Papers by Keyword: Simulation

Abstract: In the present study, a two-dimensional steady state laminar flow model was developed using fluent software in order to investigate the possibility of achieving Mg/Al cladding using a horizontal twin roll caster. The effects of parameters such as upper and lower inlets casting sequence, solidification length on the temperature field at the bond interface and outlet thickness direction were investigated. The feasibility of the model was verified by combining with experiments. The results show that the molten A5052 alloy with a high melting point is more suitable to be cast by the lower roll at the roll speed of 9 m/min and the roll gap of 5 mm. The temperature of the A5052 and AZ91 near the bond interface of the clad strip can be controlled by the solidification length. Numerical simulations can provide guidance for the optimal casting process parameters.

Abstract: The present research targeted the measurement of flue gas flow rates in industrial boiler applications, to improve boiler efficiency in Sri Lanka. This study discussed three methodologies for flow measurement and placed significant emphasis on the benefits of thermal mass flow meters, given their accuracy and reliability, especially within low flow rates. A thorough literature review was conducted to pinpoint critical parameters involved in the generation of boiler performance: flue gas composition and draft regulation. This research spotlights the deficiency in the current measurement practices, hence, a systematic approach to develop, a cost-effective and regionally adaptable solution is presented for the flue gas flow measurement. The investigation validates the proposed measurement techniques by using a combination of theoretical analysis and CFD simulations and demonstrates that the simulated flow rates are close to calculated values, with minimum differences of 0.000461 kg/s. results imply that the optimization of flue gas flow measurement can result in significant enhancements in combustion efficiency. The research ultimately contributes to the betterment of boiler operation practices in Sri Lanka by providing recommendations for future studies and practical implementations to enhance resource management and environmental sustainability within the industrial sector.

Abstract: Cleaner melt transfer is critical to the broader use of recycled aluminium alloys in high-end structural casting applications, where oxide bifilms and intermetallic inclusions, such as Fe-containing intermetallics, can significantly affect the casting's mechanical properties. In counter-gravity low- and high-pressure casting, the launder system must not only promote the sedimentation of inclusions but also deliver a stable, cleaner melt to the crucible. Prior research showed that 15° double baffles in the mid-section of the sedimentation launder at a flow rate of 100 kg·h^-1 provide high efficiency. The present work investigates the influence of baffle design at the launder-crucible interface, where the melt enters the crucible before casting. Fluid dynamic simulations were carried out at a 100 kg·h^-1 flow rate for three inlet configurations: (i) full baffle; (ii) lifted baffle; and (iii) split baffle. Inclusions of various densities and diameters were tracked. Results indicate that the full baffle, while beneficial as a benchmark and efficient, is impractical because it generates fresh oxide surfaces. The lifted baffle provided the most effective reduction in inclusions, like the full baffle setup, enhancing sedimentation and suppressing entrainment, while the split baffle showed intermediate behaviour. Moreover, the lifted configuration promoted centrifugal flow (at lower velocities, it still made a partial contribution) within the crucible, directing inclusions towards the crucible wall and the stagnation-velocity zone, and enabling the crucible itself to act as a final sedimentation stage before the counter-gravity pump extracts the melt. These results demonstrate that combining mid-launder optimisation with crucible inlet baffle design enables cleaner, more automated melt delivery, thereby strengthening the use of recycled aluminium alloys in structural casting applications.

Abstract: The mechanical joining of continuous fiber-reinforced thermoplastics (cFRTP) and metal sheets represents a promising approach for manufacturing hybrid lightweight structures. To reduce the time and cost associated with extensive experimental investigations, numerical modeling strategies are increasingly applied. In this numerical study, a further step in the modelling strategy for the direct pin-pressing (DPP) process of cFRTP and metal sheets is presented. The study focuses on modeling and simulating the occurring deformation mechanisms of decomposition, compaction, and separation of individual rovings on the mesoscale to analyze the resulting material structure. For this purpose, two simplified models were derived. The textile architecture is represented based on micrographs of cross-sections and discretized using the finite element method. The deformation of individual rovings during joining leads to a deformation of their initial elliptical cross section. To capture this level of resolution, both a cohesive zone and a pure contact approach are applied within the rovings. The highly viscous thermoplastic melt is modeled as a fluid employing the Arbitrary Lagrange–Eulerian (ALE) method. Matrix and roving meshes are coupled to account for fluid–structure interaction (FSI) during process. The study shows that coupling of matrix and rovings is necessary to obtain more accurate predictions of the deformation behaviour. Furthermore, the cohesive zone approach is better suited to simulate the emerging deformation mechanisms.

Abstract: A new efficient numerical solver inspired by front-tracking concepts is implemented within the DIGIMU® framework to accelerate full-field simulations of microstructural evolution. The solver is applied to AISI 304L stainless steel and compared with the conventional level-set formulation under laboratory hot-torsion tests and industrial multi-pass hot rolling conditions. After a limited recalibration of grain boundary mobility and solute drag parameters, both solvers provide comparable predictions of recrystallization kinetics, grain size evolution and final microstructures. The new solver achieves a reduction in computational cost close to two orders of magnitude, while preserving the predictive capabilities of DIGIMU®, thereby enabling more efficient industrial-scale simulations. Simulated predictions will be compared to Ugitech experimental work on lab torsion tests and industrial extrusion processes.

Abstract: Hollow embossing rolling (HER) is a promising continuous forming technology for producing thin metallic bipolar half plates (BPHP) with micro-channel structures used in fuel cells and electrolyzers. This study presents a simulation-based analysis of process-specific disturbances influencing the forming accuracy and quality of HER-formed BPHP. Using a validated LS-DYNA shell-based model, the effects of six disturbance variables, roller misalignments (axial, tangential, angular), roller gap variation, initial sheet thickness deviation, and changes in friction coefficient, were systematically investigated. Results show that even small roller misalignments of ±10 µm or manufacturing related roller gap deviations of +5 µm lead to significant changes in rolling force, strip draw-in, and sheet thinning behavior. Variations in friction coefficient notably affect draw-in and wrinkling tendencies. Overall, the study highlights the high sensitivity of the HER process to geometric and frictional disturbances and provides quantitative tolerance limits crucial for precision manufacturing and robust continuous BPHP forming.

Abstract: The Guided Material Flow (GMF) process is an advanced variant of the Samanta process designed for the net shape cold extrusion of gears. The GMF process employs a modified die geometry to control material flow and significantly reduce maximum tool loads, effectively overcoming traditional process limitations. Key advantages include enhanced tooth tip strength and a reduction in face end deformations, which are characteristic defects in the conventional Samanta process. Minimising these deformations reduces the requirement for subsequent machining and enhances overall material efficiency. A numerical dataset was generated to train and validate data driven surrogate models, facilitating rapid process analysis without the computational cost of continuous Finite Element Analysis (FEA). The models developed in this paper enable the precise prediction of critical process outputs, including maximum punch force, die filling behaviour, material utilisation and strain hardening at the tooth tip. This paper details the numerical data acquisition, the specific training and validation methodologies of the machine learning models and demonstrates their capability to accurately predict complex process outcomes when varying the geometry of the die active surface in the GMF process.

Abstract: Transverse (charge) welds form during billet transitions in aluminium extrusion when incoming material progressively replaces residual metal inside the die, defining the length of extrudate that must be scrapped. This study aimed to quantify charge weld evolution under industrially relevant conditions that are often underestimated in scrap length assessment, including multi-cavity flow imbalance, non-symmetric multi-profile placement, and billet-to-billet thermal stabilisation effects. Three case studies were analysed using finite element simulation in QForm UK: (i) the International Extrusion Benchmark 2023 multicavity die producing three hollow tubes with intentionally varied port and bearing designs, (ii) an industrial two-profile die with translated (non-mirrored) profile positioning to avoid post-extrusion rotation, and (iii) a complex industrial profile extruded over multiple consecutive billets. The benchmark study demonstrated strong agreement between simulation and experimental charge weld evolution for two profiles, supporting the reliability of the predicted cavity-dependent differences driven by port volume. In the translated two-profile configuration, the charge weld cut length required for full purity increased from 1674 mm to 1940 mm (+16.0%), and by +15.9% under the 95% industrial criterion (1458.1 mm vs 1690.7 mm). Billet-to-billet variability was substantial, with charge weld length increasing by +70.1% from the first to the fifth billet (2819.0 mm to 4791.7 mm), before stabilising. Overall, the results show that charge weld length is governed by residence-time differences through ports and flow channels, requiring profile-specific assessment and consideration of process stabilisation. In this context, FE simulation provides an effective means to localise the mixed zone and to support die optimisation strategies aimed at reducing scrap.

Abstract: Open-die forging is an incremental bulk metal forming process for producing large, safety-relevant components such as turbine and generator shafts. Besides achieving the target geometry, the process improves mechanical properties through grain refinement and the elimination of casting-related defects. With the increasing use of high-alloy steels, precise process control is required to prevent surface and internal cracking caused by material damage. However, predictive models for damage evolution under the thermo-mechanical conditions of open-die forging remain limited, particularly with respect to high-temperature recrystallization and the incremental process character with inherent pause times. In this work, a recrystallization-sensitive damage model was developed and validated for open-die forging. The parameters of the Lemaitre damage formulation were determined for the cold work tool steel D2 (1.2379, X155CrVMo12-1) using hot tensile tests over the relevant forging temperature range. Dynamic recrystallization kinetics were characterized by hot compression tests and described using an Avrami-type JMAK formulation, while static recrystallization behavior was analyzed by stress relaxation experiments and also modeled with JMAK kinetics. These results enabled the quantification of recrystallized fractions as functions of strain, temperature, strain rate, and dwell time. To link microstructural evolution with damage development, tailored recrystallization states were generated in dilatometer experiments and examined metallographically with respect to void formation and healing. The extended model was implemented in a finite element framework and validated through open-die forging experiments on demonstrator geometries, showing its capability to predict damage initiation under industrially relevant conditions.

Abstract: This paper presents a comprehensive structural, modal, and random vibration analysis of the SEAMS Payload using ANSYS 18.1 simulation tools. As a preliminary design-phase study, its goal is to perform a trade-off analysis between common aerospace materials before physical prototyping and validation. The study evaluates three aluminum alloys—5052- H32, 6061-T6, and 7075-T6—to optimize the payload frame structure for mechanical stresses encountered during launch and space operations. The analysis includes static structural loading to assess deformation and stress distribution, vibrational modal analysis to determine natural frequencies and mode shapes, and random vibration analysis to simulate launch-induced dynamic excitation. The simulation outcomes highlight the critical role of material selection in enhancing structural integrity, maximizing safety margins, and ensuring mechanical reliability of the payload in harsh launch environments.