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F Mujika - One of the best experts on this subject based on the ideXlab platform.

  • new correction terms concerning three Point and four Point Bending tests
    Polymer Testing, 2016
    Co-Authors: F Mujika, A Arrese, I Adarraga, Usue Oses
    Abstract:

    Abstract The present study deals with the effect of the variation of the contact Point between the support and load application rollers in three-Point and four-Point Bending tests and the possible influence of horizontal reactions, under the assumption of small Bending angles. Therefore, this study includes some factors that were not taken into account when the effect of horizontal displacements that generate span variation was investigated by the first author. The analytic approaches corresponding to three-Point and four-Point Bending have been compared with experimental results that correspond to a unidirectional carbon/epoxy specimen. The flexural modulus obtained with the new approach in all experimental conditions is near constant. Moreover, the calculated load-displacement curves obtained with that modulus matches the experimental curves.

  • Determination of compressive strength of unidirectional composites by three-Point Bending tests
    Polymer Testing, 2009
    Co-Authors: N. Carbajal, F Mujika
    Abstract:

    Abstract A simple way for obtaining compressive strength of unidirectional composites by three-Point Bending tests is proposed in the present work. The interpretation of test results includes the stress singularity induced by the applied concentrated load and the determination of the contact zone between loading roller and specimen. Unidirectional carbon/epoxy composite T6T/F593 from Hexcel Composites has been tested by three-Point Bending with different thicknesses and spans. When failure occurs by compressive stresses, experimental results agree with the strength obtained by compressive tests. The best agreement is obtained in the case of 7 mm nominal thickness and span of 120 mm.

  • On the effect of shear and local deformation in three-Point Bending tests
    Polymer Testing, 2007
    Co-Authors: F Mujika
    Abstract:

    Abstract The three-Point Bending test is analysed taking into account shear and local deformation effects in the load application and supports. A new procedure is proposed in order to obtain flexural modulus, shear modulus and local deformation stiffness. Indentation tests and three-Point Bending tests at five different spans have been carried out on two specimens of T6T/F593 carbon/epoxy unidirectional composite. Since local deformation effects are not linear, slopes of load–deflection curves have been determined in three fixed strain ranges and a fixed load range. The best results have been obtained for the highest strain range, as local deformation effects can be considered linear. It has been seen that local deformation effects can have even more importance than shear effects in the case of small spans and large thickness.

Norman A. Fleck - One of the best experts on this subject based on the ideXlab platform.

  • Optimal design of box-section sandwich beams in three-Point Bending
    International Journal of Solids and Structures, 2006
    Co-Authors: Son Phu Mai, Norman A. Fleck
    Abstract:

    Minimum mass designs are obtained for box-section sandwich beams of various cross-sections in three-Point Bending. The overall compliance of the hollow, tubular beams are decomposed additively into a global contribution due to macroscopic Bending (Timoshenko beam theory) and a local contribution associated with transverse deflection of the walls of the hollow beam adjacent to the central loading patch. The structural response is analysed for beams of square sections with various internal topologies: a solid section, a foam-filled tube with monolithic walls, a hollow tube with walls made from sandwich plates, and a hollow tube with walls reinforced by internal stiffeners. Finite element analysis is used to validate analytical models for the overall stiffness of the tubes in three-Point Bending. Minimum mass designs are obtained as a function of the overall stiffness, and the relative merits of the competing topologies are discussed.

Son Phu Mai - One of the best experts on this subject based on the ideXlab platform.

  • Experiment on box-section sandwich beams in three-Point Bending
    Journal of Sandwich Structures & Materials, 2014
    Co-Authors: Son Phu Mai
    Abstract:

    The structural stiffness is explored for box-section beams in three-Point Bending. Four hollow tubes of various topologies are designed, manufactured and tested. The observed results show that a si...

  • Optimal design of box-section sandwich beams in three-Point Bending
    International Journal of Solids and Structures, 2006
    Co-Authors: Son Phu Mai, Norman A. Fleck
    Abstract:

    Minimum mass designs are obtained for box-section sandwich beams of various cross-sections in three-Point Bending. The overall compliance of the hollow, tubular beams are decomposed additively into a global contribution due to macroscopic Bending (Timoshenko beam theory) and a local contribution associated with transverse deflection of the walls of the hollow beam adjacent to the central loading patch. The structural response is analysed for beams of square sections with various internal topologies: a solid section, a foam-filled tube with monolithic walls, a hollow tube with walls made from sandwich plates, and a hollow tube with walls reinforced by internal stiffeners. Finite element analysis is used to validate analytical models for the overall stiffness of the tubes in three-Point Bending. Minimum mass designs are obtained as a function of the overall stiffness, and the relative merits of the competing topologies are discussed.

Ji Hoon Kim - One of the best experts on this subject based on the ideXlab platform.

  • measurement of the bauschinger behavior of sheet metals by three Point Bending springback test with pre strained strips
    International Journal of Plasticity, 2014
    Co-Authors: Shunlai Zang, Myounggyu Lee, Li Sun, Ji Hoon Kim
    Abstract:

    In this paper, a novel approach is proposed to measure the Bauschinger effect, transient behavior and permanent softening of metallic sheet subjected to reverse loading. The hardening parameters related to the Bauschinger effect, transient behavior and permanent softening are optimized from the springback profiles of three-Point Bending tests with pre-strained sheets. Taking the dual phase steel sheet DP780 as an example, its Bauschinger effect, transient behavior and permanent softening determined from the new approach are compared with those of the cyclic simple shear method. Finite element simulations are also performed for three-Point Bending and U-draw/Bending of base (as-received) and pre-strained DP780 steel sheets to validate the suggested approach. The results show that the aforementioned hardening behavior determined from the new approach shows good agreements with those of cyclic simple shear tests. Moreover, reasonable springback predictions for three-Point Bending and U-draw/Bending tests are obtained as well. In particular, the proposed approach is quite suitable for the industrial applications because only uni-axial tension and three-Point Bending tests are required.

Hiroshi Yoshihara - One of the best experts on this subject based on the ideXlab platform.

  • Measurement of the Shear Properties of Extruded Polystyrene Foam by In-Plane Shear and Asymmetric Four-Point Bending Tests
    Polymers, 2019
    Co-Authors: Hiroshi Yoshihara, Makoto Maruta
    Abstract:

    The shear modulus and shear strength of extruded polystyrene foam were obtained by the in-plane shear and asymmetric four-Point Bending tests. In addition, the test data were numerically analysed, and the effectiveness of these tests was examined. The numerical and experimental results suggest that the shear modulus and shear strength obtained from the in-plane shear test are significantly smaller than those obtained from the asymmetric four-Point Bending test because the influence of the stress concentration was less significant. Although the in-plane shear test is standardised in ASTM C273/C273M-11, it is considerable to adopt the asymmetric four-Point Bending test as another candidate for obtaining the shear properties of extruded polystyrene foam.

  • mode ii fracture mechanics properties of wood measured by the asymmetric four Point Bending test using a single edge notched specimen
    Engineering Fracture Mechanics, 2008
    Co-Authors: Hiroshi Yoshihara
    Abstract:

    Abstract Using a single-edge-notched specimen of spruce, an asymmetric four-Point Bending test was conducted to obtain the mode II fracture toughness GIIc and critical stress intensity factor KIIc, and the test method was numerically and experimentally analyzed. A three-Point bend end-notched flexure test was also conducted and the results were compared with those of the asymmetric four-Point Bending tests. The crack length had a small influence on the load/loading-line displacement relationship in the asymmetric four-Point Bending test, so it was difficult to determine the value of GIIc, which requires the measurement of loading-line displacement. In contrast, the value of KIIc obtained by two tests was similar when the initial crack length ranged from 0.7 to 0.85 times the depth of the specimen. These results show that the asymmetric four-Point Bending test is a promising means of determining KIIc.

  • Measurement of the shear modulus of wood by asymmetric four-Point Bending tests
    Journal of Wood Science, 2002
    Co-Authors: Hiroshi Yoshihara, Yoshitaka Kubojima
    Abstract:

    We conducted asymmetric four-Point Bending tests of wood and obtained the shear moduli on the basis of Timoshenko's theory of Bending. Akamatsu (Japanese red pine,Pinus densiflora D. Don) and shioji (Japanese ash,Fraxinus spaethiana Lingelsh.) were used for the tests. Asymmetric four-Point Bending tests were undertaken by varying the depth/span ratios; and Young's modulus and the shear modulus were calculated by Timoshenko's Bending theory. Independent of the asymmetric Bending tests, we also conducted three-Point Bending tests, free-freeflexural vibration tests, and numerical calculations by the finite element method. Young's and shear moduli obtained by these methods were compared with those derived from the asymmetric Bending tests. Based on these comparisons, we concluded that the shear modulus can be properly obtained by the asymmetric four-Point Bending tests when the span is 20 times larger than the depth.