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  • Seam weld characterization by FEM analysys in aluminium extrusion
  • Abstract In recent years aluminum extruded hollow profiles are increasingly used in near-net shape manufacturing processes such as bending and hydroforming; in fact, by applying these secondary processes, it is possible to obtain very high complex parts, especially for the transport industry. It is known that hollow profiles obtained by direct hot extrusion necessarily have some longitudinal welding lines (so called seam welds) produced inside the die and it is common experience, during secondary forming processes, the appearance of early cracking in proximity of those lines [1,2]. At the same time, the direct hot extrusion is the only process able to…
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  • Elastic analysis in 3D anisotropic functionally graded solids by the MLPG
  • Abstract Functionally graded materials are multi-phase materials with the phase volume fractions varying gradually in space, in a pre-determined profile. This results in continuously graded mechanical properties at the (macroscopic) structural scale. Often, these spatial gradients in material behaviour render FGMs as superior to conventional composites. FGMs possess some advantages over conventional composites because of their continuously graded structures and properties. Due to the high mathematical complexity of the initial-boundary value problems, analytical approaches for elastic analyses of FGMs are restricted to simple geometries and boundary conditions. The elastic analysis in FGM demands an accurate and efficient numerical method.
    In spite…
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  • Three-dimensional simulations on the formation of droplets in a T-type microchannel
  • Abstract To date, miniaturization of fluid handling and fluid analysis devices in the medicine engineering has been emerging in the interdisciplinary research field of micro-fluidics, as a result of miniaturization of the detective device to allow parallelization as well as to reduce analysis time and sample volume. Micro-total-analysis-system (μ -TAS) researches aimed at developing miniaturized and integrated ``lab-on-a-chip'' devices for biochemical analysis applications. Droplet-based micro-mixer is the one of the key components in the developing of μ-TAS. Numerical approach on the dynamic formation of water droplets in a T-type microchannel with a 200μm × 50μm rectangular cross section and 1000μm long…
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  • Numerical simulation of bi-material problems using EFGM
  • Abstract In this work, element free Galerkin method (EFGM) has been applied to solve solid mechanics problems containing material discontinuities. The method is based on treatment of interface conditions at the variational level. Modifications are made in the EFGM to incorporate material discontinuities, which include the variational form of the governing differential equations. Two bi-material problems i.e. beam and bar has been solved using EFGM, and a clear discontinuity in the stress field has been observed at the interface of two materials.
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  • A numerical study of centre crack under thermo-mechanical load using EFGM
  • Abstract In this work, element free Galerkin method (EFGM) has been used to obtain the solution of centre crack problem under thermo-mechanical loads as it provides a versatile technique to model static as well as moving crack problems without any requirement of re-meshing. Diffraction criterion has been used to model crack geometry. The effect of crack orientation of centre crack has been studied under both mechanical and equivalent thermal loading under plane stress conditions. The values of mode-I and mode-II stress intensity factors have been evaluated by the interaction integral approach.
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  • Characterization of impact resistance of lightweight aggregate cellular concretes (LACC)
  • Abstract Concrete structures such as concrete safety barriers are often subjected to direct impact loads mainly due to vehicle crash impact. In this case, the impact resistance is one of the most critical characteristic of concrete used in such structures. The present study aims to characterize the impact resistance of lightweight aggregate cellular concrete (LACC), which will be used in concrete barriers. Impact tests on LACC specimens were carried out based on the repeated drop-weight impact test guideline recommend by ACI committee 544. Impact resistance and compressive strength of the LACC specimens were characterized and the results were used to determine…
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  • Multiphysical simulation of the servo valve in the fuel supply system of auxiliary power unit
  • Abstract In this paper, the three-dimensional model of a servo valve working in the fuel supply system of auxiliary power unit (APU) for the gas turbine engine is studied with numerical simulation of multiphysical system. The physics of electromagnetics, structural dynamics, and fluid dynamics are expressed in the form of independent system of partial differential equations, respectively. A commercial code named COMSOL is used to simulate the essential physics of the servo valve system, and the extracted data is used for the simulation of entire servo valve, which is coupled with torque motor, bushing tube, and valve orifice, etc. The valve…
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  • Experimental study on the wake characteristics of the small ducted fan using a hot-wire anemometery
  • Abstract The experimental study on the wake characteristics of turbomachineries is essential, when developing the turbomachineries such as pumps, fans, compressors, turbines. Various sources of losses are analyzed by studying the wake characteristics of turbomachineries. For more accurate analysis, various types of experimental equipments are used. Because of the high frequency response characteristics, the hot-wire anemometery has been widely used to measure the wake characteristics of the turbomachinery. In this research, the flow fields of the small ducted fan as a propulsion device of small R/C aircraft were measured using a hot-wire anemometry at inlet and outlet to analyze the wake…
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  • Fracture simulation with coupling moisture diffusion effect and external loading in fiber reinforced cementitious composites
  • Abstract Fiber reinforced cementitious composites (FRCC) are the most recently used materials in the civil engineering field due to their mechanical advantages over the cementitious materials. While, the durability performance of cement-based composites can affect the service life of the structural component or system. Sometimes, incompatible behaviors (e.g. thermal expansion, moisture diffusion) among components cause micro-cracking and further durability problems. Physical experimentations have generally been used for understanding the durability of cementitious composites, but increasingly computational simulations are being used to gain new insights. However, the most of existing simulation models are limited in coupling with micro-cracking due to moisture diffusion…
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  • Effects of throttling on the spray injection performance in a small LRE-injector
  • Abstract An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE) because it affects the evaporation rate of liquid fuel through spatial distribution and atomization of spray droplets. This paper is focused on the injection performance of a small LRE-Injector by employing the spray characteristic parameters made up of the velocity components, mean diameter, turbulence intensity, span (width of drop size distribution), number density, and volume flux of spray droplets. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along…
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