Resumen
There are many methods for crushing seabed rock such as a using a free-falling crusher, blasting, and chemical liquid expansion. Blasting and chemical liquid expansion can lead to environmental destruction, noise pollution, and civil complaints. Therefore, a free-falling crusher is generally recommended for use. Understanding the characteristics of a crusher in water and the impact force on the ground is helpful for designing a crusher and dredge work. In this study, drop tests of 50 and 70 ton crusher models that were scaled down by 15 times were investigated. The tests were conducted in a water basin by the Research Institute of Medium and Small Shipbuilding (RIMS) in Korea. Four water depths were considered with different falling locations: water surface and air. Moreover, a numerical study on Fluid-Structure Interaction (FSI) analysis for a free-falling crusher was conducted by applying the Arbitrary Lagrangian-Eulerian (ALE) element and the Grüneisen Equation of State (EoS) to fluid models. The crusher and ground were modeled as Lagrangian elements to estimate the impact force on the ground. Before comparing the crusher model, a free-falling sphere model was used to develop FSI technologies by comparing past Computational Fluid Dynamics (CFD) and experimental results. Moreover, the recommended mesh size and fluid domain for FSI analysis are provided to achieve good results via convergence tests. Comparison between experimental and numerical methods demonstrated a similar tendency such that impact force increased at a higher depth. Certain numerical results agree with average values of experimental results; however, multiple numerical cases exhibit a moderate difference. This is because of angular rotation between the crusher and ground when the crusher hits the ground during experiments.