Variation Of Material Properties Research Articles

Investigação de um sistema alternativo para o monitoramento de deformações em estruturas de concreto armado

Abstract In civil engineering, variations in material properties together with the application of different construction techniques and environmental conditions may not be fully considered in structural designs, which could lead to structural damages. Structural Health Monitoring (SHM) makes it possible to follow the behavior of a structure, allowing the evaluation of its conditions and the investigation of its damages and need for interventions. However, SHM is not commonly applied yet due to its high instrumentation cost and the complexity of its procedures. Therefore, the present work aims the development of a low-cost strain measurement system for reinforced concrete structures composed of strain gages, amplifiers, signal converters, and microprocessors. Thus, an easy-to-use and low-cost data system composed of an AD620 amplifier module and an ADS1115 converter was built. Additionally, to facilitate field instrumentations, a steel plate with strain gages arranged in a full Wheatstone bridge was also built. The evaluation of the system was conducted by lab testing a column, four-point bending tests of four beams, and the field monitoring of two columns in a residential building during construction. The results showed that the proposed system performed satisfactorily, being able to accurately measure the strains in reinforced concrete structures.

Regional variation of the cortical and trabecular bone material properties in the rabbit skull.

The material properties of some bones are known to vary with anatomical location, orientation and position within the bone (e.g., cortical and trabecular bone). Details of the heterogeneity and anisotropy of bone is an important consideration for biomechanical studies that apply techniques such as finite element analysis, as the outcomes will be influenced by the choice of material properties used. Datasets detailing the regional variation of material properties in the bones of the skull are sparse, leaving many finite element analyses of skulls no choice but to employ homogeneous, isotropic material properties, often using data from a different species to the one under investigation. Due to the growing significance of investigating the cranial biomechanics of the rabbit in basic science and clinical research, this study used nanoindentation to measure the elastic modulus of cortical and trabecular bone throughout the skull. The elastic moduli of cortical bone measured in the mediolateral and ventrodorsal direction were found to decrease posteriorly through the skull, while it was evenly distributed when measured in the anteroposterior direction. Furthermore, statistical tests showed that the variation of elastic moduli between separate regions (anterior, middle and posterior) of the skull were significantly different in cortical bone, but was not in trabecular bone. Elastic moduli measured in different orthotropic planes were also significantly different, with the moduli measured in the mediolateral direction consistently lower than that measured in either the anteroposterior or ventrodorsal direction. These findings demonstrate the significance of regional and directional variation in cortical bone elastic modulus, and therefore material properties in finite element models of the skull, particularly those of the rabbit, should consider the heterogeneous and orthotropic properties of skull bone when possible.

An open-source moose implementation of phase-field modeling of fracture in functionally graded materials

Fracture analysis of functionally graded plates is a challenging problem in materials engineering due to the complex material behavior and the presence of cracks. In this study, we propose an efficient open-source MOOSE implementation of phase field fracture analysis of functionally graded. Automatically oriented exponential finite elements are used to discretize the model, which allows for efficient and accurate computation of the fracture behavior. The functionally graded material properties are modeled using a power law function, which captures the variation of material properties along the thickness direction of the plate. The phase field model is coupled with a finite element solver to simulate the mechanical response of the plate under loading. The proposed implementation is validated using several benchmark problems available in literature. The results show that the proposed MOOSE implementation provides accurate predictions of the crack propagation and fracture behavior of functionally graded plates.

Elasticity tunes mechanical stress localization around active topological defects.

Mechanical stresses are increasingly found to be associated with various biological functionalities. At the same time, topological defects are being identified across a diverse range of biological systems and are points of localized mechanical stress. It is therefore important to ask how mechanical stress localization around topological defects is controlled. Here, we use continuum simulations of nonequilibrium, fluctuating and active nematics to explore the patterns of stress localization, as well as their extent and intensity around topological defects. We find that by increasing the orientational elasticity of the material, the isotropic stress pattern around topological defects is changed substantially, from a stress dipole characterized by symmetric compression-tension regions around the core of the defect, to a localized stress monopole at the defect position. Moreover, we show that elastic anisotropy alters the extent and intensity of the stresses, and can result in the dominance of tension or compression around defects. Finally, including both nonequilibrium fluctuations and active stress generation, we find that the elastic constant tunes the relative effect of each, leading to the flipping of tension and compression regions around topological defects. This flipping of the tension-compression regions only by changing the elastic constant presents an interesting, simple, way of switching the dynamic behavior in active matter by changing a passive material property. We expect these findings to motivate further exploration tuning stresses in active biological materials by varying material properties of the constituent units.

Ratio Variation of Maltodextrin and Gum Arabic as Encapsulant on White Jack Bean Tempe Protein Concentrate

The physical and chemical properties of encapsulated substance is directly influenced by the choice of the encapsulant. Different ratios of maltodextrin (MD) and Gum Arabic (GA) produce varying material properties. Therefore, this study aimed to obtain the optimal encapsulant ratio for white jack bean tempe protein concentrate based on physical and chemical characteristics. To achieve this, a descriptive method was employed along with One-Way ANOVA. The results showed that varying encapsulant ratio led to distinct protein content, moisture content, encapsulation efficiency, and yield. The treatment with maltodextrin and Gum Arabic ratio of 20:80 showed the highest effectiveness, with protein content, moisture content, encapsulation efficiency, and yield at 26.10 ± 0.45%, 7.93 ± 0.42%, 95.84 ± 0.71%, and 14.27%, respectively.

Determination of dynamic parameters of free vibrating materials (Nizhny Novgorod)

The most commonly used methods for determination of dynamic properties are expensive and difficult to reproduce without specialised equipment. There is a need to develop simplified techniques that allow to determine specific material properties, avoiding the use of complex laboratory tests.Purpose: The aim of this work is to develop and test a simplified methodology for determining dynamic properties of various materials using pine wood as an example.Methodology: Experimental modelling using up-to-date measuring devices and analytical processing of the obtained results.Research findings: The dynamic modulus of elasticity of pine wood is determined with high accuracy and coincides with reference values. The coefficient of vibration damping is obtained for the calculation of dynamic systems in near-resonance zones.Practical implications: The proposed methodology can be used to determine the dynamic properties of new materials in order to enter these characteristics in software databases and computer complexes.Originality: The proposed method of determining the dynamic parameters of the material is based on the analysis of two-support beam vibrations registered by an accelerometer.

Irradiation-induced age-related degradation mechanisms effect on integrity of baffle former bolts

For long-term operation of nuclear power plants, integrity of structures, systems and components should be ensured rigorously. In particular, since the complicated reactor vessel internals (RVIs) have been exposed to high temperature and neutron irradiation environment, materials reliability programs on the RVIs to resolve anticipated issues were conducted by several research institutes. The objectives of this research are to examine evaluation procedures derived from the previous works and to apply them for RVIs in two operating reactors with baffle former assembly from different electricity powers. Finite element (FE) analyses were performed employing five user-subroutines developed by the authors for reflection of multiple age-related degradation mechanisms (ARDMs) as well as pre- and post-processing. Temperature distributions due to gamma heatings, fuel cycles, typical normal operating temperature and pressure histories were considered with relevantly varying material properties. As results, effects of irradiation were quantified in terms of stresses, strains and irradiation assisted crack sensitivity parameters. Further assessment was carried out through not only investigating contribution of each ARDM but also comparing the present FE analysis results with those obtained from a different reactor type in detail.

Material Characteristics of Lime Plaster in Goguryeo Mural Tombs (I): Focusing on Lime Plaster Excavated from Anak Tomb No.3

Physical and chemical investigations were conducted on lime sample from Anak Tomb No.3 to determine the properties of the plaster material. The morphological and physical characteristics of the specimens were analyzed using both a microscope and a polarizing microscope. The constituent materials were identified through X-ray diffraction and scanning electron microscope-energy dispersive spectrometer, and the qualities of the mixed material were established through thermal analysis. Additionally, micro-computed tomography was used to non-destructively confirm the internal structure and density characteristics. The lime sample was recognized as a lime plaster material with two unique layers. Each layer shows variations in material properties. It is speculated that this lime specimen was used to finish the edges of the authentic wall within Anak Tomb No.3. Through the synthesis of various morphological attributes and physical properties; the whiteness, durability, thinness, and repetition of the layers, as well as smoothness of the lime plaster used for Anak Tomb No. 3 indicate that a high level of lime wall plastering technique was used in Goguryeo Tomb. It was possible to evaluate the refined level of lime wall manufacturing technology in the Goguryeo era.

Exploring the mechanical response of functionally graded hollow disks: insights from rotation, gravity and variable heat generation

PurposeThe purpose of the study is to perform elastic stress and deformation analysis of a functionally graded hollow disk under different conditions (rotation, gravity, internal pressure, temperature with variable heat generation) and their combinations.Design/methodology/approachThe classical method of solution, Navier's equation, is used to solve the governing equation. The analysis considers thermal and mechanical boundary conditions and takes into account the variation of material properties according to a power law function of the radius of the disk and grading parameter.FindingsThe findings of the study reveal distinct trends and behaviors based on different grading parameters. The influence of gravity is found to be negligible, resulting in similar patterns to the pure rotation case. Variable heat generation introduces non-linear temperature profiles and higher displacements, with stress values influenced by grading parameters.Practical implicationsThe study provides valuable insights into the behavior of displacement and stresses in hollow disks, offering a deeper understanding of their mechanical response under varying conditions. These insights can be useful in the design and analysis of functionally graded hollow disks in various engineering applications.Originality/valueThe originality and value of this study lies in the consideration of various loading combinations of rotation, gravity, internal pressure and temperature with variable heat generation. Furthermore, the study of effect of various angular rotations, temperatures and pressures expands the understanding of the mechanical behavior of such structures, contributing to the existing body of knowledge in the field.

Equivalent geometric imperfection for interaction buckling of welded box-section columns - Stochastic analysis

The current paper investigates recently developed GMNIA-based equivalent global and local imperfections to be applicable in the FEM-based design of welded box-section columns. While these imperfections were developed independently for the local and global buckling problems, their applicability to coupled instability problems has not yet been investigated. Therefore, this study addresses this gap by investigating the effectiveness of these imperfections in predicting pure local, global and interaction buckling capacities by comparing them against accurate stochastic analyses using Monte Carlo simulations. The current simulations take into account the variations in geometrical and material properties as well as the imperfections, leading to a highly accurate estimation of the buckling capacity of welded box-section columns. Statistical measures are used to assess the accuracy of each imperfection type and imperfection combination. The discrepancy in deterministic resistance resulting from the application of imperfections and combinations is assessed by comparing them with the accurate buckling resistance. Based on the statistical evaluation, the numerical model uncertainty is also evaluated, serving as the input data of the model factor calculation. The present paper gives a unique introduction to the calculated model factors and presents its calculation methodology for local and global buckling problems.

Moisture Performance Requirements for Insulation in Exterior Wood-Frame Walls without a Vapour Barrier

An increased interest has been observed, especially among architects, in constructing the building envelope without using a vapour barrier membrane of polyethene (PE) foil. An increasing interest in biogenic building materials has also been expressed, as their use, besides storing embedded carbon, can reduce greenhouse gas emissions, replacing nonrenewable building components. Further, building envelope construction without a vapour barrier reduces expenses and the difficulty of the work process, especially around joints and penetrations. This study aims to determine the most important material properties of biogenic thermal insulation materials that influence the moisture-robustness of exterior wood-frame walls constructed without a vapour barrier. A literature study was performed to examine which material parameters have the most influence on the moisture conditions in an exterior wall without a vapour barrier. Hygrothermal simulations of lightweight exterior walls were performed to investigate the significance of variations in material properties (e.g., equilibrium moisture content and vapour diffusion resistance) and determine their necessary characteristics when used as thermal insulation material in an exterior wall without a vapour barrier in internal humidity class 3 (defined in EN ISO 13788). The moisture-robustness of the construction is assessed based on the risk of mould growth in the layer between the thermal insulation and wind barrier. The study suggests that the moisture capacity of the available common biogenic thermal insulation materials does not significantly affect the overall moisture performance of the wall. Simulations demonstrate that, for the thermal insulation layer in internal humidity class 3, at least one of the following requirements must be met to ensure moisture-robustness in exterior walls without a vapour barrier: (I) high diffusion resistance of the thermal insulation and (II) high moisture capacity of the thermal insulation material at relative humidity between 60% and 90%. Commercial biogenic thermal insulation materials on the market do not meet the latter requirement.

Dynamic WAAM: adaptive processes for equivalent contact surface (ECS) optimization

Wire arc additive manufacturing (WAAM) integrates benefits of automation and mass customization to improve efficiency through near-net part production. While WAAM is well researched, there remain significant challenges as the complex relationship between robot, welder, and process parameters can lead to inaccuracy in geometry and variations in material properties. This research proposes a novel framework for quantifying the WAAM process and proposes dynamic adaptive strategies for improving production. This paper introduces the concept of an equivalent contact surface (ECS) for quantifying the additive welding process. Adaptive methods are then identified to optimize WAAM production. In conclusion, this paper provides an outlook on future research directions for continuing the development of this dynamic WAAM process.

Exploring the variability of hygrothermal material properties in historic bricks in London

In the UK, a large number of traditional buildings are made of solid brick walls. If appropriate retrofit measures are taken, these buildings can contribute to achieving the UK Government’s pledge to reduce greenhouse gas emissions. The vast majority of solid brick buildings in London are non-insulated. Adding internal wall insulation is one possible energy retrofit measure, however, the insulation layer can alter the moisture balance of the wall. Since the hygrothermal properties of the existing building materials can influence the moisture balance of the wall considerably, identifying the wall type and understanding its hygrothermal properties is extremely important in building retrofit. The objective of this study is to explore the variability of the hygrothermal properties of different bricks from one wall located in London. Several brick samples are selected from one case study wall in London. The hygrothermal properties of 21 historic bricks were measured, including the absorption coefficient, bulk density, drying coefficient, water content at capillary saturation to determine the variability. The experimental results show variability of some material properties, particularly the absorption coefficient. This can potentially have significant implications for solid wall retrofit and material property characterization.

Cascade amplification of optical absorption on III–V semiconductors via plasmon-coupled graphene

Plasmons in graphene (Gr) show many fascinating characteristics, such as dynamic tunability, strong field confinement of light-matter interaction, and highly responsive, which has been widely exploited for a number of applications, including photodetectors, optical modulators, and sensors. In this paper, graphene plasmons (GPs) were motivated by implanting Au nanoparticles (Au NPs) into Ta2O5 thin layers adjacent to the Gr film, and the strong localized surface plasmon resonance (LSPR) effect has been proposed and demonstrated by placing the GPs structure on a III–V semiconductor quantum well saturable absorber (SA). It has been substantiated that the heightened interaction between light and Gr via LSPR predominantly occurs through the mechanisms of resonant energy transfer and local electromagnetic field enhancement, rather than direct electron transfer. Significant improvement on the nonlinear characteristics of the GPs modulated III–V semiconductor SA has been observed with a 17.1% large modulation depth and obviously improved working stability. A 1550 nm passive mode-locked laser has been successfully constructed with a pulse width down to 523 fs by integrating the SA into the laser cavity. This work lays the foundation for the development of high-performance mode-locked lasers and also demonstrates the substantial enhancement of nonlinear optical properties of various materials not limited to III–V semiconductors provided by this GPs' modulated structure; hence, these findings offer extensive prospects for applications in various photonics and optoelectronic devices.

A comprehensive study on static response of agglomerated microstructure-dependent coated functionally graded carbon nanotubes reinforced composite nanoshells rested on complex elastic foundation

An extensive investigation into the bending behavior of nanoshells made of coated functionally graded (FG) carbon nanotubes reinforced composites has been conducted, employing a novel spatial variation in material properties. The study explored Hardcore and Softcore of coated FG nanoshells. The examination includes five distribution patterns: a fully coated tri-directional, two bidirectional patterns, a transverse unidirectional, and an axial unidirectional distribution. The shell is resting on an orthotropic Winkler, Pasternak and Kerr foundations. Galerkin method is employed to establish an analytical solution for the equilibrium equations. This approach is designed to accommodate a variety of different boundary conditions. A comprehensive examination is undertaken to demonstrate the effects of various geometric and material parameters on the deflection and stresses of nanoshells.

A micromechanical nested machine learning model for characterizing materials behaviors of bulk metallic glasses

In the present work, a novel micromechanical data-driven Machine Learning (ML) framework was proposed to characterize material parameters in bulk metallic glasses (BMGs) using nanoindentation simulations with Berkovich and spherical tips. A vast collection of data on material behavior in BMGs during nanoindentation was compiled, utilizing a series of Drucker-Prager model coefficients. The predictive model was constructed using a nested machine learning algorithm, which incorporated hyper-parameters tuning and a principal model. This nested configuration optimized the architecture of a deep neural network, acting as the key estimator for BMG material properties. The outcomes indicated that the ML model proficiently predicted critical material properties, including compressive yield strength, elastic modulus, flow stress ratio, and Poisson ratio. Notably, the ML model exhibited superior accuracy in predicting elastic modulus and compressive strength, suggesting a robust correlation with flexural elasticity and compressive strength. Furthermore, the study highlighted the significance of input feature weight functions, as they strongly influenced the ML model's performance. Each output target's dependence on the individual proportion of input features contributed to the model's adaptability in handling variations in material properties. Finally, the findings of this work contribute to a deeper understanding of the relationships between input features and material properties, facilitating improved predictions of BMG behavior.

Large-scale all-climate vanadium batteries

The vanadium redox flow battery (VRFB) is a highly promising technology for large-scale energy storage applications due to its exceptional longevity and virtually unlimited capacity. However, for this technology to be widely applicable across different geographical locations, a thorough understanding of its all-climate properties is essential. In recent years, VRFBs have been improved by optimising vanadium electrolytes, exchange membranes, carbon fabric electrodes, and casings. However, most research activities have been limited to batteries operating in moderate temperature conditions, and all-climate vanadium batteries are rarely considered. Therefore, this research work focuses on the effect of temperature on the performance of VRFBs. Existing models that deal with the thermal-hydraulic-chemical modelling of VRFBs either ignore the coupling between the governing physical processes or the variation of key material properties with temperature. In this study, we consider both the coupling of the multi-physics processes that influence the behaviour of VRFBs and the variation of their underpinning properties with temperature.

Unified EOS incorporating the finite strain theory for explaining thermo elastic properties of high temperature superconductors, nanomaterials and bulk metallic glasses

In the present research paper, we have proposed a novel EOS, which is based on the concepts of finite strain theories for predicting the thermo elastic properties of various materials viz. bulk metallic glasses, nanomaterials, and high temperature superconductors. Development of the present EOS involved deriving an innovative mathematical framework that considers the effects of finite strain, enabling the prediction of essential properties like pressure and bulk modulus under different compression ratios. For validity and applicability of the proposed EOS, we have conducted an extensive analysis by comparing the calculated thermo elastic properties with existing theoretical models or equation of sates and experimental data available in the literature. The present comparison revealed a remarkable agreement between our predictions and the observed values for a wide range of compression of nanomaterials, bulk metallic glasses, and superconductors. Our research not only introduces a comprehensive equation of state for these advanced materials but also demonstrates its effectiveness in accurately capturing their unique thermodynamic behavior. This present derived EOS can serve as a valuable tool to predict and understand the response of nanomaterials, bulk metallic glasses, and superconductors to varying pressure conditions, aiding the design and development of innovative applications in fields such as materials science, nanotechnology, and condensed matter physics.

Coextrusion of Clay-Based Composites: Using a Multi-Material Approach to Achieve Gradient Porosity in 3D-Printed Ceramics

3D printing of ceramics has started gaining traction in architecture over the past decades. However, many existing paste-based extrusion techniques have not yet been adapted or made feasible in ceramics. A notable example is coextrusion, a common approach to extruding multiple materials simultaneously when 3D-printing thermoplastics or concrete. In this study, coextrusion was utilized to enable multi-material 3D printing of ceramic elements, aiming to achieve functionally graded porosities at an architectural scale. The research presented in this paper was carried out in two consecutive phases: (1) The development of hardware components, such as distinct material mixtures and a dual extruder setup including a custom nozzle, along with software environments suitable for printing gradient materials. (2) Material experiments including material testing and the production of exemplary prototypes. Among the various potential applications discussed, the developed coextrusion method for clay-based composites was utilized to fabricate ceramic objects with varying material properties. This was achieved by introducing a combustible as a variable additive while printing, resulting in a gradient porosity in the object after firing. The research’s originality can be summarized as the development of clay-based material mixtures encompassing porosity agents for 3D printing, along with comprehensive material-specific printing parameter settings for various compositions, which collectively enable the successful creation of functionally graded architectural building elements. These studies are expected to broaden the scope of 3D-printed clay in architecture, as it allows for performance optimization in terms of structural performance, insulation, humidity regulation, water absorption and acoustics.

Vibration analysis of tri-directionally coated plate via thickness-stretching and microstructure-dependent modeling

In this study, the tri-directionally-coated functionally graded plate has different levels of microstructure and is modeled more accurately using nonclassical mechanics incorporating the intrinsic characteristic lengths as well as using a spatial variation of material properties. The free vibration behavior of the tri-directionally-coated functionally graded plate is investigated using a refined quasi-3D higher-order shear deformation theory in conjunction with nonlocal strain gradient theory. Based on the generalized field of displacement, the quasi-3D higher-order shear deformation theory is employed by reducing the number of variables from six to five variables. The equations of motion are performed based on the principle of Hamilton and solved by applying the Galerkin technique to cover various boundary conditions. Besides, the microstructure-dependent parameters, that is, the nonlocal parameter and the length scale parameter, also affect significantly the frequency of the tri-directionally-coated functionally graded plates. The multi-directionally-coated plate is softened when considering the nonlocal parameter; the multi-directionally-coated plate is, however, hardened when considering the length scale parameter.