• Korean Journal of Metals and Materials
• /
• v.49 no.12
• /
• pp.967-976
• /
• 2011

Conventional fracture tests of resistance spot welds have been performed without consideration of the paint baking process in the automobile manufacturing line. The aim of this paper is to investigate the effect of the paint baking process on load carrying capacity and fracture mode for resistance spot welded 590 dual phase (DP), 780DP, 980DP, 590 transformation in duced plasticity (TRIP), 780TRIP and 1180 complex phase (CP) steels. With paint baking after resistance spot welding, the l-shape tensile test (LTT) and nano-indentation test were conducted on the as-welded and paint baked samples. Paint baking increased the load-carrying capacity of the resistance spot welded samples and improved the fracture appearance from partial interfacial fracture (PIF) to button fracture (BF). Improvement in fracture appearance after LTT is observed on weldments of 780 MPa grade TRIP steels, especially in the low welding current range with paint baking conditions. The higher carbon contents (or carbon equivalent) are attributed to the low weldability of the resistance spot welding of high strength steels. Improvement of the fracture mode and load carrying ability has been achieved with ferrite hardening and carbide formation during the paint baking process. The average nano-indentation hardness profile for each weld zone shows hardening of the base metal and softening of the heat affected zone (HAZ) and the weld metal, which proves that microstructural changes occur during low temperature heat treatment.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.2 s.95
• /
• pp.225-233
• /
• 1999

This paper describes a versatile finite element technique which has been used to investigate of wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems analyzed to date include the surface cracks in leak-before-break situations, the development of quarter-elliptical corner defects, planar semi-elliptical surface defects and the fatigue growth of defects.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.6
• /
• pp.133-141
• /
• 2002

This paper describes a versatile finite element technique which has been used to investigate wide range of structural defects of practical importance. The procedure automatically remeshes the three-dimensional finite element model during the stages of crack growth. Problems include the surface cracks in leak-before-break situations, the shape development of multiple surface defects.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.7
• /
• pp.91-97
• /
• 1998

The analysis model is the infinite body consisted of power law creep material containing a rigid inclusion with line crack shape subjected to the arbitrarily directional stress on an infinite boundary. The crack analysis is performed using the complex pseudo-stress function. The strain rate intensity factor is determined in the closed form as new fracture mechanics parmeter which represents the magnitudes of stress and strain rate near the tip in power law creep material.

• Journal of Korean Foot and Ankle Society
• /
• v.21 no.3
• /
• pp.108-112
• /
• 2017

The midtarsal joint is composed of the talonavicular and calcaneocuboid joints. It is also known as the Chopart joint. Midtarsal joint fracture and dislocation are relatively rare and frequently missed or misdiagnosed. A proper understanding about the anatomy of the midtarsal joint is an essential part in comprehending the mechanism of injury and rationale for treatment. Anatomical reduction of midtarsal joint with correction of the column in length and shape are important; however, it is technically challenging and may require open procedure. Herein, we described a case of initial open reduction and internal fixation for midtarsal joint fracture and dislocation with a brief literature review.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.556-561
• /
• 2006

In this study, the failure of the automotive clutch disk was investigated. During the process of power transmission, clutch disk plates did repeated work of releasing and engaging the pressure plate. The effects of unbalance rotation in the abnormal vibration and torque amplitude under engaged state were measured from this experiment. In order to reduce the unbalance, a modified clutch disk shape was developed. With a three-dimensional model of the stopper pin, to predict fatigue fracture, finite element analysis was carried out and evaluated the improvement of the new clutch disk.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.31 no.5
• /
• pp.73-85
• /
• 1999

Yield and fracture are separated in the tensile failure of paper. Failure in the machine direction of photocopy paper is contrasted with failure in the cross-machine direction . The ratios of distortion (shape change) to dilatation (volume change) for individual elements at yield and fracture are described. The ratios of distortion to dilatation are measured and compared to predicted values of the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density factor, samples are prepared from machine direction to cross-machine direction in 15 degree intervals. the strain energy density of individual elements are obtained by the integration of stress from finite element analysis with elastic plus plastic strain energy density theory. Poison's ratio and the angle from the principal material direction have a great effect ion the ratio fo distortion to dilatation in paper. During the yield condition, distortion prevails over dilatation . At fracture, dilatation is at a maximum.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.17 no.1
• /
• pp.55-59
• /
• 1995

Today, with the development of modern civilization, the change of industrial structure and the increase of traffic volume and population make the number of maxillofacial injury patients also increase. Especially, the fracture possibilities of mandibular condyle have been increased because of mandibular position and shape. I experienced the case that mandibular condyle fracture caused by gun-shot injury(Bullet had been packed at the opposite condyle of input site) was treated by foreign body removal and condyle open reduction. I will represent that case with the journal review.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.04a
• /
• pp.42-49
• /
• 1999

Because the linear elastic tincture analysis has been proved to be insufficient in predicting the failure of cracked bodies, in recent years, a number of fracture concepts have been studied which remain applicable in the presence of large-scale plasticity near a crack tip. This work thereby presents a new finite element model, as accurate as possible, to analyze plane problems of ductile fracture under large-scale yielding conditions. Based on the incremental theory of plasticity, the p-version finite element analysis is employed to account for the values of J-integral, the most dominant fracture parameter, and the shape of plastic zone near a crack tip by using the J-integral method and equivalent domain integral method. The numerical results by the proposed model are compared with the theoretical solutions in literatures and the numerical solutions by the i,-version of F.E.M.

• International Journal of Concrete Structures and Materials
• /
• v.2 no.2
• /
• pp.153-160
• /
• 2008

Fracture of prestressed concrete beams is studied with a novel and robust three-dimensional meshfree method. The meshfree method describes the crack as a set of cohesive crack segments and avoids the representation of the crack surface. It is ideally suited for a large number of cracks. The crack is modeled by splitting particles into two particles on opposite sides of the crack segment and the shape functions of neighboring particles are modified in a way the discontinuous displacement field is captured appropriately. A simple, robust and efficient way to determine, on which side adjacent particles of the corresponding crack segment lies, is proposed. We will show that the method does not show any "mesh" orientation bias and captures complicated failure patterns of experimental data well.