• Title/Summary/Keyword: 4-point bending test

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A Study on 4 Point Bending Strength of Aircraft Composite Specimens (항공기 복합재료 적용 시편의 4점 굽힘 강도 연구)

  • Kong, Changduk;Park, Hyunbum;Lim, Seongjin
    • Journal of Aerospace System Engineering
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    • v.4 no.1
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    • pp.23-26
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    • 2010
  • In this study, it was performed damage assesment of small scale composite aircraft developing. This aircraft adopted the sandwich structure to skin of wing. This study aims to investigate the residual strength of sandwich composites with Nomex honeycomb core and carbon fiber face sheets after the open hole damage by the experimental investigation. The 4-point bending tests were used to find the bending strength, and the open hole was applied to introduce the simulated damage on the specimen. The bending strength test results after open hole was compared with the results of no damaged specimen test. The FEM analysis is assessed via an experimental 4-point bending test.

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Development of a Pure Bending Test Machine and Bending Collapse Characteristics of Rectangular Tubes (순수굽힘 시험기개발 및 사각관부재의 굽힘붕괴특성 연구)

  • 강신유;장인배;김헌영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.1
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    • pp.222-233
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    • 1998
  • A 4-point pure bending res machine is developed the evaluate the pure vending moment-rotation properties of the thin-walled tubes without imposing shear and tensile forces. The moment-rotation properties of the thin-walled tubes are measured up to and beyond collapse with the pure bending test machine. The test results are compared with those of finite element analyses and existing analytical solution.

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Four Point Bending Test for Adhesion Testing of Packaging Strictures: A Review

  • Mahan, Kenny;Han, Bongtae
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.4
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    • pp.33-39
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    • 2014
  • To establish the reliability of a packaging structures, adhesion testing of key interfaces is a critical task. Due to the material mismatch, the interface may be prone to delamination failure due to conditions during the manufacturing of the product or just from the day-to-day use. To assess the reliability of the interface adhesion strength testing can be performed during the design phase of the product. One test method of interest is the four-point bending (4PB) adhesion strength test method. This test method has been implemented in a variety of situations to evaluate the adhesion strength of interfaces in bimaterial structures to the interfaces within thin film multilayer stacks. This article presents a review of the 4PB adhesion strength testing method and key implementations of the technique in regards to semiconductor packaging.

An Experimental Study on the Failure Characteristics of Flip Chips in Cyclic Bending Test (플립칩의 반복 굽힘 시험 시 파손 특성에 관한 실험적 연구)

  • Lee, Yong-Sung;Jeong, Jong-Seol;Kim, Hong-Seok;Shin, Ki-Hoon
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.4
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    • pp.362-368
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    • 2009
  • In general, circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. In this paper, we report on the failure characteristics of semiconductor chips under the repeated cyclic bending. We first describe a new 4-point bending tester, which is developed according to JEDEC standard No. 22B113. The performance of the tester is then estimated through actual experiments. Test results reveal that the cracks first occur on the outer balls around 20,000 cycles and gradually propagate to the inner balls where cracks are found around 70,000 cycles.

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High Temperature Design Criteria of Cordierite Ceramic Substrate in Four-point Banding (4점 굽힘시험에서 코디어라이트 세라믹 담체의 고온설계기준)

  • Baek, Seok-Heum;Park, Jea-Sung;Choi, Hyun-Jin;Cho, Seok-Swoo;Joo, Won-Sik
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.173-174
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    • 2008
  • The four-point bending test is a widely used method to determine material parameters. The aim of the present study was to evaluate the flexural strength (or modulus of rupture) and the Weibull modulus of cordierite ceramic substrate by means of four-point bending tests. The strength data from experiments followed Weibull statistics. These data indicate that the fatigue effects are more severe when the substrate temperature in the peripheral region is near $200^{\circ}$. At temperatures well above $200^{\circ}C$ the available design strength can be as high as 65% as substrate's initial strength.

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Solder Joints Fatigue Life of BGA Package with OSP and ENIG Surface Finish (OSP와 ENIG 표면처리에 따른 BGA 패키지의 무연솔더 접합부 피로수명)

  • Oh, Chulmin;Park, Nochang;Hong, Wonsik
    • Korean Journal of Metals and Materials
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    • v.46 no.2
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    • pp.80-87
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    • 2008
  • Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

Characteristics of Structural Behavior of Unplasticized Polyvinyl Chloride (PVC-U) Pipe Buried Underground (지중매설 경질폴리염화비닐관의 구조적 거동)

  • Kim, Sun-Hee;Cheon, Jinuk;Kim, Eung-Ho
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.6 no.4
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    • pp.16-23
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    • 2015
  • The industrialization and urbanization forced to increase the density of pipelines such as water supply, sewers, and gas pipelines. The materials used for the existing pipe lines are mostly composed of concretes and steels, but it is true that the development for more durable and efficient materials has been continued performed to produce long lasting pipe lines. Recently, underground pipes serve in diverse applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. In this paper, we present the result of investigation pertaining to the structural behavior of unplasticized polyvinyl chloride (PVC-U) flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, pipe stiffness, 4-point bending test, experimental and analytical studies are conducted. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is about 8% although there are significant variations in the mechanical properties of the pipe material. In addition, it was found by the 4-point bending test there is no problem in the connection between the pipes by coupler.

Nanoscale Longitudinal Normal Strain Behavior of ${Si_3}{N_4}$-to-ANSI 304L Brazed Joints under Pure Bending Condition

  • Seo, D.W.;Lim, J.K.
    • International Journal of Korean Welding Society
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    • v.4 no.1
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    • pp.46-52
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    • 2004
  • To combine the mechanical advantages of ceramics with those of metals, one often uses both materials within one composite component. But, as known, they have different material properties and fracture behaviors. In this study, a four-point bending test is carried out on $Si_3N_4$ joined to ANSI 304L stainless steel with a Ti-Ag-Cu filler and a Cu interlayer at room temperature to evaluate their longitudinal strain behaviors. And, to detect localized strain, a couple of strain gages are pasted near the joint interfaces of the ceramic and metal sides. The normal strain rates are varied from $3.33{\times}10^5$ to $3.33{\times}10^{-1}s^{-1}$ Within this range, the experimental results showed that the four-point bending strength and the deflection of the interlayer increased with increasing the strain rate.

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Study on the Development of the Digital Image Correlation Measurements Program for Measuring the 3-Point Bending Test (이미지 상관법을 이용한 3 점 굽힘 시험 계측 프로그램 개발 관한 연구)

  • Choi, In Young;Kang, Young June;Hong, Kyung Min;Ko, Kwang Su;Kim, Sung Jong
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.10
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    • pp.889-895
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    • 2014
  • Machine parts and structures of a change in the displacement and strain can be evaluated safety is one of the important factors. Typically the strain gauge has been employed to measure the displacement and strain. However, this contact-type measurement method has disadvantages that are not measured under condition of specific object shape, surface roughness and temperature. In particularly, 3 point bending and 4 point bending test not use strain gauge. So its test used cross head displacement and deflect meter. Digital Image Correlation measurement methods have many advantages. It is non contact-type measurement method to measure the object displacements and strain. In addition, it is possible to measure the Map of full field displacements and strain. In this paper, measured the 3 point bending deflection using the Digital Image Correlation methods. In order to secure the reliability, Digital Image Correlation method and universal test machine were compared.

Tensile damage of reinforced concrete and simulation of the four-point bending test based on the random cracking theory

  • Chang, Yan-jun;Wan, Li-yun;Mo, De-kai;Hu, Dan;Li, Shuang-bei
    • Computers and Concrete
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    • v.30 no.4
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    • pp.289-299
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    • 2022
  • Based on the random cracking theory, the cylinder RVE model of reinforced concrete is established and the damage process is divided into three stages as the evolution of the cracks. The stress distribution along longitude direction of the concrete and the steel bar in the cylinder model are derived. The equivalent elastic modulus of the RVE are derived and the user-defined field variable subroutine (USDFLD) for the equivalent elastic modulus is well integrated into the ABAQUS. Regarding the tensile rebars and the concrete surrounding the rebars as the equivalent homogeneous transversely isotropic material, and the FEM analysis for the reinforced concrete beams is conducted with the USDFLD subroutine. Considering the concrete cracking and interfacial debonding, the macroscopic damage process of the reinforced concrete beam under four-point bending loading in the simulation. The volume fraction of rebar and the cracking degree are mainly discussed to reveal their influence on the macro-performance and they are calibrated with experimental results. Comparing with the bending experiment performed with 8 reinforced concrete beams, the bending stiffness of the second stage and the ultimate load simulated are in good agreement with the experimental values, which verifies the effectiveness and the accuracy of the improved finite element method for reinforced concrete beam.