• Journal of Ocean Engineering and Technology
• /
• v.6 no.1
• /
• pp.113-121
• /
• 1992

In this study, the variation of fatigue strength in CF/PEEK and CF/EPOXY, the matrix and interfacial strength of which differ from each other, has been studied from the viewpoint of microfracture behavior. The results obtained are as follows; According as the fatigue strength moves from the lower cycle range to the higher cycle range, that of CF/PEEK shows higher curve than that of CF/EPOXY does. In the early stage of fatigue life, the characteristic of fatigue crack in CF/PEEK is mainly the fracture of longitudinal fiber, while that in CF/EPOXY is the fracture of transverse fiber. The difference of fatigue strength in these materials can be explained by the fracture criteria of transverse fiber and longitudinal fiber.

• Journal of Korean Neurosurgical Society
• /
• v.59 no.5
• /
• pp.529-532
• /
• 2016

Complex regional pain syndrome (CRPS) type II is a syndrome that develops after nerve injury. Symptoms may be severe, and vary depending on the degree of sympathetic nerve involvement. As yet, there is no satisfactory treatment. We report the case of a female patient who had an L5 left transverse process fracture and an S2 body fracture, who developed symptoms of CRPS type II in her left lower leg that were aggravated during ambulation in spite of absolute bed rest for one month after the trauma. Several treatments, including bed rest, medication, and numerous nerve blocks were attempted, but the pain persisted. We finally tried injection of polydeoxyribonucleotide (PDRN) solution at the left L5 transverse process fracture site because we knew of the anti-inflammatory effect of PDRN. One day after this treatment, her symptoms had almost disappeared and three days later, she was discharged. We will also further discuss the possibility of using PDRN solution for the treatment of CRPS.

• Archives of Plastic Surgery
• /
• v.43 no.2
• /
• pp.189-196
• /
• 2016

Background Several techniques have been designed to treat fifth metacarpal fractures reported to be effective. However, these methods cannot be easily applied to the fourth metacarpal due to its central anatomical position. In this study, we sought to analyze the functional outcomes of patients who underwent transverse pinning for a fourth metacarpal bone fracture. Methods A total of 21 patients were selected and their charts were retrospectively reviewed. After fracture reduction, two transverse Kirchner wires were first inserted from the fifth metacarpal to the third metacarpal transversely at the distal part of the fractured bone, and then another two wires were inserted at the proximal part of the fractured bone. The splint was removed approximately one week postoperatively and the Kirchner wires were removed four to five weeks postoperatively. Patients started active and passive exercise one week after the operation. Pain visual analog scores, total active and passive motion, and the active and passive range of motion of the metacarpophalangeal joint and grip strength were evaluated. Results Dorsal angulation improved from a preoperative value of $44.2^{\circ}$ to a postoperative value of $5.9^{\circ}$. Six weeks after surgery, functional recovery parameters, such as range of motion and grip strength, had improved to 98% of the function of the normal side. No major complication was observed. Conclusions We suggest that the transverse pinning of fourth metacarpal bone fractures is an effective treatment option that is less invasive than other procedures, easy to perform, requires no secondary surgery, minimizes joint and soft tissue injury, and allows early mobilization.

• The Journal of Korean Academy of Prosthodontics
• /
• v.32 no.3
• /
• pp.411-430
• /
• 1994

The denture may be fractured accidentally by an impact while outside the mouth, or may be cracked or broken while in service in the mouth. The latter is generally a fatigue failure caused by repeated flexure over a period of time. This investigation compared the flexural fatigue resistance, the impact force and the transverse strength of two denture base materials with and without the grid strengthener, the T300, the T800 and the Kevlar fiber to evaluate the fracture resistance. The distribution and behavior of fibers across fracture lines were examined by Hi-Scope Compact Microvision System. Through analyses of the data from this study, the following conclusions were obtained. 1. The flexural fatigue resistance, impact strength and transverse strength of high impact strength resin were higher than those of conventional heat polymerizing resin, but statistically there was no significant difference(p>0.05). 2. All specimens with and without the grid strengthener did not show significant differences in the flexural fatigue, the impact and the transverse strength test(p>0.05). 3. All specimens reinforced with the T300, the T800 and the Kevlar fiber showed significant increase of the fatigue resistance and the impact force(p<0.05). 4. All specimens reinforced with the T800 and the Kevlar fiber showed significant increase of the transverse strength(p<0.05). 5. All specimens reinforced with the T300, the T800 and the Kevlar fiber exhibited greenstick fractures. The fibers tended to remain enveloped in the resin, resisting pull-out.

• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.6
• /
• pp.589-598
• /
• 2001

The fracture of acrylic resin dentures remains an unsolved problem. Therefore, many investigations have been performed and various approaches to strengthening acrylic resin, for example, the reinforcement of heat-cured PMMA resin using glass fibers, have been suggested over the years. The aim of the present study was to investigate the effect of short glass fibers treated with silane coupling agent on the transverse strength of heat-polymerized PMMA denture base resin. To avoid fiber bunching and achieve even fiber distribution, glass fiber bundles were mixed with PMMA powder in conventional mixer whose blade was modified to be blunt. Composite of glass fiber($11{\mu}m$ diameter, 3mm & 6mm length, silane treated) and PMMA resin was made. Transverse strength and Young's modulus were estimated. Glass fibers were incorporated with 1%, 3%, 6% and 9% by weight. Plasticity and workability of dough was evaluated. Fracture surface of specimens was investigated by SEM. The results of this study were as follows 1. 6% and 9% incorporation of 3mm glass fibers in the PMMA resin enhanced the transverse strength of the test specimens(p<0.05). 2. 6% incorporation of 6mm glass fibers in the PMMA resin increased transverse strength, but 9% incorporation of it decreased transverse strength(p<0.05). 3. When more than 3% of 3mm glass fibers and more than 6% of 6mm glass fibers were incorporated, Young's modulus increased significantly(p<0.05). 4. Workability decreased gradually as the percentage of the fibers increased. 5. Workability decreased gradually as the length of the fibers increased. 6. In SEM and LM, there was no bunching of fibers and no shortening of fibers.

• Applied Microscopy
• /
• v.31 no.4
• /
• pp.307-314
• /
• 2001

Safflower (Carthamus tinctorius L.) is a thistle-like annual plant mainly grown in dry hot climates as an oilseed or birdseed. Traditionally, the oil has mainly been sold in the health food market because it is unsaturated having high linoleic and oleic acid levels. With increased health consciousness in recent years, the oil quality has become a more general health issue. This study was designed to understand whether safflower seed powder has positive effects on the fracture healing in rats. Simple transverse fracture of rat fibula was made with a rotating diamond disc saw. The histologic changes of rats were observed with a scanning electron microscope. The fractured fibulae showed a complete fusion at the fracture site in the 4th to 5th week after a simple transverse fracture. Administration of safflower seed powder facilitated the speed of histologic changes without affecting qualitative changes. These results suggest that safflower seed powder nay have substances that help the fracture healing process.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.11
• /
• pp.2752-2761
• /
• 1993

The purpose of this study is to confirm the decreasing problems of residual bending strength, and the fracture machanism experimentally when CFRP composite laminates are subjected to Foreign Object Damage. Composite laminates used for this experiment are CFRP orthotropy laminated plates, which have two-interfaces [O/sub 6//sup o//90/sub 6//sup o/]sub sym/ and four-interfaces [O/sub 3//sup o//90/sub 6//sup o//O/sub 3//sup o]/sub sym/. When the specimen is subjected to transverse impact by a steel ball, the delamination area generated by impact damage is observed by using SAM(Scanning Acoustic Microscope). also, Thefracture surfaces obtained by three-point bending test were observed by using SEM (Scanning Electron Microscope). Then, fracture mechanism was investigated based on the observed delamination area and fracture surface. The results were summarized as follows; (1) It is found that for the specimen with more interface, the critical delamination energy is increased while delamination-development energy is decreased. (2) Residual bending strength of specimen A is greater than that of Specimen B within the impact range of impact energy 1. 65J (impacted-side compression) and 1. 45J (impacted-side tension). On the other hand, when the impact energy is beyond the above ranges, residual bending strength of specimen A is smaller than that of specimen B. (3) In specimen A and B, residual strength of CFRP plates subjected to impact damage is lower in the impacted-side compression than in the impacted-side tension. (4) In the case of impacted-side compression, fracture is propagated from the transverse crack generat-ed near impact point. On the other hand, fracture is developed toward the impact point from the edge of interface-B delamination in the case of impacted-side tension.

• Transactions of Materials Processing
• /
• v.32 no.2
• /
• pp.87-91
• /
• 2023

In the present work, the ductile fracture behaviors of ultra-high strength steel sheets along the different loading directions are investigated under various loading paths. Three loading paths, i.e., in-plane shear, uniaxial tension, plane strain tension deformations, are considered, and the corresponding specimens are described. The experiments are conducted using the digital image correlation (DIC) system to analyze the strain at the onset of the fracture. The experimental results show that the loading path for each specimen sample is linear, and different values of the fracture strains for the loading direction from the plane strain tension are observed. The ductile fracture model of the modified Mohr-Coulomb (MMC) is constructed based on the experimental data and evaluated along the rolling direction and transverse direction under various loading paths.

• The Journal of Korean Academy of Prosthodontics
• /
• v.47 no.4
• /
• pp.424-434
• /
• 2009

Statement of problem: Problems such as loosening and fractures of retained screws and fracture of implant fixture have been frequently reported in implant prosthesis. Purpose: Implant has weak mechanical properties against lateral loading compared to vertical occlusal loading, and therefore, stress analysis of implant fixture depending on its material and geometric features is needed. Material and methods: Total 28 of external hexed implants were divided into 7 of 4 groups; Group A (3i, FULL $OSSEOTITE^{(R)}$Implant), Group B (Nobelbiocare, $Br{\aa}nemark$ $System^{(R)}$Mk III Groovy RP), Group C (Neobiotec, $SinusQuick^{TM}$ EB), Group D (Osstem, US-II). The type III gold alloy prostheses were fabricated using adequate UCLA gold abutments. Fixture, abutment screw, and abutment were connected and cross-sectioned vertically. Hardness test was conducted using MXT-$\alpha$. For fatigue fracture test, with MTS 810, the specimens were loaded to the extent of 60-600 N until fracture occurred. The fracture pattern of abutment screw and fixture was observed under scanning electron microscope. A comparative study of stress distribution and fracture area of abutment screw and fixture was carried out through finite element analysis Results: 1. In Vicker's hardness test of abutment screw, the highest value was measured in group A and lowest value was measured in group D. 2. In all implant groups, implant fixture fractures occurred mainly at the 3-4th fixture thread valley where tensile stress was concentrated. When the fatigue life was compared, significant difference was found between the group A, B, C and D (P<.05). 3. The fracture patterns of group B and group D showed complex failure type, a fracture behavior including transverse and longitudinal failure patterns in both fixture and abutment screw. In Group A and C, however, the transverse failure of fixture was only observed. 4. The finite element analysis infers that a fatigue crack started at the fixture surface. Conclusion: The maximum tensile stress was found in the implant fixture at the level of cortical bone. The fatigue fracture occurred when the dead space of implant fixture coincides with jig surface where the maximum tensile stress was generated. To increase implant durability, prevention of surrounding bone resorption is important. However, if the bone resorption progresses to the level of dead space, the frequency of implant fracture would increase. Thus, proper management is needed.

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