Investigating detonation fronts in small explosive charges using a wave shaper

Amondson, David Kenneth

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https://hdl.handle.net/2142/109570 Copy

Description

Title

Investigating detonation fronts in small explosive charges using a wave shaper

Author(s)

Amondson, David Kenneth

Issue Date

2020-10-23

Director of Research (if dissertation) or Advisor (if thesis)

Glumac, Nick G

Doctoral Committee Chair(s)

Glumac, Nick G

Committee Member(s)

• Elliott, Greg S
• Stewart, Donald S
• Krier, Herman

Department of Study

Mechanical Sci & Engineering

Discipline

Mechanical Engineering

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Detonation Front
• Waveshaper
• Wave Shaper
• Attenuator
• Detonation Front Curvature
• Convergent Detonation
• Converging Detonation Wave

Abstract

Understanding detonation front curvature is critical to the successful exploitation of the power of explosives. Changing the detonation front from a diverging spherical wave to a more complex shape allows for substantial increases to the detonation velocity and pressure above the Chapman-Jouguet condition. Converging detonation fronts can detonate insensitive explosives or increase metal pushing power in explosively formed penetrators (EFPs). While there are many complicated ways to generate a convergent front in an explosive, using inert wave shaper (also called an attenuator) is a simple solution. Wave shapers have been used for decades in shaped charge applications in larger warheads, but this current research has miniaturized the design to very small charges (8 mm in diameter and 5-6 mm long). The smaller the charge, the more significant effects like corner turning and critical (or failure) diameter become. Investigation into whether a commercial hydrocode (ANSYS Autodyn) can correctly account for these phenomena was also explored. Shock physics, modeling, and experiments using high speed imaging are combined to better understand the function of a wave shaper and its effect on detonation front curvature. The wave shaper shifts the detonation front from its characteristic diverging aspect to converging. Very little published research on the effects of wave shapers exists for charge sizes of about three to four inches in diameter in both simulation and modeling, and there is virtually nothing on very small charges less than one inch in diameter. By varying the geometry, the type of explosive, and the attenuator material, the shape of the detonation wave was easily varied and has been shown here. The shape of the detonation front was imaged using a custom streak camera setup in conjunction with a framing camera. Charges were fabricated in-house using pressed PBXN-5 and PETN and assembled with machined wave shapers. There is a strong correlation between the Autodyn model and the experiment for larger wave shapers (charge size 1” diameter) and reasonable correlation for the mini wave shapers (charge size 8 mm diameter).

Graduation Semester

2020-12

Type of Resource

Thesis

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http://hdl.handle.net/2142/109570

Copyright and License Information

Copyright 2020 David Kenneth Amondson

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