• 한국공작기계학회논문집
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• 제17권3호
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• pp.34-39
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• 2008

In this study, CFRP(Carbon Fiber Reinforced Plastics) that has high specific strength and elastic modulus and low thermal strain was used as a material for the lightweight structural member. CFRP is a fiber material as anisotropic material. The anisotropic material is characterized by the change of its mechanical properties according to stacking orientation angle. CFRP orientation angle was oriented in [A/B]s in order to examine the effect of CFRP orientation angle on the characteristics of energy absorption. CFRP is very weak to the impact from the outside. So, when impact is applied to CFRP, its strength is rapidly lowered. The hybrid material was manufactured by combining CFRP to aluminum which is lightweight and widely used for structural members of the automobile. The hybrid member was shaped as a side member that could support the automobile engine and mount and absorb a large amount of impact energy at the front-end in case of automobile collision. The bending test device was manufactured in accordance with ASTM standard, and mounted to UTM for bending test. For comparing bending characteristics of the hybrid member with those of Aluminum and CFRP member, tests were performed for aluminum, CFRP and hybrid member, respectively.

• 대한치과기공학회지
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• 제40권1호
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• pp.9-15
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• 2018

Purpose: The purpose of this study is to investigate the effect of lithium disilicate glass ceramic polishing on the strength of the final prosthesis. Methods: Fourteen lithium disilicate glass ceramic specimens were prepared. These were randomly divided into two groups of seven(LPG: low polishing group, HPG: high polishing group). In LPG, SiC paper was sequentially polished using 300, 600, 800, 1000 grit, and the specifications of the test piece were adjusted. HPG was sequentially polished using 300, 600, 800, 1000, 1200, 1500, and 2000 grit. Two groups of specimens are executed 3- point bending test. Using the statistical program SPSS 22.0, the average values of the strengths of the two groups were compared in the Mann-Whiteney test. The significance level was set at 0.05. Results: The mean strength value of HPG was measured at $307.14{\pm}23.28MPa$ significantly higher than LPG(p<0.001). Conclusion : The final polishing of the prosthesis is aesthetically important but has proven to play an important role in the flexural strength, early fracture, and prolongation of the prosthesis.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.959-963
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• 1996

Hardened layer and compressive residual stress created by carburized treatment effect on bending fatigue strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs compared to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• 한국농공학회논문집
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• 제65권4호
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• pp.45-52
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• 2023

This study was conducted to examine the possibility of use as a structural material for ginseng cultivation facilities of recycled plastics. In order to determine the possibility that recycled plastic can replace timber used as a structural material for ginseng cultivation facilities, the specimens collected by elapsed time were compared with timber through bending tests. In addition, in order to analyze the effect of external environmental conditions on recycled plastic products, bending test was conducted with the specimens that had completed weathering test and accelerated heat aging test respectively. As a result, the bending strength of recycled plastic specimens with the elapsed time of 360 days was lower than that of timber. But bending strength of recycled plastic specimens exceeded the design allowable stress standard set by the Korea design standard (MOLIT, 2016). There was no degradation in quality of recycled plastic due to the external environment, and it was found that there would be no problem even if it was used as a structural material for ginseng cultivation facilities.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.671-676
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• 2005

Spring is one of major suspension part of the light commercial vehicle (LCV). In the manufacturing process it is shot-peened to improve its fatigue strength. In this paper, residual stresses by shot peening were calculated through finite element analysis, and the effects of these residual stresses on fatigue strength of leaf spring were evaluated. Fatigue tests were performed with two kinds of specimens; one is actual leaf spring assembly, and the other is simulated 3-point bending specimen. Fatigue tests were performed under the loading condition that was measured on the proving ground. From the results, the maximum load-fatigue life relation of leaf spring was defined, and test results of 3 point bending specimen are in good agreement with those of leaf spring assembly. The effects of residual stresses by shot peening on fatigue strength of leaf spring is not large in the high load range, however, in the low load range, its effects were not negligible.

• 동력기계공학회지
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• 제8권4호
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• pp.44-48
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• 2004

For many years researchers have been attempting to establish the relations among the preparation history, structure and properties of ceramics. In this study, the strength property of $Al_2O_3$ ceramics with components and giudes of the textile machinery was investigated. The optimized conditions of ressureless sintering were investigated in order to obtain the maximum strength of $Al_2O_3$ ceramics for using at the textile machinery. As the sintering conditions, $1,400{\sim}1,700^{\circ}C$ of temperatures and $30{\sim}150$ minutes of times were applied. Three-point bending test was conducted on the sintered materials to obtain the strength property. From test results, the optimum sintering temperature has $1,600^{\circ}C$. And the optimum sintering time in $1,600^{\circ}C$ has about 100 minutes.

• Structural Engineering and Mechanics
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• 제69권1호
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• pp.77-93
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• 2019

Although much research has been carried out using recycled aggregates sourced from normal strength concrete, most of the buildings to be demolished are constructed with low strength concrete. Therefore, the properties of the concrete incorporating recycled aggregates, sourced from the waste of structural elements cast with low strength concrete, were investigated in this study. Four different concrete mixtures were designed incorporating natural and recycled aggregates with and without fly ash. The results of the mechanical and durability tests of the concrete mixtures are presented. Additionally, full-scale one-way reinforced concrete slabs were cast, using these concrete mixtures, and subjected to bending test. The feasibility of using conventional reinforced concrete theory for the slabs made with structural concrete incorporating recycled aggregates was investigated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.959-964
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• 2002

The purpose of this study is to establish flexural behavior of high-strength concrete by means of both theoretical approach and experimental analysis of beams in which confinement stirrups have been introduced into pure bending zone. The experiment was carried out on full-scale high-strength reinforced concrete beams whose compressive strengths are 400 and 700kgf/cm$^2$, and confined with rectangular closed stirrups. The test results are reviewed in terms of flexural capacity and ductility.

• Journal of the Korean Wood Science and Technology
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• 제44권3호
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• pp.315-322
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• 2016

2개 이상의 보부재 집성재 요소들의 측면접착으로 제작된 "블록접착집성재"는 대단면 목조건축물의 건축부재로 활용 가능한 구조용재다. 블록접착집성재의 측면은 접착제의 종류와 도포량 및 압체압력을 각기 다른 조합으로 접착하여 박리시험과 전단블록시험으로 접착성능을 검토하였다. 실험결과 레조시놀접착제 $500g/m^2$을 도포하고 압체압력 1.5 MPa의 조건으로 제작된 블록접착집성재의 측면접착성능이 가장 양호하였다. 양호한 측면접착조건으로 제작된 블록접착집성재는 동일단면계수의 대조군 집성재와 휨 강도 성능을 비교 검토하였다. 블록접착집성재의 휨 탄성계수는 대조군 집성재와 유사하였으며, 파괴계수는 대조군집성재 보다 27% 향상되었다. 할렬은 대조군집성재 보다 블록접착집성재에서 다량 발생하였으며, 블록접착집성재의 측면접착층에서 계면파괴나 응집파괴는 관찰되지 않았다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.276-279
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• 2004

Concrete is one of the principal materials for the structure and it is widely used all over the world. but it shows extremely brittle failure under bending and tensile load. Recently to improve such a poor property. High Performance Fiber Reinforced Cementitious Composites (HPFRCC) have been developed. and it are defined by an ultimate strength higher than their first cracking strength and the formation of multiple cracking during the inelastic deformation process. This study is to develop the hybrid HPFRCC with high ductility and strain capacity in bending and tensile load. and the three-point bending test on hybrid HPRFCC reinforced with micro and macro fibers is carried out in this paper. As the results of the bending tests. hybrid HPFRCCs reinforced with PVA40+SF and PVA100+PVA660 showed the high ultimate bending stress, multiple cracks and displacement hardening under bending load.