Papers by Keyword: Numerical Simulation

Abstract: This paper presents the constructive and functional optimization of a fuel tank designed for the supply system of a spark ignition engine. The study focuses on the use of high-density polyethylene (HDPE) as a lightweight and durable material, aiming to improve fuel efficiency and safety. The 3D model of the tank was developed using CATIA V5. Numerical simulations were performed in ANSYS to evaluate the structural behavior of the tank under pressure and vacuum conditions. Although not part of the formal validation process, these simulations provide valuable insights for improving the tank geometry. The results demonstrate the potential of plastic fuel tanks to meet operational requirements.

Abstract: In bulk SiC crystal growth using the PVT method, recrystallization within the source material leads to a decrease in growth rate and source utilization. In this study, numerical simulations were used to investigate the source temperature distribution and its effect on the growth rate and source utilization. Recrystallization in the upper and lower regions was considered separately. The results showed that reducing the source temperature gradient prevents recrystallization in the upper region, and a unidirectional gradient prevents recrystallization in the lower region, leading to higher growth rates and source utilization.

Abstract: The effect of time-dependent interfacial heat transfer coefficient () within the shot sleeve and die cavity of high pressure die casting process (HPDC) has been simulated to systematically study the solidification occurring during filling. Two different-profiles have been considered with peak values of 7 kW/m²K and 12 kW/m²K for the shot sleeve, and 18 kW/m²K and 26 kW/m²K for the runner, gate, and die cavity based on the values reported in the literature. In addition, two types of gate designs were considered for plate type castings to analyze their solidification behaviour and filling velocity. Solidification typically occurs along the bottom wall of the shot sleeve, from the mid-region toward the mould-side region along the direction of pouring. At the end of filling, the solid fraction () inside the shot sleeve increases from 10 to 18% with increasing peak value for-profiles. Similarly, the solidification around the gate regions progresses rapidly above 0.4 and reduces the fluid velocity at the gate entry for profile with higher peak values. Despite the lack of consensus on the selection of value (peak value and range), this study highlights the influence profiles and gating design on solidification during filling and discusses its implications on the quality of HPDC parts.

Abstract: Warpage in injection-molded thin-walled box-shaped parts is primarily caused by non-uniform cooling and differential shrinkage. This study proposes a two-step, multi-objective optimization strategy to reduce part warpage by addressing both thermal and geometric factors. In the first step, the mold cooling system is optimized through a bi-objective formulation that simultaneously minimizes (i) the temperature standard deviation within the part and (ii) the total cooling channel length. The optimization is carried out using a coupled workflow involving parametric CAD modeling, Autodesk Moldflow simulations, and a genetic algorithm. The optimized cooling design reduces temperature non-uniformity by 44% compared to a conventional cooling layout. In the second step, a geometric optimization is performed through the addition of a reinforcing border, where maximum deflection and total part volume are minimized simultaneously. The combined optimization leads to a reduction in maximum warpage from 14.5 mm in the reference configuration to 2.06 mm in the final design. The results demonstrate the effectiveness of a sequential optimization approach in achieving significant warpage reduction while maintaining material and manufacturing efficiency.

Abstract: This study investigates the structural response of blank-holders (BHs) equipped with spatially distributed magnetorheological (MR) actuators for adaptive deep drawing. While MR actuators provide fast, independent, and high-resolution force modulation, their effectiveness depends critically on the BH’s ability to transmit spatially differentiated loads without excessive diffusion or unrealistic stress localization. The relationships between BH stiffness, actuator spacing, and pressure localization at the sheet interface remain only partially understood, limiting the implementation of distributed blank-holding strategies. To address this gap, a comprehensive finite element (FE) framework is developed, combining a full closed-cup deep-drawing model with a complementary simplified configuration that isolates local deformation mechanisms under single-actuator loading. Parametric analyses examine the influence of BH thickness, local actuator force, and actuator spacing on stress distribution, localization radius, and overlap between adjacent load paths. Results show that BH thickness is the dominant factor governing spatial resolution: thinner BHs enable sharp pressure localization, whereas thicker ones diffuse local loads and suppress stress peaks. The spacing between actuators must therefore be selected as a function of BH stiffness to avoid stress-free regions while preserving distinct pressure footprints. For the reference industrial configuration (60 mm BH thickness), an actuator spacing of approximately 150 mm achieves the optimal compromise between localization capability and continuous sheet support. The proposed framework establishes quantitative design criteria for BH geometries compatible with MR-based adaptive forming and supports the development of next-generation blank-holding systems offering enhanced process stability, reduced scrap, and improved material-flow control.

Abstract: 3D printing parameters such as printing temperatures and speeds play a vital role in the melt flow and printability of thermoplastic filaments in fused filament fabrication (FFF) technology. Inappropriate print settings mainly induce incomplete and poor printing quality due to melt flow instability. This research work focused on modeling the melt flow behavior of polylactic acid (PLA) at different printing temperatures and speeds using computer fluid dynamics (CFD) method. The shear stress and viscosity of PLA were investigated by a melt flow indexer (MFI) and rheometer in temperature ranges of 200 - 240 °C. A model of a capillary tube in MFI was set up with an initial condition of rheological properties from the experiment to simulate the hot melt extrusion relating to the melt flowability of PLA filaments. The high shear stress and low viscosity presented at the edge of filaments at every printing condition. Additionally, the shear stress and viscosity decreased linearly when the printing temperature increased, while the shear stress increased when the printing speed increased. The increase in shear stress caused high surface roughness of PLA specimens after printing. The findings can guide the optimization of the FFF 3D printing process to improve surface finish quality.

Abstract: In the paper the detailed structural changes in the cutting zone were determined using metallography. Accurate determination of parameters such as shear angle, slip angle, chip thickness, cutting ratio, chip separation point, etc. required metallographic analysis on a relatively complex sampling of the cutting area. We performed the analysis on an orthogonal cutting. We achieved orthogonal cutting by turning a thin-walled Inconel 718 and C45 alloy tubes and setting the lath bit cutting edge perpendicular to the tube axis. In real state, the shapes in the cutting zone are more complicated therefore the chip thickness was determined using quantitative metallography from the equality of areas and the resulting point of transition between the chip and the machined surface. The shear angle starts from this point and is a tangent to the cutting edge, the direction of which was determined using the Thales circle. The distance between this point and the machined surface which represents a layer which is not separated from the machined material but is planar deformed was determined too. The depth of the deformed layer and the value of deformation on the machined surface was determined by quantitative metallography. A much simpler numerical simulation was performed with the same parameters using Deform 2D/3D software package. Numerical simulation could not fully replace metallographic analysis, but to some extent numerical simulation can be used instead of metallographic analysis.

Abstract: Several studies have investigated sloshing due to seismic excitation, mainly focusing on baffle effects and cyclic or recorded seismic loads. This study analyzes the seismic impact on an 80,000 m³ fuel storage tank in Tuban, East Java. Seismic events can cause fluid sloshing, increasing pressure on the tank walls and roof. Utilizing general-purpose finite element software, the sloshing phenomena are simulated using input dynamic loading in spectral response acceleration representing typical seismic loading per the Indonesian standard (SNI). It compares the traditional API 620 method with numerical simulations, revealing a 38% difference in sloshing height and a 40% difference in dynamic hoop stress. The numerical simulations predict a lower sloshing height due to unaccounted warm gas pressure, while the traditional method estimates less dynamic hoop stress. Although the API 620 method is more straightforward for design, numerical simulations provide a deeper understanding of sloshing pressure effects, enhancing asset integrity assessment.

Abstract: In a complex medium, particularly soil, understanding water movement is essential for optimizing water management in agricultural and natural ecosystems. This study presents a theoretical and numerical analysis of the influence of temperature variations and root activity on water retention and redistribution in soils with variable saturation. A finite element model was developed to simulate water flow, integrating temperature-dependent hydraulic properties and dynamic root water uptake. Simulations revealed that a 10°C increase in soil temperature can reduce water content by up to 15% in the top 20 cm of soil due to increased evapotranspiration and reduced matric potential. Root water uptake responds dynamically to thermal conditions, with uptake rates increasing by around 20% under moderate warming, particularly in the upper soil layers. These results demonstrate the strong coupling between thermal gradients, root function, and soil moisture distribution. They improve our ability to predict soil-plant-atmosphere interactions under changing climatic conditions and provide valuable information for optimizing irrigation strategies and ensuring sustainable use of water.

Abstract: Magnesium-based bulk metallic glasses (BMGs) present fabrication challenges due to their low glass-forming ability and high critical cooling rate. Copper mold casting, with its high thermal conductivity, is the most viable method for producing Mg-based BMGs, though amorphous diameters typically remain under 10 mm, limiting practical applications. This study uses FLOW-3D CAST simulations to analyze heat transfer and solidification behavior in two copper mold designs. The simulations evaluate flow uniformity, thermal dissipation, and cooling rate distribution, aiming to correlate cooling rate with achievable BMG diameter. The results provide design guidance for casting larger amorphous Mg components.