During the relatively short history of armored vehicles (BTT) of the ground forces, which is about a hundred years old, the nature of warfare has repeatedly changed. These changes were of a cardinal nature — from positional to maneuver warfare and, further, to local conflicts and counter-terrorist operations. It is the nature of the alleged hostilities that determines the formation of requirements for military equipment. Accordingly, the ranking of the main properties of BTT also changed. The classic combination of firepower — protection — mobility has been repeatedly updated, supplemented with new components. Currently, the point of view has been established, according to which security is given priority.
A significant expansion of the nomenclature and capabilities of the means of combating BTT made its survivability the most important condition for the performance of a combat mission. Ensuring the survivability and (in a narrower sense) the security of BTT is based on an integrated approach. There can be no universal means of protection against all possible modern threats, therefore, various protection systems are installed on BTT objects that complement each other. To date, dozens of designs, systems and complexes of protective purpose have been created, ranging from traditional armor to active protection systems. Under these conditions, the formation of the optimal composition of complex protection is one of the most important tasks, the solution of which largely determines the perfection of the developed machine.
The solution to the problem of integrating protection means is based on the analysis of potential threats in the intended conditions of use. And here we should go back to the fact that the nature of the fighting and, consequently, the representative outfit of anti-tank weapons have changed a lot compared to, say, the Second World War. The most dangerous for BTT at present are two opposite (both in terms of technological level and methods of use) groups of means — high—precision weapons (WTO), on the one hand, and melee weapons and mines, on the other. If the use of the WTO is characteristic of highly developed countries and, as a rule, leads to fairly rapid results in the destruction of enemy BTT groups, then the widest use of mines, improvised explosive devices (SBU) and hand-held anti-tank grenade launchers by various armed formations is of a long nature. The experience of the US military operations in Iraq and Afghanistan is very indicative in this sense. Considering such local conflicts to be the most characteristic of modern conditions, it should be recognized that it is mines and melee weapons that are most dangerous for BTT.
The level of threat posed by mines and improvised explosive devices is well illustrated by generalized data on the losses of equipment of the US army in various armed conflicts (Table 1).
The analysis of the dynamics of losses allows us to unequivocally state that the mine protection component of the BTT complex is especially relevant today. Providing mine protection has become one of the main problems facing the developers of modern military vehicles.
To determine the ways to ensure protection, first of all, it is necessary to assess the characteristics of the most likely threats — the type and power of the mines and explosive devices used. Currently, a large number of effective anti-tank mines have been created, which differ, among other things, in the principle of action. They can be equipped with push—action fuses and multi-channel sensors - magnetometric, seismic, acoustic, etc. The warhead can be either the simplest high-explosive, or with striking elements of the shock core type, having a high armor-piercing ability.
The peculiarities of the military conflicts under consideration do not imply the presence of high-tech mines in the enemy. Experience shows that in most cases mines are used, and more often SBU, high-explosive action with radio-controlled or contact fuses. An example of an improvised explosive device with a simple push-type fuse is shown in Fig. 1
Recently, cases of the use of improvised explosive devices with striking elements of the shock core type have been recorded in Iraq and Afghanistan. The appearance of such devices is a response to the increase in mine protection of BTT. Although, for obvious reasons, it is impossible to make a high-quality and highly efficient cumulative assembly with improvised means, nevertheless, the armor-piercing ability of such SBUS is up to 40 mm of steel. This is quite enough to reliably defeat lightly armored vehicles.
The power of the mines and SBU used depends largely on the availability of certain explosives (explosives), as well as on the possibilities for laying them. As a rule, IEDs are manufactured on the basis of industrial explosives that have much greater weight and volume than combat explosives at the same power. Difficulties in hidden laying of such bulky IEDs limit their power. Data on the frequency of use of mines and IEDs with various TNT equivalents, obtained as a result of generalizing the experience of US military operations in recent years, are given in Table 2.
The analysis of the presented data shows that more than half of the explosive devices used nowadays have TNT equivalents of 6-8 kg. It is this range that should be recognized as the most likely and, therefore, the most dangerous.From the point of view of the nature of the defeat, there are types of detonation under the bottom of the car and under the wheel (caterpillar). Typical examples of lesions in these cases are shown in Fig. 2. In case of explosions under the bottom, it is very likely that the integrity (breach) of the hull and the defeat of the crew both due to dynamic loads exceeding the maximum permissible, and due to the impact of a shock wave and fragmentation flow. During explosions under the wheel, as a rule, the mobility of the car is lost, but the main factor in the defeat of the crew is only dynamic loads.
Fig 1. An improvised explosive device with a push-type fuse
Approaches to providing mine protection of BTT are primarily determined by the requirements for the protection of the crew and only secondarily by the requirements for maintaining the machine's operability.
The preservation of the operability of internal equipment and, as a result, technical combat capability can be ensured by reducing shock loads on this equipment and its attachment points. The most critical in this regard are the components and assemblies fixed to the bottom of the machine or within the maximum possible dynamic deflection of the bottom during detonation. The number of equipment attachment points to the bottom should be minimized as much as possible, and these nodes themselves should have energy-absorbing elements that reduce dynamic loads. In each case, the design of the attachment points is original. At the same time, from the point of view of the bottom design, in order to ensure the operability of the equipment, it is necessary to reduce the dynamic deflection (increase stiffness) and ensure the maximum possible reduction of dynamic loads transmitted to the attachment points of internal equipment.
The preservation of the crew's operability can be achieved if a number of conditions are met.
The first condition is to minimize the dynamic loads transmitted during the explosion to the attachment points of the crew or landing seats. In the case of attaching the seats directly to the bottom of the car, almost all the energy transmitted to this section of the bottom will be transferred to their attachment points, therefore extremely efficient energy-absorbing nodes of the seats are required. It is important that providing protection at high charge power becomes questionable.
When attaching the seats to the sides or roof of the hull, where the zone of local explosive deformations does not extend, only that part of the dynamic loads that apply to the body of the machine as a whole is transferred to the attachment points. Given the significant mass of combat vehicles, as well as the presence of factors such as the elasticity of the suspension and partial absorption of energy due to local deformation of the structure, the accelerations transmitted to the sides and roof of the hull will be relatively small.
The second condition for maintaining the crew's operability is (as in the case of internal equipment) the exclusion of contact with the bottom at maximum dynamic deflection. This can be achieved purely structurally — by obtaining the necessary clearance between the bottom and the floor of the inhabited compartment. Increasing the rigidity of the bottom leads to a decrease in this necessary gap. Thus, the crew's performance is ensured by special shock-absorbing seats fixed in places remote from the zones of possible application of explosive loads, as well as by eliminating the crew's contact with the bottom at maximum dynamic deflection.An example of the integrated implementation of these approaches to mine protection is the relatively recently appeared class of armored vehicles MRAP (Mine Resistant Ambush Protected — protected from detonation and ambush attacks), which have increased resistance to the effects of explosive devices and small arms fire (Fig. 3).
Figure 2. The nature of the defeat of armored vehicles when detonated under the bottom and under the wheel
It is necessary to pay tribute to the highest efficiency shown by the United States, with which the development and delivery of large quantities of such machines to Iraq and Afghanistan were organized. A fairly large number of companies were entrusted with this task — Force Protection, BAE Systems, Armor Holdings, Oshkosh Trucks/Ceradyne, Navistar International, etc. This predetermined a significant decontamination of the MRAR fleet, but allowed them to be delivered in the required quantities in a short time.
Common features of the approach to providing mine protection on cars of these companies are the rational V-shaped shape of the lower part of the body, increased strength of the bottom due to the use of steel armor plates of large thickness and the mandatory use of special energy-absorbing seats. Protection is provided only for the habitable module. Everything that is outside, including the engine compartment, either has no protection at all, or is poorly protected. This feature makes it possible to withstand the undermining of sufficiently powerful IEDs due to the easy destruction of external compartments and nodes with minimizing the transmission of the impact on the habitable module (Fig. 4), Similar solutions are implemented both on heavy machines, for example, Ranger by Universal Engineering (Fig. 5), and on light ones, including IVECO 65E19WM. With obvious rationality in conditions of limited mass, this technical solution still does not provide high survivability and preservation of mobility with relatively weak explosive devices, as well as bullet fire.
Fig. 3. Armored vehicles of the MRAP (Mine Resistant Ambush Protected) class have increased resistance to the effects of explosive devices and to small arms fire
Fig. 4. Separation of wheels, power plant and outdoor equipment from the habitable compartment when the car is blown up by a mine
Fig. 5. Heavy armored vehicles of the Ranger family of Universal Engineering
Fig. 6 A Typhoon family car with an increased level of mine resistance
Simple and reliable, but not the most rational from the point of view of mass, is the use of thick-sheet steel to protect the bottom. Lighter structures of the bottom with energy-absorbing elements (for example, hexagonal or rectangular tubular parts) are still used very limited.
The MRAP class also includes cars of the Typhoon family (Fig. 6), developed in Russia. In this family of cars, almost all currently known technical solutions for mine protection are implemented:
- V-shaped bottom,
- multi-layer bottom of the inhabited compartment, anti-mine pallet,
- internal floor on elastic elements,
- the location of the crew at the maximum possible distance from the most likely place of detonation,
- units and systems protected from direct impact of weapons,
- energy-absorbing seats with seat belts and head restraints.
The work on the Typhoon family is an example of cooperation and an integrated approach to solving the problem of ensuring security in general and mine resistance in particular. The main developer of the protection of cars created by the Ural automobile plant is JSC Research Institute of Steel. The development of the general configuration and layout of cabins, functional modules, as well as energy-absorbing seats was carried out by JSC Eurotechnoplast. To perform numerical simulation of the impact of the explosion on the structure of the car, specialists of LLC Sarov Engineering Center were involved.
The established approach to the formation of mine protection includes several stages. At the first stage, numerical modeling of the impact of explosion products on a sketchily designed structure is performed. Further, the external configuration and general design of the bottom, mine pallets are specified and their structure is worked out (the structures are also tested first by numerical methods, and then tested on fragments by real detonation).
Fig. 7 shows examples of numerical simulation of the impact of an explosion on various structures of mine structures, performed by JSC Research Institute of Steel as part of work on new products. After the completion of the detailed design of the machine, various options for its demolition are simulated.
Figure 8 shows the results of numerical simulation of the explosion of the Typhoon car, performed by LLC Sarov Engineering Center. According to the results of the calculations, the necessary improvements are made, the results of which are already verified by real tests for undermining. This multi-step approach allows us to evaluate the correctness of technical solutions at various stages of design and generally reduce the risk of design errors, as well as choose the most rational solution.
Fig. 7 Pictures of the deformed state of various protective structures in the numerical simulation of the impact of an explosion
Fig. 8 Pressure distribution pattern in numerical simulation of Typhoon car explosion
A common feature of the modern armored vehicles being created is the modularity of most systems, including protective ones. This makes it possible to adapt new BTT samples to the intended conditions of use and, conversely, in the absence of any threats, avoid unjustified costs. With regard to mine protection, such modularity makes it possible to quickly respond to possible changes in the types and capacities of explosive devices used and effectively solve one of the main problems of modern BTT protection with minimal costs.
Thus, the following conclusions can be drawn on the problem under consideration:- one of the most serious threats to BTT in the most typical local conflicts now are mines and IEDs, which account for more than half of the losses of equipment;
- to ensure high mine protection of BTT, an integrated approach is required, including both layout and design, circuit solutions, as well as the use of special equipment, in particular, energy-absorbing crew seats;
- BTT samples with high mine protection have already been created and are actively used in modern conflicts, which makes it possible to analyze the experience of their combat use and determine ways to further improve their design.
Alexey Mikhailovich Kimaev, Head of the Department of JSC Research Institute of Steel
The article was published in the journal Equipment and Armament No. 9 for 2012.
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