The Experts below are selected from a list of 15003 Experts worldwide ranked by ideXlab platform

Lai Fei Cheng - One of the best experts on this subject based on the ideXlab platform.

  • Effect of CVD ZrB2 coating thickness on anti-ablation performance of C/SiC composites
    Ceramics International, 2018
    Co-Authors: Lai Fei Cheng, Baisheng Ma, Li Tong Zhang
    Abstract:

    Abstract In this study, ZrB 2 coatings with different thicknesses were prepared using chemical vapor deposition on SiC (~100 µm in thickness) coated C/SiC (SiC-C/SiC) composites, and the ablation behaviors were investigated using oxyacetylene torch tests for 20 s. SiC-C/SiC composites with ZrB 2 coatings exhibited improved anti-ablation properties compared to uncoated composites, but anti-ablation properties first increased and then decreased with an increase in ZrB 2 coating thickness. Composites with 10 µm ZrB 2 coating exhibited the best anti-ablation properties, and linear and mass ablation rates were reduced by 38% and 61%, respectively, compared to uncoated composites. Anti-ablation properties of composites with thicker ZrB 2 coatings decreased because of cracks and defects in coatings caused by Residual Thermal Stress that resulted from differences in Thermal expansion coefficients between the coating and substrate. During oxyacetylene torch tests, ZrB 2 and SiC were oxidized to ZrO 2 and SiO 2 and formed four layers as Thermal barriers that provided ablation protection for inner part and prevented it from being further ablated.

  • Effect of heat treatment on the riveted joints of two-dimensional C/SiC composites
    Composites Part B-engineering, 2017
    Co-Authors: Ding Zhang, Lai Fei Cheng
    Abstract:

    Abstract A kind of riveting method for 2D C/SiC composites by chemical vapor infiltration were presented and the effect of heat treatment on the riveted joints of 2D C/SiC has been investigated through X-ray tests, mechanical tests, microstructural characterization and industrial computed tomography tests. The experimental results pointed that the order of heat treatment process and riveting process is a key factor affecting the micro-structures, total numbers of delamination defects, fiber pulling out length and tensile fracture strength of 2D C/SiC riveted joints. The heat treatment process after riveting can release assembly Stress and Residual Thermal Stress, and reduce the delamination defects in riveted joints, while the heat treatment process before riveting could increase the delamination defects and enlarge the braided holes in the riveted joints. The tensile strength increased by 23.2% when the riveted joints are riveted followed with heat treatment process, and the tensile strength of riveted joints decreased by 27.1% if the two processes are reversed.

  • Proportional Limit Stress and Residual Thermal Stress of 3D SiC/SiC Composite
    Journal of Materials Science & Technology, 2014
    Co-Authors: Shanhua Liu, Li Tong Zhang, Xiaowei Yin, Yongsheng Liu, Lai Fei Cheng
    Abstract:

    Proportional limit Stress (PLS) and Residual Thermal Stresses (RTS) of 3D SiC/SiC composite were investigated. PLS was obtained by four different methods from the monotonic Stress–strain response curve to get a convincing value. RTS in the SiC matrix was quantified by solving the geometric intersection point of the regression lines of hysteresis loops from the periodical loading–unloading–reloading cycle test curve. Classical ACK model and analytical formulas were used to analytically calculate the PLS and RTS of 3D SiC/SiC composite. Good agreement between the experimental results and the analytical calculation was observed. And relationship between the PLS and the RTS of 3D SiC/SiC was discussed.

Li Tong Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Effect of CVD ZrB2 coating thickness on anti-ablation performance of C/SiC composites
    Ceramics International, 2018
    Co-Authors: Lai Fei Cheng, Baisheng Ma, Li Tong Zhang
    Abstract:

    Abstract In this study, ZrB 2 coatings with different thicknesses were prepared using chemical vapor deposition on SiC (~100 µm in thickness) coated C/SiC (SiC-C/SiC) composites, and the ablation behaviors were investigated using oxyacetylene torch tests for 20 s. SiC-C/SiC composites with ZrB 2 coatings exhibited improved anti-ablation properties compared to uncoated composites, but anti-ablation properties first increased and then decreased with an increase in ZrB 2 coating thickness. Composites with 10 µm ZrB 2 coating exhibited the best anti-ablation properties, and linear and mass ablation rates were reduced by 38% and 61%, respectively, compared to uncoated composites. Anti-ablation properties of composites with thicker ZrB 2 coatings decreased because of cracks and defects in coatings caused by Residual Thermal Stress that resulted from differences in Thermal expansion coefficients between the coating and substrate. During oxyacetylene torch tests, ZrB 2 and SiC were oxidized to ZrO 2 and SiO 2 and formed four layers as Thermal barriers that provided ablation protection for inner part and prevented it from being further ablated.

  • Proportional Limit Stress and Residual Thermal Stress of 3D SiC/SiC Composite
    Journal of Materials Science & Technology, 2014
    Co-Authors: Shanhua Liu, Li Tong Zhang, Xiaowei Yin, Yongsheng Liu, Lai Fei Cheng
    Abstract:

    Proportional limit Stress (PLS) and Residual Thermal Stresses (RTS) of 3D SiC/SiC composite were investigated. PLS was obtained by four different methods from the monotonic Stress–strain response curve to get a convincing value. RTS in the SiC matrix was quantified by solving the geometric intersection point of the regression lines of hysteresis loops from the periodical loading–unloading–reloading cycle test curve. Classical ACK model and analytical formulas were used to analytically calculate the PLS and RTS of 3D SiC/SiC composite. Good agreement between the experimental results and the analytical calculation was observed. And relationship between the PLS and the RTS of 3D SiC/SiC was discussed.

Hong-yuan Liu - One of the best experts on this subject based on the ideXlab platform.

  • Carbon fibre pullout under the influence of Residual Thermal Stresses in polymer matrix composites
    Computational Materials Science, 2012
    Co-Authors: Yuan Yuan Jia, Wenyi Yan, Hong-yuan Liu
    Abstract:

    Abstract A single carbon fibre pullout from a polymer matrix under the influence of Residual Thermal Stresses was numerically investigated in this paper. The finite element method was first applied to obtain the Residual Thermal Stress components along the interface between the fibre and the matrix due to curing. Four typical carbon fibres, T300, AS4, T800HB-40B and IM7 with anisotropic properties embedded in epoxy matrix HY6010 were considered. A comparison study indicates that simplified isotropic fibre model would overestimate the compressive Residual axial and interfacial radial Stress by up to 30%. Therefore, the anisotropic material properties of the fibres should be considered in the theoretical study of carbon fibre pullout. The cohesive zone model was then used to study the single carbon fibre pullout test. The numerical results indicate that the Residual Thermal Stresses have a significant influence on fibre pullout at the stage of frictional sliding after interfacial debonding, which leads higher specific pullout energy. The effects of interfacial bonding condition and the fibre geometry were investigated by a parametric study. An interesting finding is that the interfacial shear strength, which is defined as the ratio of the debonding force to the embedded area, is not a constant. It decreases with the increase in the fibre embedded length. In addition, the fibre pullout energy per unit interfacial area (specific pullout energy) increases with the embedded length due to the effect of Residual Thermal Stresses and interfacial friction. But the specific pullout energy does not depend on the fibre radius, which means that reducing fibre radius alone would not enhance the fibre bridging effect.

P. M. Lesne - One of the best experts on this subject based on the ideXlab platform.

  • Residual Thermal Stresses in the pull-out specimen: A finite element calculation
    Journal of Materials Science, 1995
    Co-Authors: F. H. Leroy, M. H. Auvray, P. M. Lesne
    Abstract:

    The Residual Thermal Stress field in the pull-out specimen is calculated in the case of a high properties thermoset system (carbon-bismaleimide). The calculation is performed within the framework of the linear theory of elasticity by means of a finite element method. The specimen is modelled as a three-phase composite (holder-fibre-matrix). The meniscus which forms at the fibre entry is taken into account in order to provide a realistic Stress concentration. The latter is far higher than the matrix strength. Evidence that fibre debonding propagates from the fibre end during cooling is then produced.

Klaus Friedrich - One of the best experts on this subject based on the ideXlab platform.

  • Single fibre transverse debonding: Stress analysis of the Broutman test
    Composites Part A: Applied Science and Manufacturing, 2000
    Co-Authors: T. Schüller, W. Beckert, Bernd Lauke, Christophe Ageorges, Klaus Friedrich
    Abstract:

    The paper presents an extended analytical approach for the interfacial transverse Stress that is generated by the Broutman test specimen under compression. The analysis is based on the division of the specimen into a bulk region and a near fibre region. Treating separately each region a compound equation for the interfacial Stress can be derived. The equation also includes Residual Thermal Stress and fibre anisotropy. A 3D finite element model was used to validate the approach. The calculations are performed for two commonly used material systems (carbon/glass fibre, epoxy resin). A comparison between the finite element results and the analytical solutions indicates that the accuracy of the analytical approach is very good.