The Experts below are selected from a list of 6363 Experts worldwide ranked by ideXlab platform

Jiashi Yang - One of the best experts on this subject based on the ideXlab platform.

N.k. Naik - One of the best experts on this subject based on the ideXlab platform.

  • Performance of Ceramic-Composite Armors under Ballistic Impact Loading
    Journal of Materials Engineering and Performance, 2020
    Co-Authors: Santosh Kumar, Kiran Akella, Makarand Joshi, Asim Tewari, N.k. Naik
    Abstract:

    Analysis of typical Ceramic-composite armors is presented for their ballistic impact performance. Specifically, armor configurations are given for enhancing ballistic limit velocity with minimum armor areal density. The studies are performed using the analytical model presented earlier (Naik et al. in Int J Damage Mech 22(2):145–187, 2013). Wave theory and energy balance between the kinetic energy of the moving projectile and the energy absorbed by different mechanisms by both the armor and the projectile are considered. Analytical predictions and typical experimental results available in the literature are compared. A good match is observed. It is observed that in certain range of armor areal density, ballistic limit velocity remains the same. The explanation for such a behavior is provided considering different major energy absorbing mechanisms at different areal densities of the armor. Further, effects of armor configuration, incident impact velocity and Ceramic Plate material on ballistic impact performance are presented. Among the Ceramic Plate materials considered, alumina 99.9% gives higher ballistic limit velocity.

  • Stress wave micro–macro attenuation in Ceramic Plates made of tiles during ballistic impact
    International Journal of Mechanical Sciences, 2014
    Co-Authors: Rahul Goel, Mandar D. Kulkarni, Kedar S. Pandya, N.k. Naik
    Abstract:

    Abstract Stress wave attenuation studies during ballistic impact are presented for longitudinal tensile waves propagating along the planar direction within a Ceramic Plate made of hexagonal tiles bonded with an adhesive. When a stress wave reaches an interface between the Ceramic tile and the adhesive layer, reflection and transmission of the incident stress wave takes place leading to attenuation of the wave. This is because of impedance mismatch at the Ceramic–adhesive and adhesive–Ceramic interfaces. This phenomenon is referred to as macro attenuation. Reflection and transmission of the impact induced stress waves would also take place at the interfaces between grains and grain boundaries within the Ceramic Plate. This would also lead to attenuation of stress waves, and is referred to as micro attenuation. Micro attenuation is modeled using the stress wave attenuation coefficient. Stress wave attenuation studies are carried out based on both micro and macro attenuation. An algorithm is presented for tracking impact induced planar stress waves and predicting their intensities and extent of attenuation. It is observed that stress wave attenuation is significant as the waves propagate within the Ceramic Plate. A combination of micro and macro attenuation would give the correct estimate of planar stress distribution around the point of impact.

Zheng-hua Qian - One of the best experts on this subject based on the ideXlab platform.

  • Propagation of thickness-twist waves in a piezoelectric Ceramic Plate in contact with viscous fluids
    Acta Mechanica, 2009
    Co-Authors: Zheng-hua Qian, Jiashi Yang, Nan Liu, Sohichi Hirose
    Abstract:

    We study theoretically the propagation of thickness-twist waves in an unbounded piezoelectric Ceramic Plate with unattached electrodes and viscous fluids between the Plate surfaces and the electrodes. Based on the theories of piezoelectricity and viscous fluids, an equation that determines the dispersion relations of the waves is obtained, showing the dependence of the phase velocity on material and geometric parameters. Due to the viscosity of the fluid, the dispersion relations are complex in general, representing damped waves with attenuation. The dispersion relations obtained can reduce to the results of a few special cases with known results. The results of the present paper are useful for developing and designing fluid sensors for measuring fluid viscosity or density.

  • Propagation of thickness-twist waves in a piezoelectric Ceramic Plate with unattached electrodes.
    Ultrasonics, 2009
    Co-Authors: Zheng-hua Qian, Kikuo Kishimoto, Jiashi Yang
    Abstract:

    We analyze the propagation of thickness-twist waves in an unbounded piezoelectric Ceramic Plate with air gaps between the Plate surfaces and two electrodes. These waves are also called anti-plane or shear-horizontal waves with one displacement component only. An exact solution is obtained from the equations of the linear theory of piezoelectricity. Dispersion relations of the waves are obtained and plotted. Results show that the wave frequency or speed is sensitive to the air gap thickness. This effect can be used to manipulate the behavior of the waves and has implications in acoustic wave devices.

Qiuwang Wang - One of the best experts on this subject based on the ideXlab platform.

  • Numerical analysis of steady state and transient analysis of high temperature Ceramic Plate-fin heat exchanger
    Nuclear Engineering and Design, 2014
    Co-Authors: Vijaisri Nagarajan, Yitung Chen, Qiuwang Wang, Ting Ma
    Abstract:

    Abstract In this study three-dimensional model of Ceramic Plate-fin high temperature heat exchanger with different fin designs and arrangements is analyzed numerically using ANSYS FLUENT and ANSYS structural module. The ability of Ceramics to withstand high temperature and corrosion makes silicon carbide (SiC) suitable candidate material to be used in high temperature heat exchanger. The operating temperature of heat exchanger is 950 °C and the operating pressure is 1.5 MPa. The working fluids are helium, sulfur trioxide, sulfur dioxide, oxygen and the water vapor. Fluid flow and heat transfer analysis are carried out for steady and transient state in FLUENT. The obtained thermal and pressure load for the steady and transient state from ANSYS FLUENT are imported to ANSYS structural module to obtain the principal stress and the factor of safety. Different arrangements of rectangular fins, triangular fins, inverted bolt fins and ripsaw fins are studied. From the results it is found that the minimum stress and the maximum safety factor are obtained for inverted bolt fins. The triangular fins have the maximum principal stress and minimum factor of safety. However, the fluid flow and heat transfer analysis show inverted bolt fins and triangular fins produce higher pressure drop and friction factor. The steady state maximum principal stress is 10.08 MPa, 9.90 MPa and 11.43 MPa for straight, staggered and top and bottom ripsaw fin arrangement. The corresponding safety factors are 21.80, 21.95 and 19.01, respectively. The ripsaw fin design is chosen to be the best design since it gives less stress, more safety factor, less pressure drop, friction factor and reasonable heat transfer rate. From the results it is also found that thermal stress is more significant than the mechanical stress.

  • hydraulic and thermal performances of a novel configuration of high temperature Ceramic Plate fin heat exchanger
    Applied Energy, 2014
    Co-Authors: Vijaisri Nagarajan, Yitung Chen, Qiuwang Wang
    Abstract:

    A novel fin configuration for high temperature Ceramic Plate-fin heat exchanger (PFHE) was developed using the three-dimensional computational fluid dynamics (CFD) FLUENT code. Numerical analysis was carried out for different types of fins and their results were compared with the selected design. The working fluids used in the model were sulfur trioxide, sulfur dioxide, oxygen and water vapor. Fluid flow, heat transfer, pressure drop and properties like Nusselt number, friction factor and j-factor were studied for various fin configurations. The rip saw fin design (case 9) with thickness of 0.05mm gives the maximum heat transfer performance with less pressure drop and friction factor. The numerical result was compared with the analytical result for rectangular fins and they were found to be in reasonable agreement. In addition to it, the results from the selected ripsaw design were compared with the result from the model with no fins (case 1). It was found that thermal enhancement factor of 2.3211 and average Nusselt number of 4.215 was obtained for the selected design. The results of the rip saw fin design were found in good agreement with the analytical results of a rectangular fin. Further effects of Reynolds number on pressure drop and Nusselt number were studied.

  • Hydraulic and Thermal Performances of a High Temperature Ceramic Plate-Fin Heat Exchanger (PFHE)
    2013
    Co-Authors: Vijaisri Nagarajan, Yitung Chen, Qiuwang Wang, Ting Ma
    Abstract:

     Meshing was done in Ansys Workbench. Selected number of nodes and faces for ripsaw fin design were 532,599 and 1,496,152  The heat exchanger dimensions were taken from Ponyavin et al. and they are in the order of few millimeters  The mass flow rate for the cold flow was 3.148•10-6 kg/s and the hot flow was 1.409•10-6 kg/s for a single channel  Heat transfer and friction factor results for rectangular and ripsaw fin designs were validated with the correlations obtained from Manson  Nine different fin designs with single-banking configuration were modeled  The current study has hot channel (helium), cold channel (SO3, SO2, O2 and water vapor) and separating solid (SiC)  Rectangular, triangular, bolt type and ripsaw fin designs were modeled Geometry of various fin designs

Kikuo Kishimoto - One of the best experts on this subject based on the ideXlab platform.

  • Propagation of thickness-twist waves in a piezoelectric Ceramic Plate with unattached electrodes.
    Ultrasonics, 2009
    Co-Authors: Zheng-hua Qian, Kikuo Kishimoto, Jiashi Yang
    Abstract:

    We analyze the propagation of thickness-twist waves in an unbounded piezoelectric Ceramic Plate with air gaps between the Plate surfaces and two electrodes. These waves are also called anti-plane or shear-horizontal waves with one displacement component only. An exact solution is obtained from the equations of the linear theory of piezoelectricity. Dispersion relations of the waves are obtained and plotted. Results show that the wave frequency or speed is sensitive to the air gap thickness. This effect can be used to manipulate the behavior of the waves and has implications in acoustic wave devices.