Mr. Sanghaun Kim Profile

Sanghaun Kim

at Seoul National Univ

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Publications (3)

Proceedings Article | 6 April 2006 Paper

Experimental test for numerical simulation of SMA characteristics and its simulation

Sanghaun Kim, Hyunho Choi, Manwon Yoon, Maenghyo Cho

Proceedings Volume 6170, 61700Z (2006) https://doi.org/10.1117/12.658915

KEYWORDS: Shape memory alloys, Actuators, Temperature metrology, Thermal effects, Protactinium, Numerical simulations, Manufacturing, Computer simulations, Power supplies, Smart structures

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Shape memory alloy (SMA) can exhibit interesting features such as the diverse material behaviors according to the induced temperature and stress. SMA changes its material properties progressively under cyclic loading conditions and finally reaches stable path(state) after a certain number of stress/temperature loading-unloading cycles, so called 'training' completion. The presence of permanent deformation, due to plastic strains or irreversible martensite variants during the material training, shifts the material characteristic curves of SMA wire. In this study, SMA wires that have been in a stable state through the training are used. Stress-strain curve of SMA wire at different temperature levels are measured. In addition, we observe other important effects such as the effect of mechanical/thermal training, rate effect according to thermal cycle times or strain rates, etc. Until now, the rate effect is not considered significantly in the SMA research and only extremely slow time rate is considered in most SMA experiments. It is common to use rate independent constitutive relations in the modeling and simulation of SMA behaviors. Therefore to make the actuators using an SMA wire which has the fast response or short-time thermal cycle environment, rate dependency should be properly considered. The result of two-way experiment at each (short or long) cycle time in phenomenological aspect shows that stress-strain-temperature relations and hysteresis characteristics depend upon the cycle time. In short-time cycle, strain-temperature curve moves in counterclockwise and the size of hysteresis envelop is large. As the time rate of the thermal cycle increases, the size of the hysteresis envelop is getting smaller and strain-temperature curve moves along the clockwise direction above a certain thermal cycle time. Above that thermal cycle time, hysteresis trajectory is fixed in the stable state. These new effects of SMA are investigated and the effect would be explained qualitatively. The present work presents the experimental test using 1-D SMA wire after training completion by mechanical/thermal cycling. Through these tests, we measure the characteristics of SMA. With the estimated SMA properties and effects, we compare the experimental results with the simulation results based on the SMA constitutive equation including the training and thermal rate effect.

Proceedings Article | 28 February 2005 Paper

Numerical simulation of double SMA wire actuator using two-way shape memory effect of SMA

Maenghyo Cho, Sanghaun Kim, Gun-In Kim

Proceedings Volume 5649, (2005) https://doi.org/10.1117/12.582270

KEYWORDS: Shape memory alloys, Actuators, Numerical simulations, Temperature metrology, Thermodynamics, Computer simulations, Numerical analysis, Smart structures, 3D modeling, Algorithm development

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Proceedings Article | 21 July 2004 Paper

Morphing of composite plate and beam actuated by SMA

Maenghyo Cho, Sanghaun Kim

Proceedings Volume 5387, (2004) https://doi.org/10.1117/12.539470

KEYWORDS: Shape memory alloys, Composites, Actuators, Computer simulations, Numerical simulations, Thermodynamics, Temperature metrology, Algorithm development, Numerical analysis, Smart structures

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