• Transactions of Materials Processing
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• v.26 no.5
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• pp.293-299
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• 2017

In this paper, finite element stamping analysis was carried out for the front lower arm to examine the applicability of solid element with damage theory to predict shear fracture phenomena induced by sheared edge as well as deformation mechanisms. Mechanical properties related to deformation and damage theory were determined from tensile test. Shear fracture was predicted by normalized Cockcroft-Latham model with initial imposition of the damage value along the sheared edge. Simulation results illustrated that the analysis with solid element and damage theory predicted edge profile, strain distribution, and forming load more accurately than the analysis with shell element. Simulation with solid element can also predict the shear fracture more exactly comparing to analysis with shell element and forming limit curve.

• Structural Engineering and Mechanics
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• v.56 no.2
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• pp.157-167
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• 2015

The impact behavior of epoxy-based nanocomposites reinforced with carbon nano tube (CNT), carbon nano fiber (CNF) and mixed contents of these nanoparticles was investigated using Izod impact test. The results showed that while the impact strength of nanocomposites containing 1 wt% of CNT and 1 wt% of CNF increased 19% and 13% respectively, addition of mixed contents of these nanofillers (0.5-0.5 wt%) demonstrated higher improvement (21%) in the impact resistance. The trend of the results is explained on the basis of different fracture mechanisms of nanocomposites. Furthermore, the fracture surface of specimens and the dispersion state of nanoenhancers have been studied using scanning electron microscopy (SEM) photographs.

• Advances in materials Research
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• v.3 no.1
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• pp.283-295
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• 2014

In this paper, the microstructure, hardness, tensile deformation and fracture behavior of high strength alloy steel X2M is presented anddiscussed. The influence of both composition and processing on microstructure of the as-provided material and resultant influence of microstructure, as a function of orientation, on hardness, tensile properties and final fracture behavior is highlighted. The macroscopic mode and intrinsic microscopic features that result from fracture of the steel specimens machined from the two orientations, longitudinal and transverse is discussed. The intrinsic microscopic mechanisms governing quasi-static deformation and final fracture behavior of this high strength steel are outlined in light of the effects oftest specimen orientation, intrinsic microstructural effects and nature of loading.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.322-325
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• 2000

In the previous report1), the grinding characteristics of quartz were investigated. In this paper, the grinding mechanisms of brittle materials including ceramics and quartz are modeled and a new parameter SDR(Surface roughness Direction Ratio) is proposed to characterize the grinding mechanisms of such materials. A set of experiments were performed to verify the effectiveness of the suggested parameter. The experimental results indicate that the plastic deformation is the dominant material removal mode at the grinding conditions which show the higher value of SDR. In the case of quartz, the material was removed by brittle fracture in a lower value of SDR and by plastic deformation in a higher value of it. SDR is not affected by wheel mesh size when brittle fracture occured. But in the plastic deformation case, SDR value increases with wheel mesh size.

• Journal of Trauma and Injury
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• v.37 no.1
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• pp.48-59
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• 2024

Purpose: Research on rib fracture management has exponentially increased. Predicting fracture patterns based on the mechanism of injury (MOI) and other possible correlations may improve resource allocation and injury prevention strategies. The Chest Injury International Database (CIID) is the largest prospective repository of the operative and nonoperative management of patients with severe chest wall trauma. The purpose of this study was to determine whether the MOI is associated with the resulting rib fracture patterns. We hypothesized that specific MOIs would be associated with distinct rib fracture patterns. Methods: The CIID was queried to analyze fracture patterns based on the MOI. Patients were stratified by MOI: falls, motor vehicle collisions (MVCs), motorcycle collisions (MCCs), automobile-pedestrian collisions, and bicycle collisions. Fracture locations, associated injuries, and patient-specific variables were recorded. Heat maps were created to display the fracture incidence by rib location. Results: The study cohort consisted of 1,121 patients with a median RibScore of 2 (range, 0-3) and 9,353 fractures. The average age was 57±20 years, and 64% of patients were male. By MOI, the number of patients and fractures were as follows: falls (474 patients, 3,360 fractures), MVCs (353 patients, 3,268 fractures), MCCs (165 patients, 1,505 fractures), automobile-pedestrian collisions (70 patients, 713 fractures), and bicycle collisions (59 patients, 507 fractures). The most commonly injured rib was the sixth rib, and the most common fracture location was lateral. Statistically significant differences in the location and patterns of fractures were identified comparing each MOI, except for MCCs versus bicycle collisions. Conclusions: Different mechanisms of injury result in distinct rib fracture patterns. These different patterns should be considered in the workup and management of patients with thoracic injuries. Given these significant differences, future studies should account for both fracture location and the MOI to better define what populations benefit from surgical versus nonoperative management.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.875-879
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• 2000

In the previous report1), the grinding characteristics of quartz were investigated. In this paper, the grinding mechanisms of brittle materials including ceramics and quartz are modeled and a new parameter SDR(Surface roughness Direction Ratio) is proposed to characterize the grinding mechanisms of such materials. A set of experiments were performed to verify the effectiveness of the suggested parameter. The experimental results indicate that the plastic deformation is the dominant material removal mode at the grinding conditions which show the higher value of SDR. In the case of quartz, the material was removed by brittle fracture in a lower value of SDR and by plastic deformation in a higher value of it. SDR is not affected by wheel mesh size when brittle fracture occured. But in the plastic deformation case, SDR value increases with wheel mesh size.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.561-566
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• 2015

In this study, the effect of temperature effect of the rubber matrix filled with nano sized silica particles composites with silica volume fraction of 19-25% was investigated by the Charpy impact test. The Charpy impact test was conducted in the temperature range from $-40^{\circ}C$ to $0^{\circ}C$. The critical energy release rate GIC of the rubber matrix composites filled with nano sized silica particles was considerably affected by temperature and it was shown that the maximum value was appeared at higher temperature between temperature tested and it was shown that the value of GIC increases as temperature tested increases. The major fracture mechanisms were matrix deformation, silica particle debonding and delamination, microcrack between particles and matrix, and/or pull out between particles and matrix which is ascertained by SEM photographs of Charpy impact surfaces fracture.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.359-367
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• 2000

Particulate composites of Al2O3/SiC, Al2O3/ZrO2 and Al2O3/ZrO2/SiC have been fabricated to investigate their R-curve behaviors and toughening mechanisms. Al2O3 containing 30 vol% SiC particles of 3${\mu}{\textrm}{m}$ showed rising R-curve behavior owing to the strong crack bridging by SiC particles. The fracture toughness reached 9.1 MPa {{{{ SQRT {m} }} at the crack length of 1000${\mu}{\textrm}{m}$. On the other hand, ZrO2-toughened Al2O3 had a high flat R-curve since it rose steeply in the short crack region due to the well known transformation toughening. For Al2O3/ZrO2/SiC composites, the R-curve behavior was similar to that of Al2O3/SiC but with slightly higher toughness. The SiC particles in this composite decreased the amount of transformable tetragonal phase to reduce the effect of transformation toughening by 50%. It was also found that the fracture toughness of this composite with two different toughening mechanisms was markedly lower than that estimated by the simple addition of two contributions.

• Journal of Korean Foot and Ankle Society
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• v.21 no.2
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• pp.70-74
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• 2017

Fractures and fracture-dislocations of the ankle are caused by a variety of mechanisms. In addition to fractures, injuries of soft tissue, such as ligaments, tendons, nerves, and muscles may also occur. Among these, a tibialis posterior tendon injury is difficult to be identified due to swelling and pain at the fracture site. It is difficult to observe tibialis posterior tendon injury on a simple radiograph; it is usually found during surgery by accident. There are some studies regarding irreducible ankle fracture-dislocations due to interposition of the tibialis posterior tendon; however, to the best of our knowledge, there has not been any report about interposition of injured tibialis posterior tendon. Herein, we report a case of an irreducible fracture-dislocation of the ankle due to injured tibialis posterior tendon interposition that was observed intraoperatively, interrupting the reduction of ankle fracture-dislocation. We obtained satisfactory clinical result after reduction of the trapped tendon, fracture reduction, and internal fixation; therefore, we are willing to report this case with the consent of the patient. This study was conducted with an approval from the local Institutional Ethics Review Board.

• International journal of steel structures
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• v.18 no.5
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• pp.1784-1800
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• 2018

Tension-shear loading is a common loading condition in steel structures during the earthquake shaking. To study ductile fracture in structural steel under multiple stress states, experimental investigations on the different fracture mechanisms in Chinese Q235 steel were conducted. Different tension-shear loading conditions achieved by using six groups of inclined notch butterfly configurations covering pure shear, tension-shear and pure tension cases. Numerical simulations were carried out for all the specimens to determine the stress and strain fields within the critical sections. Two tension-shear fracture models were calibrated based on the hybrid experimental-numerical procedure. The equivalent fracture strain obtained from the round bar under tensile loading was used for evaluating these two models. The results indicated that the tension-shear criterion as a function of the shear fracture parameter had better performance in predicting the fracture initiation of structural steel under different loading conditions.