Modelling and Experimental Validation of a Novel Ultrasonic Planetary Core Drill (UPCD) Tool Design X.Li, A.Bolhovitins, R.Timoney, P.Harkness, M.Lucas University of Glasgow, UK 1 st Space Glasgow Research Conference, Glasgow, UK, 28 October, 2014

Outline  Background  UPCD Assembly  Numerical Model  Simulation Results  Conclusions

Background SELEX GALILEO – ExoMars Mission Conventional Driller/Corer NASA – Jet Propulsion Laboratory (JPL) Ultrasonic/Sonic Driller/Corer (USDC) operated from the Sojourner platform

Background Compared with conventional drilling/coring, USDC has the following advantages: UoG/MP Drill in Tenerife 2011  Light-weighted, compact, low pre-load, low power  Operate with a minimum axial load and holding torque which is suitable for low gravity environments  Operate at extreme temperatures  Avoid drill bit jamming, breaking, dulling etc  Capable of drilling a wide range of rocks

UPCD Assembly

The chaotic motion of the free mass create stress which propagates through the drill stems to the rock surface, rock fractures once stress exceeds the compressive limit Due to piezoelectric effect, piezoceramic rings convert high frequency voltage into ultrasonic vibration at the transducer base, and the level is adjustable depending on the power consumption. The ultrasonic transducer assembly drives a free flying mass which bounces between the horn tip and the base of drill stems at sonic frequencies. UPCD Mechanism A tapered horn is used to amplify the vibration and ensure a considerable level of vibration at the horn tip Three drill stems will be used with each length 10cm. UPCD assembly target mass is 7kg, target power consumption 40W.

Numerical Model UPCD assembly dynamic equations:

Simulation Results

Conclusions  A novel driller/corer device has been developed with the USDC mechanism however employs two compression springs for different purposes  Dynamics of the UPCD process has been modelled and analysed, compression spring rates are optimized which delivers the maximum effective impulse from the drill to the rock  Experiments with dual springs are currently being performed which allows to validate the simulation results  A 1/2 wavelength ultrasonic transducer has been designed to decrease the weight and length of the UPCD assembly

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