• Title/Summary/Keyword: Strength Method

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Strength Evaluation for Adhesive Bonds of Adhesive with FRP Ship Body Structure (FRP 선체구조용 접착제의 접착강도 평가)

  • Ahn, Seok-Hwan;Choi, Han-Kyu;Nam, Ki-Woo
    • Journal of Ocean Engineering and Technology
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    • v.24 no.1
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    • pp.146-152
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    • 2010
  • Recently, the applied frequency of composite materials was increased from the viewpoint of lightweight, high strength and low cost when a leisure boat and a fishing boatwere built. However, studies on the mechanical properties of composite material with ship are rare. Specially, a leisure boat and fishing boat with FRP had been built by hand lay-up method. However, the vacuum infusion method is rising recently for ship building. The manufactured these FRP plates were combined by using the adhesive. Therefore, in this study Cleavage peel strength, Shear strength and fatigue limit of adhesive bonds by tensileloading were estimated. From test results, the strengths of FRP specimens made by the vacuum infusion method are higher than that of the hand lay-up method.

A Study on the Strength Estimation of Concrete Using Microwave (마이크로파를 이용한 콘크리트 강도추정에 관한 연구)

  • 박일용;이종균;박영진;안형준;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.219-222
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    • 1999
  • Concrete is to be important quality in placement point and exact test method needed about early judgement method concrete on placement point. But early judgement method of concrete proposed various kind of method because the problems of accuracy and the time required of test exists, it is used within the limits. This study is to propose of early strength judgement by using microwave for accurate estimating early strength of concrete and to develop test machine. Through out this study we find that belows. 1) Strength development of concrete specimen according to the time heated by microwave showed the height strength development in 9 minutes regardless of slump and w/c. 2) As cooling time is long, strength of concrete specimen according to the time heated by microwave showed high strength development and this tendency is like regardless of heating time, w/c and slump. 3) As w/c is high, accelerating strength development according to w/c showed lower strength development and this tendency is like regardless of slump, heating time and cooling time. 4) As slump is big, compressive strength of specimen in standard curing showed lower value and as w/c is big, strength development showed lower

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A comparative study on the tensile bonding strength of gold alloy solder joints by dental soldering method (치과용 납착 방법에 따른 금합금 납착 연결부의 인장 결합강도 비교 연구)

  • Cho, Mi-Hyang;Lee, Myung-Kon
    • Journal of Technologic Dentistry
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    • v.30 no.1
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    • pp.49-55
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    • 2008
  • In this study, to provide the fundamental data on stable connection method for successful implants prosthesis, We fabricated the solder joint of gold alloy bar specimens by gas flame soldering method and laser welding and soldering method. It compared and studied the tensile strength of two soldering method by universal testing machine. The results using universal testing machine were as follow : The mean of tensile strength of solder joint bar in gas flame soldering method specimens was 363.89 $\pm$17.62 MPa, and the mean strength of laser welding and soldering method was 125.91 $\pm$ 19.66 MPa, so gas flame soldering method was better than laser welding and soldering method and the finding better way to improve tensile strength is needed in laser welding method. On weak loading condition and the part which is needed an accuracy, laser welding method is more effective and on long-span prosthesis and frequent chewing loading part, laser welding technique is recommended first and applying additional gas flame soldering technique would be better for making much more successful prosthesis.

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Strength Estimation of Stylene-Butadien Latex Modified Concrete by Factorial Experimental Design (요인 실험분석에 의한 SB 라텍스 개질 콘크리트의 강도예측)

  • Yun, Kyong-Ku;Lee, Joo-Hyung;Hong, Chang-Woo
    • Journal of Industrial Technology
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    • v.21 no.B
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    • pp.307-315
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    • 2001
  • The purpose of this study was to provide the evaluation and prediction of strengths of SB latex modified concrete(LMC) using a statistical method and factorial experimental design method. The main experimental variables were as follows ; W/C ( 4 levels ; 31, 33, 35, 42%), S/a( 2 levels ; 55, 58%) and L/C(2 levels ; 5, 15%). The compressive strength and flexural strength of LMC were selected as a factor of response. The statistical method was carried out to analyze the results, together with factorial experimental design method and response surface method. The analysis showed that if L/C had been 15%, W/C appeared to be around 33% to achieve the design strength of $350kgf/cm^2$. In this case, the flexural strength and the slump came to around $68kgf/cm^2$ and 18cm, respectively. Eventhough the L/C varied, the design strength and W/C could be predictable together with slump value and flexural strength. As a result of series of experiments in this study, W/C and L/C were proved to be the main factors influencing on the compressive and flexural strength of LMC. Both of strength and slump values could be predictable from the mixing proportion of LMC.

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Formulation of the Panel Method with Linearly Distributed Dipole Strength on Triangular Panels (삼각형 패널 상에 선형적으로 분포된 다이폴 강도를 갖는 패널법의 정식화)

  • Oh, Jin-An;Lee, Jin-Tae
    • Journal of the Society of Naval Architects of Korea
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    • v.57 no.2
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    • pp.114-123
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    • 2020
  • A high-order potential-based panel method based on Green's theorem, with piecewise-linear dipole strength on triangular panels, is formulated for the analysis of potential flow around a three-dimensional wing. Previous low-order panel methods adopt square panels with piecewise-constant dipole strength, which results in inherent errors. Square panels can not represent a high curvature lifting body, such as propellers, since the four vertices of the square panel do not locate at the same flat plane. Moreover the piecewise-constant dipole strength induces inevitable errors due to the steps in dipole strength between adjacent panels. In this paper a high-order panel method is formulated to improve accuracy by adopting a piecewise linear dipole strength on triangular panels. Firstly, the square panels are replaced by triangular panels in order to increase the geometric accuracy in representing the shape of the object with large curvature. Next, the step difference of the dipole strength between adjacent panels is removed by adopting piecewise-linear dipole strength on the triangular panels. The calculated results by the present method is compared with analytical ones for simple non-lifting geometries, such as ellipsoid. The results for an elliptic wing with zero thickness at finite angle of attack are compared with Jordan's results. The comparison shows reasonable agrements for the both lifting and non-lifting bodies.

Proposal of Bond Strength Evaluation Method for Overlay Concrete at Field (유한요소해석을 이용한 현장 덧씌우기 콘크리트의 부착강도 평가 방법 제안)

  • Lee, Bong-Hak;Hong, chang-Woo;Lee, Joo-Hyung;Kim, Seong-Hwan
    • Journal of Industrial Technology
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    • v.21 no.B
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    • pp.295-300
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    • 2001
  • Significant improvements in bond strength between new and existing concrete can be achieved through the modification of the new concrete by latex modification. But, no test method has been adopted as a standard to measure the bond strength between the concrete used to repair and the substrate being repaired. The performance of old and the new concrete construction defends upon band strength between old and the new concrete. Current adhesion strength measurement method is inaccurate method that ignore effect of stress concentration by shape of specimens. Therefore, this research calculates stress concentration coefficient using finite element analysis and direction tensile strength test (pull-off test). The result shows that the required core depth is 2.5 cm. Elastic modulus and overlay thickness do not influence in stress concentration.

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An Experimental Study on Early Strength Development of High-Strength Concrete to Apply Slip-Form (슬립폼 적용을 위한 고강도콘크리트의 조기강도 발현성상에 관한 실험적 연구)

  • 주지현;여동구;강석표;길배수;남재현;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.10a
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    • pp.355-358
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    • 2000
  • Nowadays, with high-storied and large-sized of structures, high-strength concrete is applied to the various kinds of concrete structure. Among of them, for reduction of completion time, high-strength concrete is applied to the high-storied tower, building which is constructed continuously by the slip-form method and it is expected to be on the increase. In this case, it is very important to grasp development of early-strength to apply the slip-form method. But the strength data prior 1 day is rare. Therefore, to apply slip-form method in field, this study aim is to present basic data for development of early-strength of high-strength concrete, through examining development of strength by different curing temperature, replacement of fly-ash.

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Flexural and shear behavior of large diameter PHC pile reinforced by rebar and infilled concrete

  • Bang, Jin-Wook;Lee, Bang-Yeon;Kim, Yun-Yong
    • Computers and Concrete
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    • v.25 no.1
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    • pp.75-81
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    • 2020
  • The purpose of this paper is to provide an experimental and analytical study on the reinforced large diameter pretensioned high strength concrete (R-LDPHC) pile. R-LDPHC pile was reinforced with infilled concrete, longitudinal, and transverse rebar to increase the flexural and shear strength of conventional large diameter PHC (LDPHC) pile without changing dimension of the pile. To evaluate the shear and flexural strength enhancement effects of R-LDPHC piles compared with conventional LDPHC pile, a two-point loading tests were conducted under simple supported conditions. Nonlinear analysis on the basis of the conventional layered sectional approach was also performed to evaluate effects of infilled concrete and longitudinal rebar on the flexural strength of conventional LDPHC pile. Moreover, ultimate strength design method was adopted to estimate the effect of transverse rebar and infilled concrete on the shear strength of a pile. The analytical results were compared with the results of the bending and shear test. Test results showed that the flexural strength and shear strength of R-LDPHC pile were increased by 2.3 times and 3.3 times compared to those of the conventional LDPHC pile, respectively. From the analytical study, it was found that the flexural strength and shear strength of R-LDPHC pile can be predicted by the analytical method by considering rebar and infilled concrete effects, and the average difference of flexural strength between experimental results and calculated result was 10.5% at the ultimate state.

A Study on the Pull-out test for Non-Destructive Evaluation of Concrete Strength (콘크리트 비파괴강도 추정을 위한 인발시험법에 대한 연구)

  • 한만엽;김동욱
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.639-642
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    • 1999
  • Pullout test known as Lok test among the test methods to evaluate concrete strength strength is a test method which is used to decide the form removal time by assessing the early strength of concrete in a new construction, or to control the quality of newly placed concrete. This method has inconvenience to place inserts on the form work in advance, however, the placing work is quite simple and it has advantage that the strength can be measured at field as long as the inserts are placed. In this study, the first step is to investigate the properties of test method itself, by performing the laboratory test which covers deviation of the method and factors affecting the results, etc. The second step is to correlate the result with cylinder strength and other NDT methods such as rebound hammer, ultrasonic method, etc. And that, the results are compared with foreign results to find the differences between the two. In this research, new factors such as moisture content, area of aggregate failure cross section and area of aggregate separation cross section, etc as well as wate-cement ratio and age are investigated.

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Evaluation of Static Strength on Ceramic /Metal Bonded Joints Considering Stress Singularity (응력특이성을 고려한 세라믹/금속 접합재의 정적강도평가)

  • 김기성
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.1
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    • pp.59-68
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    • 1997
  • Recently, the cases of using bonded dissimiliar materials which have each of the different components tend to increase for the purpose of developing new materials and using the special objects in the field of industry. Among the cases the strength evaluation of the joining materials of vehicle engine and the structural materials with ceramic/metal bonded joints becomes more important. But the residual stress occurs, because the joining of ceramics and metals is performed in extremely high temperature. It becomes a dominant cause to reduce the strength of the ceramic/metal bonded joints. In this paper, strength evaluation method of ceramic/metal bonded joints considering stress singularity was investigated by boundary element method and 4-point bending test. An advanced method of quantitative strength evaluation for ceramin/metal bonded joints is to be suggested.

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