Mahmoud Ahmadein

Tanta University

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Naser A. Alsaleh

Imam Mohammad ibn Saud Islamic University

Menghuai Wu

Montanuniversität Leoben

Ammar H. Elsheikh

Lebanese American University

Andreas Ludwig

Montanuniversität Leoben

Sabbah Ataya

Suez University

Abdellah Kharicha

Montanuniversität Leoben

M. A. El‐Sayed

Arab Academy for Science, Technology, and Maritime Transport

Khamis Essa

University of Birmingham

Hany Hassanin

Canterbury Christ Church University

Joy Djuansjah

Imam Mohammad ibn Saud Islamic University

Cooperative Institutions

RWTH Aachen University

Montanuniversität Leoben

University of Birmingham

Tanta University

Imam Mohammad ibn Saud Islamic University

Kafrelsheikh University

Foundry (United Kingdom)

Helwan University

FH Aachen

Islamic University

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Heat Transfer Coefficient Determination in a Gravity Die Casting Process with Local Air Gap Formation and Contact Pressure Using Experimental Evaluation and Numerical Simulation

International Journal of Metalcasting (2021)

Thomas Vossel N. Wolff Björn Pustal Andreas Bührig‐Polaczek Mahmoud Ahmadein

Abstract Anticipating the processes and parameters involved for accomplishing a sound metal casting requires an in-depth understanding of the underlying behaviors characterizing a liquid melt solidifying inside its mold. Heat balance represents a major factor in describing the thermal conditions in a casting process and one of its main influences is the heat transfer between the casting and its surroundings. Local heat transfer coefficients describe how well heat can be transferred from one body or material to another. This paper will discuss the estimation of these coefficients in a gravity die casting process with local air gap formation and heat shrinkage induced contact pressure. Both an experimental evaluation and a numerical modeling for a solidification simulation will be performed as two means of investigating the local heat transfer coefficients and their local differences for regions with air gap formation or contact pressure when casting A356 (AlSi7Mg0.3).

Air gap (plumbing)

Shrinkage

Die casting

Thermal contact

Liquid metal

10.1007/s40962-021-00663-y

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Citations (13)

Modeling Dendrite Coarsening and Remelting during Directional Solidification of Al-06wt.%Cu Alloy

Materials (2024)

Ibrahim Sari Nashmi H. Alrasheedi Mahmoud Ahmadein Joy Djuansjah Lakhdar Hachani

Research efforts have been dedicated to predicting microstructural evolution during solidification processes. The main secondary arm spacing controls the mushy zone’s permeability. The aim of the current work was to build a simple sub-grid model that describes the growth and coarsening of secondary side dendrite arms. The idea was to reduce the complexity of the curvature distribution with only two adjacent side arms in concurrence. The model was built and applied to the directional solidification of Al-06wt%Cu alloy in a Bridgman experiment. The model showed its effectiveness in predicting coarsening phenomena during the solidification of Al-06wt%Cu alloy. The results showed a rapid growth of both arms at an earlier stage of solidification, followed by the remelting of the smaller arm. In addition, the results are in good agreement with an available time-dependent expression which covers the growth and coarsening. Such model can be implemented as a sub-grid model in volume average models for the prediction of the evolution of the main secondary arms spacing during macroscopic solidification processes.

Directional solidification

Dendrite (mathematics)

Ostwald ripening

Supercooling

10.3390/ma17040912

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Citations (3)

Multipoint Forming Using Hole-Type Rubber Punch

Metals (2022)

Abror Tolipov Hany Hassanin M. A. El‐Sayed Hossam Mohamed Eldessouky Naser A. Alsaleh

Reconfigurable multipoint forming is a flexible sheet forming technique aimed at customised sheet metal products. However, one drawback of multipoint forming is the cost and time needed to set up and align the upper and lower pin matrices. This study introduces an optimisation study of a novel hole-type rubber punch replacing the top pin matrix of multipoint incremental forming, aiming to reduce pins setting up and alignment complexity and time. Finite element modelling and design of experiments were used to investigate the effect of hole-type rubber punch configuration such as hole size, hole type, and the compression ratio on the wrinkling, thickness variation, and shape deviation. This research shows that the most significant process parameter in all responses was the hole size. The compression ratio of the material was found to be insignificant in wrinkling and shape deviation. The hole-type rubber punch parameters were found to be a hole size of 9 mm, circular hole type, and a compression ratio of 75%. This experimentally resulted in an improved parts wrinkling of 80%, when compared to using solid rubber punch, with the added benefits of reduction of the cost and time needed to set up and align the pin matrices.

10.3390/met12030491

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Citations (1)

Modeling of cooling and heat conduction in permanent mold casting process

Alexandria Engineering Journal (2021)

Mahmoud Ahmadein Ammar H. Elsheikh Naser A. Alsaleh

Motivated by the need to understand the heat transfer process in permanent mold casting, the heat conduction problem in the casting and the mold is modeled as transient one-dimensional heat flow in a double-layer cylinder with radial interfacial heat flux to emulate the cooling process of the casting. The cylinder is cooled down by dissipating heat to surrounding by convection. Green's function method, which obtained by separation of variables technique, is used to obtain a closed form solution of temperature distribution. The results of the derived analytical expressions are verified with numerical results of finite-element analysis and the published experimental results. The simulations are performed for different casting/mold materials with diversified thermo-physical properties to figure out the relationship between those properties and heat transfer process. The analytical results are justified by their good agreement with both of numerical and experimental results and its time efficiency in computation which offers advantages in potential real-time application to casting process monitoring. The mean absolute percentage error between the obtained temperatures using the developed analytical model and the measured ones was 14.5% and 2.4% for the casting and mold, respectively.

Cooling curve

10.1016/j.aej.2021.06.048

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Citations (22)

Benchmark experiments and numerical modelling of the columnar-equiaxed dendritic growth in the transparent alloy Neopentylglycol-(d)Camphor

IOP Conference Series Materials Science and Engineering (2015)

László Sturz Menghuai Wu G. Zimmermann Andreas Ludwig Mahmoud Ahmadein

Solidification benchmark experiments on columnar and equiaxed dendritic growth, as well as the columnar-equiaxed transition have been carried out under diffusion-dominated conditions for heat and mass transfer in a low-gravity environment. The system under investigation is the transparent organic alloy system Neopentylglycol-37.5wt.-%(d)Camphor, processed aboard a TEXUS sounding rocket flight. Solidifications was observed by standard optical methods in addition to measurements of the thermal fields within the sheet like experimental cells of 1 mm thickness. The dendrite tip kinetic, primary dendrite arm spacing, temporal and spatial temperature evolution, columnar tip velocity and the critical parameters at the CET have been analysed. Here we focus on a detailed comparison of the experiment "TRACE" with a 5-phase volume averaging model to validate the numerical model and to give insight into the corresponding physical mechanisms and parameters leading to CET. The results are discussed in terms of sensitivity versus numerical parameters.

Equiaxed crystals

Dendrite (mathematics)

10.1088/1757-899x/84/1/012086

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Citations (9)

Experimentation and modeling of grain nucleation and solidification of Aluminum Alloys in Absence and Presence of Shear

Mahmoud Ahmadein Andreas Bührig‐Polaczek

Source

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Citations (3)

The resolution uncertainty associated with digital indications revisited: the inclusion of the quantization effect and the impact of noise presence in the estimation process

Metrologia (2018)

Ahmed A. Hawam Ebtisam H. Hasan Gouda M. Mahmoud Mahmoud Ahmadein

The indicated value on the displaying device of a digital measuring instrument is usually considered as the resultant of rounding the measurand value to the nearest indication. This hypothesis is conventional and forms the basis of estimating the resolution uncertainty associated with digital indications. However, the essential quantization process needed in converting the measurand analog signal into a digital form makes the precise estimation of the resolution uncertainty shift from the one based on the aforementioned hypothesis. In this study, the effect of the quantization process on the resolution uncertainty was analyzed, a proposed algorithm for the estimation process was presented, and finally the impact of noise presence was considered. Based on the current study, the measurement result usually has a shift from the indicated value. In the presence of noise, the resolution uncertainty of stable indications can be reduced if the peak-to-peak noise could be quantified with adequate accuracy. Also, the current study recommends the revision of the broad applicability of the conventional estimation method of the resolution uncertainty and encourages standardization bodies to specify the main requirements in digital measuring instruments that guarantee their indicating behavior.

10.1088/1681-7575/aaebb6

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Citations (5)

Analysis of macrosegregation formation and columnar-to-equiaxed transition during solidification of Al-4wt.%Cu ingot using a 5-phase model

Journal of Crystal Growth (2014)

Mahmoud Ahmadein Menghuai Wu A. Ludwig

A 5-phase mixed columnar-equiaxed solidification model was recently introduced to predict the as-cast structure, and a series of laboratory experiments were performed previously to verify the model. The focus of the current work is to analyze the formation of macrosegregation, which accompanies the formation of the as-cast structure including the columnar-to-equiaxed transition (CET). The as-cast structure and macrosegregation map of a cylindrical Al-4 wt.% Cu ingot poured at 800 °C are used as a reference to validate the calculations. Good agreement between the calculations and the experiment regarding both the macrosegregation and CET is achieved. Thermal-solutal convection and equiaxed crystal sedimentation in such ingot are verified to be key mechanisms governing the formation of macrosegregation. The competitive equiaxed/columnar growth, the soft and hard blocking mechanisms predominate the CET. The numerical study of grid sensitivity indicates that the global segregation pattern and CET are not significantly affected by grid size; however, some fine details of the segregation map which are predicted by fine grid (~0.5 mm) are smeared or locally averaged by the coarse grid (~2 mm). Such details were also not resolved in the measurement. Future investigations are demanding.

Equiaxed crystals

Ingot

10.1016/j.jcrysgro.2014.07.039

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Citations (43)

Identification of Relevant Parameters for a Gap and Pressure Dependent Heat Transfer Model for Different Cooling Conditions in Gravity Die Casting

N. Wolff Andreas Bührig‐Polaczek Björn Pustal Mahmoud Ahmadein

Die casting

Identification

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Citations (0)

Designing Lightweight 3D-Printable Bioinspired Structures for Enhanced Compression and Energy Absorption Properties

Polymers (2024)

Akhil Harish Naser A. Alsaleh Mahmoud Ahmadein Abdullah A. Elfar Joy Djuansjah

Recent progress in additive manufacturing, also known as 3D printing, has offered several benefits, including high geometrical freedom and the ability to create bioinspired structures with intricate details. Mantis shrimp can scrape the shells of prey molluscs with its hammer-shaped stick, while beetles have highly adapted forewings that are lightweight, tough, and strong. This paper introduces a design approach for bioinspired lattice structures by mimicking the internal microstructures of a beetle’s forewing, a mantis shrimp’s shell, and a mantis shrimp’s dactyl club, with improved mechanical properties. Finite element analysis (FEA) and experimental characterisation of 3D printed polylactic acid (PLA) samples with bioinspired structures were performed to determine their compression and impact properties. The results showed that designing a bioinspired lattice with unit cells parallel to the load direction improved quasi-static compressive performance, among other lattice structures. The gyroid honeycomb lattice design of the insect forewings and mantis shrimp dactyl clubs outperformed the gyroid honeycomb design of the mantis shrimp shell, with improvements in ultimate mechanical strength, Young’s modulus, and drop weight impact. On the other hand, hybrid designs created by merging two different designs reduced bending deformation to control collapse during drop weight impact. This work holds promise for the development of bioinspired lattices employing designs with improved properties, which can have potential implications for lightweight high-performance applications.

Gyroid

Lattice (music)

10.3390/polym16060729

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Citations (2)