The Discovery and Benefits of Munroe Effect - Report Example

The Discovery and Benefits of Munroe Effect al Affiliation The concept of Munroe effect: The concept of Munroe effect has to do with a form of shaped charge which is an explosive component used to break through thick targets by use of high velocity jets. A usual shaped charge is made up of a conical hole that contains highly explosive materials. The conical hole is covered along with a compliant substance, such as copper. The extreme high stresses elicited by the blast of the explosives have got some sort of focusing impact on the liner, thereby transforming it into an elongated, slim, stretching jet with an inbuilt tip speed of about 12km/s (Alberta & Alberta Educational Communications Corporation, 1996). A mathematical analysis, and substantiation for this jet’s penetration into a hard target is established with the objective of accurate prediction of the resultant crater depth and width. Initially, the model incorporates the dynamics fluids methodology in a jet with an elastic-plastic solid technical component in the target. Apart from the tip, the exploitation of the high aspect ratio is aimed at reduction of the problem’s dimensionality by use of slender body theorem. Doing so results into obtaining of a novel structure of partial differential equations mainly for the free-boundaries linking the fluid, elastic, and plastic regions and hence it is through velocity whereby the jet’s potential is obtained (Haines & Eagle, 1976). So as to obtain intuition, there should be a systematic consideration of the paradigm of a circular cavity’s expansion, and contraction under induced pressure. This yields a high possibility of residual displacements and stresses. Proper and systematic application of these ideas ensures the development of a more pragmatic penetration model. Close to the jet’s tip, a squeeze-films analogy is used to determine the plastic flow of the intended target (Haines & Eagle, 1976). This then leads to the proposal of the jet’s flow models on the basis of simple geometric analysis in the slim region. A specific tip scaling hence ends up leading to a sort of consideration of a two-dimensional filling-flow form of impacting on an obstruction, such as a beam or membrane. The discovery of Munroe effect: The discovery of the Munroe effect, that is, the aspect of shaped-charged explosives can be traced back to the concepts of the civilian segment. Franz Xaver von Baader, a German mining expert, proposed the concept of adopting empty, conical component adjacent to a detonating charge so as to enhance its efficacy (Alberta & Alberta Educational Communications Corporation, 1996). However, at such a time (1972), the only available explosive was gunpowder. Since it was not a sky-scraping explosive, it was unable to fabricate a detonating shockwave, hence exposing its incapability of producing the targeted shaped charge effect. A crucial practical occurrence in the account of explosives was in 1867, when a scholar known as Alfred Nobel came up with the detonator. Since then, the 1st implementation of the intended hollow charge effect was finally created in 1883 by Max von Foerster after almost a whole century. Later in 1886, Gustav Bloem (a German) discovered a methodology of detonating caps with hemispherical lining components within a shell. His invention was characterized by a lined cavity, hence being considered as an actual developer of the shaped charge concept (Alberta & Alberta Educational Communications Corporation, 1996). This was the time when Professor Charles E. Munroe had been employed at the U.S. Naval torpedo laboratory, just as a civilian chemist. His main obligation was to seek for much better propellants, and so he had to be in collaboration with the laboratories of E. I. du Pont while carrying out his smokeless powder research. The main challenge faced by Munroe by then was the issue of powder deterioration due to longer storage periods that they were succumbed to. Munroe independently came up with the idea of establishing an un-lined shaped charge which received great acceptance globally. While Munroe might not have been the original developer of the hollow charge explosion concept, he is still in memory due to his most fruitful demonstrations of its impacts. At the onset of 1888, he demonstrated a number of experiments whereby he showed out the power of either the lined or unlined shaped charges. For unlined charged effects demonstrations, he adjacently aligned a steel plate to explosive blocks, with letters USN (United States Navy) having been inscribed on the endpoint. After explosion, those letters were exactly reproduced on that steel plate. Munroe also demonstrated that the plate’s level of indentation increased with placement of explosives within a cylinder and with the cavity being made in them oppositely to the point of explosion. The cavity could thus form a much deeper indentation due to the subsequent focus of explosion’s products. Munroe also employed this methodology to obtain dramatic leave engravings on copper plates. The incidences of the first and the second world wars accelerated massive research efforts into shaped charge explosives, in line all the other weapon systems. With Munroe being one of the main investigators of such explosives in the early century, then Henry Hans Mohaupt (in the U.S. and Britain) and Franz Rudolph Thomanek (in Germany) certainly became the foremost inventors of modern military surveillance purposes. These modern researchers independently conducted their experiments with the ultimate objectives of gaining insights into the hollow, lined cavity-shaped penetrating charges. These two researchers created room for US in 1941to create highly explosive anti-tank grenades as well as projectiles. These grenades ware later restructured to fit onto rocket motors that became very lethal due to their penetration power. After World War II, significant advancements in this technology were enhanced through the 1950s. This was also the time when high-speed flash radiographic methodologies and photography became available, and massive numerical simulations that were aided by the most powerful computer operating systems were utilized for proper understanding of the physics pertaining jet expansion. A practical development termed as 6.5” anti-tank aircraft rocket (ATAR) was utilized by U.S. during the Korean War. The concept of shaped charge effect: The shaped-charge effect and its overall mechanism of penetrating through resistant substances have been studied extensively. A distinctive configuration of such a device is comprised of explosives that are put behind a lining component, with a detonator situated behind the explosives. The entire assembly is then placed within a metal casing that is cylindrical in shape. The liner normally takes a conical shape, but can on the other hand be hemispherical or can take other forms of shapes that are in line of symmetry with the central axis. Aluminum, steel, depleted uranium and copper are the most commonly used liner materials. The ignition of explosives by a detonator, tend to propagate a detonation wave through a given medium at an average velocity of 6-7 km/s; hence leading to creation of a high-pressure front of about 3x1010 Pa. (Marshall, 1917). This high-pressure front then expands the casing, thereby causing its breakage and fragmentation. Most importantly, that pressure front tends to travel to the explosives head within the liner, hence collapsing it towards the direction and magnitude of the entire central axis. The liner component is converted into two fast-moving jets that are well endowed with minimal radial velocity, due to the explosive’s momentum focus along the central axis. The forward accelerating jet has got a thin, lance-like indentation and normally springs forward at a speed of 6-12km/s, whereas the other back-up jet has an average speed of about 1km/s and is hence left behind. A much longer jet is endowed with very high penetrating ability, and so; the distance variation between the target and the explosive device (known as the stand-off) should be receive careful and keen estimation. The jet’s tip should normally hit the target at about 50µs after its release or detonation, with an overall surface temperature of around 500oC (United States, 1900). The target then undergoes massive plastic deformation that is formed under pressure as soon as it is hit by the jet due to the very high temperature that is produced. This makes the target to expand around the jet hence creating a hole. The transfer of momentum to the target leads to lose of energy, hence bringing the jet to a halt eventually. According to Meyer (1987), the charge location that is relative to the target is usually critical for optimal penetration due to two main reasons. If there is very close charge detonation, then there is subsequent hindrance for the full jet development. But all in all, the jet disperses and disintegrates after a relative short distance, which is mostly considered as being below 2 meters. Such standoffs makes it break into particles which tend to tumble and drift off penetration axis, such that the consecutive particles tend to broaden rather than get deeper into the hole. Very long standoffs can lead to reduction in velocity due to air drag, thus degrading penetration (Marshall, 1917). The original concept was very essential in that, many variants such as plane charge, cutting charge and explosively formed projectiles (EFPs) are being used in this modern development. A cutting charge normally acts within the longitudinal direction mainly along the central detonation axis. In a plane charge, the lining is developed with a wider angle. This results in a situation whereby the explosion turns the structured liner inside out instead of forming a liner jet (Akhaven, 2000). This then ends up resulting in a weaker explosion with minimal penetrating intensity, but a wider range of destruction. The most frequent use of EFPs can be witnessed in the military unit. The lining of an EFP is structured in such a way that all features of the emerging jet have got equal velocity. Almost all the liner is transformed into the jet, thereby leading to the formation of a higher kinetic energy that can be utilized against targets within greater distance. Application of Munroe effect: Shaped charges are mainly unleashed for the ultimate tasks of breaking through hard objects, both in military and civilian applications. They are mostly useful for petroleum engineers, and are also utilized for hydrocarbon reservoir categorization as well as being used for rock strata breaching. The matter of fact is that, bore expansion in oil-fields needs careful and proper optimization of a range of components, such as deformation characteristics, rock thickness, stress on rock layers, strength etc. In this case, shaped charges are deemed as very effective simply because they have the ability to generate a directed and localized force that can penetrate an oil well’s cement lining without any form of strata disturbance (United States, 1900). Shaped charge explosives can also be used in tunneling, mining, large civilian projects and excavation works where accurate breaches should be established under strict conditions. In military, all the three, that is; the army, air force, and the navy uses shaped charges (Akhaven, 2000). The army utilizes them for manufacture of anti-tank weapons, bunker buster bombs and armor-piercing rounds. The navy on the other hand uses them in torpedoes and underwater operations. The air force on their side utilizes them in developing missiles used for attacking enemy spacecraft and even air-crafts. The shaped charge blast effect has played a very essential role in both civilian and military engineering. It has been used for blasting several mines, roadways, tunnels, and even rail tracks across and along very many landscape and mountain formations around the globe. It is also used extensively by oil companies including Bloomberg for expanding and drilling of oil wells. It has also played an essential role in warfare, especially as bunker buster and anti-tank projectile weapons. Shaped charges are mostly utilized wherever accurate breaches in cynical materials are required, and in line with this, there is a research in progress that is aimed at escalating their penetrating power and efficacy as well as breach precision (Meyer, 1987). There is a high expectation that they will remain as one of the most popular detonation devices for a much longer time period due to their efficiency and effectiveness. From the above study, we can come up to the conclusion that the aspect of Munroe effect has gone through a number of developmental stages with massive technical improvements that have ensured a lot of efficiency and vulnerability in terms of their usage. The application and handling of shaped charges is normally very sensitive due to its powerful intensity, and hence its misuse can cause massive destructions (Marshall, 1917). References: Alberta., & Alberta Educational Communications Corporation. (1996). Fields around point charges. Edmonton, AB: Access Network. Akhaven, J. (2000).The Chemistry of Explosives (2nd Ed.) Haines, G. K., & Eagle, M. (1976). Explosives. New York: Morrow. Marshall, A. (1917). Explosives: Vol I. (Explosives.) London: Churchill. Meyer, R. (1987). Explosives. Weinheim, Federal Republic of Germany: VCH Verlagsgesellschaft. United States., United States., & United States. (1900). Explosives. Washington, D.C: U.S. Dept. of the Interior, Bureau of Mines. Appendix: 1. Dissipation of elastic waves generated from the tip at finite angle into the outer bulk: 2. Axis-symmetric elastic-plastic penetration of a shaped charge: Read More