Properties Of Constituent Materials Research Articles

Thermomechanical Nonlinear Vibration of Axially Loaded Functionally Graded Material Cylindrical Panels Including Porosity

For the first time, the combined influences of axial compressive load, porosity, geometric imperfection, elastic edge restraint, and elevated temperature on the nonlinear free vibration of functionally graded material (FGM) cylindrical panels are investigated in this paper. Unlike previous studies, the structural model considered in this paper includes practical situations and conditions arising in the design process and application of FGM cylindrical panels. The properties of material constituents are assumed to be temperature-dependent, and the effective properties of porous FGM are determined using a modified rule of mixture. Governing equations in terms of deflection and stress function are established based on first-order shear deformation theory, taking into account von Kármán–Donnell nonlinearity and initial geometric imperfection. Analytical solutions are assumed to satisfy simply supported boundary conditions, and the Galerkin method is applied to derive a time differential equation containing both quadratic and cubic nonlinear terms. This differential equation is numerically integrated employing the fourth-order Runge–Kutta scheme to determine the frequencies of nonlinear free vibration. Parametric studies are carried out to assess numerous effects on both linear and nonlinear frequencies of porous FGM cylindrical panels. The study reveals that natural frequencies are strongly decreased and that frequency nonlinearity is more significant due to axial compressive loads.

Machine learning techniques for predictive modelling and uncertainty quantification of the mechanical properties of woven carbon fibre composites

Carbon fibre composites owe their exceptional mechanical properties to the characteristics of their constituents; fibres and resin. However, uncertainty in these individual constituent properties can introduce significant variations in the macroscale mechanical performance of composites. These variations are amplified in the presence of various plies in the composite and pose a challenge to quantify during manufacturing stages. In this study, uncertain constituent material properties are propagated to the macroscale composite through multiscale homogenisation to compute the varied resultant thin-shell stiffness matrices. An in-house-built automated simulation environment has been used to create a physics-conforming trainable database for model training, testing, validation and uncertainty quantification using Gaussian Process Regression (GPR), Artificial Neural Networks (ANNs), and Multiple Linear Regression (MLR). Through rigorous comparative analyses, the superior performance of GPR is demonstrated when compared to alternative techniques with R² ≥ 0.99 and NRMSE < 10⁻⁷. Further, the findings approve the validity of GPR for extrapolatory predictions. For instance, a randomly sampled [-5, 5] % variation of constituent material properties leads to extreme uncertainties in macroscale ± 0.067 %, for axial stiffness with excellent GPR predictive accuracy of R² = 0.99. This slightly increases to ± 0.14 % for a variation of [-10, 10] %. Moreover, the extreme uncertainties indicate that the direct axial and bending stiffnesses are more sensitive to variations in constituent properties than others. Additional investigations presented in the paper produce predictive models and uncertainty bounds for all stiffness entries that are of high importance for macroscale property control during manufacturing.

Mechanical deformation in lithium-ion battery electrodes: modelling and experiment

Abstract Models that can accurately describe deformation and stress in lithium-ion batteries are required to inform new device designs that can better withstand mechanical fatigue. Developing such models is particularly challenging because (i) there is a need to capture several different materials including, active materials, binders, current collectors and separators, and (ii) the length scales of interest are highly disparate (ranging from a few microns, relevant to active material particles, up to centimeters, relevant to whole devices). In this study we present a continuum mechanical model that resolves individual active material particles of a nickel-manganese-cobalt-oxide cathode, and predicts the mechanical response of the cathode coating as a whole. The model is validated by comparison with experimental tests which mimic industrial-scale electrode calendaring, and then a parametric study is conducted to provide insight into the roles of the material and geometric properties of the electrode's constituents on the cathode's overall behavior.

Tensile and bond properties at elevated temperatures of a PBO-FRCM composite system for strengthening concrete elements: Experimental and analytical investigations

This paper presents experimental and analytical investigations on the tensile and bond behaviour at elevated temperature of a polypara-phenylene-benzo-bisthiazole (PBO) fabric reinforced cementitious matrix (FRCM) system for strengthening concrete elements. Direct tensile (DT) and single lap direct shear tests (DS) were performed under steady-state conditions at the following temperatures: 20 °C, 85 °C, 150 °C, 230 °C and 300 °C. The results obtained were evaluated in terms of strength, stiffness, ultimate strain, load vs. slip response at the interface PBO FRCM/concrete and failure modes. Overall, the tensile and bond properties were significantly affected by the temperature increase. These results are mainly associated with the reductions of mechanical properties of the FRCM constituent materials as well as the degradation of the interaction between the fibres and the inorganic matrix at elevated temperatures. The experimental results were then used (i) to evaluate the suitability of the Aveston–Cooper–Kelly (ACK) model in describing the tensile response of FRCM at elevated temperatures and (ii) to calibrate temperature-dependent local shear bond stress vs. slip laws for the FRCM-concrete interaction.

Recent Advances in 1D Photonic Crystals: Diverse Morphologies and Distinctive Structural Colors for Multifaceted Applications

Abstract1D photonic crystals (1DPCs) with hierarchically structured lamellar periodic frameworks that enable precise control of light‐matter interactions and contribute robust structural colors represent a groundbreaking advancement in optical materials. The microstructural characteristics and the constituent material properties of these photonic materials play pivotal roles in determining their optical performance and functionality. In recent years, a diverse array of novel 1D photonic structures crafted from various materials emerged, showcasing their tremendous potential in advanced applications. This article provides an in‐depth review of the recent developments in 1DPCs, emphasizing their morphological designs, fabrication strategies, and optical applications. In detail, 1DPCs featuring distinct geometrical morphologies, including lamellar, helical, fibrous, spherical, and nanochained structures are systematically introduced, highlighting the unique optical properties arising from their periodic microstructures. Then, various fabrication methods, involving some innovative techniques utilizing standing‐wave optics, UV dual photopolymerization, and inkjet printing, are succinctly summarized for constructing different photonic structures by using diverse building materials. Subsequently, some typical application examples of 1D photonic materials are listed and discussed involving visual sensing, intelligent displays, anti‐counterfeiting technology, photonic pigments, and optical devices. Finally, the passage addresses the current challenges and presents a forward‐looking perspective on the future fabrication and application of 1DPCs.

Identifying the influence of split tensile strength to crack width of high-strength reinforced concrete beam with polypropylene fiber from medical mask waste

Cracks in concrete structures due to tensile weakness can be repaired by using fiber concrete, including medical mask waste as an additive in high-strength concrete mixes. This research the influence of polypropylene fiber from medical mask waste on the mechanical characteristics, flexural behavior, and crack width of high-strength reinforced concrete (RC) beams. The initial stage involved examining the properties of the concrete constituent materials. The testing process was based on a high-strength concrete mix design using the Aitchin method mix design sheet. Compressive strength and split tensile strength were tested at fiber content (0 %, 0.15 %, 0.20 %, and 0.25 %). The three-point flexural testing procedure was carried out at 28 days on 1200×100×150 (mm) RC beams. The use of LVDT, strain gauge, and other measuring devices supported the acquisition of the required data. The results showed that the split tensile strength reached the optimum value of 66.19 MPa at 0.24 % fiber content. Polypropylene fiber from medical mask waste in RC beams showed a positive impact on reducing crack width at increased split tensile strength. Waste mask fiber content of 0.15 %, 0.20 % and 0.25 % gave stable and better results compared to 0 % content (no fiber). With high steel stress (fs), and high strain, it offers the potential to improve the mechanical properties of high-strength concrete, thereby reducing the width of cracks that occur. This improves the tensile weakness of the concrete. The effect of split tensile strength on the crack width (w) of beams with the formula approach: wexp=3.74ftf-1.513, wan=0.187ftf-0.022 shows that the experimental results have a significant effect on decreasing the crack width that occurs in high-strength RC beams, thereby improving the quality of concrete

Effect of Alkaline Environment on the Bond Behavior of TRM Composites Through Single-lap Shear Tests

Textile Reinforced Mortars (TRM) are increasingly used for strengthening existing masonry structures, offering a sustainable solution. This system consists of textile fibers embedded in an inorganic matrix, typically cement or lime-based mortars, applied to the substrate’s surface. Although the mechanical properties of these composite systems have been extensively studied, there is still limited understanding of their long-term performance and durability. This study aims to enhance knowledge in this area by examining the bond behavior of TRM composites exposed to an alkaline environment using single-lap shear tests. For this purpose, single-lap shear specimens were constructed using clay brick as the substrate, a lime-based mortar, and two different fabrics—basalt and glass. These specimens were subjected to an alkaline solution to simulate accelerated aging conditions, with constant temperature and pH. The specimens were tested after 1000, 3000, and 5000 hours of exposure to evaluate their bond behavior compared to control specimens of the same age. Additionally, the effect of the alkaline environment on the material properties of the composite constituents was investigated. Elastic modulus tests were conducted on cylindrical mortar samples and compared to reference samples, displaying satisfactory resistance to alkaline conditions. The study identified and compared the strength, stiffness, and failure mode of each specimen to the reference stage, providing valuable design parameters for various field applications.

Thermo-electrical postbuckling behavior of carbon nanotubes-reinforced composite beams with piezoelectric layers and tangentially restrained ends

An analytical investigation on the buckling and postbuckling behavior of carbon nanotube-reinforced composite beams integrated with surface-bonded piezoelectric layers under uniform temperature rise is presented in this paper. Carbon nanotubes (CNTs) are reinforced into isotropic matrix through uniform distribution and functionally graded distributions. The properties of material constituents are assumed to be temperature-dependent and effective properties of CNT-reinforced composite are estimated using an extended rule of mixture. Equilibrium equations of the beams are established based on Euler-Bernoulli theory including von Kármán nonlinearity and solved using analytical solutions and Galerkin method. Critical temperatures and postbuckling load-deflection paths are determined using an iteration algorithm. Parametric studies are performed to examine the influences of CNT distribution and volume fraction, applied voltage, in-plane and out-of-plane conditions of the ends, slenderness, and thickness ratio of layers on the critical loads and postbuckling load carrying capacity of beams. Results reveal that CNT volume fraction and degree of in-plane ends constraint have slight and significant influences on the critical temperatures and thermal postbuckling paths, respectively. The study also finds that negative and positive voltages increase and decrease the thermal buckling temperatures of piezoelectric CNT-reinforced composite beams.

Redesign an aircraft windshield to improve its mechanical resistance against simultaneous bird impacts

The bird impact on aircraft components is one of the most serious accidents which can happen in the aviation industry. Among the various parts of an aircraft, the bird impact on the windshield is more important due to the possibility of causing injury to the pilot. Standard windshields are designed to withstand a bird strike, however, in a group flight of birds, several birds can strike the windshield at the same time. The results of practical tests and simulations show that the current windshields are seriously damaged in the simultaneous collision of several birds and the possibility of birds penetrating the cabin is very high. In this research the mechanical properties of standard windshield constituent materials are obtained. Initially practical tests are carried out and simulation results are verified for single bird strike. Using these results, the simultaneous impact of three birds on a windshield is simulated. It was shown that the resistance of the standard windshield against simultaneous collisions is insufficient. So the thicknesses of the windshield layers are determined in such a way that the new windshield is resistant and bird penetration into the cabin does not happen.

Specimen size effect on the fracture energy of architected stretchable materials

ABSTRACT Architected stretchable materials with well-organized micro-architectures evolve very rapidly due to their potential in customizing mechanical properties and achieving exotic functions. In many applications, the architected stretchable materials are required to sustain large deformation, and their fracture is size-dependent. However, the size effect on the fracture of architected stretchable materials is still elusive. Here, we study this issue by experiment and finite element calculation. It is found that the fracture energy of architected stretchable materials increases with the specimen size ratio, H/h, within a range. When H/h reaches a transition ratio, R t , the fracture energy approaches a plateau. This transition ratio differentiates the size-dependent and size-independent fracture behavior of architected stretchable materials. The mechanical properties of constituent material only have a minor effect on the transition ratio. The degree of constraint and stress concentration at the node, which are affected by the geometry of the unit-cell, dominate the specimen size effect. The result gives a practical guidance in choosing the specimen size to measure the steady state fracture energy of this class of materials. This work provides insights into the fracture of architected stretchable materials and design for fracture-resistant architected stretchable devices.

Creep constitutive law prediction via short-term evaluation using a small size testing method

To efficiently assess the mechanical reliability and long-term durability of solid oxide fuel cells (SOFCs) and solid oxide electrolyser cells (SOECs), a suitable creep test method and prediction of the material response is necessary. This study investigates the effectiveness of the small punch (SP) testing method for Ni–YSZ composites and in rapidly determining the constitutive creep law for SOFC materials. The creep properties of Ni–YSZ composites are evaluated under a 1% H2 environment at temperatures of 800–900 °C and stresses of 36–58 MPa. The finite element method is used to simulate the SP tests and generate numerical creep curves. These curves are fitted to the experimental curves to obtain the parameter set in the creep constitutive law of the strain hardening model. The numerical and experimental creep curves are well-fitted with only a 0.44% difference and convergent parameter sets equal to C1=1.0× 10−12, C2=1.03, C3 = -1.70, C4=96.78 in the strain hardening law, indicating the usefulness of the SP method and creep constitutive law for characterising and predicting the creep properties of SOFC constituent materials. This study highlights the importance of accurate characterisation of creep properties for predicting the long-term performance and reliability of SOFCs.

Assessing thermophysical properties of parameterized woven composite models using image-based simulations

Mesoscale simulations of woven composites using parameterized analytical geometries offer a way to connect constituent material properties and their geometric arrangement to effective composite properties and performance. However, the reality of as-manufactured materials often differs from the ideal, both in terms of tow geometry and manufacturing heterogeneity. As such, resultant composite properties may differ from analytical predictions and exhibit significant local variations within a material.We employ mesoscale finite element method simulations to compare idealized analytical and as-manufactured woven composite materials and study the sensitivity of their effective properties to the mesoscale geometry. Three-dimensional geometries are reconstructed from X-ray computed tomography, image segmentation is performed using deep learning methods, and local fiber orientation is obtained using the structure tensor calculated from image scans. Suitable approximations to composite properties, using analytical unit cell calculations and effective media theory, are assessed. Our findings show that an analytical geometry and sub-unit cell geometry provide reasonable approximations of the full-scale predictions for the effective thermal properties of a multi-layer production composite.

An inversion method for evaluating ballastless track degradation based on multi-channel analysis of surface wave

Due to the heterogeneous properties of constituent materials, traditional Multi-channel analysis of surface wave (MASW) method is unsuitable for evaluating ballastless track as surface waves exhibit different dispersion patterns. To overcome this limitation, firstly, the implementation process of MASW was introduced, and the phase shift method was employed to perform dispersion analysis of multi-channel surface wave signals. Secondly, a wave field solution model of ballastless track was established using the time-domain finite-difference method. Subsequently, the stiffness matrix method was improved to account for the heterogeneous properties of the constituent materials and to calculate the theoretical surface wave dispersion curve of ballastless track, followed by the analysis of surface wave dispersion characteristics in ballastless track and the proposal of an inversion method. Finally, the optimal excitation central frequency and receivers’ deployment were analyzed in the MASW method, and the inversion analysis of ballastless track degradation were conducted. Results shown that the surface wave dispersion curve is more sensitive to CA mortar degradation at low frequencies and concrete slab degradation at high frequencies. Appropriate excitation central frequency and receivers’ deployment are essential for accurately extracting the surface wave dispersion curve from the dispersion energy of ballastless tracks. The inversion method proposed in this study provides a more accurate evaluation of ballastless track degradation compared to assuming ballastless track as a homogeneous structure during inversion analysis.

Crack extension at the concrete–rock interface damaged by high-pressure water environment: DIC research

As a weak link in hydraulic structures such as arch dams, the fracture property of the concrete–rock interface is impacted by various factors, including the material properties of the individual constituents and the fracture process zone (FPZ) at the crack tip. Because the heel area of an extra-high dam has been exposed to a high-pressure water environment, this paper aims to investigate the whole fracture process of the concrete–rock interface after the water pressure effect. In this test, the water pressure was set at 0, 1, 2, and 4 MPa, and the crack deformation of the concrete–rock composite beam under three-point bending (TPB) was monitored in real-time by the digital image correlation (DIC) technique. DIC has been discovered to aid in understanding the damage caused by a high-pressure water environment to material properties. The stable crack extension of TPB composite beams after the high-pressure water exposure was greatly limited, and the corresponding crack length was decreased by up to 35%. The FPZ characteristic length was reduced by 19% when exposed to a high-pressure water environment, resulting in a drop in cohesive toughness on the fictitious crack. KR resistance curves for the concrete–rock interface fracture were constructed to consider the damage to material properties and FPZ evolution by high-pressure water exposure. For a reference for fracture analysis in the dam heel of extra-high dams, the calculation model of critical crack size in elastic fracture and the prediction equation of FPZ characteristic length in nonlinear fracture were constructed for a TPB composite beam.

Computational modeling and simulations for predicting the nonlinear responses of reinforced concrete beams

PurposeThe ultimate capacity and ductility behavior of a reinforced concrete (RC) beam generally depends on its constituent material properties. This study aims to use ANSYS to accentuate the nonlinear parametric finite element (FE) simulations of RC sections under monotonic loading.Design/methodology/approachThe concrete matrix and steel reinforcement are the primary constituent materials of RC beams. The material properties such as tensile reinforcement area, tensile bars yield strength, concrete compressive strength and strain rate in tensile reinforcement at nominal strength have significantly influenced the ultimate response of RC beams. Therefore, these intensive parameters are considered in this study to ascertain their effect on the RC beam's ultimate behavior. The nonlinear response up to the ultimate load capacity and the crack evolutions of RC beams are predicted efficiently.FindingsThe parametric study reveals that increasing the tensile steel reinforcements (from Ast = 213–857 mm2) significantly improves the ultimate load capacity by 229% and yield deflections by 20%. However, it declines the ultimate deflection by 47% and ductility by 56% substantially. Varying the strain limit (?tn = 0.010–0.0015) of tensile reinforcement has proficiently increased the ultimate load-resisting capacity by 20%, whereas the ductility declined by 62%. When the concrete strength increases (from fck = 25–65 MPa), the cracking load increases profoundly by 51%, whereas the ultimate capacity has found an insignificant effect.Originality/valueThe load-deflection response plots extracted from the proposed numerical model exhibit satisfactory accuracy (less than 9% deviation) against the experimental curves available in the literature, which emphasizes the proficiency of the proposed FE model.

Abstract 622: Automated Platform For Large Scale Structural Simulations Of Atherosclerotic Lesions

Coronary artery disease persists as the world’s leading cause of death and often associated with atherosclerotic plaque disruption in the face of excessive plaque structure stress (PSS). Lesion tolerance of PSS correlates with the material and morphological properties of the arterial constituents. 2D-Finite Element Analysis (FEA) performed on models generated from arterial images (e.g. optical coherence tomography (OCT)) has procured a deeper understanding of lesion biomechanics but not the full complex 3D morphological-mechanical response. OCT frame sparsity and manual burden associated with 3D model generation have continuously plagued 3D simulations and automated large-scale studies. We present a fully automated software platform to determine 3D arterial stress distributions from deep-learning labeled OCT images of complex lesions by interpolating labeled frames. A preliminary study showed that frames with a high PSS (over 150 kPa) had significantly larger lipid arc angles, lumen-plaque eccentricity, lipid area, and calcium area, mirroring clinical observations. Such promising results validate the potential for the platform to be utilized for plethora of applications from unprecedented large scale in-silico studies to enhance clinical metrics, optimization of patient-specific angiography operations, and training data for emerging AI simulations.

Effect of variable volume fraction distribution and geometrical parameters on the bending behavior of sandwich plates with FG isotropic face sheets

This article analyzes the bending behavior of functionally graded sandwich plate structures submitted to sinusoidal loads using the hyperbolic quasi-3D shear deformation plate theory. In this theory, the number of unknowns is reduced from six to only five unknowns using an undefined integral without needing any shear correction factor. Furthermore, the effective constituent material properties of the upper and lower layers of the functionally graded sandwich plate are assumed to vary smoothly and continuously only in the thickness direction. In contrast, the core layer is still homogeneous and isotropic. The governing equilibrium equations of simply supported functionally graded sandwich plates are derived using the principle of virtual displacement. Their analytical solution is obtained using Navier’s technique for various schemas of functionally graded sandwich plates. The effects of the power law index, side-to-thickness ratio, and aspect ratio on the bending behavior are investigated.

3D Shape‐Morphing Display Enabled by Electrothermally Responsive, Stiffness‐Tunable Liquid Metal Platform with Stretchable Electroluminescent Device

Abstract3D displays are of great interest as next‐generation displays by providing intensified realism of 3D visual information and haptic perception. However, challenges lie in implementing 3D displays due to the limitation of conventional display manufacturing technologies that restrict the dimensional scaling of their forms beyond the 2D layout. Furthermore, on account of the inherent static mechanical properties of constituent materials, the current display form factors can hardly achieve robust and complex 3D structures, thereby hindering their diversity in morphologies and applications. Herein, a versatile shape‐morphing display is presented that can reconfigure its shape into various complex 3D structures through electrothermal operation and firmly maintain its morphed states without power consumption. To achieve this, a shape‐morphing platform, which is composed of a low melting point alloy (LMPA)‐graphene nanoplatelets (GNPs)‐elastomer composite, is integrated with a stretchable electroluminescent (EL) device. The LMPA in the composite, the key material for variable stiffness, imparts shape memory property and forms conductive pathways with GNPs enabling rapid electrothermal actuation. The stretchable EL device provides reliable illumination in 3D shape implementations. Experimental studies and proof‐of‐concept demonstrations show the potential of the shape‐morphing display, opening new opportunities for 3D art displays, transformative wearable electronics, and visio‐tactile automotive interfaces.

Stochastic vibration and buckling analysis of functionally graded sandwich thin-walled beams

Stochastic vibration and buckling analysis of functionally graded sandwich thin-walled beams with I-section based on the first-order shear deformation theory is for the first time proposed in this paper. The material properties of beams in both web and two flanges are assumed to be continuously varied in its thickness. Additionally, the constituent material properties are randomly changed according to the lognormal distributions. These stochastic variabilities are then propagated to the stochastic responses of the thin-walled beam through a beam solver with hybrid series-type approximation functions. To achieve efficient evaluations for stochastic responses including natural frequencies and critical buckling loads, polynomial chaos expansion (PCE) based surrogate model is developed. The efficiency and accuracy of PCE’s results are assessed by comparing with those of crude Monte Carlo simulation. Sensitivity analysis is carried out to compare the importance of the uncertainty in material properties to stochastic responses. New results reported in this paper can be interesting benchmarks for scientific and engineering community in the future.

BOND BEHAVIOUR OF EXTERNALLY BONDED BALSALT-FRCM SYSTEM AND CALCAREOUS STONE

The effectiveness of FRCM (Fibre Reinforced Cementitious Mortar) as strengthening system is influenced by the bond behaviour between reinforcement and substrate at different interfaces. Differently from what observed in case of organic binders, the interaction between inorganic matrix and fibres is mostly of mechanical type. Inorganic binders can hardly impregnate all fibre filaments, which leads often to adhesion problems at the interface matrix-fibre.The paper aims to furnish a contribution to the understanding of the physical phenomena that characterize the mechanical behaviour of Basalt FRCM materials and their bond with masonry structures. Two different calcareous stone and two different mortars were considered as variables. First, the mechanical properties of constituent materials were estimated; then the bond behaviour were investigated through single-lap shear bond test. The test results were collected and processed in terms of bond strength and failure modes.