Variation Of Material Properties Research Articles

The Casimir, Van der Waals, and electrostatic forces’ effects on the response of magneto-electro-elastic nanosensor/switch beams under thermal environment

This study investigates the impact of Casimir, Van der Waals, and electrostatic forces on nanomechanical switches’ thermomechanical and free vibration behavior. The analysis is conducted using a novel higher-order beam theory and the nonlocal strain gradient elasticity. The motion equations of the nanosensor/switch beam are derived using Hamilton’s principle and solved using Navier’s method for general boundary conditions. The nanoswitch is composed of electroelastic barium-titanate (BaTiO3) and magnetostrictive cobalt-ferrite (CoFe2O4) materials, which are modeled using a power-law approach to account for functionally graded material property variations across the beam’s thickness. The impact of different parameters, such as Casimir, Vander Waals, electrostatic forces, and variations in material composition, size parameters, and gap distance, on a nanoswitch system’s bucking and free vibration is comprehensively examined. With the intermolecular and electrostatic forces, the temperature dependency of barium-titanate and cobalt-ferrite nanoswitch materials, which have not been extensively studied in any previous research, is considered in the modeling of free vibration, and the buckling behavior of a nanoswitch for the first time. This research represents the first comprehensive analysis of these factors. Considering the investigated parameters, the study’s findings can provide helpful insights into developing micro/nano-electromechanical systems, including switches, sensors, and actuators.

Influence of material parameter variability on the predicted coronary artery biomechanical environment via uncertainty quantification.

Central to the clinical adoption of patient-specific modeling strategies is demonstrating that simulation results are reliable and safe. Indeed, simulation frameworks must be robust to uncertainty in model input(s), and levels of confidence should accompany results. In this study, we applied a coupled uncertainty quantification-finite element (FE) framework to understand the impact of uncertainty in vascular material properties on variability in predicted stresses. Univariate probability distributions were fit to material parameters derived from layer-specific mechanical behavior testing of human coronary tissue. Parameters were assumed to be probabilistically independent, allowing for efficient parameter ensemble sampling. In an idealized coronary artery geometry, a forward FE model for each parameter ensemble was created to predict tissue stresses under physiologic loading. An emulator was constructed within the UncertainSCI software using polynomial chaos techniques, and statistics and sensitivities were directly computed. Results demonstrated that material parameter uncertainty propagates to variability in predicted stresses across the vessel wall, with the largest dispersions in stress within the adventitial layer. Variability in stress was most sensitive to uncertainties in the anisotropic component of the strain energy function. Moreover, unary and binary interactions within the adventitial layer were the main contributors to stress variance, and the leading factor in stress variability was uncertainty in the stress-like material parameter that describes the contribution of the embedded fibers to the overall artery stiffness. Results from a patient-specific coronary model confirmed many of these findings. Collectively, these data highlight the impact of material property variation on uncertainty in predicted artery stresses and present a pipeline to explore and characterize forward model uncertainty in computational biomechanics.

Investigating the Impact of Productivity on Surface Roughness and Dimensional Accuracy in FDM 3D Printing

Over the past three decades, 3D printing technologies have undergone significant advancements, revolutionizing various industries, such as automotive. Additive manufacturing has played a crucial role in reducing product development time and enabling the direct printing of functional parts. One of the key advantages of additive manufacturing is its ability to provide greater design freedom compared to traditional manufacturing methods. This means that complex geometries and varying material properties can be easily printed. In this research paper, the author focused on investigating the impact of layer thickness and part orientation on the surface roughness and accuracy of printed parts. The main objective was to identify the optimal combination of layer thickness and part orientation that would yield the best results in terms of surface roughness and accuracy, considering printing time as a variable. The results from printing time, accuracy and surface roughness measurements showed that the vertical orientation is the superior for cylindrical orientation.

Thermal buckling in multi-directional porous plates: The effects of material grading and aspect ratio

In the present study, a trigonometric shear deformation plate theory was employed to perform a thermal buckling analysis of multi-directional functionally graded (FG) plates. During the manufacturing of the multi-directional graded plate, the formation of pores is abounded. Hence, the effect of porosity on the buckling performance was investigated by considering the variation of porosity in the plate for power law gradation variation of material properties. The adverse effect of porosity on the material properties was taken into account by employing the rule of mixture relation. Finite element results show that the thermal expansion coefficient is unaffected by the presence of porosity. For simply supported boundary conditions, the non-linear governing equations are solved for different thermal loads such as uniform, linear, and non-linear. A parametric study was performed in which the effect of grading parameters, aspect ratio, and side-to-thickness ratio under variable temperature change was studies. Critical material grading indices for multi-directional plates have been identified that help researchers and industry personnel in fabrication planning.

Integration of Swin UNETR and statistical shape modeling for a semi-automated segmentation of the knee and biomechanical modeling of articular cartilage

Simulation studies, such as finite element (FE) modeling, provide insight into knee joint mechanics without patient involvement. Generic FE models mimic the biomechanical behavior of the tissue, but overlook variations in geometry, loading, and material properties of a population. Conversely, subject-specific models include these factors, resulting in enhanced predictive precision, but are laborious and time intensive. The present study aimed to enhance subject-specific knee joint FE modeling by incorporating a semi-automated segmentation algorithm using a 3D Swin UNETR for an initial segmentation of the femur and tibia, followed by a statistical shape model (SSM) adjustment to improve surface roughness and continuity. For comparison, a manual FE model was developed through manual segmentation (i.e., the de-facto standard approach). Both FE models were subjected to gait loading and the predicted mechanical response was compared. The semi-automated segmentation achieved a Dice similarity coefficient (DSC) of over 98% for both the femur and tibia. Hausdorff distance (mm) between the semi-automated and manual segmentation was 1.4 mm. The mechanical results (max principal stress and strain, fluid pressure, fibril strain, and contact area) showed no significant differences between the manual and semi-automated FE models, indicating the effectiveness of the proposed semi-automated segmentation in creating accurate knee joint FE models. We have made our semi-automated models publicly accessible to support and facilitate biomechanical modeling and medical image segmentation efforts (https://data.mendeley.com/datasets/k5hdc9cz7w/1).

Effect of Capsule Thickness and Material Properties on the Central Optical Power of Natural Human Lens

Background: A thin membrane capsule covers the eye lens and links the lens and the applied forces by the ciliary muscles. The capsule converts the tension of the concentrated zonules to distributed surface tractions over the cortex surface during the lens accommodation. The gradual changes of the capsule geometry and material properties with age and its important role in the design of intraocular lens implants were the motivation of extensive researches on describing the capsule biomechanical behavior. Aim: The present work aimed to study the lens accommodation response to different capsule thicknesses and material properties at different ages. Materials and Methods: A material and geometry parametric study was performed, drawing some guidelines on the choice of lens capsule thickness and biaxial/uniaxial material parameters and exploring the response sensitivity of the finite element model at different age groups Results: The 16-, 35- and 48-year-old lenses were considered for lens accommodation simulation. The sensitivity of lens accommodation was studied at each age group by considering constant thickness (cnst-t) and variable thickness (var-t) capsules and biaxial (Biax) and uniaxial (Uniax) material characteristics tests. The lens was stretched through zonules, and corresponding absolute changes in central optical power (COP) were measured. Conclusion: After the stretch, the lens anterior and posterior curvatures increased, producing a change in COP. The Biax models underestimated the ΔCOP compared to the Uniax models. The 16-year lens model was more sensitive to material properties than thickness variation, while thickness variation was more relevant to the ΔCOP of the 35-year lens model. The 48-year model had the least sensitivity to capsule thickness and material property variations.

Thermoelectric properties of heavily Co-doped β-FeSi2

Element doping is a widely employed strategy to enhance the thermoelectric (TE) properties of various materials. β-FeSi2 is a promising low-cost high-temperature TE material with exceptional thermal stability; however, the doping limit of β-FeSi2 is usually very low, which limits the tunability of electrical and thermal properties. Recently, a high doping content of 0.16 in β-FeSi2 has been achieved by the introduction of iridium (Ir), leading to the highest reported figure of merit (zT) of 0.6 in β-FeSi2. Motivated by the successful heavy doping with Ir, this work aims to explore element heavy doping in β-FeSi2 with cobalt (Co), a cheaper, more readily available dopant with a smaller atomic radius and closer electronegativity to iron (Fe). In this study, we successfully obtained a record-high doping content of 0.24 in Co-doped β-FeSi2 through a prolonged annealing process. Despite the absence of a substantial enhancement in the zT of Co-doped β-FeSi2 at high doping levels, with a maximum zT of 0.3 at 900 K in Fe0.92Co0.08Si2, we observed a transition in the carrier transport mechanism as a function of Co doping content, attributed to changes in the band structure. At a low Co doping content (x ≤ 0.12), Fe1–xCoxSi2 demonstrates dominant carrier transport via impurity levels within the band gap, exhibiting hopping conduction. As the Co doping content increases (x > 0.16), the impurity levels overlap and form an impurity band, and the carrier transport turns into the impurity band conduction. The observed band conduction behavior of Fe1–xCoxSi2 (x > 0.16) mirrors that of Ir-doped β-FeSi2, but Fe1–xCoxSi2 shows much lower mobility, which can be attributed to the localized feature of the impurity band introduced by the Co doping. Overall, this study provides insights into the heavy Co doping and its influence on the TE properties and carrier conduction mechanisms in β-FeSi2, helpful for the further development of this TE system.

Mathematical Formulation and Numerical Simulation of the Mechanical Behavior of Ceramic/Metal (TiB/Ti) FG Sheets Subjected to Spherical Indenter

The main motivation for the present work is to provide an improved description of the response of Functionally Graded (FG) structures under a spherical indenter, considering material nonlinearities. This is achieved through the implementation of elastoplastic material behavior using integration points to avoid the division of the structure into multiple layers. The current paper proposes a numerical investigation into the mechanical response of functionally graded materials (FGMs) in contact with a rigid hemispherical head indenter. The numerical model considers both the Mori–Tanaka model and self-consistent formulas of Suquet to accurately model the smooth variation of material properties through the thickness of the elastoplastic FG material. The model execution involves a UMAT user material subroutine to implement the material behavior into ABAQUS/Standard. The user material UMAT subroutine is employed to introduce material properties based on the integration points, allowing for an accurate representation and analysis of the material’s behavior within the simulation. The developed numerical model is validated through a comparison with experimental results from the literature, showing a good correlation that proves the efficiency of the proposed model. Then, a parametric study is conducted to analyze the effect of the indenter dimension, the indentation depth and the gradient index on the indentation force, the contact pressure evolution, von Mises equivalent stress and equivalent plastic strain distributions located on the vicinity of the contact zone. The results showed that the elastoplastic response of TiB/Ti FG plates is significantly influenced by the gradient index, which determines the properties of the FG composite through the thickness. These results may help development engineers choose the optimal gradation for each industrial application in order to avoid contact damage.

An electromagnetic Hopkinson bar for low wave impedance material and complex stress paths loading tests

The split Hopkinson bar has been widely used for testing the dynamic mechanical properties of various materials. However, there are still difficulties in ensuring stress uniformity when testing some low wave impedance materials such as soft materials and brittle materials and difficulty in achieving true multi-axial and multi-directional synchronous loading experiments and other issues. To overcome these issues, this paper uses an electromagnetic Hopkinson bar for experimental research and introduces its principle and implementation process. Finite element analysis and experimental methods were used to verify the feasibility of the electromagnetic Hopkinson bar in addressing the relevant issues. The superiority of the new device was demonstrated by its capability in performing compression experiments on two typical low wave impedance materials: polymethacrylates (PMMA) and polyurethane (PU), and two-way tension experiments on 2024 aluminum alloy. The results indicate that the electromagnetic Hopkinson bar can effectively solve the problem of uniform stress in low wave impedance materials testing, and can achieve synchronous loading of complex stress paths.

Analysis of an interfacial crack between two nonhomogeneous piezoelectric materials using a new domain-independent interaction integral

Considering the difficulties introduced by piezoelectric material non-homogeneity and discontinuities to interfacial crack analysis, a domain-independent interaction integral (DII-integral) is proposed to derive the stress intensity factors (SIFs) and electric displacement intensity factor (EDIF) of an interfacial crack between nonhomogeneous piezoelectrics. For continuously varying material properties, traditional interaction integral (I-integral) needs to compute the derivatives of material parameters with respect to the x1 direction of the local coordinate system, while the proposed DII-integral is demonstrated to be unrelated to any derivatives of material parameters. Furthermore, a significant improvement is achieved that the new formulation of I-integral remains valid even when the integration domains include intricate and multiple interfaces, as long as the material interfaces are perfectly bonded. Firstly, the intensity factors (IFs) calculated by the combination of the DII-integral and the extended finite element method are compared with the analytical solutions, and it is found that the relative errors of the IFs are all less than 1.79 % with various crack lengths, which verifies the accuracy of the proposed method. For the piezoelectric bi-material model with continuously nonhomogeneous properties, the calculated IFs match each other well (relative deviation < 1.3 %) for different sizes of integration domains. In addition, for the perfectly bonded interface with discontinuous electromechanical properties, the IFs are almost identical (relative deviation < 0.85 %) whether or not the integration domain contains the material interface, which further numerically verifies the good domain-independence of the established DII-integral. For an interfacial crack near extra interfaces, the differences in elastic stiffness and piezoelectric coefficient between interface sides have an obvious influence on mode-I SIF, but mode-II SIF and EDIF are affected mainly by piezoelectric coefficient and dielectric permittivity.

Analysis of microstructure, surface morphology, and scratch resistance of high velocity oxy-fuel coated nickel based hybrid nano-composites

In recent years, high velocity oxygen fuel (HVOF) coating technology has gained significant interest in the field of surface engineering. In this study, we have investigated the microstructure, surface morphology, and scratch resistance of HVOF coated Nickel based novel hybrid nano-composites. The coatings were prepared using a high-velocity oxy-fuel (HVOF). HVOF coatings have the ability to enhance the surface properties of various materials, making them more resistant to wear, corrosion, and erosion. Thermal spraying technique, and the microstructure and surface morphology of the coatings were analyzed using scanning electron microscopy (SEM). The scratch test was performed using a TR-101, DUCOM made Scratch tester to evaluate the scratch resistance of the coatings. The results of the study revealed that the HVOF coated novel hybrid nano-composites exhibited a fine-grained microstructure with a dense and homogeneous surface morphology. The scratch resistance of the coatings was significantly improved due to the addition of nano composites. The load required to cause the first visible scratch on the coated surface was found to be significantly higher than that of the uncoated substrate. The scratch morphology of the coatings was also studied, which revealed that the scratch-induced damage was mainly due to the plastic deformation of the coating material. The results suggest that the HVOF coated novel hybrid nano composites have great potential in improving the surface properties of various engineering materials and can be used in applications where high wear resistance is required. Overall, the study demonstrates that the combination of HVOF coating technology and hybrid nano-composites can result in coatings with improved microstructure, surface morphology, and scratch resistance, which makes them ideal for use in applications wherever wear resistance is critical.

Application of Pomegranate Rind Extract for Improvement of Functional Properties of Various Materials—A Critical Review

Application of Pomegranate Rind Extract for Improvement of Functional Properties of Various Materials—A Critical Review

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.

The Effect of Earthquake Motion on Rockfall with Material Property Variation

The Effect of Earthquake Motion on Rockfall with Material Property Variation

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.