• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.2
• /
• pp.65-71
• /
• 2002

Turbine blade is subject to cyclic bending force by steam pressure. Stress analysis by fractography is already established technology as means far seeking cause of fracture and has been widely employed. In the X-ray frctography, plastic deformation and residual stress near the fracture surface can be determined and information of internal structure of material can be obtained. Therefore, to find a fracture mechanism of torsion-mounted blade in nuclear power plant, based on the information from the fracture surface obtained by fatigue test, the correlation of X-ray parameter and fracture mechanics parameter was determined and then the stress intensity factor to actual broken turbine blade was predicted.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.778-783
• /
• 2001

Turbine blade is subject to cyclic bending force by steam pressure. Stress analysis by fractography is already established technology as means for seeking cause of fracture and has been widely employed. In the X-ray fractography, plastic deformation and residual stress near the fracture surface can by determined and information of internal structure of material can be obtained. Therefore, to find a fracture mechanism of torsion-mounted blade in nuclear power plant, based on the information from the fracture surface obtained by fatigue test, the correlation of X-ray parameter and fracture mechanics parameter was determined and then the load applied to actual broken turbine blade was predicted.

• Journal of Korean Foot and Ankle Society
• /
• v.4 no.1
• /
• pp.35-38
• /
• 2000

Osteochondral fracture is common in adolescent and usually occurs in the knee and ankle. Many authors have written concerning osteochondral fracture of the ankle joint, however, many of these pertain only to the talus. The author has found an osteochondral fracture of the articular surface of the medial malleolus within the ankle joint not previously described. We report a case of this lesion that was treated by arthroscopic osteochondral fragment removal.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.12
• /
• pp.114-119
• /
• 1996

In the case of surface cracked plate specimen, we can not measure the fracture toughness of ductile materials by the ASTM E 813 standard method. In this report, using the Acoustic Emission method, we found out crack initiation point and investigated fracture toughness which was calculated by FEM. The method used in this paper shows that fracture toughnes by using AE technique is reliable.

• Journal of the Korean Society of Safety
• /
• v.17 no.1
• /
• pp.18-24
• /
• 2002

This study verified the relationship between fracture mechanics parameters(${\Delta}K,\;K_{max}$) and X-ray parameters ($(\sigma}_r,;B$) for G365 steel at elevated temperature up to $300{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase in low ${\Delta}K$ region, reach to a maximum value at a certain value of $K_{max}$ or ${\Delta}K$ and then decrease. Residual stress was independent on stress ratio by arrangement of ${\Delta}K$ and half value breadth was independent by the arrangement of $K_{max}$. The equation of ${\sigma}_r-{\Delta}K$ was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• Journal of the Korean Ceramic Society
• /
• v.47 no.5
• /
• pp.365-372
• /
• 2010

This paper was to evaluate the influence of kiln process parameter(kiln angle, kiln rotating speed) of lightweight aggregate using waste glass and bottom ash with industrial by-products on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis. In the results of surface plot and contour plot, it has verified that kiln residence time of lightweight aggregate increase as kiln angle and rotating speed decreases. For this reason, pore size and quantity tend to increase by active reaction of forming agent. It seems to be that increase in pore size and quantity have caused decreasing density, fracture load and thermal conductivity, and increasing water absorption. In conclusion, optimization of kiln process parameter on thermal conductivity, density, water absorption, fracture load and porosity by response surface analysis are kiln angle 2.4646%, kiln rotating speed 40.7089 rpm.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.4
• /
• pp.117-123
• /
• 2002

X-ray diffraction observation of fracture surfaces yields useful information to analyze the causes of failure accidents of engineering structures. This experimental technique, named X-ray fractography, has been developed especially in metal and mechanical engineering fields. The distributions of the residual stress and the half value breadth of diffraction profiles beneath the fatigue fracture surface were measured with SNCM 439, HT100 and Ti-6Al-4V alloy. The size of the maximum plastic zone was successfully determined on the basis of the measured distributions. This size was correlated to maximum stress intensity factor. The distributions of the half value breadth of diffraction profiles on the fatigue fracture surfaces were measured with SNCM 439. HT100. The equations of x-ray parameter distribution were possible to estimated fracture parameters of fatigue fracture surfaces.

• Journal of the Korean institute of surface engineering
• /
• v.48 no.6
• /
• pp.283-291
• /
• 2015

The purpose of this study was to investigate effects of TiN coating on the fatigue fracture of dental implant system with various cyclic loads. TiN coated abutment screw, the fixture, and abutment of internal hex type were prepared for fatigue test. The fatigue test was carried out according to ISO 14801:2003(E) using tensile and compression tester with repeated load from 30% to 80% of static fracture force. Morphology and fractured surface was observed by field emission scanning electron microscope(FE-SEM) and energy dispersive X-ray spectroscope(EDS). The fracture cycle drastically decreased as repeated load increased. Especially, in the case of TiN-coated abutment screw, fracture cycle increased compared to non-coated abutment screw. The fatigue crack was propagated fast as repeated load increased. The plastic deformation region decreased, whereas, cleavage fracture region increased as repeated load increased.

• Laser Solutions
• /
• v.3 no.3
• /
• pp.31-37
• /
• 2000

In this paper, the possibilities of the laser overlap spot welding were studied to utilize the advantageous properties of amorphous metal foils. In order to estimate the usage of amorphous metals foils as structural members, the tensile shear strength and the fracture features were investigated. Although the crystalline zone on the surface was formed, it was not the direct cause of the fracture of the weld. The fracture of the weld resulted from the geometry discontinuity between the workpiece and the protrusion zone, which was formed during the weld process. The vein pattern - the typical feature of the fracture of the amorphous metal - was formed on the fracture surface. The tensile shear stress was reached to 1200 N/㎟ (2-foils overlap welding) and 900 N/㎟ (10-foils overlap welding), whereas the tensile strength of the workpiece was 1500-2000 N/㎟.

• Journal of the Korean Society for Precision Engineering
• /
• v.24 no.10
• /
• pp.31-36
• /
• 2007