• Applied Microscopy
• /
• 제45권3호
• /
• pp.155-169
• /
• 2015

Plastic deformation was introduced to the austenitic (${\gamma}$) stainless steel of SS304 by air blast shot peening, ultrasonic shot peening, and ultrasonic nanocrystalline surface modification. Various deformation structures were formed. The hardness, the deformation structure and the underlying grain refinement mechanism were investigated. In the deformed region, planar dislocation arrays and deformation twin (DT), the DT-DT intersection and ${\varepsilon}$-martensite structures, and ${\alpha}^{\prime}$-martensite were formed in the respective regions of low, medium, and high strain. The grain refinement mechanism is found to be closely related to the 1) sub-division of coarse grains by DT, shear bands and their intersection, and 2) formation of nano-sized ${\alpha}^{\prime}$-martensite due to the high plastic deformation.

• 대한기계학회논문집
• /
• 제5권2호
• /
• pp.88-93
• /
• 1981

The three force components of shear spinning are calculated by a newly proposed deformation model. The spinning process is understooed as shearing deformation arter uniaxial yuelding by ending, and shear stress .tau.$\sub$rz/ becomes .kappa. the yueld limit in pure shear, in the deformation zone. The tangential forces are calculated and then the feed forces and normal foeces are obtained by assuming a nuiform distribution of roller pressure on the contact surface. An optimum contact area is obtaned by minimizing the bending energy required to obtain the assumed deformation mechanism. The calculated forces are compared with experimental data form published literature and present experiments. Good agreement cetween calculated and experimental values for working forces is obtained over a wide range of process variables.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.663-666
• /
• 2008

For a fill dam, when a long time has passed since its completion, it is very hard to judge its safety and to maintain effectively it due to limitation and restriction in data showing safety status. Conventional method based on a specific point data by surface settlement gauge is commonly used to define deformation characteristic of dam. However, point data-based deformation analysis cannot provide deformation data of the entire dam. In this study a state-of-the-art terrestrial laser scanning technology is introduced to analyze the entire deformation of dam. As a result, it is known that 3D scanning technique can also be effectively used in evaluating dam safety and then establishing adequate maintain plan.

• Journal of Advanced Marine Engineering and Technology
• /
• 제29권6호
• /
• pp.671-677
• /
• 2005

In internal combustion engines the usual material for the cylinder liner is because of its good wear resistance Apparently this wear resistance arises from the at iron to form a hard glazed surface when under sliding friction. When the cylinder liner wear limits, it shall be replace with new one according to the classification soci manufacturer's standards. However, adoption of alternative repairing method such a metalizing, thermo plastic deformation process became inevitable taking enormous cost renewal into consideration. In this paper. the material properties of cylinder liner of grey discussed on the basis of the results of experimental work of the thermo plastic deformation the worn out cylinder liner made of grey cast iron.

• 한국정밀공학회지
• /
• 제22권7호
• /
• pp.71-78
• /
• 2005

The purpose of this study is to suggest a hyperfine maskless writing technique by using the nanoindentation and HF wet etching technique. Indents were made on the surface of Pyrex7740 glass by the hyperfine indentation process with a Berkovich diamond indenter, and they were etched in $50\;wr\%$ HF solution. After etching process, convex structure was obtained due to the deformation-induced hillock phenomena. In this study, effects of indentation process parameters (etching time, normal load, loading .ate, hold-time at the maximum load) on the morphologies of the indented surfaces after isotopic etching were investigated from an angle of deformation energies. Finally, sample characters were written to show the possibility of the application.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2002년도 춘계학술대회 논문집
• /
• pp.163-168
• /
• 2002

Hot forging is widely used in the manufacturing of industry machine component. The mechanical, thermal load and thermal softening which are happened by the high temperature in hot forging process. Tool life decreases considerably due to the softening of the surface layer of a tool caused by a high thermal load and long contact time between the tool and billet. Also, tool life is to a large extent limited by wear, heat crack and plastic deformation in hot forging process. These are one of the main factors affecting die accuracy and tool life. That is because hot forging process has many factors influencing tool life, and there was not accurate in-process data. In this research, life prediction of hot forging tool by wear and plastic deformation analysis considering tempering parameter has been carried out for automobile component. The new developed technique in this study for predicting tool life can give more feasible means to improve the tool life in hot forging process.

• Coupled systems mechanics
• /
• 제4권3호
• /
• pp.237-249
• /
• 2015

In the gear meshing process, gear temperature field concerns the meshing surface friction, the friction heat depends on the contact pressure, the contact pressure is affected by the elastic deformation of gears and the temperature field caused by the thermal deformation, so the temperature field, stress field and displacement field should be mutual coupling. It is necessary to consider in meshing gear pair in the operation process of thermodynamic coupling contact stress (TCCS) and thermodynamic coupling deformation (TCD), and based on thermodynamic coupling analysis (TCA) of gear teeth deformation.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 가을 학술발표회 논문집
• /
• pp.467-474
• /
• 2002

Colluvial sell has a very unique deformation property, particularly when it is subject to the cutting work entailed in a variety of construction. In this study, the cut slope tying on a colluvial layer in which the transmission tower had been installed were investigated to find out the cause of deformation. In-situ tests such as boring, surface-wave analysis (MASW) were employed to look into the physical composition of underground layers and FEM including LEM were carried out to simulate the construction steps. The result shows that the stress relaxation followed by road construction induced the deformation of the slope and damage in the foundation of the transmission tower.

• Structural Engineering and Mechanics
• /
• 제24권6호
• /
• pp.727-740
• /
• 2006

A simple plane-strain solution is derived in this paper for the functionally graded multilayered isotropic elastic cylinder under static deformation. The solution is obtained using method of separation of variables and is expressed in terms of the summation of the Fourier series in the circumferential direction. While the solution for order n = 0 corresponds to the axisymmetric deformation, that for n = 2 includes the special deformation frequently utilized in the upper and lower bounds analysis. Numerical results for a three-phase cylinder with a middle functionally graded layer are presented for both axisymmetric (n = 0) and general (n = 2) deformations, under either the traction or displacement boundary conditions on the surface of the layered cylinder. The solution to the general deformation case (n = 2) is further utilized for the first time to find the upper and lower bounds of the effective shear modulus of the layered cylinder with a functionally graded middle layer. These results could be useful in the future study of cylindrical composites where FGMs and/or multilayers are involved.

• 한국재료학회지
• /
• 제24권1호
• /
• pp.1-5
• /
• 2014

This study is experimentally investigated whether or not a relationship exists between the mechanical properties and damping capacity of cold-rolled 316 L stainless steel. Deformation-induced martensite was formed with surface relief and directionality. With the increasing degree of deformation, the volume fraction of ${\varepsilon}$-martensite increased, and then decreased, while ${\alpha}^{\prime}$-martensite increased rapidly. With an increasing degree of deformation, tensile strength was increased, and elongation was decreased; however, damping capacity was increased, and then decreased. Tensile strength and elongation were affected in the ${\alpha}^{\prime}$-martensite; hence, damping capacity was influenced greatly by ${\varepsilon}$-martensite. Thus, there was no proportional relationship between strength, elongation, and damping capacity.