Behavior Of Materials Research Articles

Cross-scale method of MD-FE for modeling mechanical damage behaviors of ferrite-cementite steels

Inspired by the experimentally observed ferrite-cementite interface damage and ferrite matrix damage, this work develops a cross-scale method using the cohesive zone model (CZM) as a bridge to study the mechanical damage behavior of ferrite-cementite steel at the micro-nano scale. The CZM parameters for the damage region of ferrite-cementite steel were obtained by molecular dynamics (MD) simulations, which were then applied to cohesive elements in the finite element (FE) framework, thus enabling crack initiation and propagation at the micro-scale. Simulation results show that the ferrite-cementite interface is more susceptible to damage resulting in cracking compared to the ferrite matrix, which is consistent with the experimental observation that there are extensive debonded voids due to interface damage. The implementation of this work provides a new way to study the micro-nano scale mechanical behavior of heterogeneous materials containing both interface damage and matrix damage.

Numerical Study of the Thermal Behavior of a Wall Containing Phase Change Material (PCM) in a Hot and Dry Climate

Current buildings in Burkina Faso, particularly in the Sahelian zone, built with local materials are energy-intensive and sources of discomfort for the occupants. However, the role of housing is to provide man with shelter which protects him from external climatic conditions and offers him thermal comfort. In this work, we present a numerical study of the thermal behavior of a wall containing a phase change material (PCM) in the Sahelian zone. The MCP used in this study is RT27 paraffin with a melting temperature of 27°C and a latent heat of fusion of 179kJ/kg. The equations obtained were adimensionalized and discredited by the finite element method and solved using COMSOL Multiphysics software version 5.3. To this end, we were interested on the one hand in the study of the evolution of the flow of heat and the temperature at the level of the external and internal walls of the wall. On the other hand, we studied the effect of the location of a layer of PCM mortar, simple plaster or cement plaster on the temperature of the internal wall of the wall. The results show the magnitude of heat flux and temperature is greatly reduced by the incorporation of PCM into the wall.

Dynamic Behavior and Permanent Indentation in S2-Glass Woven Fabric Reinforced Polymer Composites under Impact: Experimentation and High-Fidelity Modeling

This paper studies the behavior of S2-glass woven fabric reinforced polymer composite under low-velocity impact at 18–110 J energy. A macro-homogeneous finite element model for the prediction of their response is implemented, considering the non-linear material behavior and intralaminar and interlaminar failure modes for the prediction of impact damage. The model accurately predicted the permanent indentation caused by impact. By applying the Ramberg-Osgood formulation, different initial stiffness values are examined to assess the post-impact unloading response. This approach reveals the significant role of initial stiffness in inelastic strain accumulation and its consequent effect on permanent indentation depth. A higher initial stiffness correlates with increased inelastic strain, influencing the impactor rebound and resulting in greater permanent indentation. By accurately predicting permanent indentation, and damage accumulation for different impact energies, this study contributes to a better understanding of the impact behavior of composite materials, thereby promoting their wider application.

Variability and loss of uniqueness of numerical solutions in FEM×DEM modeling with second gradient enhancement

AbstractIn the last decade, a new multi‐scale FEM×DEM approach has been developed using Finite Element Method (FEM) coupled with Discrete Element Method (DEM) as a constitutive law to account for the specificities of the mechanical behavior of granular materials. In FEM×DEM model, a DEM calculation is performed on a particle assembly (volume element—VE) at each Gauss point. Recent publications have demonstrated that FEM×DEM approach naturally captures the discrete and anisotropic nature of granular materials. Despite its advantages, FEM×DEM with classical FEM, suffers from mesh dependency, especially when material enters softening phase and exhibits strain localization. To overcome this limitation, FEM×DEM model has been enriched by incorporating a local second gradient model. Nevertheless, the existence of multiple possible solutions is observed. In this paper, we study the variability and loss of uniqueness of numerical solutions to a boundary value problem. Different VEs with equivalent mechanical properties are generated and used to model the pressuremeter tests by means of FEM×DEM. The modeling results show a great variability of the numerical results, both in shape of borehole and in different modes of shear bands. For the same VE, the loss of uniqueness of numerical solutions is evidenced by a slight modification of loading history at the level of the internal pressure applied to the borehole. Finally, we show that when a certain heterogeneity is introduced by using different VEs within the same BVP, even if the uniqueness of the solution is not guaranteed, the set of possible solutions seems more restrained.

Semantics-Enabled Data Federation: Bringing Materials Scientists Closer to FAIR Data

AbstractThe development and discovery of new materials can be significantly enhanced through the adoption of FAIR (Findable, Accessible, Interoperable, and Reusable) data principles and the establishment of a robust data infrastructure in support of materials informatics. A FAIR data infrastructure and associated best practices empower materials scientists to access and make the most of a wealth of information on materials properties, structures, and behaviors, allowing them to collaborate effectively, and enable data-driven approaches to material discovery. To make data findable, accessible, interoperable, and reusable to materials scientists, we developed and are in the process of expanding a materials data infrastructure to capture, store, and link data to enable a variety of analytics and visualizations. Our infrastructure follows three key architectural design philosophies: (i) capture data across a federated storage layer to minimize the storage footprint and maximize the query performance for each data type, (ii) use a knowledge graph-based data fusion layer to provide a single logical interface above the federated data repositories, and (iii) provide an ensemble of FAIR data access and reuse services atop the knowledge graph to make it easy for materials scientists and other domain experts to explore, use, and derive value from the data. This paper details our architectural approach, open-source technologies used to build the capabilities and services, and describes two applications through which we have successfully demonstrated its use. In the first use case, we created a system to enable additive manufacturing data storage and process parameter optimization with a range of user-friendly visualizations. In the second use case, we created a system for exploring data from cathodic arc deposition experiments to develop a new steam turbine coating material, fusing a combination of materials data with physics-based equations to enable advanced reasoning over the combined knowledge using a natural language chatbot-like user interface.

Enhancing Magnetic Material Data Analysis with Genetic Algorithm-Optimized Variational Mode Decomposition

As the application of machine learning technology in predicting and optimizing material performance continues to grow, handling the electromagnetic data of magnetic materials, especially in removing unavoidable data noise and accurately extracting resonance peaks in the imaginary part of electromagnetic information, has become a significant challenge. These steps are crucial for revealing the deep electromagnetic behavior of materials and optimizing their performance. In response to this challenge, this study introduces an innovative approach—Genetic Algorithm-Optimized Variational Mode Decomposition for Signal Enhancement (GAO-VMD-SE). This method, through the Variational Mode Decomposition (VMD) technique optimized by genetic algorithms, not only effectively reduces noise in the data, thereby improving the Signal-to-Noise Ratio (SNR) and reducing the Mean Absolute Error (MAE), but also significantly enhances the hidden resonance peak information in complex permittivity and permeability data to achieve a comprehensive improvement in key performance indicators. Experimental results prove that this method surpasses traditional analysis techniques in key performance metrics such as the peak width ratio, peak overlap ratio, and the number of peaks. Especially in identifying characteristic peaks related to the Snoek limit, GAO-VMD-SE can effectively reveal the peak features hidden in complex data, thus providing important insights for evaluating the performance of materials at specific frequencies. Moreover, the effectiveness of this method in denoising not only enhances the quality and accuracy of material data analysis but also achieves a 1% to 10% enhancement in peak information extraction. This optimized data processing capability and versatility make GAO-VMD-SE not only suitable for evaluating the performance of magnetic materials but also show significant practical application value in processing spectral data and other time series signal data applications.

Fabrication and Characterization of a Magnetic 3D‐printed Microactuator

AbstractConventional MEMS microactuators have, in recent years, been complemented by 3D‐printed actuatable microstructures fabricated via two‐Photon‐Polymerization (2PP). Herein, a novel compact 3D‐printed magnetically actuatable microactuator with a diameter of 500µm is demonstrated, originally designed for micro‐optical systems. It is fabricated by incorporating a composite of NdFeB microparticles and epoxy resin into a designated reservoir of the printed mechanical structure within a simple post‐processing step. The microactuator structure features mechanical springs, allowing for continuous positioning with large displacement. Mechanical studies by nanoindentation of IP‐S bulk structures reveal a viscoelastic material behavior, described by a two‐element General Kelvin‐Voigt viscoelasticity model. The obtained material parameters are then used to simulate and characterize the spring behavior of the microactuator. Actuation experiments are conducted using an external microcoil. The actuator displacement is measured for triangular current pulses with a peak current of 106 mA and durations of 1 to 100 s, resulting in displacements of 69.1 to 88.9 µm. Hysteretic behavior of the actuator is observed, attributable to viscoelasticity and magnetic properties of the core material. Numerical simulations of the experiment demonstrate this behavior as well. On‐the‐fly demagnetization and the implementation of closed‐loop control allow for both high repeatability and precise positioning.

Three-dimensional frictional contact within the framework of couple stress elasticity

This work investigates a three-dimensional size-dependent frictional contact problem of a rigid spherical punch sliding on an elastic half-space. The size-dependent material behaviors are governed by the couple stress theory, and the corresponding frequency response functions, which include two additional length-related elastic parameters, are obtained. Based on the conjugate gradient method and the discrete convolution-fast Fourier transform algorithm, a semi-analytical model is established to predict the frictional size-dependent contact behaviors and then the detailed parameter analysis is performed. The transverse effects of the couple stress, which are induced due to the considerations of the two additional elastic parameters in couple stress theory, are investigated in the contact problems for the first time. And the dependences of the size-dependent contact behavior on the coupling effects of the friction and the two additional elastic parameters are presented.

Analysis of Plastic Deformation of Pipes Due to Deflagration to Detonation Transition Using Static Equivalent Pressure

Abstract Explosions of premixed gases with deflagration to detonation transition (DDT) are a risk in the process industry with potentially catastrophic consequences. Robust and simple design methods are required for industrial use. Such a simplified design method based on finite element analysis is proposed to model the dynamic behavior of pipes loaded by gas explosions of premixed gases including DDT. The focus is on so-called long pipes, where the DDT is not affected by reflections at blind flanges. First, it is reviewed how the pressure load of the gas explosion and the resulting material behavior has been modeled in previous publications. The analytical equations are then extended for describing the pressure load as a function of time and location by considering the leading compression wave as it affects the pressure load of the overdriven detonation. The extended analytical equations are parameterized using Chapman-Jouguet conditions and experimental results from publications for both static equivalent pressure and the location of the DDT. To describe the plastic material behavior at high strain rates, the well-known Johnson-Cook plasticity model is used. The material parameters of the model are derived from simple experiments, which are available in an industrial environment. The comparison of a finite element simulation with experimental data shows that the concept of equivalent static pressure can be extended to an finite element analysis, which in the future will allow the sizing of complete pipe systems including tees, bends, and flanges while considering plastic deformation.

Adaptive and Robust Vitrimers Fabricated by Synergy of Traditional and Supramolecular Polymers.

Vitrimers offer a unique combination of mechanical performance, reprocessability, and recyclability that makes them highly promising for a wide range of applications. However, achieving dynamic behavior in vitrimeric materials at their intended usage temperatures, thus combining reprocessability with adaptivity through associative dynamic covalent bonds, represents an attractive but formidable objective. Herein, we couple boron-nitrogen (B-N) dative bonds and B-O covalent bonds to generate a new class of vitrimers, boron-nitrogen vitrimers (BNVs), to endow them with dynamic features at usage temperatures. Compared with boron-ester vitrimers (BEVs) without B-N dative bonds, the BNVs with B-N dative bonds showcase enhanced mechanical performance. The excellent mechanical properties come from the synergistic effect of the dative B-N supramolecular polymer and covalent boron-ester networks. Moreover, benefiting from the associative exchange of B-O dynamic covalent bonds above their topological freezing temperature (Tv), the resultant BNVs also possess the processability. This study leveraged the structural characteristics of a boron-based vitrimer to achieve material reinforcement and toughness enhancement, simultaneously providing novel design concepts for the construction of new vitrimeric materials.

Tensile assessment of woven CFRP using finite element method: A benchmarking and preliminary study for thin-walled structure application

Abstract Carbon-fiber-reinforced polymers (CFRPs) are a composite material popular for thin-walled structure applications because of their advantages over other materials. In this study, numerical simulation analysis based on the finite-element method to identify the tensile behavior of CFRP woven material has been carried out. The method used has been verified and validated using a benchmarking procedure with the results of previous research. Errors in the simulation results are less than 10%, indicating a valid method that can be used for further research. The stress–strain distribution of each layer, the effect of ply orientation on tensile strength, the comparison of failure criteria used, and the comparison of several types of reinforcements often used have been investigated. The results showed that the characteristics of each inner layer received tensile loading visualized in the form of stress strains. Choosing the right layer angle on CFRP woven can affect the performance and strength of the material. Failure criteria that are appropriate to specific application conditions are important. Puck criteria can be used for simple applications, which require only the analysis of the main stresses in the material. Tsai–Hill and Tsai–Wu criteria can provide more accurate predictions and are better suited for loading conditions and more complex material types. Carbon fiber has better characteristics when compared to S-glass and E-glass.

System Identification Using Self-Adaptive Filtering Applied to Second-Order Gradient Materials

For many engineering applications, it is sufficient to use the concept of simple materials. However, higher gradients of the kinematic variables are taken into account to model materials with internal length scales as well as to describe localization effects using gradient theories in finite plasticity or fluid mechanics. In many approaches, length scale parameters have been introduced that are related to a specific micro structure. An alternative approach is possible, if a thermodynamically consistent framework is used for material modeling, as shown in the present contribution. However, even if sophisticated and thermodynamically consistent material models can be established, there are still not yet standard experiments to determine higher order material constants. In order to contribute to this ongoing discussion, system identification based on the method of self-adaptive filtering is proposed in this paper. To evaluate the effectiveness of this approach, it has been applied to second-order gradient materials considering longitudinal vibrations. Based on thermodynamically consistent models that have been solved numerically, it has been possible to prove that system identification based on self-adaptive filtering can be used effectively for both narrow-band and broadband signals in the field of second-order gradient materials. It has also been found that the differences identified for simple materials and gradient materials allow for condition monitoring and detection of gradient effects in the material behavior.

Study on Plastic Constitutive Relation and Ductile Fracture Criterion of AM60B Magnesium Alloy.

It is currently a challenge to accurately predict the deformation and fracture behavior of metal parts in automobile crashes. Many studies have shown that the deformation and fracture behavior of materials are significantly affected by the stress state during automobile crashes with complex stress state characteristics. In order to further promote the application of die-cast magnesium alloys in automobiles, it is particularly important to study the material deformation and fracture behavior of die-cast magnesium alloys. In this paper, the mechanical properties of the AM60B die-cast magnesium alloy sheet under four stress states (shear, tension, R10 notch tension, and cupping) were designed and tested. Based on the von Mises isotropic constitutive model and Swift weighted Hockett-Sherby hardening model, the plastic constitutive model of die-cast magnesium alloy was established. Based on the plastic model and the fracture model (JC, MMC, and DIEM) considering the influence of three stress states, the deformation and fracture behavior of the AM60B die-cast magnesium alloy front-end members in three-point bending were predicted by experiments and finite element simulation. The experimental results show that the deformation mode and loading-displacement curve trend of the AM60B die-cast magnesium alloy front members are the same, the crack initiation point and crack initiation time are the same, and the crack shape is similar. The results show that the complex stress state constitutive model parameters and the DIEM fracture model obtained in this paper can accurately predict the deformation and fracture failure behavior of the AM60B die-cast magnesium alloy sheet.

Ballistic impact resistance and flexural performance of natural basalt fiber with carbon and glass fibers in inter‐ply hybrid composites

AbstractThe ballistic and flexural behaviors of basalt (natural fabric), carbon, glass fiber, and their hybrid composites, were investigated in this study. The main objective of the paper was the addition of natural basalt fiber to the carbon and glass fibers with inter‐ply hybrid sequences to search for possible usage to the ballistic loads carrying structures. The composite and hybrid composite plates produced nine layers with cross‐ply stacking sequences ([0/90]9). The ballistic impact tests were conducted using a specially designed ballistic test setup and the flexural tests were performed through the standard three‐point bending test. The results showed that basalt/epoxy absorbed the most energy under ballistic loading among all models. It was observed that the basalt‐glass‐basalt/epoxy (BGB) hybrid composite had an energy absorption capacity very close to the basalt/epoxy composite. When BGB and carbon‐glass‐carbon/epoxy (CGC) hybrid models were compared, the energy absorption capacity of CGC was 62.7% less than BGB. Unlike the ballistic test result, basalt/epoxy had the lowest flexural strength, while carbon/epoxy had the highest flexural strength. Among the hybrid models, it was seen that BGB had the lowest flexural strength, while CGC had the highest flexural strength. The flexural strength of the CGC is 38% higher than BGB. The study found that basalt fiber has high ballistic resistance, whether alone or when combined with commonly used fibers. It also suggests that basalt fiber is a promising candidate for future research and development in the field of protective materials.Highlights Basalt (natural fabric) composite materials behavior. Hybridization of basalt with carbon and glass. Target plates damage resistance according to applied ballistic loads. Target plates damage resistance according to applied flexural loads. Non‐hybrid and hybrid composites plates comparisons.

Performance of Engineered Cementitious Composites (ECC) in shield tunnel segmental joints: A comparative study with ordinary reinforced concrete

Shield tunnel segmental joints are traditionally vulnerable, limited by their tensile capacity and susceptibility to cracking. Engineered Cementitious Composites (ECC) offer a promising solution due to their superior tensile strength, exceptional crack resistance, and remarkable toughness. However, the application of ECC in tunnel segment joints remains unexplored. To address this gap, this paper conducted comprehensive full-scale tests of ECC segmental joints versus ordinary reinforced concrete (RC) segmental joints. It investigated mechanical responses including material behavior, deflection, joint action, bolt strain, crack development, and failure modes. Results revealed that: (1) ECC joints provided a 33.97 % higher stable bearing capacity and a 50 % increase in initial cracking strength compared to RC joints. (2) ECC joints excelled in crack control, maintaining crack widths below 0.2 mm, while RC joints experienced significant cracking with widths exceeding 1 mm. (3) In terms of toughness, ECC joints surpassed RC by 66 % in the elastic stage and 123 % in the normal serviceability stage, with 96 % higher ductility. (4) ECC joints significantly outperformed RC joints in bolt stress uniformity and concentration, achieving a 43.21 % reduction in average bolt stress. (5) Regarding multi-scale mechanical effects, ECC joints increased the toughness and strength advantage over RC by more than 45 % in the elastic phase. These results reveal the potential of ECC in significantly enhancing the durability and resilience of shield tunnels, particularly in harsh environments subjected to high ground stress or seismic activities.

Research on multi-scale hysteresis constitutive model of giant magnetostrictive materials considering multi-field coupling

The magnetization and magnetostrictive strain of giant magnetostrictive materials exhibit a complex nonlinear trend under the coupling of multiple fields, including magnetic field, temperature field, and prestress field. To enhance prediction accuracy, we propose a three-dimensional magnetic-thermal-force coupled nonlinear multi-scale hysteresis vector model. This model is derived from the principles of thermodynamics and continuum mechanics, taking into account the interactions among magnetic domains, grains, polycrystals, and macroscopic scales. It combines the volume-averaging principle of magnetic domain microscopy with the generalized Jiles-Atherton hysteresis model. The predicted hysteresis magnetization and magnetostrictive strain curves obtained from this model are in good agreement with experimental results. By analyzing the predicted hysteresis magnetization and magnetostrictive strain under different conditions, we demonstrate that our proposed model can comprehensively describe the effects of temperature and prestress on the multi-field coupled hysteresis behaviors of giant magnetostrictive materials. Moreover, it provides theoretical guidance for both macroscopic and microscopic optimization in designing active devices incorporating super magnetostrictive materials.

Surface roughness evolution and heterogeneous plastic deformation of austenitic stainless steel during micro deep drawing: Modeling and experiment

The present work involves the numerical simulation and experimental study on the surface roughness evolution and heterogeneous plastic deformation (strain localization and concomitant surface morphology evolution) in grain scale of micro deep drawn parts of austenitic stainless steel (ASS) 304 foils. A three-dimensional modeling framework was used to simulate the micro deep drawing (MDD) process. The simulation involved the development of a Voronoi-based polycrystalline geometry model (VPGM), a multi-stress-strain response model, and a crystal plasticity finite element methods (CPFEM) model. The results indicate that CPFEM model exhibits higher accuracy in the localized stress and strain, thickness distribution fluctuation and surface roughness evolution of the fabricated parts compared to multi-stress-strain response model. Therefore, the plastic deformation heterogeneity in MDD is in-depth discussed based on CPFEM model. The results show that the coarse-grained foils correspond to the intense strain localization, which is the main cause of surface roughening. Considering the average grain size is close to the thickness of ASS foils, mounding features on the rough surface may readily develop further into potentially fractured sites during deformation. On the other hand, crystal orientation influence plastic deformation by affecting the slip behavior of materials. The effect of crystal orientations including {011} 〈211〉 (Brass), {011} 〈100〉 (Goss), and {112} 〈110〉 components on deformation is discussed. The results indicate a strong correlation between the magnitude of the Schmid's factor and the ease of deformation. Additionally, variations in Schmid's factor across different directions result in differences in deformation accumulation, which affects the thickness distribution along the radial direction and the distribution of earrings and wrinkles along the circumferential direction of the fabricated micro parts.

3D DEM-based particle-scale analysis of drained and undrained triaxial behaviors of granular materials

3D DEM-based particle-scale analysis of drained and undrained triaxial behaviors of granular materials

Failure Analysis and Fatigue Behavior of Natural Fibers Reinforced Composite Materials under Cyclic Loading

This research investigates the failure analysis and fatigue behavior of composite materials reinforced with a combination of glass fiber, sisal fiber under cyclic loading conditions. The study aims to elucidate the synergistic effects of these diverse natural fibers in enhancing the mechanical properties and fatigue resistance of the composite materials. Experimental methods, including mechanical testing and microscopic analysis, are employed to discern the individual contributions of each fiber type and their combined influence on failure modes and fatigue life. The project seeks to provide valuable insights into the optimal integration of glass, sisal to achieve a balanced composite material that exhibits superior durability and performance. The outcomes of this research contribute not only to the advancement of natural fibers composites but also offer practical guidelines for designing resilient materials for various engineering applications.

Three-Dimensional Columnar Microstructure Representation Using 2D Electron Backscatter Diffraction Data for Additive-Manufactured Haynes®282®.

This study provides a methodology for exploring the microstructural and mechanical properties of the Haynes®282® alloy produced via the Powder Bed Fusion-Electron Beam (PBF-EB) process. Employing 2D Electron Backscatter Diffraction (EBSD) data, we have successfully generated 3D representations of columnar microstructures using the Representative Volume Element (RVE) method. This methodology allowed for the validation of elastic properties through Crystal Elasticity Finite Element (CEFE) computational homogenization, revealing critical insights into the material behavior. This study highlights the importance of accurately representing the grain morphology and crystallographic texture of the material. Our findings demonstrate that created virtual models can predict directional elastic properties with a high level of accuracy, showing a maximum error of only ~5% compared to the experimental results. This precision underscores the potential of our approach for predictive modeling in Additive Manufacturing (AM), specifically for materials with complex, non-homogeneous microstructures. It can be concluded that the results uncover the intricate link between microstructural features and mechanical properties, underscoring both the challenges encountered and the critical need for the accurate representation of grain data, as well as the significance of achieving a balance in EBSD area selection, including the presence of anomalies in strongly textured microstructures.