Mechanisms of Linear Shaped Charge Cutting -- A New Explanation

Abstract

This paper discusses the theory and experiment involved in the discovery of the mechanisms of Linear Shaped Charges, which are much different from those for Conical Shaped Charges. Linear Shaped Charges (LSC) have been assumed to function in the same manner as Conical Shaped Charges (CSC) in the published literature on the subject. Much work has been done on CSC for military purposes, but there is limited information about the mechanics of LSC. Previous theories have cited the formation of a Monroe Jet as the dominant process. The Monroe Effect describes what happens to a target below the charge following detonation of the charge, and prescribes a fluid jet process for penetration. The fluid jet comprised of the liner material is the cutting device in CSC and has been extensively studied. Recent work at the University of Missouri at Rolla (UMR) cutting concrete with LSC has surprisingly shown that there is not a fluid jet process in LSC. After completing several reinforced concrete penetration tests, minimally deformed copper blades were found in the debris. Initially, the blades were suspected to be misfires or malfunctioned charge remnants. However, results were good and blades were found after every single test. Upon closer inspection, the ribbons were found to be folded copper and they were suspected to be the bottom liner of the LSC. A test series was conducted to verify the new theory by experiment. The civilian use of LSC has been mainly limited to steel cutting. There is a good reason why the blades were not discovered before. In steel cutting the liner welds to the sides of the steel being cut as it passes. However, in cutting reinforced concrete, the initial shock from detonation/impact powders the concrete and allows the powdered concrete to catch the blades. Theoretically the difference in mechanisms between CSC and LSC can be explained by the method of initiation. CSC are top initiated and result in a horizontal detonation plane moving downward toward the target. In LSC, the initiation is at the end of the charge and after some run up distance, the detonation travels down the charge as a vertical plane. This fact and the experiments detailed in the paper present a new explanation for the mechanics of Linear Shaped Charges.

Meeting Name

31st Annual Conference on Explosives and Blasting Technique (2005: Feb. 6-9, Orlando, FL)

Department(s)

Mining Engineering

Keywords and Phrases

The Monroe Effect; Blast Energy; Horizontal Detonation Plane; Vertical Detionation Plane

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2005 International Society of Explosives Engineers (ISEE), All rights reserved.

Publication Date

09 Feb 2005

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