• Journal of Welding and Joining
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• v.5 no.2
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• pp.53-59
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• 1987

The effect of applied stress, current density and heat-treatment after welding on the time to fracture, fracture behavior was investigated by the method of constant load tensile testing under catholic charging with hydrogen in E.B. welded 250,300 Grade 18% Ni Maraging steel sheet. The main results obtained are as follows: 1. All specimen showed the characteristic delayed failure and the time to fracture showed decreasing tendency with the increase in current density and applied stress. 2. Hydrogen embitterment susceptibility of notched specimen after solution-treatment and aging after welding was more increased than that of aged smooth specimen and as welded specimen. 3. Fracture surface showed a typical intergranular fracture on the border, a dimple pattern in the center of specimen and some quasi-cleavage fracture between the intergranular and the dimple.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.373-388
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• 2010

Fracture causes serious problems in many instance of prosthetic failures. But it is hard to find the definite causes when fractures occur. Fractography encompasses the examination of fracture surfaces that contain features resulting from the interaction of the advancing crack with the microstructure of the material and the stress fields. All fractured specimens(implant retaining screw) retrieved from Gangneung-Wonju national university dental hospital for 3 years(from 2007 to 2009). After pretreatment of samples, the scanning electon microscope were used for surface examination and fracture analysis. In case of most of the fractured specimens, fracture took place by fatigue fracture and fractured surface represents fatigue striation. Fatigue striation indicate the progression of the crack front under cyclic loading, are characteristic of stage 2 crack growth. The site of crack initiation and stage 1 crack growth were not easily identified in any of the failure, presumably because of the complex microstructural features of the polycrystalline sample. In case of fractured by overload, dimpled or cleavage surface were observed. Using the interpretation of characteristic markings(ratchet mark, fatigue striation, dimple, cleavage et al) in fracture surfaces, failure events containing the crack origin, crack propagation, material deficiency could be understand. Using the interpretation of characteristic markings in fracture surfaces, cause and mechanism of fractures could be analyzed.

• Journal of the Korean Geotechnical Society
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• v.36 no.3
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• pp.25-36
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• 2020

In this research, three-point bending tests were performed using a rectangular frozen specimen with various fine contents and notch offset distance from the center of the specimen to investigate the fracture characteristic of the frozen sand. Based on the test results, mode I fracture toughness was calculated, and mixed-mode (mode I + II) fracture characteristics were investigated using the fracture energy which was calculated until the maximum point of the load-displacement curve. As the fine contents increase, the peak load and mode I fracture toughness increase until 10% fine contents. Furthermore, as the notch offset distance increases, the fracture energy required for crack start also increases due to the increase in mode II load at the crack tip.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.475-476
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• 2009

• Proceedings of the KOSOMBE Conference
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• v.1990 no.11
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• pp.64-67
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• 1990

Bending strength, bending elastic modulus ,and fracture toughness of different types of dental composite resins were deter mined. The relationship between bending strength, fracture toughness and filler volume fraction of dental composite resin was understood. In Acoustic Emission(AE) behavior during fracture toughness test, characteristic generation patterns of each type were understood. The fracture toughness values, AE generation patterns, and the nature of fracture surface were analyzed to understand fracture behavior of dental composite resin.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.335-340
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• 2002

By the recently, Environmental pollution is serious by the highly economic growth and expansion of lively country basic industry. Especially, in case of industrial waste and life waste leaped into a pollution source. Also, research for processing of waste and recycling countermeasure is a pressing question on national dimension because it is prohibited an ocean disposal and reclamation. In this study, it looked for fracture characteristic value of recycling a coal ash to decrease environmental pollution by picky and exhaustion of natural resources and to reduce self-weight to prepare for a tall building and earthquake. So a coal ash examined to be possible to do as construction material. It achieved compressive strength test and three points bending test with initial notch depth rate and age for variables to show a basic research data. From the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. From the results of the compressive strength test, the elastic modulus was experimentally proposed. Also on the basis of the three points bending test, the fracture parameters - notch sensitivity, fracture energy, initial compliance were experimentally proposed. The results that the strength and fracture energy value are lower than concrete or mortar is described in this paper. Also, it shows that the deflection at fracture decreases as the age increases and the notch sensitivity decrease. However, it is judged to be available to construction material if research is continuously gone forward.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.90-96
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• 2011

In this study, the characteristic of fractured portion and shape on solder joints were investigated according to the thermal shock test for Automotive Application Component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as Lead-free solder. The value of pull and shear strength was decreased in principle after 432 cycles thermal shock test. In addition, fracture mode was verified by using EDS and SEM to observe fractured shape on the solder joints before and after thermal shock. In before thermal shock test, the fracture mode revealed typically solder layer's fracture mode. In after thermal shock test, we identified multiple fracture mode of the ductile and brittle fracture. Even though same composition of solder was used to experimental for estimating. the fracture mode varied on the fracture portion's height and the directional angles of shear strength. In conclusion, we identified that mechanical strength was affected on the solder layer's fracture mode.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.381-389
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• 2001

The objective of this paper is to evaluate the fracture resistance characteristics of SA508 Cl.1a to SA508 Cl.3 welds manufactured for the reactor coolant loop piping system of nuclear power plants. The effect of the crack plane orientation to the welding process orientation and the preheat temperature on the fracture resistance characteristics were discussed. Results of the fracture resistance test showed that the effect of the crack plane orientation to the welding process orientation of the fracture toughness is significant, while that of preheat temperature on the fracture toughness is negligible. The micro Vickers hardness test, the metallographic observation and the fractography analysis were conducted to analyse the crack jump phenomenon on the L-R crack plane orientation in the multi-pass welding zone. As these results, it is shown that the crack jump phenomenon was produced because of the inhomogeneity between welding beads and the crack plane orientation must be considered for the safety of the welding zone in the piping system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.7 s.166
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• pp.1147-1154
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• 1999

The objective of this paper is to evaluate the fracture resistance characteristics of SA508 CL.1a carbon steel, and their associated welds manufactured for primary coolant piping system of nuclear power plants. The effect of various parameters such as pipe size, welding method and chemical composition on the material properties were discussed. Test results showed that the offset of pipe size on tincture toughness was negligible, while the effect of welding method on fracture toughness was significant. In addition, Fracture toughness for carbon steel was influenced by silicon contents due to the different steel refining processes.

• Radiation Oncology Journal
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• v.32 no.4
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• pp.213-220
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• 2014

Insufficiency fracture occurs when normal or physiological stress applied to weakened bone with demineralization and decreased elastic resistance. Recently, many studies reported the development of IF after radiation therapy (RT) in gynecological cancer, prostate cancer, anal cancer and rectal cancer. The RT-induced insufficiency fracture is a common complication during the follow-up using modern imaging studies. The clinical suspicion and knowledge the characteristic imaging patterns of insufficiency fracture is essential to differentiate it from metastatic bone lesions, because it sometimes cause severe pain, and it may be confused with bone metastasis.