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RISS 인기검색어
- 검색키워드
- 저자 : Harish P. Cherukuri (검색결과 2 건)
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Harish P. Cherukuri,Patrick Ulysse,Ronald E. Smelser,Kannan Subramanian,Deepti Kotaru 한국소성가공학회 2010 기타자료 Vol.2010 No.6
Rapid quenching of aluminum extrusions often results in residual stresses and distortion. The out-of-plane normal component of the residual stress is typically very large and results in undesirable bending (bowing) of the extruded shape. Three-dimensional models to predict the residual stresses and bending of extruded thin-walled shapes are difficult to implement since the wall-thicknesses are often very small compared with the axial dimensions. In this paper, a generalized planestrain model is presented to predict the residual stresses and distortion. For illusrative purposes of the model, a Z-shaped extrusion is chosen. The model predicts the bowing of the extruded shape along with the in-plane and out-of-plane stress components. An internal state-variable model is used for the constitutive description. The residual stresses and distortion are studied for cold and warm water quenching and three different cases of spray quenching. The numerical results indicate that cold water quenching and the two spray quenching cases with the higher discharge rates lead to significantly larger residual stresses compared to the remaining two cases. For each case, the out-of-plane bows of the extruded shapes are also shown to be significant.
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Laser generated elastic waves in a semi-infinite domain
Bongsoo Jang,Harish P. Cherukuri 한국산업응용수학회 2007 한국산업응용수학회 학술대회 논문집 Vol.3 No.2
Thermo-elastic waves generated by a pulsed laser in solid is of great interest due to the extensive applications of pulsed laser technologies in material processing and non-destructive detecting(NDT) and characterization. Since wavelength of ultrasonic waves is smaller than the usual size of defect, the method using ultrasonic waves generated by a laser can detect the presence of small defects. Lasers are capable of producing ultrasonic waves very accurately and have an advantage of producing high intensity power and directionality. Thus, the method of a pulsed laser is being commonly used to generate ultrasonic waves for NDT. In this study, one dimensional analytical and numerical investigation of laser generate elastic waves in a semi-infinite solid strap is presented. Assuming uncoupled thermo-elasticity theory, analytic solutions for the thermal and the mechanical equations are obtained by the Laplace transform techniques. Laser interaction with a solid specimen is studied when the optical absorption coefficient varies. A weaker displacement is observed for a large absorption coefficient. Numerical approximated solutions are compared with the analytical solutions.
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