B. Emek Abali

Uppsala University | UU · Department of Materials Science and Engineering

Aligned with the Sustainability Development Goals (SDGs), we present the complete methodology of preparing bio-based polymer filaments to be used in additive manufacturing, specifically by means of so-called Fused Filament Fabrication (FFF) in 3D printing. Filament production and 3D printing were both developed and optimised in this work. First, we...

Especially at high frequencies, as they occur in 5G or relevant applications, electromagnetism in electronic components plays a significant role in system behavior. Moreover, dissipative effects are triggered by mechanical deformation. Indeed, dissipation is an energy loss and thus the industry tries to minimize this effect by optimizing the design...

This study presents some results on the mechanical behavior of polylactide (PLA) material, produced using the fused deposition modeling (FDM) additive manufacturing technique. We investigate the effect of infill density on the mechanical properties of PLA specimens. We used tensile specimens, prepared according to ISO 527-2 standard, and tested the...

Materials may demonstrate electromagnetism and thermomechanics coupling. Although we benefit from this coupling in our modern lives, comprehending this coupling is challenging. We intuitively understand that temperature increase causes an expansion in polymers and alloys. Typical example is a plastic water bottle left in the sun, the expansion is v...

Dynamic failure in advanced ceramic materials is a complex mechanical phenomenon, which is challenging to study in experimental and computational works. This work models and investigates the crack initiation, growth, propagation, and branching in two-dimensional single crystalline boron carbide at the nanometer length-scale and picosecond time-scal...

Additive manufacturing techniques, especially fused deposition modelling (FDM) based polymer 3-D printers are opening new possibilities in engineering design. Multiscale structures have a macroscale and miscroscale geometry. Composite materials are available as filaments allowing multiphysics applications. Microscale structure or even heterogeneous...

This paper presents a large experimental campaign and the corresponding analysis quantifying mortar curing effects on the pull-out performance of bonded anchor systems. Standard confined pull-out tests were performed on two commonly used adhesive anchor systems. The two investigated bonded anchor systems were based on different materials, where the...

In this work, parallel plate capacitors are numerically simulated by solving weak forms within the framework of the finite element method. Two different domains are studied. We study the infinite parallel plate capacitor problem and verify the implementation by deriving analytical solutions with a single layer and multiple layers between two plates...

A fundamental understanding of the interaction between microstructure and underlying physical mechanisms is essential, especially for developing more accurate multi-physics models for heterogeneous materials. Effects of microstructure on the material response at the macroscale are modeled by using the generalized thermomechanics. In this study, str...

In this work, the dynamical behavior of a pantographic structure undergoing large deformations is analyzed. A harmonic force is applied on the structure, while its motion in time is recorded by means of a high-speed camera system. The resulting displacement field is obtained via the digital image correlation (DIC) method for the whole domain. A par...

In elasticity, microstructure-related deviations may be modeled by strain gradient elasticity. For so-called metamaterials, different implementations are possible for solving strain gradient elasticity problems numerically. Analytical solutions of simple problems are used to verify the numerical approach. We demonstrate such a case in a two-dimensi...

Crack initiation and propagation as well as abrupt occurrence of twinning are challenging fracture problems where the transient phase-field approach is proven to be useful. Early-stage twinning growth and interactions are in focus herein for a magnesium single crystal at the nanometer length-scale. We demonstrate a basic methodology in order to det...

Advancement in manufacturing methods enable designing so called metamaterials with a tailor-made microstructure. Microstructure affects materials response within a length-scale, where we model this behavior by using the generalized thermomechanics. Strain gradient theory is employed as a higher-order theory with thermodynamics modeled as a first-or...

Infill density used in additive manufacturing incorporates a structural response change in the structure. Infill pattern creates a microstructure that affects the mechanical performance as well. Whenever the length ratio of microstructure to geometry converges to one, metamaterials emerge and the strain-gradient theory is an adequate model to predi...

A theoretical-computational framework is proposed for predicting the failure behavior of two anisotropic brittle materials, namely, single crystal magnesium and boron carbide. Constitutive equations are derived, in both small and large deformations, by using thermodynamics in order to establish a fully coupled and transient twin and crack system. T...

Metamaterials exhibit significantly different mechanical deformation than in classical “first-order” theory. One possible modeling approach is to use a “straingradient” theory by incorporating also higher gradients of displacements into the formulation. This procedure clearly brings in additional constitutive parameters. In this study, a numerical...

Microstructure related deviation from elastic response is known as “size-effect.” Metamaterials—for example modeled by strain gradient elasticity—capture this effect adequately by means of additional parameters to be determined. We employ a methodology based on asymptotic homogenization in order to obtain metamaterials parameters and then present t...

A computational method is proposed for simulating and informing on controlling failure pattern development in anisotropic brittle solids experiencing extreme mechanical loading. Constitutive equations are derived by using thermodynamics in order to establish a fully coupled and transient fracture mechanics model. A phase-field approach is developed...

Miniaturization increases more complexity in Integrated Circuits (IC) as well as circuit boards. Several electronic components are assembled on a Printed Circuit Board (PCB). The board is a composite material of a fiber reinforced thermosetting polymer based matrix. Within and on the board, conducting traces and vertical interconnect access (via) c...

Physical systems are modeled by field equations, these are coupled, partial differential equations in space and time. Field equations are often given by balance equations and constitutive equations, where the former is axiomatically given and the latter is thermodynamically derived. This method has difficulties in damage mechanics in generalized co...

Even though heterogeneous porous materials are widely used in a variety of engineering and scientific fields, such as aerospace, energy-storage technology, and bio-engineering, the relationship between effective material properties of porous materials and their underlying morphology is still not fully understood. To contribute to this knowledge gap...

Phase-field modelling has been shown to be a powerful tool for simulating fracture processes and predicting the crack path under complex loading conditions. Note that the total energy of fracture in the classical phase-field formulations includes the strain energy density from the linear elasticity theory resulting in singular stresses at the crack...

Strain gradient theory is an accurate model for capturing the size effect and localization phenomena. However, the challenge in identification of corresponding constitutive parameters limits the practical application of the theory. We present and utilize asymptotic homogenization herein. All parameters in rank four, five, and six tensors are determ...

This paper makes a rigorous case for considering the continuum derived by the homogenization of extensive quantities as a polar medium in which the balances of angular momentum and energy contain contributions due to body couples and couple stresses defined in terms of the underlying microscopic state. The paper also addresses the question of invar...

Pantographic structures are examples of metamaterials with such a microstructure that higher-gradient terms’ role is increased in the mechanical response. In this work, we aim for validating parameters of a reduced-order model for a pantographic structure. Experimental tests are carried out by applying forced oscillation to 3D-printed specimens for...

Additive manufacturing develops rapidly, especially, fused deposition modeling (FDM) is one of the economical methods with moderate tolerances and high design flexibility. Ample studies are being undertaken for modeling the mechanical characteristics of FDM by using the Finite Element Method (FEM). Even in use of amorphous materials, FDM creates an...

During curing of thermosetting polymers, crosslinking results in hardening or stiffening of the material. In electronics, for example in encapsulating integrated circuits (die bonding), thermosets are fully cured in a controlled environment (under UV-light or within a thermal oven) such that the highest stiffness possible has been achieved. In buil...

As there are different computational methods for simulating problems in generalized mechanics, we present simple applications and their closed-form solutions for verifying a numerical implementation. For such a benchmark, we utilize these analytical solutions and examine three-dimensional numerical simulations by the finite element method (FEM) usi...

Thermosetting polymers are used in building materials, for example adhesives in fastening systems. They harden in environmental conditions with a daily temperature depending on the season and location. This curing process takes hours or even days effected by the relatively low ambient temperature necessary for a fast and complete curing. As materia...

Additive manufacturing introduced substructure and computational determination of metamaterials parameters by means of the asymptotic homogenization Abstract Metamaterials exhibit materials response deviation from conventional elasticity. This phenomenon is captured by the generalized elasticity as a result of extending the theory at the expense of...

Strain gradient theory is an accurate model for capturing size effects and localization phenomena. However, the challenge in identification of corresponding constitutive parameters limits the practical application of such theory. We present and utilize asymptotic homogenization herein. All parameters in rank four, five, and six tensors are determin...

Additive manufacturing provides high design flexibility, but its use is restricted by limited mechanical properties compared to conventional production methods. As technology is still emerging, several approaches exist in the literature for quantifying and improving mechanical properties. In this study, we investigate characterizing materials’ resp...

Miniaturization increases more complexity in Integrated Circuits (IC) as well as circuit boards. Several electronic components are assembled on a Printed Circuit Board (PCB). The board is a composite material of a fiber-reinforced thermosetting polymer-based matrix. Within and on the board, conducting traces and vertical interconnect access (via) c...

Metamaterials response is generally modeled by generalized continuum based theories. Their inherent substructure leads to a necessity for higher‐order theories, and especially in damage mechanics, such a generalization is difficult to acquire. We exploit the action formalism in order to obtain the governing equations in generalized damage mechanics...

In this paper, a novel parameter determination technique is developed for material models in continuum mechanics aimed at describing metamaterials. Owing to their peculiar mechanical properties and behaviors, such as extreme elasticity or high strength-to-weight ratio, metamaterials are of interest to be simulated by reduced-order modeling by means...

The application of generalized continuum mechanics is rapidly increasing in different fields of science and engineering. In the literature, there are several theories extending the classical first‐order continuum mechanics formulation to include size‐effects [1]. One approach is the strain gradient theory with the intrinsic features of regularizing...

Herein, the effects of recycled polymers on the mechanical properties of additively manufactured specimens, specifically those derived by fused deposition modelling, are determined. The intention is to investigate how 3D-printing can be more sustainable and how recycled polymers compare against conventional ones. Initially, sustainability is discus...

As thermoset polymers find frequent implementation in engineering design, their application in structural engineering is rather limited. One key reason relies on the ongoing curing process in typical applications such as post-installed adhesive anchors, joints by structural elements or surface-mounted laminates glued by adhesive polymers. Mechanoch...

Metamaterials exhibit materials response deviation from conventional elasticity. This phenomenon is captured by the generalized elasticity as a result of extending the theory at the expense of introducing additional parameters. These parameters are linked to internal length scales. Describing on a macroscopic level a material possessing a substruct...

By using modern additive manufacturing techniques, a structure at the millimeter length scale (macroscale) can be produced showing a lattice substructure of micrometer dimensions (microscale). Such a system is called a metamaterial at the macroscale, because its mechanical characteristics deviate from the characteristics at the microscale. Conseque...

Mechanochemistry in Li-ion batteries involve interaction of ions migrating in a cell with mechanical stresses as well as electromagnetic fields. We aim at modeling this multiphysics in a battery cell by involving thermomechanics with the corresponding balance equations of mass, momentum, energy and electromagnetism with the aid of the Maxwell equat...

Animation of Schrödinger's solution

Animation of Schrödinger's solution

Animation of Schrödinger's solution

In order to validate a computational method for solving viscous fluid flows, experiments are carried out in an eccentric cylindrical cavity showing various flow formations over a range of Reynolds numbers. Especially, in numerical solution approaches for isothermal and incompressible flows, we search for simple experimental data for evaluating accu...

The paper ‘ Zur Dynamik elastisch gekoppelter Punktsysteme’ by Schrödinger (1914) does not seem to have attracted the attention that it deserves. We translate it into English here and we discuss its results in detail, with a view to its possible influence in the modern theories of generalised continua. The clever solution found, in terms of Bessel...

In der technischen Mechanik werden physikalische Systeme mithilfe der Differentialgleichungen modelliert. Wir möchten nun allgemein Lösungsverfahren der Differentialgleichungen studieren. Zur Vereinfachung der Notation und Erleichterung der Einführung fangen wir mit den gewöhnlichen Differentialgleichungen an. Dies bedeutet, dass eine einzige Varia...

Übungen zur Lösung von Gleichungen mit einer Variable.

Übungen zur Integration und Differentiation.

Python ist eine Programmiersprache, die für Ingenieure entwickelt worden ist. Die Ingenieure können vieles, leider zählt das Programmieren oft nicht dazu. Deshalb wurde Python so entwickelt, dass Implementierungen – bezüglich anderer Sprachen wie C++ oder Java – vereinfacht eingebettet werden. Somit können Ingenieure relativ intuitiv ziemlich kompl...

Konkrete Anwendungen in SciPy für Data-Approximation, Regression und maschinelles Lernen.

Übungen zur Lösung von gewöhnlichen Differentialgleichungen.

Rechnerübungen in Scipy zur Lösung der Gleichungen mit einer Variable.

Übungen zur Interpolation und Approximation.

Nahezu alle ingenieurwissenschaftlichen Systeme werden mit Differentialgleichungen beschrieben. Zur Lösung dieser Differentialgleichungen gibt es viele Möglichkeiten. Es gibt keine einzige Methode, die alle Differentialgleichungen lösen kann, es gibt aber Funktionen wie scipy.integrate.ode, die versuchen, die allerbeste Methode zu detektieren. Die...

Eine Gleichung mit einer Variable ist eine Funktion f(x) mit dem Argument x und mit der Ausgabe \(y=f(x)\) für die Eingabe x. Die Aufgabe ist die Bestimmung der Eingabe x, die eine gegebene Ausgabe y generiert. Dies kann umgewandelt werden, sodass wir \(f(x)-y=0\) haben und dann den Wert für x suchen, der die Ausgabe null erzeugt. Die Lösung so ein...

Die Lösung einer einzigen Gleichung ist ein seltener Fall in technischen Problemen. Oft besteht die Aufgabe aus der Lösung eines Gleichungssystems. Insbesondere die Zusammenstellung der diskreten Elemente wie in der Finite-Volumen-Methode sowie in der Finite-Elemente-Methode erfordert die Lösung eines Gleichungssystems.

Anwendungen zur numerischen Integration und Differentiation mittels SciPy Paketen in Python.

Rechnerübungen zur Interpolation in SciPy.

Eine symbolische Integration oder Differentiation bedeutet, dass die Grundregeln von der Maschine bekannt sind und die Funktionen an sich, statt des numerischen Wertes angegeben werden. Eine numerische Integration oder Differentiation erzielt den numerischen Wert der Funktion.

Eine gewöhnliche Differentialgleichung hat eine einzige Veränderliche t und Variablen \(\phi _i(t)\), die von dieser Veränderlichen abhängen. Eine partielle Differentialgleichung hat mehrere Veränderliche und Variablen, die von diesen Veränderlichen abhängen. Solche Differentialgleichungen tauchen oft in physikalischen Systemen auf. Wir studieren d...

Zahlreiche Übungen erleichtern das Lernen, indem man sieht, wie die numerische Methoden in der Tat funktionieren. Aufgaben und Schritt für Schrtitt die Lösungen sind in diesem Teil zu finden. Übungen zur Darstellung und Fehler.

Eine numerische Berechnung hat immer einen Fehler. Der Fehler kommt aus drei unterschiedlichen Gründen zustande. Erstens ist die Abrundung einer Zahl notwendig, da der Speicherplatz eines Rechners begrenzt ist. Zweitens führt jede Operation wie Addition, Subtrahieren, Multiplikation, Division einen Fehler ein. Die Operationen sind aus analogem Grun...

In einem Experient werden diskrete Werte für diskreten Zeiten aufgenommen. Dabei ist eine Interpolation notwendig, um Werte zwischen den gemessenen Werten zu bestimmen. Allerdings kann es sein, dass die Messung eine gewisse Steuerung beinhaltet. In diesem Fall ist eine Approximation besser, indem die Werte geglättet werden. Viele praktische Methode...

Wir stellen zahlreiche Kurzaufgaben, um die Themen zu wiederholen und sie mit der Ingenieurspraxis zu verknüpfen. Statt einer Aufgabe zum Lösen, erstellen wir Szenarien und bitten um Stellungnahme. Dabei sind die Aufgaben möglichst realitätsnah, allerdings sind sie theoretisch und die vorgeschlagenen Antworten sind nicht immer eindeutig. Es ist wic...

Die gleiche Zahl kann im Binärsystem und Zehnersystem dargestellt werden. Für unser Verständnis benutzen wir das Zehnersystem. Der Rechner wandelt alles in das Binärsystem um. Wir schreiben beispielhaft einen Code zur Umwandlung.

Different numerical implementations have been proposed in the literature for computation in generalized mechanics. A computational benchmark problem is beneficial to highlight the differences or even validate an approach. We briefly present the strain gradient elasticity theory and its weak form. A relatively simple analytic solution in strain grad...

As the length scale starts decreasing such that the inner substructure of the material becomes dominant in material response, the well-known theory of elasticity shows inadequacies. As a remedy, generalized mechanics is proposed leading to additional, inner substructure related parameters to be determined. In order to acquire them, for a so-called...

Various engineering systems exploit the conversion between electromagnetic and mechanical work. It is important to compute this coupling accurately, and we present a method for solving the governing equations simultaneously (at once) without a staggering scheme. We briefly present the theory for coupling the electromagnetism with mechanics and use...

Electrically induced tissue damage is a coupled phenomenon in multiphysics. Conducting electricity produces heat and this increases the temperature. The soft tissue like skin, organs, brain, or muscles is burnt under successive heating. This damage is modeled by using a damage parameter with a corresponding evolution law above a threshold temperatu...

This book presents a selection of cutting-edge methods that allow readers to obtain novel models for nonlinear solid mechanics. Today, engineers need more accurate techniques for modeling solid body mechanics, chiefly due to innovative methods like additive manufacturing—for example, 3D printing—but also due to miniaturization. This book focuses on...

This book features selected manuscripts presented at ICoNSoM 2019, exploring cutting-edge methods for developing novel models in nonlinear solid mechanics. Innovative methods like additive manufacturing—for example, 3D printing— and miniaturization mean that engineers need more accurate techniques for modeling solid body mechanics. The book focuses...

Technische Systeme werden von Ingenieur*innen modelliert und durch numerische Methoden simuliert. Dieses Lehrbuch bietet eine unkomplizierte Einführung in numerische Methoden, mit zahlreichen, praxisrelevanten Beispielen, die mithilfe der Programmiersprache Python gelöst werden. In ingenieurwissenschaftlichen Studienrichtungen sowie in allen Forsch...

The mechanical properties of nanoparticles, especially those designed for biomedical purposes, have a large impact on their performance and have been scarcely studied. Thermoresponsive polymer-based nanoparticles are increasingly being used in biomedical applications, therefore, it is crucial to determine their thermo-mechanical response in the reg...

Metamaterials are functionalized by specifying a structure at a microscopic length scale such that they provide a tailored deformation response at a macroscopic length scale. Their modeling at the macroscale is attained by using the generalized mechanics that incorporates higher gradients of the displacement leading to additional parameters effecte...