• Title/Summary/Keyword: flexural strength

Search Result 3,301, Processing Time 0.027 seconds

Mechanical Properties and Reliability of Sand Casting 3D Printing Materials (사형 주조 3D 프린팅용 소재의 기계적 특성 및 신뢰성)

  • Son, Hyeon Jin;Jang, Seongwan;Lee, Hwan Jong;Yang, Jeong Jik;Jeong, Yeong Geun;Bae, Chang-Jun
    • Korean Journal of Materials Research
    • /
    • v.30 no.1
    • /
    • pp.38-43
    • /
    • 2020
  • Sand casting 3D printing uses a binder jetting method to produce a mold having complicated shape by spraying a binder on sand coated with activator. Appropriate heat treatment process in sand mold fabrication can increase the degree of polymerization to improve flexural strength. However, long heat treatment of over 24 hours decreases flexural strength and reliability due to chemical bond decomposition through thermal degradation. The main role of the activator is to control the reaction rate between the polymer chains. As a result, when the activator composition is increased from 0.15 wt% to 0.25 wt%, the flexural strength is increased by 218 N/㎠. However, excess activator (0.40 wt%) has been shown to decrease reliability without increasing flexural strength. The main role of the binder is to control the flexural strength of the specimen. As the binder composition is increased from 2.00 wt% to 4.00 wt%, the flexural strength increases to about 255 N/㎠, indicating the maximum flexural strength increase. Finally, the reliability of the flexural strength of the fabricated specimens is evaluated by a Weibull plot. Weibull modulus calculations are used to evaluate the flexural strength reliability of the specimens, and maximum reliability value of 11.7 is obtained at 0.20 wt% activator composition. Therefore, it is confirmed that this composition has maximum flexural strength reliability.

Properties of EMNC According to Addition Contents Variation for Nanosilica (2) -For Mechanical, Electrical Properties (나노 실리카 충진함량 변화에 따른 EMNC의 특성 연구 (2) -기계적, 전기적 특성 중심으로-)

  • Park, Jae-Jun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.25 no.11
    • /
    • pp.886-894
    • /
    • 2012
  • In order to develop electrical insulation materials, epoxy-nanosilica-microsilica mixture composites (ENMC) was synthesized, and mechanical properties such as their tensile and flexural strength, and AC insulation breakdown strength were investigated. Properties of mechanical strength and AC insulation breakdown strength are analyzed as scale and shape parameter with respect to weibull plot. Their tensile and flexural strength, AC insulation breakdown strength were compared original epoxy or EMC to ENMC. The 4 phr nano-silica addition and the 65 wt% micron-silica mixture composite (ENMC) was found to have the highest tensile and flexural strength. In the tensile strength was improved 29%, and flexural strength was improved 60.9% higher than those of the original epoxy. In the insulation breakdown strength, ENMC_4 phr was improved 17% and ENMC_5 phr was improved 15.8% higher than those of the EMC.

Fracture Behavior of Reinforced Concrete Beams Repaired by Latex-Modified Concrete (LMC로 보강된 철근콘크리트 보의 파괴거동)

  • 김성환;정원경;김기헌;김동호;윤경구
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2003.05a
    • /
    • pp.475-480
    • /
    • 2003
  • Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

  • PDF

Correlations between Compressive Strength and Biaxial Flexural Strength on High-Heated Concrete (고온 수열 콘크리트의 압축강도와 이축휨강도의 상관성 검토)

  • Lee, Gun-Cheol;Kwon, Hyun-Woo;Kim, Young-Min;Heo, Young-Sun
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • 2021.05a
    • /
    • pp.239-240
    • /
    • 2021
  • In this study, we conducted a study to evaluate the more accurate mechanical properties of concrete damaged by fire. In relation to this, in this study, the results of compressive strength and biaxial flexural strength were compared for concrete that received high temperature heat. As a result, both the compressive strength and the biaxial bending strength decreased as the heating temperature increased. As a result of examining the correlation between the compressive strength and the biaxial flexural strength, the biaxial flexural strength was smaller than the compressive strength.

  • PDF

Flexural Performance of Polypropylene Fiber Reinforced EVA Concrete (폴리프로필렌 섬유보강 EVA 콘크리트의 휨 성능)

  • Sung, Chan Yong;Nam, Ki Sung
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.58 no.2
    • /
    • pp.83-90
    • /
    • 2016
  • This study was performed to evaluate the effective analysis of flexural performance for polypropylene fiber (PF) reinforced EVA concrete that can be used in marine bridge, tunnel and agricultural structures under flexural load. The control design was applied in ready mixed concrete using 10 % fly ash of total binder weight used in batch plant. On the basis of the control mix design, there was designed mix types that contained PF ranged from 0 % to 0.5 % by volume ratio into two mix types of using 0 % and 5.0 % EVA contents of total binder weight. Before evaluating the flexural performance, we tested compressive strength and flexural strength to evaluate whether polypropylene fiber reinforced concrete could be used or not in site. The method of flexural performance evaluation was applied by ASTM C 1609. These results showed the maximum compressive strength and flexural strength was measured at each E5P1 and E5P2. Concrete reinforced with PF exhibited deflection-softening behavior. In the concrete reinforced with 0.4 % PF contents and containing 5.0 % EVA, the flexural performance was the best.

Flexural properties, interlaminar shear strength and morphology of phenolic matrix composites reinforced with xGnP-coated carbon fibers

  • Park, Jong Kyoo;Lee, Jae Yeol;Drzal, Lawrence T.;Cho, Donghwan
    • Carbon letters
    • /
    • v.17 no.1
    • /
    • pp.33-38
    • /
    • 2016
  • In the present study, exfoliated graphite nanoplatelets (xGnP) with different particle sizes were coated onto polyacrylonitrile-based carbon fibers by a direct coating method. The flexural properties, interlaminar shear strength, and the morphology of the xGnP-coated carbon fiber/phenolic matrix composites were investigated in terms of their longitudinal flexural strength and modulus, interlaminar shear strength, and by optical and scanning electron microscopic observations. The results were compared with a phenolic matrix composite counterpart prepared without xGnP. The flexural properties and interlaminar shear strength of the xGnP-coated carbon fiber/phenolic matrix composites were found to be higher than those of the uncoated composite. The flexural and interlaminar shear strengths were affected by the particle size of the xGnP, while the particle size had no significant effect on the flexural modulus. It seems that the interfacial contacts between the xGnP-coated carbon fibers and the phenolic matrix play a role in enhancing the flexural strength as well as the interlaminar shear strength of the composites.

Effect of different coloring liquids on the flexural strength of multilayered zirconia

  • Yu, Na-Kyoung;Park, Mi-Gyoung
    • The Journal of Advanced Prosthodontics
    • /
    • v.11 no.4
    • /
    • pp.209-214
    • /
    • 2019
  • PURPOSE. The purpose of this study was to evaluate the effect of two coloring liquids (aqueous and acid-based coloring liquids) and the position of multilayered zirconia on the flexural strength of multilayered zirconia. MATERIALS AND METHODS. The multilayered zirconia specimens were divided into upper and lower positions. The specimens were divided into three subgroups (n=10): non-shaded, acid-based coloring liquid, and aqueous coloring liquid. The specimens were cut using a milling machine and were immersed in either a acid-based coloring liquid or aqueous coloring liquid 2 times for 5 seconds. The specimens were sintered in a sintering furnace according to the manufacturer's introduction. The flexural strength of the specimen was measured using a universal testing machine and the surface of the specimen was observed using a field emission scanning electron microscope. RESULTS. The flexural strength of multilayered zirconia was 400 - 500 MPa. There was no statistically significant difference among all groups (P>.05).The flexural strength of the multilayered zirconia was not influenced by the kind of coloring liquid used (P>.05). The flexural strength of the multilayered zirconia colored with the coloring liquids was not influenced by its position (P>.05). CONCLUSION. The different coloring liquid application did not affect the flexural strength of multilayered zirconia of all positions.

Design of Ground Floor Slab According to the Method for Evaluating the Tensile Performance of Steel Fiber Reinforced Concrete (강섬유 보강 콘크리트 인장성능 평가방법에 따른 지반 바닥슬래브의 설계)

  • Lee, Jong-Han;Cho, Baik-Soon;Cho, Chang-Oh
    • Journal of the Korea Concrete Institute
    • /
    • v.28 no.1
    • /
    • pp.95-104
    • /
    • 2016
  • Flexural strength of concrete ground slab reinforced with steel fiber is evaluated using the equivalent flexural strength ratio of steel fiber reinforced concrete based on the yield line theory. Recently, the European standard specifies that the tensile performance of the steel fiber reinforced concrete be evaluated directly from the residual flexural strength after the cracking of concrete. Thus, in the study, an experiment was carried out to evaluate the conventional equivalent flexural strength ratio and the residual flexural strength of the steel fiber reinforced concrete. Then the design flexural strength was investigated according to the location of a point load, based on the ratio of the radius of contact area of the load to the radius of relative stiffness. Design flexural capacity obtained from ACI 360R-10 was smaller than that from TR 34 (2003 & 2013). In addition, TR 34 (2013), which evaluates the design flexural capacity based on the residual flexural strength, showed slightly smaller value than TR 34 (2003).

An Experimental Study on Flexural Tensile Strength and Bond Strength Between Concrete-to-Concrete (콘크리트의 휨인장강도 및 신·구콘크리트 사이의 부착강도에 관한 실험 연구)

  • Yang, In-Hwan;Yoo, Sung-Won;Seo, Jung-In
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.13 no.3 s.55
    • /
    • pp.155-163
    • /
    • 2009
  • The purpose of this paper is to investigate the bond strength between old and new concrete as well as flexural tensile strength of concrete. To achieve this purpose, a comprehensive experimental program has been set up and strength tests using a series of specimens have been carried out. The present study represents that the flexural bond strength between old and new concrete is much smaller than that of flexural tensile strength. The ratio of bond strength to flexural tensile strength ranged through 15~27%. It is seen that concrete-to-concrete bond strength has been affected by curing condition. Also, test results of tensile strength show that recommendation by ACI 363 committee is estimated to be more realistic than another recommendations for predicting tensile strength of concrete.

A study on the Flexural strength of zirconia CAD/CAM block (지르코니아 CAD/CAM block의 강도에 관한 연구)

  • Lee, Jung-Soo
    • Journal of Technologic Dentistry
    • /
    • v.30 no.2
    • /
    • pp.65-69
    • /
    • 2008
  • Recently, zirconia is widely used in the field of dental ceramics thanks to the proliferation of CAD/CAM systems. Accordingly, different types of zirconia block are being solid in the market. However, there are no precise, objective standards for properties of zirconia. This study concerns the flexural strength of zirconia ceramic for CAD/CAM block. The test specimens used for this study were ZirBlank(Acucera), ZirBlank shade(Acucera), VITA, Cercon(Densply) and Cerasys. The test results suggest that ZirBlank shade block shows the highest flexural strength and density among the zirconia blocks tested. Its flexural strength was $971{\pm}58MPa$ and its density was 99.89%. On the other hand, Cerasys block shows the lowest flexural strength of $576{\pm}36MPa$ and the lowest density of 94.85%. Given all, the density of the specimens is found to be directly proportional to strength and inversely to grain size.

  • PDF