Yousef Heider

Yousef Heider
RWTH Aachen University · Institute of General Mechanics

PD Dr.-Ing. habil.

About

64
Publications
23,520
Reads
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865
Citations
Introduction
The current focus in Heider's research group is on the development, implementation, verification and validation of modern schemes for engineering applications in multiphase, multi-scale computational mechanics. This includes machine learning (neural networks and reinforcement learning) in multi-scale modeling, data-driven material models, porous media mechanics, Lattice-Boltzmann method, phase-field modeling of fracture and phase-change materials, and solution schemes of coupled problems.
Additional affiliations
October 2018 - September 2019
Columbia University
Position
  • Research Associate
May 2014 - present
RWTH Aachen University
Position
  • Group Leader
July 2007 - July 2011
Universität Stuttgart
Position
  • PhD Student
Education
May 2014 - June 2021
RWTH Aachen University
Field of study
  • Mechanics
August 2007 - July 2012
Universität Stuttgart
Field of study
  • Mechanics
October 2005 - July 2007
Universität Stuttgart
Field of study
  • Computational Mechanics

Publications

Publications (64)
Article
Full-text available
Despite a wide range of current and potential applications, one primary concern of brittle materials is their sudden and swift collapse. This failure phenomenon exhibits an inability of the materials to sustain tension stresses in a predictable and reliable manner. However, advances in the field of fracture mechanics, especially at the nanoscale, h...
Article
Full-text available
This paper examines the frame-invariance (and the lack thereof) exhibited in simulated anisotropic elasto-plastic responses generated from supervised machine learning of classical multi-layer and informed-graph-based neural networks, and proposes different remedies to fix this drawback. The inherent hierarchical relations among physical quantities...
Article
Full-text available
This research work introduces a novel phase-field thermo-hydro-mechanical (P-THM) modeling approach that allows to deeply understand and model the freezing–thawing cyclic process in a fluid-saturated porous medium. In this, a biphasic macroscopic, non-isothermal porous media model, augmented by the phase-field method (PFM), is applied to account fo...
Article
Full-text available
Supervised machine learning via artificial neural networks (ANN) has gained significant popularity for many geomechanics applications that involves multi-phase flow and poromechanics. For unsaturated poromechanics problems, the multi-physics nature and the complexity of the hydraulic laws make it difficult to design the optimal setup, architecture,...
Article
Full-text available
Motivated by the successful implementation of the phase-field method (PFM) to simulate complicated fracture patterns at moderate computational costs in solid materials, many research groups have started since 2012 applying the PFM to model hydraulic fracturing, especially that occurs in porous geomaterials. These research works have contributed to...
Article
Full-text available
Although modeling of fractures in solid materials has been within the focus of researchers for decades, a generally applicable and reliable numerical description is still an open topic. The complexity of fracture description hides within its multiscale nature, whereby the nano- and macroscale material behavior often vary significantly, and the tran...
Article
Full-text available
In this paper, we present a reliable micro‐to‐macroscale framework to model multiphase fluid flow through fractured porous media. This is based on utilizing the capabilities of the lattice Boltzmann method (LBM) within the phase‐field modeling (PFM) of fractures in multiphase porous media. In this, we propose new physically motivated phase‐field‐de...
Article
Full-text available
Nonwovens are a type of textile that possess a wide range of unique properties, such as lightweight and damping characteristics, which make them suitable for many applications as in medicine and engineering. In this study, the focus lies on the mechanical response of nonwovens as a multiphase porous layer excited by an underlying vibrating plate. T...
Article
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The fusion welding process of metallic components, such as using gas tungsten arc welding (GTAW), is often accompanied by detrimental deformations and residual stresses, which affect the strength and functionality of these components. In this work, a phase-field model, usually used to track the states of phase-change materials, is embedded in a the...
Article
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This research work presents an experimental and numerical study of the coupled thermo-hydro-mechanical (THM) processes that occur during soil freezing. With focusing on the artificial ground freezing (AGF) technology, a new testing device is built, which considers a variety of AGF-related boundary conditions and different freezing directions. In th...
Article
Full-text available
Whether naturally- or artificially-induced due to human activities, decreasing or increasing the suction in multiphase-fluid-saturated porous materials can lead to enormous changes in their thermo-hydromechanical properties. In this, both the mathematical description and the numerical modeling of the coupled problem present a challenging task. The...
Poster
Full-text available
This research work introduces a novel phase-field thermo-hydro-mechanical modeling approach that allows to deeply understand and model the solid-liquid phase change processes occurring in fluid-saturated porous media.
Thesis
Full-text available
Fracture mechanics counts to the most emerging and promising fields of engineering mechanics. In the last few decades, the topics of crack initiation and propagation in solid and porous materials have attracted numerous theoretical, experimental, and numerical studies. This was driven by many challenges and necessities in engineering fields, such a...
Article
This contribution presents a meta-modeling framework that employs artificial intelligence to design a neural network that replicates the path-dependent constitutive responses of composite materials sampled by a numerical testing procedure of Representative Volume Elements (RVE). A Deep Reinforcement Learning (DRL) combinatorics game is invented to...
Presentation
Full-text available
Video **** https://www.youtube.com/watch?v=o2SvtEn2s-I ******* The focus in this presentation is laid on the following two instances related to suction-induced fractures in porous materials. (1) The desiccation-induced fracturing, which occurs due to an increase of the capillary pressure (air pressure minus water pressure) in low-permeable, unsatu...
Article
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Loss-in-Weights (LiW) feeders are commonly oriented in a horizontal way. In this work, an experimental proof of concept, including mechanical and electrical design, construction, and operation, of a vertical LiW feeder prototype is performed. In a systematic design process, based on functional design specifications, the semi-automated vertical LiW...
Chapter
The vast majority of neat bioepoxy resins have poor mechanical properties that inhibit their wide implementation in structural applications. Hence, most of the reviewed studies managed to improve these properties through (i) changing the chemical structure of the bioepoxy polymer via choosing appropriate curing agents to cross‐link the bioepoxy mon...
Article
Full-text available
In this work, the problem of brittle fracture in a fluid‐saturated porous material is extended by considering the non‐isothermal states of the sample. The temperature field will affect the problem in two aspects: 1) Temperature‐dependent material parameters, such as elasticity modulus (E) and critical energy release rate (Gc). 2) Thermal expansion...
Article
Full-text available
The welding process of metallic components, such as using gas tungsten arc welding (GTAW), is often accompanied by detrimental deformations and residual stresses, which affect the strength and functionality of these welded components. In this work, a phase‐field model, usually used to track the state of the phase‐change materials, is embedded in a...
Article
Full-text available
In this contribution, the Shan‐Chen (SC) two‐phase flow model of the lattice Boltzmann method (LBM) is numerically implemented to simulate multiphase fluid flow on microtomography (µ‐CT) data of a sphere packing. From the model, the saturation degrees of the fluid phases, i.e. invading and displaced fluids, are extracted from the computed lattice d...
Article
Full-text available
The focus in this research is on introducing an accurate and stable numerical modeling framework and to compare the numerical results with experimental data from the literature for desiccation‐induced fracturing of unsaturated porous materials. The macroscopic modeling approach is based on combined continuum porous media mechanics and a diffusive p...
Article
Full-text available
The purpose of this work is to develop a statistical methodology that identifies the correlations among critical material attributes, critical process parameters, and critical quality attributes of a volumetric vertical micro-auger dosing process. This contributes to improving the accuracy and consistency in delivering of powders by using a well-de...
Article
Full-text available
This paper presents a numerical approach for the simulation of fluid flow through porous media by proposing a theoretical and numerical meso-to-macro multiscale framework, which combines the advantages of the lattice Boltzmann method (LBM) with the continuum Theory of Porous Media (TPM) to efficiently and accurately model fluid transport in heterog...
Article
Full-text available
Discrete Element Method (DEM) proved to be an essential tool to optimize the industrial auger dosing process for pharmaceutical powders. During the DEM parameter calibration process of a certain powder, several parameter combinations might lead to a similar bulk response, which could also vary for other bulk responses. Therefore, a methodology is n...
Article
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This paper introduces a numerical study of latent heat storage systems, based on phase-change materials (PCMs) with various heat transfer enhancement techniques. In this, three alternative systems are considered: (1) a PCM-saturated open-celled metallic foam, (2) multiple immiscible PCM constituents with different melting temperatures and (3) a PCM...
Article
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One of the key challenges in the implementation of discrete element method (DEM) to model powder’s flow is the appropriate selection of material parameters, where empirical approaches are mostly applied. The aim of this study is to develop an alternative systematic numerical approach that can efficiently and accurately predict the influence of diff...
Conference Paper
Full-text available
The focus in this research is on introducing an accurate and stable numerical modeling framework and to compare the numerical results with experimental data from the literature for desiccation-induced fracturing of unsaturated porous materials. The macroscopic modeling approach is based on combined continuum porous media mechanics and a diffusive p...
Article
Full-text available
This manuscript introduces a unified mathematical framework to replicate both desiccation-induced and hydraulic fracturing in low-permeable unsaturated porous materials observed in experiments. The unsaturated porous medium is considered as a three-phase solid-liquid-gas effective medium of which each constituent occupies a fraction of the represen...
Article
Full-text available
Naturally derived hydrogels are the most common bioink material for droplet-based bioprinting. The mechanical stability of the printed construct and the cell viability are closely related to the gelation process of natural hydrogels, which is initiated by the coil-to-helix transition in a single polymer chain and followed by association of helices....
Article
Full-text available
Ultrasonic welding (USW) of metals is counted as a solid state consolidation of the involved parts, in which the growing interface temperature is far below the melting point of the material. This type of welding is a joining technique, in which a combined effect of the applied pressure and the ultrasonic frictional vibrations on the surface of the...
Article
Full-text available
In pharmaceutical solid dosage forms development, the physical properties of powders play a significant role in their flowability and help in understanding the flow behavior and optimizing the design of powder handling equipment. In particular, powder flow depends strongly on the interparticulate interactions between the particles, where with more...
Article
In this paper a dynamic thermomechanical analyzer was used to perform stress‐relaxation tests on human periodontal ligament samples and a viscoelastic model is employed to correlate the test data. The results show that the stress‐strain curves of the three samples can be predicted by the used constitutive model, which uses five parameters. The corr...
Article
Full-text available
The aim in this research work is to develop a numerical model of fracturing of saturated, brittle porous materials. Different sources of the energy dissipation can be distinguished in this process, such as the crack propagation, the injection fluid flow in the crack and the fluid flow the surrounding porous domain (e.g. due to leak‐off). In this st...
Article
Full-text available
The underlying study introduces a numerical modeling framework and a comparison with experimental data of hydraulic fracture in dense low-permeable brittle rocks. This is based on the continuum theory of porous media (TPM) extended by a diffusive phase-field modeling (PFM) approach. Proceeding with a biphasic material consisting of a solid and a fl...
Article
Full-text available
This paper addresses brittle fracture simulation using the phase-field modelling (PFM) as an effective and prominent method to predict crack onset and topology in heterogeneous solids and porous materials. This includes the study of the significant crack behaviour change due to the inhomogeneous nature of the materials, where the Weibull distributi...
Article
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The un­der­ly­ing re­search work in­tro­duces a study of the me­chan­i­cal prop­er­ties of poly­car­bon­ate ure­thane (PCU), used in the con­struc­tion of var­i­ous med­ical de­vices. This com­prises the dis­cus­sion of a suit­able ma­te­r­ial model, the ap­pli­ca­tion of el­e­men­tal ex­per­i­ments to iden­tify the re­lated pa­ra­me­ters and the n...
Article
Full-text available
The following research contribution addresses the topic of fracture in highly brittle materials considering a combined computational approach, which includes physically-motivated molecular dynamics (MD) simulations and multi-dimensional phase-field modelling (PFM). This novel approach provides an efficient and accurate insight into multi-scale frac...
Article
Full-text available
The following contribution presents a numerical model for the description of the compression of gas diffusion layers (GDL) of polymer electrolyte membrane fuel cells (PEMFC). Proceeding from a macroscopic multiphasic modelling approach for porous materials, the work below instills the neo-Hookean material law of finite deformations within the frame...
Article
Full-text available
Ultrasonic welding (USW) is an alternative solution for the bonding process especially in automotive industry. Ultrasonic welding of metals is a joining technique as a combination of applying pressure and frictional vibrations within the range of ultrasonic frequencies. In automotive industry, ultrasonic welding is often used for wired connections....
Article
Heat transport in biological tissues and its modelling with different approaches, such as Pennes's bioheat equation and porous media theories, is investigated in this study. Breast cancer detection is envisaged as an application. The suitability of the widely-used Pennes model for breast cancer detection by means of infrared imaging is investigated...
Article
In this contribution, an experimental study and FE simulations based on J-integral theory and the phase-field modelling approaches are presented in order to systematically study the temperature and strain-rate dependency of glass fracture behaviour. First, a series of three-point bending tests are successfully carried out under different stain-rate...
Article
Full-text available
The underlying research work aims to develop a numerical model of pressure-driven fracturing of saturated porous media. This is based on the combination of the phase-field modelling (PFM) scheme together with a continuum-mechanical approach of multi-phase materials. The proposed modelling framework accounts for the crack nucleation and propagation...
Article
The main objective of the present work is the development of a simplified, efficient and easy-to-implement single-phase material model, which is able to describe the essential effects characterising the behaviour of multi-phase saturated materials, such as of intervertebral discs (IVDs). The presented new model mainly focuses on extending a viscoel...
Article
Full-text available
The aim of this work is to numerically simulate the gelation of a crosslinking polymer, which is a very complex process involving chemical reactions and phase transitions from a viscous fluid to a viscoelastic solid. A phenomenological model is proposed to simulate the gelation process of agarose droplets, considering the thermal boundary condition...
Article
Full-text available
In this contribution, the numerical simulation of hydraulic fracture of fluid-saturated porous materials is carried out on a continuum-mechanical scale using the theory of porous media (TPM), extended by a phase-field modeling (PFM) approach. Following this, behaviors such as crack nucleation and propagation, solid matrix deformation and interstiti...
Article
Full-text available
In order to better understand and ease the determination of material and model parameters required for the macroscopic modelling of brittle fracture, a bottom-up comparative study between molecular dynamics (MD) simulations and the continuum phase-field modelling (PFM) is carried out. In particular, based on the MD simulations of fracture of a high...
Article
Proximal femur fractures are very common injuries especially among older patients. Although, there are various alternatives and improvements in implant design and operating techniques, the treatment still represents a big medical challenge. Therefore, the understanding of crack initiation and propagation in the proximal femur is of great interest....
Article
Full-text available
Continuum porous media theories, extended by a diffusive phase-field modeling (PFM) approach, introduce a convenient and efficient tool to the simulation of hydraulic fracture in fluid-saturated heterogeneous materials. In this, hydraulic- or tension-induced fracture occurs in the solid phase. This leads to permanent local changes in the permeabili...
Article
Full-text available
In this work, a novel comparative method for highly brittle materials such as aragonite crystals is proposed, which provides an efficient and accurate in-sight understanding for multi-scale fracture modeling. In particular, physically-motivated molecular dynamics (MD) simulations are performed to model quasi-static brittle crack propagation on the...
Article
This paper presents a new efficient monolithic finite element solution scheme to treat the set of PDEs governing a two-dimensional, biphasic, saturated TPM model with intrinsically coupled and incompressible solid and fluid constituents for infinitesimal and large elastic deformation. Our approach, which inherits some of its techniques from CFD, is...
Conference Paper
Full-text available
A novel combined method for highly brittle materials, which provides an efficient and accurate insight into multi-scale fracture modeling, is proposed. In particular, physically- motivated molecular dynamics simulations are performed to predict crack propagation, in the nanoscale, and therewith determine material and other parameters required for t...
Chapter
Full-text available
The focus of the present contribution is on the numerical modelling of hydraulic fracture in fluid-saturated heterogeneous materials, which can be carried out on a macroscopic scale using extended continuum porous media theories. This accounts for the crack nucleation and propagation, deformation of the solid matrix and change in the flow of the in...
Article
The numerical simulation of liquefaction phenomena in fluid-saturated porous materials within a continuum-mechanical framework is the aim of this contribution. This is achieved by exploiting the Theory of Porous Media (TPM) together with thermodynamically consistent elasto-viscoplastic constitutive laws. Additionally, the Finite Element Method (FEM...
Thesis
Full-text available
The numerical modelling of fluid-saturated porous media dynamics within a continuum-mechanical framework is the ultimate aim of this dissertation. This purpose is achieved by exploiting the Theory of Porous Media (TPM) together with thermodynamically consistent constitutive laws for the material modelling. Additionally, the Finite Element Method (F...
Conference Paper
Full-text available
Offshore wind energy farms have gained much attention during the last years in Germany and all over the world. In the construction of offshore wind turbines, piled foundations have been mostly used so far. However, gravity base foundations represent a good alternative as they minimize the typical high risks of the offshore works, such as weather-de...
Article
Full-text available
From a macroscopic perspective, saturated porous materials like soils represent volumetrically interacting solid–fluid aggregates. They can be properly modelled using continuum porous media theories accounting for both solid-matrix deformation and pore-fluid flow. The dynamic excitation of such multi-phase materials gives rise to different types of...
Article
The problem of dynamic wave propagation in semi-infinite domains is of great importance, especially, in subjects of applied mechanics and geomechanics, such as the issues of earthquake wave propagation in an infinite half-space and soil-structure interaction under seismic loading. In such problems, the elastic waves are supposed to propagate to inf...
Article
Proceeding from the governing equations describing a saturated poroelastic material with intrinsically incompressible solid and fluid constituents, we compare the monolithic and splitting solution of the different multi-field formulations feasible in porous media dynamics. Because of the inherent solid–fluid momentum interactions, one is concerned...
Article
The mechanical behavior of saturated porous materials is largely governed by the interaction between the solid skeleton and the pore fluid. This interaction is particularly strong in dynamic problems and leads to numerical challenges especially in the case of incompressible constituents. In fact, the permeability plays a significant role in this co...