analysis and simulations of low power plasma blasting for processing lunar materials v.1

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Analysis and Simulations of Low Power Plasma Blasting for Processing Lunar Materials

Analysis and Simulations of Low Analysis and Simulations of Low Power Plasma Blasting for Processing Power Plasma Blasting for Processing

Lunar MaterialsLunar Materials

MartMartíín E. Baltazar-Ln E. Baltazar-Lóópez, Steve Best, pez, Steve Best, Henry W. Brandhorst, Jr., Zachary M. BurellHenry W. Brandhorst, Jr., Zachary M. Burell

Space Research Institute, Auburn University, AL 36849-5320

Matthew E. Heffernan and Frank RoseMatthew E. Heffernan and Frank RoseRadiance Technologies, Auburn, AL, 36849

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Overview

• Introduction• Objectives• Experiments with Plasma Blasting• Numerical simulation• Results• Conclusions

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Introduction

Significant transportation cost

Safety concerns

Complications of Drilling and excavating on the Moon’s surface

Chemical explosives

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Introduction

Plasma Blasting is analternative method for surface blasting

Incorporates the use of electrically powered

plasma blasting

Allows easily adjusted explosive yield control for

additional safety

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Introduction

Minimal scattering of fly-rock

No chemical reaction inert, non-explosive

Reusable discharge portion

Reduced equipment mass

Potential advantages

for space application

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Introduction

Such a system was developed and successfully tested at the

Space Research Institute (SRI) facilities

ProbeInductorCapacitor 1

Capacitor 2

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Introduction

Experimental testing with plasma blasting

can be expensive

… and time-consuming

sometimes several tests are needed in order to obtain a single valid data point

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Introduction

• To complement and validate the experimentation

•To predict the volume to be blasted and correlate with energy levels

• Could even be used as an alternative to experimentation… within certain limits

Need of Simulation

with the corresponding savings in time and money

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Objectives

Apply numerical techniques to analyze Apply numerical techniques to analyze and simulate the capabilities of the plasma and simulate the capabilities of the plasma blaster to be used in space missions.blaster to be used in space missions.

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Experiments with Plasma Blasting Technology

Blasting test on a 24” dia. X 36” long,concrete cylinder sample (non-reinforced) with 12” probe and 52kJ pulse

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Test setup characteristics of 24” dia. X 36” long, steel-reinforced concrete cylinder sample

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Steel-Reinforced concrete cylinder 6.2 ft3 (0.17m3) after blast test

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Blast test shot on granite rock, with 12” Probe and 52kJ pulse

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Numerical methods to simulate blasting

Finite volume Finite differenceFinite element method with explicit time integration scheme

Numerical methods used to simulate the blast

effects problems

Hydrocodes

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Hydrocodes …

Extensively used to simulate explosions and other high rate events

•High pressures (Giga Pascal range)

•Thermodynamic influences

•High strain rates

originated by chemical explosives.

…but…

Incipiently used to model plasma blasting

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In this work, ANSYS AUTODYN, a three dimensional hydrocode is used to simulate the plasma blasting of concrete samples

with the purpose of getting an estimation of the damage of plasma blasting and then to validate those simulations with experimental results.

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Hydro-code simulations

•Model electro-hydraulic loading on concrete cylinders using 2-D and 3-D axial symmetry.

•Concrete was modeled using a porous EOS and a Drucker-Prager strength model.

• Determined that the Drucker-Prager criterion gave the best results for this application based upon previous physical observations

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Hydro-code simulations

•The program has the option to present the results in terms of damage with a relative scale going from zero to one, and graphically with a scale of colors

• is possible to specify stochastic failure mechanism to take into account the heterogeneities in material .

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Results

2-D simulations demonstrated congruence between numerical and experimental results for blastsperformed on 12’’ and 18’’ concrete cylinders

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Results

24”x 36” cylindrical concrete sample models after 300µs simulation time of a 600MPa blast @ 60µs pulse width

(a) y-plane view of 3D simulation and (b) 2D simulation

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Results

Time-history sequence of cracks and damaged zones

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Results

Cracks and damage

along different radial planes after 300µs simulation

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Results

Cracks and damage along different longitudinal planes after 300µs simulation

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Results

Damage sequence transparent view

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Summary and Conclusions

• Experiments of plasma blasting on concrete and granite rocks were performed with the purpose to emulate rocks and lunar soil.

• Two and three dimensional simulations of plasma blasting on concrete samples were performed.

• The mechanisms of damage and failure of plasma blasting can be simulated by hydrocodes and the solutions are very congruent with the experimental results.

• The heterogeneous nature of blasted concrete samples was numerically verified by the asymmetry of cracks and damage along different radial and longitudinal (transversal) planes.

• It is possible to analyze various structural response situations including damage and failure over a wide range of loading conditions without the need of setting up an experimental rig for each analysis, realizing a savings in time and experimental costs.

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Acknowledgements

• This work was supported under NASA Contract No. 07-060287 , “Highly Efficient High Peak Power Electrical Systems for Space Applications” funded through Radiance Technologies, Inc.

• Any opinions expressed are those of the authors and do not necessarily reflect the views of NASA.

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analysis and simulations of low power plasma blasting for processing lunar materials v.1

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