• Title/Summary/Keyword: Specimen area

Search Result 772, Processing Time 0.029 seconds

AN EXPERIMENTAL STUDY OF LASER EFFECTS ON A BASE METAL ALLOY FOR DENTAL CASTING (레이저가 치과주조용 비귀금속합금에 미치는 영향에 관한 실험적 연구)

  • Kim, Kyoung-Nam
    • The Journal of the Korean dental association
    • /
    • v.22 no.9 s.184
    • /
    • pp.781-792
    • /
    • 1984
  • The purpose of this experiment was to study the effects of laser on a base metal alloy for dental casting. In this study, microhardness, corrosion resistance, wear resistance, interaction behavior of metal-ceramic interface, and bond strength were tested before and after the laser treatment for metal-ceramic alloy. The conclusion arised from this study are as follows: 1. The hardness of lased area was higher than that of unlased area. 2. The corrosion resistance was higher in lased specimen than in unlased specimen. 3. the wear resistance was higher in Iased specimen than in unlased specimen. 4. The EDAX showed that Mo, Si and Al were increased in lased surface but Ni and Cr not increased. 5. The SEM of lased area revealed a typical microstructure. 6. The bond strength of lased specimen was increased in 11.2% than of unlased specimen.

  • PDF

Evaluation of Optimized Ring Specimen Shape for the Hoop Behavior Test of Nuclear Fuel Clad Tube (핵연료 피복관의 후우프 거동시험을 위한 시편의 최적형상 평가)

  • 서기석
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • 2000.04a
    • /
    • pp.171-178
    • /
    • 2000
  • In order to evaluate the tensile behaviors of hoop direction for the nuclear fuel cladding tubes the shapes of specimen and jig fixtures for the ring test are decided with various conditions under the elastic-large plastic deformations. The axial displacement of the jig cylinders is converted to the circumferential direction elongations of specimen. The stress distributions on specimen are depended on the radii and locations of specimen and jig size and central angle. Therefore we calculated the stress distributions and decided the optimum shapes to get the uniform stress in the area of specimen gage length. Form the analysis the stress distributions in gate area are reviewed with the radii and location of specimen notch and the central angle of jig cylinder,. The optimum shapes of specimen and jig are proposed to the clad tube having 10.62 mm in diameter and 0.63mm in thickness for 16x16 PWR nuclear fuel assembly.

  • PDF

The Area Measurement of Composite Specimen using Digital Image Processing (디지털 영상처리를 이용한 복합재료 시편의 면적 측정)

  • Son, Byung Jik;Lee, Kyu Hwan
    • Journal of the Korean Society for Advanced Composite Structures
    • /
    • v.6 no.2
    • /
    • pp.17-22
    • /
    • 2015
  • In this paper, we study the calculation for the fracture area of the composite material specimens using digital image processing techniques. This study was able to calculate the area of the fracture region through the main operation step 7 on the basis of improved image. To extract the area in the original image, we have to use opening operation, close operation, the Hit-or-Miss operation and Bottom hat filter, Top hat filter, etc. In particular, to extract the area of the composite specimen discussed in this study, we have to use the combination of the operations and filters because it is non-isotropic material, or should develop a new algorithm based on it.

The Estimation of Mechanical Properties of the High Frequency Induction Hardening SM45C Steel by Acoustic Emission (음향방출법에 의한 SM45C 고주파 열처리 강의 기계적 특성 평가)

  • Rhee, Zhang-Kyu;Kim, Bong-Gag
    • Proceedings of the Safety Management and Science Conference
    • /
    • 2009.11a
    • /
    • pp.471-481
    • /
    • 2009
  • This study is deal with the high frequency induction hardening (HF at $850^{\circ}C$, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen which was tempered at $150^{\circ}C$, did not appear any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE amplitude distribution showed between 45~60dB. (2) The HF specimen which was tempered at $300^{\circ}C$, slip and fracture occurred at the hole area of the tensile specimen. As it passes the yield point, the AE energy increased intermittently and AE amplitude distribution showed between 70~85dB. In addition, after the maximum tensile load, it showed high amplitude and energy distribution. The AE amplitude showed between 45~70dB. (3) The HF specimen which was tempered at $450^{\circ}C$, a brittle fracture occurred as if it is torn in the direction of $45^{\circ}$ on parallel area over the both sides of the tensile specimen, which led to several peak to be appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

  • PDF

Transmission Electron Microscopy Specimen Preparation for Layer-area Graphene by a Direct Transfer Method

  • Cho, Youngji;Yang, Jun-Mo;Lam, Do Van;Lee, Seung-Mo;Kim, Jae-Hyun;Han, Kwan-Young;Chang, Jiho
    • Applied Microscopy
    • /
    • v.44 no.4
    • /
    • pp.133-137
    • /
    • 2014
  • We suggest a facile transmission electron microscopy (TEM) specimen preparation method for the direct (polymer-free) transfer of layer-area graphene from Cu substrates to a TEM grid. The standard (polymer-based) method and direct transfer method were by TEM, high-resolution TEM, and energy dispersive X-ray spectroscopy (EDS). The folds and crystalline particles were formed in a graphene specimen by the standard method, while the graphene specimen by the direct method with a new etchant solution exhibited clean and full coverage of the graphene surface, which reduced several wet chemical steps and accompanying mechanical stresses and avoided formation of the oxide metal.

The Analysis of Mechanical Properties of the High Frequency Induction Hardening SM45C Steel by Acoustic Emission (음향방출법에 의한 SM45C 고주파 열처리 강의 기계적 특성 평가)

  • Rhee, Zhang-Kyu
    • Journal of the Korean Society of Mechanical Technology
    • /
    • v.13 no.2
    • /
    • pp.93-100
    • /
    • 2011
  • This study deals with the high frequency induction hardening (HF at $850^{\circ}C$, 120kHz & 50kW condition) SM45C steel. (1) The HF specimen, which was tempered at $150^{\circ}C$, did not show any tempering effect. A brittle fracture occurred at rounded area of the tensile specimen. AE (acoustic emission) amplitude distribution showed between 45dB and 60dB. (2) A slip and fracture occurred at the hole area of the HF specimen which was tempered at $300^{\circ}C$. As they pass the yield point, the AE energy is increased intermittently and AE amplitude distribution exists between 70dB and 85dB. In addition, after imposing the maximum tensile load, AE signals showed high amplitude and energy distribution. The AE amplitude showed between 45dB and 70dB. (3) A brittle fracture occurred at HF specimen which was tempered at $450^{\circ}C$ as if it is torn in the direction of $45^{\circ}$ on parallel area over the both sides of the tensile specimen, which lead to several peak appeared in AE energy. It was found that the AE amplitude was relatively low and the AE energy was high.

Calculation Method for Nominal Area of Rock Core Specimen During Direct Shear Test (암석코어시편의 절리면 직접전단시험을 위한 겉보기 면적 계산방법)

  • Kang, Hoon;Park, Jung-Wook;Park, Chan;Oh, Tae-Min;Cho, Jung-Woo
    • Tunnel and Underground Space
    • /
    • v.30 no.6
    • /
    • pp.551-558
    • /
    • 2020
  • This note presents the calculation of nominal area for rock core specimen under direct shear testing condition. The initial nominal area was assumed as ellipsoid, and the equations for calculating the nominal area are derived. The normalized shear displacement and normalized nominal area have an identical relationship regardless of the ellipsoid shape. New testing constants and the generalized method were suggested to calculate the decrease of the nominal area. The method was applied to calculate the direct shear testing data and the changes of result were discussed.

A Study on the Characteristics and Error Ranges of Automotive Application Component's Mechanical Bonding Strength for the Its Reliability Evaluation (신뢰성 평가를 위한 자동차 전장 부품의 기계적 접합강도 특성 및 오차범위에 관한 연구)

  • Jeon, Yu-Jae;Kim, Do-Seok;Shin, Young-Eui
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.24 no.12
    • /
    • pp.949-954
    • /
    • 2011
  • In this study, the characteristics and error ranges of the mechanical bonding strength were analyzed according to before and after thermal shock test for various chips of automotive application component using Sn-3.0Ag-0.5Cu solder. In the after thermal shock test, the mechanical bonding strengths tend to decrease, meanwhile decreasing rates of mechanical strengths were less then 12% at specimen's bonding area below 3.5$mm^2$, and were from 17 to 21% at specimen's bonding area above 12 $mm^2$. On the other hand, Specimen's mean deviation rates were about 5% at specimen's bonding area more than 12 $mm^2$. Inversely, at specimen's bonding area is less then 3.5 $mm^2$, mean deviation rates were increased to about 8%. It means that the smaller device size is, the larger mean deviation rate. In addition, error ranges and deviation rates of the mechanical bonding strengths may differ slightly depending on their bonding area. Furthermore, process conditions as well as method of mechanical reliability evaluation should be established to reduce the error ranges of bonding strength.

Impact Damge and Residual Bending Strength of CFRP Composite Laminates Subjected to Impact Loading Fracture Mechanism and Impact Damage of Orthotropy Laminated Plates (충격하중을 받는 CFRP 적층판의 충격손상과 굽힘 잔류강도 직교 이방성 적층판의 충격손상과 파과메카니즘)

  • 심재기;양인영;오택열
    • 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.