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  • Open Access


    Use of Flow Simulation to Develop Robust Injection and Vent Schemes that Account for Process and Material Variability in Liquid Composite Molding Process

    J. Wang1, E. Andres, P. Simacek, S.G.Advani

    CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.3, pp. 155-182, 2012, DOI:10.3970/cmes.2012.088.155

    Abstract In Liquid Composite Molding (LCM) processes, the process design requires an infusion and venting scheme which will saturate all the empty spaces between the fibers during mold filling resulting in a composite part without voids. However, the inherent material and process variability can change the filling patterns significantly which complicate this task. The objective of this work is to develop methodologies and tools to automate infusion process design and integrate it within the CAD design environment. The methodologies and algorithms developed examine the designed part geometry and material layups for ease of manufacturing with feasible infusion schemes by accounting for… More >

  • Open Access


    Numerical Simulation of Gas-assisted Injection Molding Process for A Door Handle

    Qiang Li, Jie Ouyang1, Xuejuan Li2, Guorong Wu2, Binxin Yang2

    CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 247-268, 2011, DOI:10.3970/cmes.2011.074.247

    Abstract A unified mathematical model is proposed to predict the short shot, primary and secondary gas penetration phenomenon in gas-assisted injection molding (GAIM) process, where the Cross-WLF model and two-domain modified Tait equation are employed to simulate the melt viscosity and density in the whole process, respectively. The governing equations of two-phase flows including gas, air and polymer melt are solved using finite volume method with SIMPLEC technology. At first, two kinds of U-shaped gas channels are modeled, where the shape corner and generous corner cases are studied. At last, as a case study, the short shot, primary and secondary gas… More >

  • Open Access


    Numerical Simulation of Melt Filling and Gas Penetration in Gas Assisted Injection Molding

    Qiang Li1, Jie Ouyang1, Guorong Wu1, Xiaoyang Xu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 215-232, 2011, DOI:10.32604/cmes.2011.082.215

    Abstract The governing equations of two-phase flows including gas and polymer melt are presented, which are solved using finite volume and domain extension methods with SIMPLEC technology. The melt filling and primary gas penetration in gas-assisted injection molding (GAIM) process are simulated, where the Cross-viscosity model is employed to describe the melt rheological behavior, and the CLSVOF(coupled Level Set and Volume of fluid) method is employed to capture the moving interfaces. In order to test and verify the coupled methods, melt filling in a rectangular plate with an insert is simulated, and the numerical results are in good agreement with those… More >

  • Open Access


    Computations of a Compressible Turbulent Flow in a Rocket Motor-Chamber Configuration with Symmetric and Asymmetric Injection

    W.A. El-Askary1,2, A. Balabel2, S.M. El-Behery2, A. Hegab3

    CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.1, pp. 29-54, 2011, DOI:10.32604/cmes.2011.082.029

    Abstract In the present paper, the characteristics of compressible turbulent flow in a porous channels subjected to either symmetric or asymmetric mass injection are numerically predicted. A numerical computer-program including different turbulence models has been developed by the present authors to investigate the considered flow. The numerical method is based on the control volume approach to solve the governing Reynolds-Averaged Navier-Stokes (RANS) equations. Turbulence modeling plays a significant role here, in light of the complex flow generated, so several popular engineering turbulence models with good track records are evaluated, including five different turbulence models. Numerical results with available experimental data showed… More >

  • Open Access


    Improved Material Point Method for Simulating the Zona Failure Response in Piezo-Assisted Intracytoplasmic Sperm Injection

    Y. Gan1, Z. Chen2,3, S. Montgomery-Smith4

    CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.1, pp. 45-76, 2011, DOI:10.3970/cmes.2011.073.045

    Abstract The material point method (MPM), which is an extension from computational fluid dynamics (CFD) to computational solid dynamics (CSD), is improved for the coupled CFD and CSD simulation of the zona failure response in piezo-assisted intracytoplasmic sperm injection (piezo-ICSI). To evaluate the stresses at any zona material point, a plane stress assumption is made in the local tangent plane of the membrane point, and a simple procedure is proposed to find the effective point connectivity for the orientation of the local tangent plane. With an iterative algorithm in each time step, the original MPM is improved to better simulate fluid… More >

  • Open Access


    Modeling and Solution for Gas Penetration of Gas-Assisted Injection Molding Based on Perturbation Method

    Huamin Zhou1, Hua Zhang, Dequn Li2

    CMES-Computer Modeling in Engineering & Sciences, Vol.46, No.3, pp. 209-220, 2009, DOI:10.3970/cmes.2009.046.209

    Abstract Gas-assisted injection molding is an innovative process to manufacture hollow polymeric products, in which gas penetration is the primary and key problem. An analytical solution of the gas penetration interface is presented, based on perturbation method. First, the governing equations and boundary conditions are transformed to be dimensionless, where Capillary number Ca is introduced. Then matching asymptotic expansion method is applied to solve these equations, by using Ca and as perturbation parameters to get the inner and outer solutions, respectively. By matching these two solutions, the analytical model of gas penetration is obtained. More >

  • Open Access


    A Real-Coded Hybrid Genetic Algorithm to Determine Optimal Resin Injection Locations in the Resin Transfer Molding Process

    R. Mathur1, S. G. Advani2, B. K. Fink3

    CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.5, pp. 587-602, 2003, DOI:10.3970/cmes.2003.004.587

    Abstract Real number-coded hybrid genetic algorithms for optimal design of resin injection locations for the resin transfer molding process are evaluated in this paper. Resin transfer molding (RTM) is widely used to manufacture composite parts with material and geometric complexities, especially in automotive and aerospace sectors. The sub-optimal location of the resin injection locations (gates) can leads to the formation of resin starved regions and require long mold fill times, thus affecting the part quality and increasing manufacturing costs. There is a need for automated design algorithms and software that can determine the best gate and vent locations for a composite… More >

  • Open Access


    Numerical Solutions of Unsteady MHD Flow Heat Transfer Over a Stretching Surface with Suction or Injection

    G. Venkata Ramana Reddy1,*, Y. Hari Krishna1

    FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.3, pp. 213-222, 2018, DOI: 10.3970/fdmp.2018.00411

    Abstract The objective of the present problem is to investigate a two-dimensional unsteady flow of a viscous incompressible electrically conducting fluid over a stretching surface taking into account a transverse magnetic field of constant strength. Applying the similarity transformation, the governing boundary layer equations of the problem converted into nonlinear ordinary differential equations and then solved numerically using fourth order Runge-Kutta method with shooting technique. The effects of various parameters on the velocity and temperature fields as well as the skin-friction coefficient and Nusselt number are presented graphically and discussed qualitatively. More >

  • Open Access


    Experimental study of interfacial phenomena between the heavy oil and maximum solvent concentration as function of injection pressures

    Hameed Muhamad1, Simant Upreti 2, Ali Lohi3, Huu Doan4

    FDMP-Fluid Dynamics & Materials Processing, Vol.12, No.3, pp. 111-123, 2016, DOI:10.3970/fdmp.2016.012.111

    Abstract Heavy Oil is an up and coming energy resource that is aggressively being sought after as the world’s energy demand increases. As technology continues to improve, this once costly energy source is quickly becoming a more viable alternative. Vapor extraction (Vapex) process is an emerging technology for viscous oil recovery that has gained much attention in the oil industry. The vapor extraction of heavy oil system is presented to describe experimental setups and procedures used to perform different experiments of vape extraction process. The generated experimental data were used to calculate the live oil maximum interfacial solvent concentration as function… More >

  • Open Access


    Arrangement of Monomer Injection in the Characteristics of Copolymer

    Mohsen Ghorbani1, Hossein Eisazadeh2

    FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.2, pp. 153-164, 2010, DOI:10.3970/fdmp.2010.006.153

    Abstract Polypyrrole/Poly(vinyl acetate) (PPy/PVAc) copolymer was prepared by the copolymerization of vinyl acetate and pyrrole using FeCl3and benzoylperoxide as an oxidant in the presence of various surfactants such as sodium dodecylbenzenesulfonate and poly(ethylene glycol) in the aqueous/non-aqueous media. The PPy/PVAc copolymer was characterized in terms of conductivity, morphology, chemical structure, particle size and yield. The results indicate that the morphology, particle size, yield and electrical conductivity of the products are dependent on the type of surfactant and the arrangement of monomer injection. The chemical structure of obtained product was determined by FTIR spectroscopy. By comparison FTIR spectra between pure PPy and… More >

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