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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

An axisymmetric finite element solution for elastic wave propagation through threaded connections

Land, J. George 07 November 2008 (has links)
An axisymmetric finite element solution method is developed for axial wave propagation through a series of threaded connections in rock drills. A piston impacts axially on a string of rods held together by threaded joints and the wave propagates through these joints before reaching the bit. The energy lost in the joints limits the maximum effective depth of the drill. Several computational techniques are used to efficiently model the problem. Non-reflecting boundaries are used to numerically absorb the waves as they exit a joint. The stored waves are then re-initiated into the next joint eliminating modeling of the entire assembly of rods. The preload in the threads is modeled by shrinking the threaded sleeve onto the rods. A new dynamic relaxation damping scheme is used which starts with an undamped model and then increases the damping until the solution converges. This method converges more rapidly than the standard constant damping. / Master of Science

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