Microstructural Simulations Research Articles

Quantifying laser irradiation-induced temperature field of particle reinforced metal matrix composites

While particle-reinforced metal matrix composites (PMMCs) are composed of particles and matrix with distinctly different thermomechanical properties, the thermal differences and coupled interactions between individual phases greatly determine the thermal characteristics of PMMCs under laser irradiation. In this work, we quantify the temperature evolution characteristics within SiCp/Al under laser irradiation by microstructural thermal finite element simulations and experimental investigation. Specifically, a 2D thermophysical FE model of laser-SiCp/Al interaction for the two-phase PMMCs material under laser irradiation is developed, which incorporates the temperature-dependent thermophysical properties of particles, matrix and interfaces, along with the considerations of the shape and distribution characteristics of particles, as well as the comprehensive thermal conditions. Furthermore, a 3D equivalent thermal FE model for experimental validation of predicted laser-induced temperature of SiCp/Al is developed, based on the derived equivalent properties. Meanwhile, an in-situ temperature measurement system is constructed for exploring temperature evolution characteristics during the on-going laser irradiation process, which validates a derivation of 1.7 % of predicted temperature by the equivalent thermal FE model. Finally, the impact of laser processing parameters on the temperature field of SiCp/Al is addressed. These findings provide valuable insights for understanding the thermal mechanisms of PMMCs under laser irradiation, and also the parameter optimization for laser processing of PMMCs.

Microstructural Simulations of Polymer Composites by a Viscoelastic Spring Lattice Model

AbstractAn improved viscoelastic spring lattice model is used to analyze the mechanical properties of polymer composites containing different microstructures, as exemplified by hydroxyl‐terminated polybutadiene‐based solid propellants. A drop‐on‐demand structural model is programmed using the C language to simulate the real solid propellant microstructure. The results show that increasing the particle content has a positive effect on the tensile strength of the propellant, but is detrimental to the ductility. The increase in particle size decreases the maximum tensile strength of the material, reflecting the importance of the dewetting process in the microstructure analysis. Finally, the model accurately predicts that initial defects have a destructive effect on the mechanical properties of the material.

Multiscale computational study to predict the irradiation-induced change in engineering properties of fusion reactor materials

In this study, we address the impact of irradiation conditions in a tokamak on the engineering properties of materials, leading to potential degradation of in-vessel components over their lifecycle. Our approach involves a predictive model for irradiation-induced damage, employing a multiscale computational framework. This framework integrates various simulation techniques, including Monte Carlo-based neutronics (OpenMC), dislocation dynamics (DD) using MoDELib, and finite element analysis (FEA) with Code_Aster. This integration offers a versatile solver capable of analysing tokamak components exposed to different irradiation doses and temperature conditions.To showcase the utility of this multiscale computational framework, we present a case study focused on tungsten monoblock designs. We assess the failure probabilities of these designs at different stages of their lifecycle. Neutron heating and damage energy values are obtained from OpenMC neutronics simulations. The neutron heating values serve as volumetric heat sources for the FEA thermal simulation. We calculate the displacement per atom (dpa) across the monoblock at various full power days (day 0, day 100, and day 1000) using the damage energy values. The irradiation-induced defect densities, dependent on temperature and dpa, are inputs to DD microstructural simulations performed on the representative volume element (RVE) using MoDELib. This allows us to obtain the yield stress of the material. Subsequently, the thermal fields from the FEA thermal simulation, along with the dpa and temperature-dependent yield stress from the DD simulation, are implemented for FEA mechanical simulations.To evaluate the failure probability of the monoblock designs at different stages of their lifecycle, we conduct an SDC-IC assessment, incorporating a plastic flow localization rule within the current framework. This comprehensive approach provides insights into the thermo-mechanical behaviour of in-vessel components subjected to neutron irradiation, offering a predictive capability for assessing their performance over time.

Integrated microstructural simulations and mechanical property predictions for age-precipitated Al–Mg–Si alloys

Integrated microstructural simulations and mechanical property predictions for age-precipitated Al–Mg–Si alloys

Insights into Performance and Degradation of Commercial Ni-Rich Cathodes: A Modeling Perspective

Li-ion batteries are widely used in consumer electronics due to their high energy density and currently gain further importance with regards to future mobility and their application in electric vehicles. While a high nickel content in stoichiometries like LiNi0.8Mn0.1Co0.1O2 (NMC811) increases the achievable capacity in a given voltage window, it also poses challenges to structural stability during cycling [1]. Therefore, application and further development of those materials requires a deep understanding of their performance limitations as well as their degradation. Since extensive testing is time-consuming and expensive, predictive simulation tools are needed that are able to describe the electrochemical behavior of the cell.In this contribution, we will present 3D microstructure-resolved electrochemical continuum simulations conducted in the simulation framework BEST. It is based on a thermodynamically consistent transport theory for mass and charge in the electrolyte and the active material [2]. Owing to the finite volume discretization of the governing equations, it is straightforward to use voxel-based image data obtained by focused ion beam - scanning electron microscopy (FIB-SEM) as the simulation domain. Previous studies have shown the importance of microstructural simulations with regards to battery operation [3] and contributed to a deeper insight into the cell aging [4]. This approach will be complemented by a pseudo-2D (p2D) model considering different aging modes, thus providing additional predictions on the cell aging.In our work we analyze commercial NMC811/graphite cells. We demonstrate a very good agreement at the beginning of life between our simulations and experimental data obtained in rate tests and electrochemical impedance spectroscopy (EIS). In the high-energy cathodes we found a very low content (3 vol-%) of carbon binder domain (CBD), which is insufficient to establish a conductive network. Hence, the electronic conductivity of the active material determines the effective conductivity of the electrode and limits the performance at high degrees of lithiation. Additionally, we evaluate the degradation of the NMC active material using our simulation approach.Combining the 3D microstructure-resolved simulations with an efficient p2D model provides a valuable toolchain to gain a comprehensive understanding of the performance limitations as well as the relevant aging modes in commercially available high-energy cathodes.Acknowledgement:This work has been funded by the ‘Bundesministerium für Bildung und Forschung’ within the project MiCha under the reference number 03XP0317D. The authors acknowledge support by the state of Baden-Württemberg through bwHPC (JUSTUS 2).

Three-dimensional microstructural simulation of the thermodynamic behavior of recycled concrete under freeze-thaw action

A thermal-water-mechanical coupling model was utilized to simulate pore water crystallization and melting heat transfer processes in recycled concrete. Based on the random spherical microstructure of recycled concrete, The characteristics of aggregates, new mortar, old mortar, and the interface transition zones (ITZ1, ITZ2, and ITZ3) between natural aggregates and new mortar, old aggregates, and mortar, as well as new and old mortar, were clearly described. The proposed model was validated by comparing it with experimental data available in the literature. Three-dimensional microstructural finite element simulations were performed to assess the influence of the water-to-cement ratio of new mortar, the water-to-cement ratio of old mortar, aggregate gradation, replacement ratio of recycled aggregates, aggregate volume fraction, and temperature difference on the performance of recycled concrete. The research results demonstrated that the aggregate gradation, replacement ratio of recycled aggregates, and aggregate volume fraction significantly affected recycled concrete's freeze-thaw characteristics. In contrast, the influence of the water-to-cement proportions of fresh and old mortar was relatively small. The impact of environmental temperature differences should also be given due attention.

Experimental and Numerical Investigation into the Mechanical Behavior of Composite Solid Propellants Subject to Uniaxial Tension.

To further explore the quasi-static mechanical characteristics of composite solid propellants at low strain rates, an investigation was conducted on the mechanical behavior and damage mechanisms of a four-component hydroxy-terminated polybutadiene (HTPB) propellant by means of experiments and numerical simulation. A uniaxial tensile test and scanning electron microscope (SEM) characterization experiment were carried out. A microstructural model, which accurately represents the mesoscopic structure, was developed via the integration of micro-CT scanning and image-processing techniques. The constructed microstructural model was utilized to conduct a numerical simulation of the mechanical behavior. The experimental results demonstrated that the maximum tensile strength increases with increasing strain rate, and the primary cause of propellant failure at low strain rates is the dewetting phenomenon occurring at the interface between the larger particles and the matrix. The maximum tensile strength is 0.48 MPa when the strain rate is 0.00119 s-1, and the maximum tensile strength is 0.37 MPa when the strain rate is 0.000119 s-1. The simulation results indicated a consistent trend in variation when comparing the simulation and experimental curves. This suggested that the established model exhibits a high level of reliability, and provides a promising approach for carrying out microstructural simulations of heterogeneous propellants in future. The mechanical behavior of the propellant can be effectively described by utilizing a mesoscopic finite element model that incorporates the superelastic constitutive model of the matrix and the bilinear cohesive model. This framework facilitates the representation of mesoscopic damage evolution, which consequently provides insights into the damage mechanism. Additionally, the utilization of such models assists in compensating for the limitations of damage evolution characterization experiments.

Development of high strength welding consumable for arc welding carbon steels

High-tensile gas metal arc welding (GMAW) consumables are becoming increasingly common in industries such as Railways, Lifting, and Excavation (L&E) due to the need for superior mechanical performance. AWS ER90S-G grade welding consumable (with a minimum of UTS 620 MPa) is widely used alongside the commonly used AWS ER70S-6 (with a minimum of UTS 480 MPa). However, the microstructure of high-tensile wire rods often contains hard phases such as martensite, making it difficult to draw. To overcome this challenge, ER90S-G grade welding wire development was studied using microstructural analysis, mechanical testing, and physical simulations. The input material (wire rod) underwent mechanical descaling, dry drawing, intermediate annealing, wet drawing, copper coating, and spooling to produce a final wire with a diameter of 1.2 mm. A suitable microstructure (Ferrite + Carbides) is crucial for smooth wire drawing, and it is highly recommended to anneal at the intermediate stage to avoid wire breakages.

Production of a Non-Stoichiometric Nb-Ti HSLA Steel by Thermomechanical Processing on a Steckel Mill

Obtaining high levels of mechanical properties in steels is directly linked to the use of special mechanical forming processes and the addition of alloying elements during their manufacture. This work presents a study of a hot-rolled steel strip produced to achieve a yield strength above 600 MPa, using a niobium microalloyed HSLA steel with non-stoichiometric titanium (titanium/nitrogen ratio above 3.42), and rolled on a Steckel mill. A major challenge imposed by rolling on a Steckel mill is that the process is reversible, resulting in long interpass times, which facilitates recrystallization and grain growth kinetics. Rolling parameters whose aim was to obtain the maximum degree of microstructural refinement were determined by considering microstructural evolution simulations performed in MicroSim-SM® software and studying the alloy through physical simulations to obtain critical temperatures and determine the CCT diagram. Four ranges of coiling temperatures (525–550 °C/550–600 °C/600–650 ° C/650–700 °C) were applied to evaluate their impact on microstructure, precipitation hardening, and mechanical properties, with the results showing a very refined microstructure, with the highest yield strength observed at coiling temperatures of 600–650 °C. This scenario is explained by the maximum precipitation of titanium carbide observed at this temperature, leading to a greater contribution of precipitation hardening provided by the presence of a large volume of small-sized precipitates. This paper shows that the combination of optimized industrial parameters based on metallurgical mechanisms and advanced modeling techniques opens up new possibilities for a robust production of high-strength steels using a Steckel mill. The microstructural base for a stable production of high-strength hot-rolled products relies on a consistent grain size refinement provided mainly by the effect of Nb together with appropriate rolling parameters, and the fine precipitation of TiC during cooling provides the additional increase to reach the requested yield strength values.

Experimental and numerical investigations on the micro-damage behaviour of glass fibre-reinforced plastics

The formation and influence of micro-damage in glass fibre-reinforced plastics (GFRP) is carried out by numerical and experimental investigations. A quasi-static material characterisation is performed and the stiffness and strength of unidirectional, undamaged material in longitudinal and transverse direction as well as in the 23-plane are determined. Since the desired micro-damage could not be generated in unidirectional laminates due to abrupt failure, a [0∘/90∘]s layup has been identified to be most suitable to generate micro-damage in a reproducible way in the 90° layers, which is done using a tension–tension fatigue test program. During these experiments, micro-damage is detected optically and by means of ultrasonic birefringence, where the latter method shows a reduction in shear modulus due to fibre–matrix debonding prior to final inter-fibre failure. The shear modulus degradation is indirectly measured by the change in the velocity of sound. Since this method is limited to measurements in the 13- and 23-plane, all experiments are accompanied with microstructural simulations with detailed statistical volume elements (SVE), to study the influence of micro-damage under various loading conditions and directions. For loading in fibre direction, no influence on the mechanical properties is observed for the investigated fibre–matrix debonding. However, this is different for transverse loading, where a transverse shear stiffness loss of around 8% results in a decrease of transversal stiffness of around 18%, if the load direction is perpendicular to the damage plane. A similar behaviour is observed for the strength, which is reduced by a factor of 2 for the same configuration.

Influence of reduced carbon content on microstructure and mechanical behavior of Inconel 718 prepared by laser powder bed fusion

• Successful production of a reduced carbon Inconel 718 alloy via SLM. • Significant changes in the precipitation behavior of NbC and γ’’ are achieved. • Reductions in NbC content and finer γ’’ precipitation verified By Thermocalc. • Reduced γ’’ size results in improved tensile strengths at both 25 °C and 650 °C. Inconel 718 powder with reduced carbon content was used to manufacture coupons via laser powder bed fusion (LPBF) to study the influence of carbon content on microstructures and mechanical properties of HIP'ed and heat-treated material. The carbon concentration in this material was kept deliberately low (0.01 wt%) relative to a typical commercial powder composition (0.04 wt%) of IN718 in order to minimize the precipitation of primary carbides during post-processing heat treatments, which have been observed to be deleterious to elevated temperature mechanical properties such as elongation, stress rupture ductility, and notch sensitivity. The final microstructure of the lean C alloy is shown to have a significantly reduced NbC population relative to the baseline material. Furthermore, other microstructural variations such as an increased δ phase population and decreased γ’’ particle size were observed. Empirical observations agreed with microstructural simulations calculated by the ThermoCalc/TC-PRISMA precipitation module. These changes to the microstructure resulted in a 10% increase in the yield strength at both 25 and 650 °C in the lean C alloy, bringing the strength of LPBF-printed material closer to that of wrought IN718. Overall, the reduction in carbon content in the raw material has significant effects beyond limiting the pre-solution treatment precipitation of NbC, primarily by freeing Nb for formation of δ and γ’’ phases.

Discovering mechanisms for materials microstructure optimization via reinforcement learning of a generative model

The design of materials structure for optimizing functional properties and potentially, the discovery of novel behaviors is a keystone problem in materials science. In many cases microstructural models underpinning materials functionality are available and well understood. However, optimization of average properties via microstructural engineering often leads to combinatorically intractable problems. Here, we explore the use of the reinforcement learning (RL) for microstructure optimization targeting the discovery of the physical mechanisms behind enhanced functionalities. We illustrate that RL can provide insights into the mechanisms driving properties of interest in a 2D discrete Landau ferroelectrics simulator. Intriguingly, we find that non-trivial phenomena emerge if the rewards are assigned to favor physically impossible tasks, which we illustrate through rewarding RL agents to rotate polarization vectors to energetically unfavorable positions. We further find that strategies to induce polarization curl can be non-intuitive, based on analysis of learned agent policies. This study suggests that RL is a promising machine learning method for material design optimization tasks, and for better understanding the dynamics of microstructural simulations.

Learning constitutive models from microstructural simulations via a non-intrusive reduced basis method: Extension to geometrical parameterizations

Two-scale simulations are often employed to analyze the effect of the microstructure on a component’s macroscopic properties. Understanding these structure–property relations is essential in the optimal design of materials for specific applications. However, these two-scale simulations are typically computationally expensive and infeasible in multi-query contexts such as optimization and material design. To make such analyses amenable, the microscopic simulations can be replaced by inexpensive-to-evaluate surrogate models. Such surrogate models must be able to handle microstructure parameters in order to be used for material design. A previous work focused on the construction of an accurate surrogate model for microstructures under varying loading and material parameters by combining proper orthogonal decomposition and Gaussian process regression. However, that method works only for a fixed geometry, greatly limiting the design space. This work hence focuses on extending the methodology to treat geometrical parameters. To this end, a method that transforms different geometries onto a parent domain is presented, that then permits existing methodologies to be applied. We propose to solve an auxiliary problem based on linear elasticity to obtain the geometrical transformations. The method has a good reducibility and can therefore be quickly solved for many different geometries. Using these transformations, combined with the nonlinear microscopic problem, we derive a fast-to-evaluate surrogate model with the following key features: (1) the predictions of the effective quantities are independent of the auxiliary problem, (2) the predicted stress fields automatically fulfill the microscopic balance laws and are periodic, (3) the method is non-intrusive, (4) the stress field for all geometries can be recovered, and (5) the sensitivities are available and can be readily used for optimization and material design. The proposed methodology is tested on several composite microstructures, where rotations and large variations in the shape of inclusions are considered. Finally, a two-scale example is shown, where the surrogate model achieves a high accuracy and significant speed up, thus demonstrating its potential in two-scale shape optimization and material design problems.

A Review on Modelling and Simulation of Laser Additive Manufacturing: Heat Transfer, Microstructure Evolutions and Mechanical Properties

Modelling and simulation are very important for revealing the relationship between process parameters and internal variables like grain morphology in solidification, precipitate evolution, and solid-state phase transformation in laser additive manufacturing. The impact of the microstructural changes on mechanical behaviors is also a hot topic in laser additive manufacturing. Here we reviewed key developments in thermal modelling, microstructural simulations, and the predictions of mechanical properties in laser additive manufacturing. A volumetric heat source model, including the Gaussian and double ellipsoid heat sources, is introduced. The main methods used in the simulation of microstructures, including Monte Carlo method, cellular automaton, and phase field method, are mainly described. The impacts of the microstructures on mechanical properties are revealed by the physics-based models including a precipitate evolution based model and dislocation evolution based model and by the crystal plasticity model. The key issues in the modelling and simulation of laser additive manufacturing are addressed.

Preface

Nowadays, the research and development level and industrialization scale of advanced materials have become an important symbol to measure the economic and social development, scientific and technological progress and national defense strength of a country or region. Compared with the traditional mechanical manufacturing, the composite mechanical and electronic engineering and its technology with the introduction of artificial intelligence technology have a greater application prospect, and can meet the needs of increasingly complex industrial production and manufacturing in the era of highly developed industrial capacity. Advanced materials and mechanical and electronic mutual integration, mutual promotion, the penetration of relevant research and results affect the development of various fields in China, which is of great significance to accelerate China’s social upgrading and transformation and seize the commanding heights of a new round of scientific and technological revolution. It is highly delighted to introduce the 2022 2nd International Conference on Advanced Materials and Mechatronics (ICAMM 2022), which held during June 24-26, 2022 in Dali, China. The purpose of the conference is to build a bridge of communication for experts, scholars and personnel from all walks of life in the field of materials and electromechanics, and to help and promote the intersection and integration of different disciplines.About 100 participants from academic, high-education institutes and other organizations took part in the conference. The conference model was divided into two sessions, including oral presentations and keynote speeches. In the first part, some scholars, whose submissions were selected as the excellent papers, were given 15 minutes to perform their oral presentations one by one. Then in the second part, keynote speakers were each allocated 30-45 minutes to hold their speeches.In the keynote presentation part, we invited four professors as our keynote speakers. The first keynote speaker, Researcher. Wanbiao Hu, Yunnan University. His research direction: Starting from the scientific basis, application and cutting-edge issues of electronic materials, develop the transport properties of electromagnetic materials, electronic information storage, energy storage and conversion materials and devices. The second keynote speaker, Prof. Lin Zhang, Northeastern University. Dr Zhang completed his doctorate in materials physics and chemistry with the microstructural simulations of low-carbon steels and Ni-based alloys at the Northeastern University in 2002. And then we had Prof. Hongying Hou, Kunming University of Science and Technology. Our finale keynote speaker, Prof. Dr. Yarub Al-Douri, American University of Iraq, Sulaimani. His research field focuses on renewable energy, modelling and simulation, semiconductors, optical studies, nanoelectronics and nanomaterials.List of Committee member is available in this Pdf.

Microstructural simulations on CrAlN HPPMS coatings

Due to their outstanding mechanical properties, hard coatings possess a wide range of applications as protective layers. However, an experimental determination of the properties of such thin coatings is not only difficult but also cost and time intensive. In this regard, numerical methods, such as the finite element method (FEM), have the ability to reduce the experimental effort, significantly. Usually, for characterisation of hard coatings indentation tests are performed to determine the hardness, the Young's modulus or the adhesive behaviour. With the aid of FE simulations, additional important effects such as residual stresses or the microstructure on material properties can be investigated.In the presented work FE simulations of indentation tests using a Berkovich pyramid were carried out to investigate the mechanical behaviour of hard coatings in depth. During a sensitivity study, FE models with different grain boundary behaviours representing stronger and weaker responses as well as different crystallographic orientations were established and analysed. The performed simulations were validated by indentation test data and cross sections of the coatings. As a result, the incorporation of grain boundary behaviour in the simulation model affects the macroscopic mechanical behaviour of the coating system significantly. Finally, these simulation results deliver insights into the effect of the grain boundaries of the investigated hard coating and can provide suggestions for optimization.

A modular framework to obtain representative microstructural cells of additively manufactured parts

The repeating nature of additive manufacturing (AM) translates into quasi-periodic repeating hierarchical microstructures, which vary depending on the working principle of the AM technology. The geometry and internal characteristics of these repeating microstructures affect the geometrical accuracy and mechanical properties of AM parts. We propose a modular and generic framework for AM microstructures to automatically determine a representative microstructural cell with average shape and microstructural information based on micrograph processing and morphological shape analyses. A general microstructural mapping procedure is presented to map and average different microstructural features inside the representative cell. Moreover, an extension of the method is proposed to recover a representative cell with a periodic shape as required for subsequent numerical micromechanical simulations under periodic boundary conditions to unravel process-structure–property relationships. The framework is demonstrated on a virtually generated microstructure and on the metallic and polymeric microstructure of two parts manufactured with different AM processes, showing the framework's versatility for different materials and AM technologies. The three test cases show the framework's modularity, where different procedures were applied to overcome the challenges of each particular case while keeping the primary method the same. We also discuss applications of the framework, such as enabling statistical investigations of spatial variations of the microstructural features across AM parts and providing essential input for microstructural and mechanical numerical simulations.

A method to manipulate non-steady-state columnar-to-equiaxed transition in powder bed fusion additive manufacturing using an electron beam

Site-specific control of solidification grain structure is one of the largest attractiveness of manufacturing metallic parts with powder bed fusion additive manufacturing. In this study, we manufacture non-weldable superalloy Alloy713ELC with powder bed fusion additive manufacturing using an electron beam (PBF-EB) and achieve various bulk solidification grain structures, i.e. near fully equiaxed structure, interlocked zigzag structure, and columnar structures with various grain widths, through controlling process parameters under a line order scan strategy. An analytical transient model, which is capable of simulating heat transfer in PBF-EB single-layer melting under the experimental conditions, is established and validated by compared to numerical models of computational fluid dynamics and finite element method in PBF-EB single-track melting. The evolutions of solidification grain structure are rationalized using microstructural characterization and simulations based on various models. It is found that the mechanisms of columnar grain refinement and columnar-to-equiaxed transition (CET) are related to the Walton and Chalmers selection effect, which is governed by the spatial and temporal variations of solidification direction, and to the effect of convection within mushy zone. Based on the grain structure evolution mechanisms, we propose a method to manipulate CET or to achieve a novel interlocked zigzag grain structure in PBF-EB.

Effect of deformation modes on continuous dynamic recrystallization of extruded AZ31 Mg alloy

Herein, uniaxial compression experiments, with a series of true strains at different temperatures (573–673 K) and strain rates (3 ×10−3 - 3 ×10−1 s−1), are conducted on AZ31 magnesium alloy with different initial textures. The deformation modes and dynamic recrystallization (DRX) behavior are investigated using electron back-scattered diffraction /transmission electron microscopy and crystal plasticity finite element modeling (CPFEM). A unitive constitutive equation is established for different initial textures, and the activation energies of extrusion direction (ED) and transverse direction (TD) samples are found to be 134.5 kJ/mol and 138.4 kJ/mol, respectively. The microstructural investigations and CPFEM simulations are performed to identify the characteristics of DRX processing during compression and categorize according to the deformation modes originating from the difference in initial texture of alloy. Moreover, it is revealed that basal<a> slip prevails in the TD sample at all strain rates under consideration, whereas prismatic<a> slip dominates the initial deformation of the ED specimen. Consequently, more pronounced kink bands and superior compressed peak stress are observed, corresponding to the higher density of prismatic<a> slip in the ED sample than that in the TD sample. Accordingly, these kink bands along with elevated deformation energies accelerate the development of an early continuous dynamic recrystallization with a higher volume fraction and a smaller grain size of the ED sample compared to the TD specimen. The improvement in strength and ductility of the ED sample after being deformed at a strain of 1.2 is attributed to the smaller grains and the weaker texture than those of the TD specimen. For the first time, the role of prismatic slips and kink bands in the recrystallization process is discussed in detail.

Predicting the mechanical behavior of a polypropylene-based nonwoven using 3D microstructural simulation

Based on filtration simulations, virtual filter media development is used to design new nonwoven microstructures with increased filtration performance. However, the processability in the subsequent manufacturing processes of these new designs is not guaranteed. The ability to predict the mechanical properties of the new designs is crucial to predict their processability. This paper introduces a microstructural simulation model based on micro-computed tomography scans (µCT scans) to predict the three-dimensional elastic-plastic behavior of nonwoven filter media with polypropylene fibers. A microstructural analysis is performed to investigate the requirements of a representative volume element (RVE). Digital twins of the µCT scans are modeled based on the microstructural analysis. The results of an RVE convergence study serve to corroborate the existence of RVEs for this kind of material. Microstructural simulations for the load cases of tension, compression, and shear in all three spatial directions are performed on µCT scans and digital twins. The calculations are validated using the results of an extensive 3D material testing program. The distinct deformation mechanisms under the load cases of tension, compression, and shear in the machine direction, cross direction, and z-direction are discussed. Finally, the results show the dependency of the effective elastic-plastic deformation behavior on a small number of selected microstructural parameters. This dependency enables the usage of digital twins to predict the deformation behavior of virtual microstructure designs.