Wave velocities in granular materials under microgravity

X. Zeng, J. H. Agui, M. Nakagawa

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Velocities of primary (P) and shear (S) waves in granular materials are highly dependent on confining stress. These wave velocities are related to mechanical properties of the materials such as stiffness, density, and stress history. Measurements of the wave velocities using piezoelectric sensors provide scientists and engineers a technique for nonintrusive characterization of those mechanical properties. For aerospace engineering, measuring the wave velocities under microgravity, which simulates low loading and stress conditions, has a number of potential applications. It can help the understanding of the soil mechanics and the development of appropriate materials handling technologies in extraterrestrial environments, which will be crucial to meeting NASA's future space exploration goals. This paper presents the technique and results of experiments conducted at NASA Glenn Research Center using the 2.2 s drop tower. Velocities of P and S waves in three sizes of glass beads and one size of alumina beads were measured under initially dense or loose compaction states. It was found that under microgravity, the wave signals were significantly weaker and the velocities were much slower. The material that makes up the beads has a strong influence on the wave velocities as well. The initial compaction state also has some influence on the wave velocities.

Original languageEnglish
Pages (from-to)116-123
Number of pages8
JournalJournal of Aerospace Engineering
Issue number2
Publication statusPublished - 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • General Materials Science
  • Aerospace Engineering
  • Mechanical Engineering


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