Ricochet of steel spheres on sand with varying water content

Yoon Keon Kim, Woo Chun Choi

Research output: Contribution to journalArticlepeer-review


The explosion of a building generates plenty of debris that flies far away. The flying debris is hazardous because it contains large amounts of kinetic energy. Therefore, determining the safety distance from the debris is essential. However, debris ricochet that collides onto the ground affects the safety distance because the ricochet phenomenon is influenced by the condition of the medium. In this study, experiments and finite element analysis were performed to investigate the ricochet based on the water content of sand. From a direct shear test, the internal friction angle and cohesion of sand were obtained based on the water content. The effects of internal friction angle and adhesion on the yield stress and ricochet were investigated. The results indicated that as the water content increased, the internal friction angle increased and then decreased, and the cohesion continued to decrease. The yield stress was proportional to the internal friction angle and inversely proportional to adhesion. Therefore, lower yield stress resulted in deeper penetration of debris, leading to higher energy loss, which increased the kinetic energy loss factor. Thus, the condition of the medium should be considered for setting a proper safety distance suitable for the surrounding environment of the building.

Original languageEnglish
JournalAdvances in Mechanical Engineering
Issue number12
Publication statusPublished - 2020

Bibliographical note

Funding Information:
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was financially supported by the Foundation Research Program (grant no. UD170027GD) through the Agency for Defense Development grant funded by the Defense Acquisition Program Administration.

Publisher Copyright:
© The Author(s) 2020.


  • Ricochet
  • cohesion
  • debris
  • internal friction angle
  • safety distance
  • sand
  • water content
  • yield stress

ASJC Scopus subject areas

  • Mechanical Engineering


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