Penetrating the Enemy's Defenses Using Numeric Computations

A special laboratory at IMI Systems provides the defense establishment with ballistic computation services based on parallel computing. A peek into the activity of the laboratory that has been defined as a national knowledge center

Photo: IDF

IMI Systems operates a special numeric computation laboratory regarded as a national knowledge center. The laboratory provides the Israeli defense establishment, including the IDF, IMOD and other Israeli defense industries with ballistic computation services based on parallel computing. Among other things, the laboratory at IMI is responsible for the computations that served as the basis for the development of the 120mm APAM-MP-T M329 and HE-MP-T M339 tank cartridges, the Iron Fist system, protective measures against Qassam rockets and warheads for many of the munitions in the catalogs of the Israeli defense industries.

"We operate under the R&D and engineering element of the Maneuvering Division at IMI Systems," says a senior source at the company. "The activity is divided into different disciplines, including chemistry, mechanics and us – computational science and engineering. Essentially, our task is to provide automated computation capabilities for the purpose of modeling physical processes in the field of ballistics. "

The Objective: Fewer Tests

The laboratory relies on a server facility installed over the last few years at IMI that includes thousands of processors, providing a parallel computing infrastructure. The servers are interconnected through a high-speed communication infrastructure and jointly enable users to run models such as ballistic cycles for barrel-fired ammunition, calculating the interception point of the Iron Fist system and the reinforced concrete penetration envelope of an air-launched warhead.

"In the past, we conducted numerous tests. This method is costly, risky and betrays too many details to the enemy. During the last decade, we have operated differently. Every product being designed starts with analyses and simulations that we perform. We take the idea, be it a projectile or a bomb, model the whole product into hundreds of millions of small elements with each element computed separately, and then we compute everything together so as to provide a single, weighted result. In this way, we determine the performance characteristics of the product and what should be improved before the actual test," they explain at IMI Systems.

"Our developments are divided into two categories: (developments according) to the Company's export needs and (developments according) to the requirements of the defense establishment. IMOD supports us with NIKC (National Infrastructure & Knowledge Centers) funds through two channels, a confidential channel and an overt channel. The overt channel includes entry into new technologies such as machine learning and maintenance of existing computer infrastructures.

"In some classified activities, actual scale tests cannot be conducted so as not to betray anything to the other side. For this purpose, we developed the ability to conduct reduced-scale tests, in which we rely on computerized simulation of the real product. We can conduct a reduced-scale test that simulates a firing of an advanced munition out of a 40mm cannon. The testing environment we developed enables us to obtain the real data required in order to develop such products. "

Modeling Blasts, too

In order to model the behavior of a bomb or projectile, dedicated software is required. Some of the readily available software products are purchased overseas, while others are developed in-house at IMI Systems. "The simulation models the physical process. Blasting effects, bunker penetration, the aerodynamics of projectiles. These are specialized software products developed for parallel computing. We model material behavior as well. We have material science and engineering specialists as well as a laboratory for testing material strength and the blast effects of propellants. The option of modeling materials is critical to the overall modeling of the ballistic process," they say at IMI Systems.

"In the actual test, the processes are very fast. It takes about 100-200 microseconds for a shaped charge to penetrate the target. An air-launched warhead penetrates a target that is not excessively deep within 5-6 milliseconds. You photograph the entry and exit, but still have no information about what actually goes on in the context of the physical process. The simulation enables computations of internal, external and terminal ballistics. In any case, it is impossible to give up the testing completely, but the computations make it possible to reduce the number of tests.

"In order to perform the computations, you divide the medium into a collection of small elements with each element (also called a box) computed separately. Then you take all of the elements and perform a combined computation. In order to correctly model the physical behavior of the whole, including dynamic load, you sometimes need millions of such elements. The smaller the element – the more accurate the result. It depends on the computation capability. To this day, we have handled models of up to one hundred and fifty million elements for the modeling of the system as a whole. Such computations enable us to calculate, at the physical level, the mass, momentum, and energy using an equation of state. "

The computational capabilities enable the State of Israel to obtain feedback for a weapon system that had failed or deviated from its performance envelope. In this respect, IMI Systems cooperates with the IDF's Testing & Quality Assurance (TQA) unit. Those capabilities enable other companies to take advantage of the knowledge accumulated by IMI Systems. At IMI Systems they explain that in some unique fields, the IAF encourages other industries to have the products developed by IMI Systems owing to the computational capabilities it possesses.

"In the case of air-launched warheads, you want the warhead to survive a specific target. Whether the target is a reinforced concrete wall, the roof of a hangar or any other target you wish to penetrate, the weapon envelope should survive. The thinner the weapon envelope, the more space it contains for propellant – and vice versa. These ratios are determined through optimization calculations. We also work with specialized materials developed in cooperation with academia," they explain at IMI Systems. "Another aspect is sales to overseas clients. During the selling process, some clients want to adapt the product to a specific scenario. Sometimes they want a different propellant, or a cheaper one. The client has his own considerations, and at this point, you need the support of a computational capability. "

Matrix Physical Computations

One of the capabilities that changed the way weapon systems are developed by IMI Systems is the ability to perform matrix physical (Multiphysics) computations. This is the ability to calculate multiple physical phenomena that affect the behavior of the munition – simultaneously. This capability made the development of the 120mm APAM-MP-T M329 and HE-MP-T M339 tank cartridges possible. "The Multiphysics (capability) enabled us to develop the 120mm APAM-MP-T M329 and HE-MP-T M339 tank cartridges. These cartridges reach their targets at a speed of Mach 3, about 900 meters per second. They are required to retain their integrity during the penetration and explode inside the target. This would have been nearly impossible to accomplish unless we had that computational capability," they say at IMI Systems.

While in the past each physical effect had to be calculated separately and then everything had to be calculated together, as a whole, while attempting to isolate the specific effect that you wanted to correct, today you can compute the same problem concurrently. "This means the ability to compute all of the effects on the projectile being fired," explains the senior source. "One of the fields that evolved owing to this computational capability is the field of warhead penetration calculations. Concrete strength calculations are critical during the development process. If you designed a warhead for a specific concrete strength and the enemy added an additional 10 cm thick layer of concrete, the munition would not penetrate the concrete, and the mission would fail. With the Multiphysics capability, you can evaluate the behavior of the warhead very accurately and reach a situation where you can penetrate almost anything – even if the enemy had made minor adjustments to the structure of which you were not aware.

"After the Qassam rocket was defined as a threat, we developed protective measures against these rockets. These measures consisted of specialized roofs you install over public buildings. The computational capability we developed here made this possible. We also invented a Qassam firing system in order to check our calculations. Another computational activity covers the firing of kinetic projectiles. This projectile exits the barrel at a speed of Mach 5 with sabots that enable it to travel through a barrel having a larger diameter than the projectile itself. The sabots are released when the projectile exits the barrel, and you need to calculate their release so they do not interfere with the projectile's flight. These calculations cover flow processes, the motion of the sabots, pressure calculations, dynamic strength calculations and other factors.

"The development of the Iron Fist system was also based on the Multiphysics capability. A successful evaluation of the point where the projectile will engage the threat determines the success of the interception. When you develop such capabilities, they are strategic. If the other side knows what you are doing, on the crucial day you will not be able to penetrate or to intercept. The enemy can also attempt to disrupt the development process by interrupting the supply of materials or systems, hence the high degree of confidentiality. "

Another challenge is to diagnose, at the outset of the development process, the materials with which the weapon or munition would have to cope. At IMI Systems they explain that in most cases, the client defines the challenges for the weapon/munition. "Every client has his own intelligence, so he asks us to deal with scenarios he is familiar with. Additionally, we know the materials available in the market. Most protective measures consist of materials available naturally and in the enemy's environment. For example, how do you reinforce concrete? We know that one of the methods is to add metal fibers into the mix. There are open-source articles from which you can learn, and you can also contact local concrete manufacturers and find out. This knowledge enables us to estimate what the other side has and design the warhead accordingly," concludes the senior source.

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