University of Twente Student Theses


Sound Propagation in Granular Materials of Two Stiffnesses

Holleman, W.H.L. (2016) Sound Propagation in Granular Materials of Two Stiffnesses.

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Abstract:The subject of the research was wave propagation in granular materials by using photo elastic discs. The response of these particles is not trivial and highly non-linear since the wave follows preestablished force chains and the path depends on the frequency. Earlier research has shown that wave speed is strongly dependent on the yield modulus of the particles. In a mix of rubber and sand particles a sharp drop in wave speed can be found when increasing the volume fraction of rubber (Kim and Santamarina 2008). This research focuses on finding the same drop in wave speed in a mix of two different kind of particles, but using yield moduli that are much closer together than sand and rubber. The second goal is to study sound propagation through the strongest force chains that are formed in the particle mix. Two complementary methods are used in order to reach these goals: high speed imaging and piezoelectric transduction. The high speed imaging is used to identify the force chains in the network and the propagation of the wave in these force chains. The particles that are used are photo elastic discs, so that the force chains can be made visible. Piezoelectric sensors (piezo’s) are used to measure the time of flight (ToF) of the wave though the particles.
Item Type:Internship Report (Master)
Faculty:ET: Engineering Technology
Programme:Mechanical Engineering MSc (60439)
Keywords:photo elastic, sound propagation, wave speed, force chain, granular, particles
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