched vertically due to the seat impact [6] When no or inappropriate restraint systems are used, the head can hit the roof of the vehicle. Head contact with a stiff roof structure may cause high acceleration peaks in the head and extremely high loads in the neck. Such high neck loads are life-threatening and must be prevented [6]. 3. LANDMINE PROTECTION SYSTEMS Underbody mine blast threats pose a high risk to a vehicle and its crew [10]. Military vehicle and its equipment should be designed with the respect to ergonomic rules, which are significant for the safety of the passengers [4]. Thanks to constant progress in technology and advanced materials, it is possible to achieve reliable protection which enables withstanding the mine attacks. Protection parts of the vehicles are assembled both inside and outside the vehicle [8]. Landmine protection systems can be divided into two groups: the external protection and the internal protection. The components of the complex landmine protection systems are presented in fig. 3. The external protection absorbs and deflects the major portion of the blast energy to minimize the effects that are transferred into the vehicle and to the crew. COMPLEX LANDMINE PROTECTION SYSTEMS EKSTERNAL PROTECTION INTERNAL PROTECTION VEHICLE STRUCTURE PERSONAL POTECTION EQUIPMENT WHEELS ENERGY ABSORBING SEATS ARMOUR MATERIALS ADDITIONAL EQUIPMENT ARMOUR WINDOWS GPS NAVIGATION SYSTEMS RADIO COMMUNICATION SYSTEMS Fig. 3 Complex landmine protection systems [7] [8] [10] [11] [14]

5 DEVELOPMENTAL TENDENCY OF LANDMINE PROTECTION IN VEHICLE 71 In case of the internal protection, special installations inside the vehicle are designed to handle the remaining effects of the detonated mine. What is more, vehicles should have armoured windows so that the crew has good all-round orientation. Combat vehicles should be fitted with electronic support systems such as GPS navigation systems, night-sights and radio communication systems [4]. The developmental tendency of landmine protection systems is based on complex, effective vehicle protection which means assuring the protection of the passengers. The functions of the complex protection systems are: absorption of the major portion of the explosion energy by the bottom protection. Furthermore, the functions also include the prevention of penetration by the shrapnel and projectiles by the use of special materials. They protect the crew from secondary effects by the installation of special seats, special elements of the equipment which diminish the shock effects [7]. 4. NUMERICAL MODELLING OF MINE DETONATION Vehicle mine protection is an emerging field of international research. There is a need for experimental researches as well as modeling (fig. 4) and understanding the interaction of mine blast products with structures, the resulting loading and the damage mechanisms. For example, the application of numerical modeling is used to predict the vulnerability of the armoured vehicle passengers of anti vehicle blast mine. Results of numerical modeling provide the insight in the methods that can be used to restrict the vulnerability of the combat vehicle crews of the effects of anti vehicle blast mines. The correct evaluation of the effect of this type of explosion is significant for the design of the protection structures. Protective equipment must be designed to mitigate the effect of a landmine blast. The expression of the numerical model makes an analysis of blast mine effect possible. Numerical modeling and simulation are ones of the several steps of the development process of a product. 5. CONCLUSION Fig. 4 Model of new bottom technology [8] The standard for the future construction of the military vehicle is to assure the landmine protection. One of the greatest challenges placed on vehicle to blast mines is assessing the structural response of the vehicle as well as evaluating the injury sustained by the passengers of a vehicle due to the acceleration induced by the blast. There is a need of a complex, effective vehicle protection which means assuring the protection of the passengers especially against landmine detonation. Experimental researches as well as numerical modeling helps in understanding the interaction of mine blast products with structures, the resulting loading and the damage mechanisms. Based on the current status, recommendations for future work include expansion of the validation of experimental and numerical models as well as exploration of actual incidents both from a technical and a medical standpoint.

6 72 E. KANIA REFERENCES 1. JD Reineckea, IM Snymana, R Ahmeda, FJ Beetgeb: Vehicle landmine protection validation testing, A CSIR Defence, Peace, Safety and Security, PO Box 395, Pretoria, JD Reinecke, IM Snymam, R Ahmed, FJ Beetge: A safe and secure South Africa Vehicle landmine protection validation testing 3. M. Szudrowicz: Skuteczność opancerzenia pojazdów, Wojskowy Instytut Techniczny 4. M. J. Multarzyński: Nie tylko pancerz chroni. Wyposażenie pojazdów opancerzonych i mino odpornych na Eurosatory 2008, Nowa Technika Wojskowa, Sierpień 2008r, str Injuries from Antitank Mines in Southern Croatia 6. RTO TECHNICAL REPORT TR-HFM-090 Test Methodology for Protection of Vehicle Occupants against Anti-Vehicular Landmine Effects; Chapter 2: The mine detonation process and occupational loading Brig Gen Chris Gildenhuys: The Future of Light and Medium Armour in the Land Operational Environment for the South African Army, Conference Materials at 8th Annual Light and Medium Armoured Vehicles 2-6 February 2009 London 9. R. Fallet: Mine explosion and blast effect on vehicle analysis of the potential damages on passengers 2 nd European HyperWorks Technology Conference, Strasbourg September 30 th October 1 st, R.G. Kargus, T.H. L.A. Frydman: Methodology for establishing the mine/ied resistance capacity of vehicle seats for crew protection, K. Wiliams, F. Fillion Gourdeau: Numerical simulation of Light Armoured Vehicle Occupant Vulnerability to Anti Vehicle Mine Blast, 7 th International LS DYNA Users Conference; TENDENCJE ROZOWOJOWE ŚRODKÓW OCHRONY PRZECIWMINOWEJ POJAZDÓW Streszczenie W artykule przedstawiono przegląd tendencji rozwojowych ochrony przeciwminowej pojazdów pancernych. Scharakteryzowano przebieg detonacji min, jej oddziaływanie na konstrukcje pojazdów wojskowych i ich pasażerów. Przeanalizowano obecne wymagania ochrony przeciwminowej. Przedstawiono również założenia do dalszych badań.