Martin Diehl

KU Leuven | ku leuven · Department of Materials Engineering and Department of Computer Science

Predicting, understanding, and controlling the mechanical behavior is the most important task when designing structural materials. Modern alloy systems—in which multiple deformation mechanisms, phases, and defects are introduced to overcome the inverse strength–ductility relationship—give raise to multiple possibilities for modifying the deformatio...

Dual phase (DP) steels are advanced high strength alloys typically used for structural parts and reinforcements in car bodies. Their good combination of strength and ductility and their lean composition render them an economically competitive option for realizing multiple lightweight design options in automotive engineering. The mechanical response...

Continuum modeling approaches are well established in materials science and engineering of metals. They enable the quantitative investigation of diverse questions related to the improved understanding of mechanics and microstructure evolution of various material classes. Applicable to time and length scales relevant in manufacturing and service, co...

Metals and alloys are mechanically anisotropic. Hence, it is required to include elastic and plastic anisotropy when simulating the mechanical behavior of metallic materials. Crystal plasticity modeling is an approach for the incorporation of mechanical anisotropy into continuum models. Since crystal plasticity models are applicable to time and len...

Crystal plasticity-based digital twins are an alternative to expensive and time-consuming experiments for the investigation of micro-mechanical material behavior. However, before using simulations as an alternative for experiments, the capabilities and limitations of the modeling approach need to be known. This is best done by juxtaposing the predi...

A common bottleneck in state-of-the-art composite micromechanics models is their reliance on constituent properties, such as interface properties. The last round-robin activity to measure interfacial strength occurred two decades ago and reported large variability for the same carbon-epoxy interface. Despite this outcome, test methods to extract in...

The development of fibre breaks governs the longitudinal tensile failure of a unidirectional ply bundle. The common assumption is that such fibre breaks also create matrix plasticity, matrix cracking and fibre-matrix debonding to alleviate stress concentrations. We, therefore, performed holotomography scans at a 150 nm resolution to identify whethe...

Fibre-reinforced polymers (FRP) have a good balance between strength, toughness, weight, corrosion resistance, formability and price. They are used in vehicles, wind turbines, buildings and other applications 1. Currently, their weight-saving advantage is partly mitigated by a lack of confidence in the prediction of their mechanical behaviour 2. Th...

Combining tomographic imaging with digital volume correlation allows in-situ 3D strain mapping, leading to a quantitative assessment of damage mechanisms and associated material properties in structural materials. Being based on pattern recognition, digital volume correlation is well-suited for materials with intrinsic and stable microstructural he...

Fibre-reinforced polymers (FRP) have a good balance between strength, toughness, weight, anti-corrosion and price. They are used to save energy, materials and costs in energy-generation, transportation, construction and others. 1 Currently, their low-weight advantage is partly mitigated by a lack of confidence in their mechanical behaviour. 2 This...

Realistic microscale domains are an essential step towards making modern multiscale simulations more applicable to computational materials engineering. For this purpose, 3D computed tomography scans can be very expensive or technically impossible for certain materials, whereas 2D information can be easier obtained. Based on a single or three orthog...

The mechanical properties of fibre-reinforced polymer composites (FRPCs) are governed by the properties of the fibre, matrix, and interface. Numerous single-fibre testing methods have been developed to investigate these constituents. Unfortunately, the environment in such model composites is not representative of real composites. We, therefore, exp...

A bainite dual-phase (FB) steel containing polygonal ferrite and granular bainite is thermo-mechanically rolled, followed by an accelerated cooling. Two different cooling rates are applied to obtain two different materials. The aim of the study is to explore the reasons for the differences in the mechanical response experimentally observed for thes...

Realistic microscale domains are an essential step towards making modern multiscale simulations more applicable to computational materials engineering. For this purpose, 3D computed tomography scans can be very expensive or technically impossible for certain materials, whereas 2D information can be easier obtained. Based on a single or three orthog...

In the present work, a spectral solver is developed for integration of certain differential equations of solid mechanics, namely static stress equilibrium in composite materials, described in cylindrical or spherical polar coordinates. The spectral approach is encompassed in approximating the displacement field using expansion into a series of Cheb...

High-resolution three-dimensional crystal plasticity simulations are used to investigate deformation heterogeneity and microstructure evolution during cold rolling of interstitial free (IF-) steel. A Fast Fourier Transform (FFT)-based spectral solver is used to conduct crystal plasticity simulations using a dislocation-density-based crystal plastic...

Predicting microstructure and (micro-)texture evolution during thermo-mechanical processing requires the combined simulation of plastic deformation and recrystallization. Here, a simulation approach based on the coupling of a full-field dislocation density based crystal plasticity model and a cellular automaton model is presented. A regridding/reme...

The complex interplay between chemistry, microstructure, and behavior of many engineering materials has been investigated predominantly by experimental methods. Parallel to the increase in computer power, advances in computational modeling methods have resulted in a level of sophistication which is comparable to that of experiments. At the continuu...

The demand for safety and reliability in pipelines has been increasing steadily. Dual-phase steels, especially with a bainite matrix and a well-dispersed martensite-austenite constituent (MA), provide ingredients necessary for the improvement of the yield ratio and toughness. To design alloy elements and ensure that dual-phase steels have the requi...

Damage in metallic materials usually originates at grain boundaries where deformation leads to local strain incompatibility and stress concentration. Characteristics of a grain boundary affects its tendency to damage, but a quantitative understanding is still lacking. In this work, we utilize machine learning to predict grain boundaries susceptible...

Physics-based crystal plasticity models rely on certain statistical assumptions about the collective behavior of dislocation populations on one slip system and their interactions with the dislocations on the other slip systems. One main advantage of using such physics-based constitutive dislocation models in crystal plasticity kinematic frameworks...

The capability of high-resolution modeling of crystals subjected to large plastic strain is essential in predicting many important phenomena occurring in polycrystalline materials, such as microstructure, deformation localization and in-grain texture evolution. However, due to the heterogeneity of the plastic deformation in polycrystals, the simula...

Lath martensite is a complex hierarchical compound structure that forms during rapid cooling of carbon steels from the austenitic phase. At the smallest, i.e., `single crystal’ scale, individual, elongated domains, form the elemental microstructural building blocks: the name-giving laths. Several laths of nearly identical crystallographic orientati...

open access links: https://link.springer.com/article/10.1007%2Fs11661-020-05947-2 https://rdcu.be/b6P8O https://doi.org/10.1007/s11661-020-05947-2 This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, for...

A severe obstacle for the routine use of crystal plasticity models is the effort associated with determining their constitutive parameters. Obtaining these parameters usually requires time-consuming micromechanical tests that allow probing of individual grains. In this study, a novel, computationally efficient, and fully automated approach is intro...

Predicting process–structure and structure–property relationships are the key tasks in materials science and engineering. Central to both research directions is the internal material structure. In the case of metallic materials for structural applications, this internal structure, the microstructure, is the collective ensemble of all equilibrium an...

The demand for heavy-gauge steel plates for use in the large structures has been increasing steadily. Controlled rolling is an effective method of both increasing the strength of steel plates and improving their toughness. Techniques for controlling the texture of polycrystalline materials are very important because texture distribution has a stron...

The influence of grain shape and crystallographic orientation on the global and local elastic and plastic behaviour of strongly textured materials is investigated with the help of full-field simulations based on texture data from electron backscatter diffraction (EBSD) measurements. To this end, eight different microstructures are generated from ex...

Primary static recrystallization is a restoration process during which the critically strong deformed microstructure is atomistically reconstructed into a polycrystal with orders of magnitude lower defect density. Advances in diffraction methods catalyzed research activities directed towards more accurate understanding of recrystallization. While t...

We present a new approach to predict the evolution of anisotropic yield functions by coupling large scale forming simulations with crystal plasticity-spectral based virtual experiments, realizing a multi-scale model for metal forming. Employing a fast spectral method solver enables us to conduct on-the-fly full-field virtual experiments to evolve t...

Although magnesium alloys deform extensively through shear strains and crystallographic reorientations associated with the growth of twins, little is known about the strengthening mechanisms associated with this deformation mode. A crystal plasticity based phase field model for twinning is employed in this work to study the strengthening mechanisms...

Although magnesium alloys deform extensively through shear strains and crystallographic re-orientations associated with the growth of twins, little is known about the strengthening mechanisms associated with this deformation mode. A crystal plasticity based phase field model for twinning is employed in this work to study the strengthening mechanism...

DAMASK Overview 2019

The local and global behavior of materials with internal microstructure is often investigated on a (representative) volume element. Typically, periodic boundary conditions are applied on such “virtual specimens” to reflect the situation in the bulk of the material. Spectral methods based on Fast Fourier Transforms (FFT) have been established as a p...

Low-alloyed steels with body-centered cubic crystal structure are a material class that is widely used for sheet metal forming applications. When having an adequate crystallographic texture and microstructure, their mechanical behavior is characterized by an isotropic in-plane flow behavior in combination with a low yield strength. The decisive pro...

https://damask.mpie.de Editor's choice: https://www.sciencedirect.com/science/article/pii/S0927025618302714?via%3Dihub Crystal Plasticity (CP) modeling is a powerful and well established computational materials science tool to investigate mechanical structure–property relations in crystalline materials. It has been successfully applied to study...

The correct copyright line for this article is “The Author(s) 2017. This article is an open access publication”, rather than “The Minerals, Metals & Materials Society 2017” (as in the original HMTL version of the article).

Phase-field studies of solid-state precipitation under strong chemo-mechanical coupling are performed and benchmarked against the existing analytical solutions. The open source software packages OpenPhase and DAMASK are used for the numerical studies. Solutions for chemical diffusion and static mechanical equilibrium are investigated individually f...

Handbook of Mechanics of Materials Editor-in-chief: Hsueh, Chun-Hway Schmauder, S., Chen, C.-S., Chawla, K.K., Chawla, N., Chen, W., Kagawa, Y. (Eds.) ISBN 978-981-10-6885-0 The local and global behavior of materials with internal microstructures is often investigated on a (representative) volume element. Typically, periodic boundary conditions...

The solution of a continuum mechanical boundary value problem requires a constitutive response that connects deformation and stress at each material point. Such connection can be regarded as three separate hierarchical problems. At the top-most level, partitioning of the (mean) boundary values of the material point among its microstructural constit...

Dual-phase steels are characterized by high level of mechanical properties and thereby are used in automotive industry for the components with responsible applications. They are not leaders in the wide spectrum of used high-strength steels, but their potential is not completely used yet. The paper presents development of damage mechanisms of the co...

A coupled experimental-numerical approach is used to investigate the strain partitioning in microstructures of high-strength steels. The comparison between calculated and measured strain fields reveals significant deviations in some regions of the microstructure; these deviations can be explained by the missing subsurface microstructure in the simu...

Dualphasenstähle werden aufgrund ihrer mechanischen Eigenschaften im Automobilbau für sicherheitskritische Bauteile verwendet. Obwohl sie die ersten in großem Umfang eingesetzten hochfesten Stähle sind, ist ihr Potenzial nicht ausgeschöpft. Am Max-Planck-Institut für Eisenforschung (MPIE) in Düsseldorf werden deshalb die Schädigungsmechanismen dies...

Various mechanisms such as anisotropic plastic flow, damage nucleation, and crack propagation govern the overall mechanical response of structural materials. Understanding how these mechanisms interact, i.e. if they amplify mutually or compete with each other, is an essential prerequisite for the design of improved alloys. This study shows—by using...

Modern high-performing structural materials gain their excellent properties from the complex interactions of various constituent phases, grains, and subgrain structures that are present in their microstructure. To further understand and improve their properties, simulations need to take into account multiple aspects in addition to the composite nat...

DAMASK Overview 2016

Microstructures of metallic structural materials have become increasingly complex, incorporating typically more than one microstructural feature to adjust the material properties according to specific needs. To predict the behaviour of such complex materials, the underlying effects like interaction of different phases, hardening of slip systems, tw...

We present a virtual laboratory to investigate the anisotropic yield behavior of polycrystalline materials by using high resolution crystal plasticity simulations. Employing a fast spectral method solver enables us to conduct a large number of full-field virtual experiments with different stress states to accurately identify the yield surface of th...

We present a study on the plastic deformation of single crystalline stochastic honeycombs under in-plane compression using a crystal plasticity constitutive description for face-centered cubic (fcc) materials, focusing on the very early stage of plastic deformation, and identifying the interplay between the crystallographic orientation and the cell...