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Comparison of the pendulum motion of a buoy subjected to wave load with experiments
전철웅,신정훈,손정현 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
This paper describes a method for the coupled analysis between incompressible smoothed particle hydrodynamics (ISPH) and multibody dynamics (MBD). ISPH is a numerical technique used to calculate the motion of a fluid that is expressed as a system of particles. The analysis program for SPH-MBD coupled analysis is developed. The fluid force acting on a body should be calculated to solve the coupled problem. The method for fluid–body interaction at an acceleration level is proposed. The fluid force is considered as the external force and moment for a body. The motion of a body due to the fluid force and other forces is calculated by an implicit HHT- a integration technique in MBD. A pendulum model is used to verify the accuracy of the analysis program. An experimental setup is designed using a dimensional water tank. Four wave conditions are used. The wave height and the pendulum motion of a buoy are compared with experimental results. Simulation results reveal that period and wave height are consistent with experimental findings, and the pendulum motion of a buoy shows a maximum error of 12.2 %.
Chute design of mackerel automatic grader using multibody dynamics
전철웅,김지욱,손정현 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1
An automatic mackerel grader is a machine that automatically sorts mackerel according to size. The chute spreads the mackerel to allow the latter to enter each roller evenly. Sorting is simulated to confirm that the multibody dynamics model of the automatic grader correctly sorts the mackerel. This process is completed according to the shape of the chute to confirm the effect on performance. A new shape of the chute and the application are proposed and evaluated by a comparison with conventional chute shapes. RecurDyn, a multibody dynamics program, is used for the sorting simulation. The contact parameters are defined by Hertzian contact theory using the material information of mackerel and C/S steel. A rigid-body mackerel model is used to express the behavior of mackerel. Sorting is simulated for each shape. The sorting accuracy and error of the new shape are compared with those of two existing shapes. The new shape shows a 0.29 mm sorting error and better sorting accuracy than the existing shapes.
Effect Analysis of Design Parameter of Trawl Door by Considering Interaction with Seabed
전철웅,손정현,박성호 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.11
In this study, a seabed comprising numerous particles was simulated using discrete element method. To express the viscosity of the seabed, the material and cohesion properties of medium clay were used. The trawl door was defined by a series of polygons. Researchers used the CATIA software suite to obtain polygon data for the trawl door. First, the shape model of the trawl door was established. Next, mesh data were exported to a text file used to define the polygon elements in the program. To reduce analysis time, parallel computing (general-purpose computing on graphics processing units) was used. Following the L9-Taguchi experimental design method, the design parameters of the trawl door were determined using three levels of four factors including the front fillet angle, length and depth of the trawl door, and angle of attack. The average trawl door contact forces were compared to determine optimal trawl door design.
전철웅,손정현 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12
The graphic processor unit (GPU) is an ideal solution to problems involving parallel data computations. A serial CPU-based program of dynamic analysis for multi-body systems is rebuilt as a parallel program that uses the GPU’s advantages. We developed an analysis code named GMAP to investigate how the dynamic analysis algorithm of multi-body systems is implemented in the GPU parallel programming. The numerical accuracy of GMAP is compared with the commercial program MSC/ADAMS. The numerical efficiency of GMAP is compared with the sequential CPU-based program. Multiple pendulums with bodies and joints and the net-shape system with bodies and spring-dampers are employed for computer simulations. The simulation results indicate that the accuracy of GMAP’s solution is the same as that of ADAMS. In the net type system that has 2370 spring-dampers, GMAP indicates an improved efficiency of about 566.7 seconds (24.7% improvement). It is noted that the larger the size of the system, the better the time efficiency.