Effects Of Material Properties Research Articles

A meshfree TSDT-based approach for modeling a skew plate

Taking into account new frontiers in materials technology to improve construction materials, we investigate the bending analysis of a Functionally Graded Material (FGM) skew plate using a meshless approach based on Third-order Shear Deformation Theory (TSDT). We assume that the material distribution is functionally graded across the thickness of the skew plate. The proposed approach uses both mixture rule theory and the meshless method. The mixture rule theory is used to estimate the effective material properties of the skew plate.

Application of Hashin–Shtrikman bounds homogenization model for frequency analysis of imperfect FG bio-composite plates

Despite abundant theoretical investigations on the dynamic behavior of functionally graded (FG) structures, the study on frequency analysis of FG bio-composite structures is limited. FG bio-composite materials due to their biocompatibility potentials and good material properties can be applied in biomedical applications, especially dental implants. In this investigation, a natural frequency response of the FG bio-composite plate is analyzed within the framework of the newly developed refined higher-order shear deformation plate theory. Additionally, the imperfection impact on frequency behavior is evaluated while three imperfection distribution patterns are taken into account. The constitutive materials of FG bio-composite plate are Hydroxyapatite and Titanium. The effective material properties of the structure are determined with the help of the upper Hashin–Shtrikman bounds homogenization model. In continuation, to solve the derived governing equations of imperfect FG bio-composite plate, Galerkin's analytical method is employed. Also, the precision of the used theory is validated, the obtained outcomes are compared and an acceptable matching is found. Later, the sensitivity of different considerable variables is comprehensively assessed and discussed.

(Keynote) Evidence of the Interplay of Temperature on Local and Global Battery Phenomena

Temperature is an important parameter in electrochemical processes and battery operation; for instance, open circuit voltage and resistance values of cells are temperature sensitive. Several recent studies have shown temperature within battery packs are not uniform. This non-uniformity of temperature produces localized thermal gradients within cells that can dictate cell construction, thermal management scheme, cell bussing, etc. Our research group has been working to understand how thermal gradients within battery cells effect material properties, electrochemical performance and stability. We have demonstrated through a range of electrochemical and materials characterization techniques, how dynamic external conditions, specifically thermal gradients and transients, can induce differing degradation modes of the positive and negative electrodes. The directionality and magnitude of thermal gradient dictate the degradation mode, whether loss of lithium inventory, loss of active material, etc.We have also observed strong electrochemical-mechanical coupling the result of low temperature cycling, where lithium plating on the negative electrode causes a physical deformation and collapse of the cylindrical cell jellyroll. In this talk, we will present in-operando optical microscopy and X-ray computed tomography data to show how dynamic electrical and external thermal conditions can irreversibly effect the chemistry, structure and subsequent safety of lithium-ion battery materials, components and cells. Lastly, the importance of testing materials and cells outside of isothermal laboratory conditions in favor of operating under dynamic thermal conditions, to include austere and stressful operating conditions will be discussed.

Non-linear stability characteristics of randomly distributed CNT-reinforced fiber composite beams under thermo-mechanical loadings

The aim of the present study is to elucidate the non-linear stability characteristics of randomly distributed carbon nanotube-reinforced fiber composite (RD-CNTRFC) beams subjected to thermo-mechanical loading. Effective material properties of RD-CNTRFC are estimated using the Eshelby-Mori-Tanaka approach and Halpin–Tsai micromechanical techniques. The material properties are considered to be temperature-dependent, and the influence of carbon nanotube (CNT) agglomeration is also incorporated in material properties estimation of hybrid matrix. The strain-displacement relations are assumed by incorporating the higher-order shear deformation theory and geometrical nonlinearity (von Kármán). The governing partial differential equations are obtained by minimizing the total potential energy of the beam. Buckling loads of beam subjected to in-plane compressive loads are estimated using Eigen value approach. Similarly, buckling temperatures are also determined by solving Eigenvalue problem iteratively due to temperature-dependent material properties. The non-linear equilibrium paths under thermal and mechanical loadings are traced through iterative Eigenvalue approach. Numerical results are presented to elucidate the influence of various parameters like CNT agglomeration, ply sequences, span-to-depth ratio, boundary conditions, and mass fraction of CNTs.

Energy-based efficient residual stress prediction of titanium alloys with lack-of-fusion porosity in powder bed fusion

Residual stress and porosity exert adverse effects on the mechanical properties of metal parts fabricated by powder bed fusion. However, the modeling of the correlation between process parameters, process-induced porosity, and residual stress remains challenging. In this paper, a thermo-mechanical model of titanium alloy with porosity is established, where the relation between process parameters, porosity, and effective material properties is identified. The porosity is first predicted based on the power conservation principle in the process. The effective material properties of as-built titanium alloy with porosity are estimated using a homogenization method. Subsequently, the stress and distortion resulting from temperature variation are predicted using the shear deformation theory. The predicted results exhibit excellent agreement with the predictions and experimental results in the literature. Furthermore, the effect of the main process parameters on the porosity, residual stress, and distortion is investigated. The results show that excessive laser power, small laser radii, and extensive scan tracks contribute to a significant lack-of-fusion porosity. Additionally, the normal stress along the scan direction and vertical deflection are the major residual stress and distortion of titanium alloy with porosity, respectively. The proposed model can serve as a guideline for the design and fabrication of PBF-built titanium alloys.

Circular inclusion with a refined linearized version of Steigmann–Ogden model

The plane deformation of an infinite elastic matrix enclosing a single circular inclusion incorporating stretching and bending resistance for the inclusion–matrix interface is revisited using a refined linearized version of the Steigmann–Ogden model. This refined version of the Steigmann–Ogden model differs from other linearized counterparts in the literature mainly in that the tangential force of the interface defined in this version depends not only on the stretch of the interface but also on the bending moment and initial curvature of the interface (the corresponding bending moment relies on the change in the real curvature of the interface during deformation). Closed-form results are derived for the full elastic field in inclusion–matrix structure induced by an arbitrary uniform in-plane far-field loading. It is identified that with this refined version of the Steigmann–Ogden model a uniform stress distribution could be achieved inside the inclusion for any non-hydrostatic far-field loading when R = 3 χ int / λ int (where R is the radius of the inclusion, while λ int and χ int are the stretching and bending stiffness of the interface). Explicit expressions are also obtained for the effective transverse properties of composite materials containing a large number of unidirectional circular cylindrical inclusions using, respectively, the dilute and Mori–Tanaka homogenization methods. Numerical examples are presented to illustrate the differences between the refined version and two typical counterparts of the Steigmann–Ogden model in evaluating the stress field around a circular nanosized inclusion and the effective properties of the corresponding homogenized composites.

Natural Frequency Characteristics of Stiffened FG Multilayer Graphene-Reinforced Composite Plate with Circular Cutout Resting on Elastic Foundation

In this research, natural frequency response of functionally-graded multilayer graphene-reinforced composite plate with circular cutout reinforced by orthogonal stiffeners is investigated for the first time. The structure is surrounded by Winkler-type elastic support. The plate is composed of polymethyl methacrylate (PMMA) as matrix material and reinforced by graphene platelets (GPLs). The material of the orthogonal stiffeners is the same as that for the matrix. Rule of mixtures and Halpin–Tsai approach are applied to estimate the effective material properties of the composite plate. Third-order shear deformation plate theory and finite element procedure is employed to obtain the element matrices of the structure. Natural frequencies and mode shapes of the stiffened plate are reported for different variables such as nanofillers dispersion patterns, width and height of the stiffeners, aspect ratio of plate, plate thickness ratio, weight fraction of nanofillers, number of stiffeners, boundary conditions, elastic foundation stiffness parameter and size of circular cutout. The obtained results denote that with the addition of a set of stiffeners, fundamental frequency enhanced up to 32.3% with just about 10% increase of mass.

Computational Design of Flexible Planar Microstructures

Mechanical metamaterials enable customizing the elastic properties of physical objects by altering their fine-scale structure. A broad gamut of effective material properties can be produced even from a single fabrication material by optimizing the geometry of a periodic microstructure tiling. Past work has extensively studied the capabilities of microstructures in the small-displacement regime, where periodic homogenization of linear elasticity yields computationally efficient optimal design algorithms. However, many applications involve flexible structures undergoing large deformations for which the accuracy of linear elasticity rapidly deteriorates due to geometric nonlinearities. Design of microstructures at finite strains involves a massive increase in computation and is much less explored; no computational tool yet exists to design metamaterials emulating target hyperelastic laws over finite regions of strain space. We make an initial step in this direction, developing algorithms to accelerate homogenization and metamaterial design for nonlinear elasticity and building a complete framework for the optimal design of planar metamaterials. Our nonlinear homogenization method works by efficiently constructing an accurate interpolant of a microstructure's deformation over a finite space of macroscopic strains likely to be endured by the metamaterial. From this interpolant, the homogenized energy density, stress, and tangent elasticity tensor describing the microstructure's effective properties can be inexpensively computed at any strain. Our design tool then fits the effective material properties to a target constitutive law over a region of strain space using a parametric shape optimization approach, producing a directly manufacturable geometry. We systematically test our framework by designing a catalog of materials fitting isotropic Hooke's laws as closely as possible. We demonstrate significantly improved accuracy over traditional linear metamaterial design techniques by fabricating and testing physical prototypes.

Electrochemical-Electromagnetic Coupled Physics-Based Mathematical Modeling of Li-Ion Batteries: A Theoretical Proof of Concept

This theoretical study presents a novel proof-of-concept modeling approach that couples a P2D physics-based electrochemical model with a 3D electromagnetic model to analyze the behavior of lithium-ion batteries under AC perturbations in the 0.1 Hz–100 kHz frequency range that generates an impedance response in a cylindrical Li-ion battery cell. The coupling between the two models was done by connecting them in series and adding the separate impedances from both models. By considering effective material properties for the electromagnetics model, and by using the Nyquist and Bode plots as figures of merit, it was shown that such a hybrid coupling can be used to predict the impedance of such a system. This research lays the groundwork for future experimental validation and optimization of battery designs in applications involving AC perturbations, offering insights for enhanced energy storage and conversion systems.

An application of cold spray additive manufacturing for thermoelectric generator thermal interfacing

The influence of thermal interface resistance is an important design problem for the optimisation of heat transfer systems. For thermoelectric generators (TEG), it can limit the ability to convert thermal energy directly to electrical energy. This paper describes an experimental and numerical study of the influence of thermal interface resistance on TEG module performance. A test apparatus was constructed to evaluate TEGs under varying temperature and heat source/sink conditions. The effect of heat source/sink interface finish grades, corresponding to medium quality (N8-N6) and very fine (N5-N4) surface finishes, at varying clamp forces, is evaluated. Then the application of cold spray additive manufactured copper, as a novel method of TEG module thermal interfacing is explored. Experimental data is accompanied with numerical analysis using TEG ideal equations and the effective material properties approach with the incorporation of temperature dependency and fabrication quality factors to improve modelling accuracy. A system of simultaneous heat flow equations is then established to numerically solve for the presence of thermal interface resistance. The results show that high clamp forces (3600 N) and very fine finish grades were sufficient to minimise thermal interface resistance to the range 0–5.98 ×10−5m2KW−1, representing a loss of 0–9.9% in maximal achievable power. For the cold spray thermally interfaced TEG module, resistance estimates were lower and in the range 0–5.4 ×10−6m2KW−1, corresponding to a 0–1.0% loss in power.

Experimental characterization and numerical analysis of CFRPs at cryogenic temperatures

The thermo-mechanical performance of carbon fiber reinforced polymers (CFRPs) is affected by temperature changes due to the dissimilar nature of the constituents and dissimilar properties. For instance, under cryogenic conditions, the effective mechanical performance of the composite system can be significantly reduced. In this work, dynamic mechanical analysis (DMA) tests and coupon mechanical tests at room and cryogenic temperatures (through immersion in liquid nitrogen), are combined with computational micromechanics to analyze the development of micro-residual stresses from curing to cryogenic conditions, and their influence on the mechanical performance of a unidirectional CFRP. The results confirm the stiffness increase in the matrix and in the composite under cryogenic conditions, but the high tensile triaxial stress state that is developed during cooling reduces the overall composite strength, despite the increase of the matrix strength with decreasing temperature. To capture the failure modes and the evolution of the properties appropriately, the elastic-plastic response and the pressure dependent failure model are formulated to appropriately represent the shear response of the composite system and matrix failure under complex triaxial stress states, enabling a complete analysis and the identification of effective material properties, based on a reduced number of simple tests on the neat resin and on the composite system at different temperatures, which otherwise would be impossible to obtain considering the dimensional and technological restrictions of performing mechanical tests at cryogenic conditions.

Static and vibration analyses of functionally graded porous shell structures by using an averaged edge/node-based smoothed MITC3 element

In this paper, a combined scheme of edge/node-based smoothed finite element method (ENS-FEM) and the mixed interpolation of the tensorial components for the three-node triangular element (MITC3) named aENS-MITC3 is developed to investigate the static and free vibration for functionally graded (FG) porous shells. The effective material properties of FG porous shells are estimated using the rule of mixture, which incorporates an additional term for porosity in the through-thickness direction. The improved first-order shear deformation theory (FSDT) is used to accurately describe the shear stress distributing evenly throughout the thickness and is zero on the top and bottom surfaces of the doubly curved shell. Using Hamilton's principle, the governing equation of FG porous shells is established. The obtained numerical results of aENS-MITC3 are compared with other existing methods in the literature to show the effectiveness of the present method. Then, the effect of geometric parameters, porosity coefficients and power law indexes on the displacements and natural frequencies of FG porous curved shells are examined.

Bending results of graphene origami reinforced doubly curved shell

The present work investigates higher order stress, strain and deformation analyses of a shear deformable doubly curved shell manufactures by a Copper (Cu) core reinforced with graphene origami auxetic metamaterial subjected to mechanical and thermal loads. The effective material properties of the graphene origami auxetic reinforced Cu matrix are developed using micromechanical models cooperate both material properties of graphene and Cu in terms of temperature, volume fraction and folding degree. The principle of virtual work is used to derive governing equations with accounting thermal loading. The numerical results are analytically obtained using Navier's technique to investigate impact of significant parameters such as thermal loading, graphene amount, folding degree and directional coordinate on the stress, strain and deformation responses of the structure. The graphene origami materials may be used in aerospace vehicles and structures and defence technology because of their low weight and high stiffness. A verification study is presented for approving the formulation, solution methodology and numerical results.

Effects of the orientation distribution of thin soft inclusions on the effective elastic moduli of microheterogeneous material

Many natural composite materials such as carbonate rocks contain systems of oriented or partially oriented thin inclusions (microcracks) filled with a soft elastic cement. In this paper we have studied the influence of the inclusion orientation, shape, and elastic properties on the effective elastic properties of micro-inhomogeneous materials. We have calculated the components of the compliance tensor of such materials as a function of crack density. The results were obtained for thin ellipsoidal inclusions with elastic compliance much larger than the elastic compliance of the matrix. To calculate the effective compliance tensor, we have used the “non-interaction approximation” (NIA). The application of the NIA allows us to evaluate the influence of peculiarities in the spatial distribution of inclusions on the effective properties of the medium. To simplify the calculations, we have used the special tensorial basis (T-basis). We have obtained the explicit expressions for the effective elastic compliance tensor of inhomogeneous materials. To verify the analytical expressions, we have compared our results for elastic moduli to the results obtained by numerical modeling of a material containing crack-like inclusions. The results obtained by using the two methods are in very good agreement, thus indicating that our analytic method can be applied even at sufficiently large values of crack density.

Challenges in permeability characterisation for modelling the manufacture of wind turbine blades

As wind turbine blades continue to increase in size, and market competition grows, lean manufacturing has become even more important for OEMs. The rapid development of new blade designs, with greater performance, and reduced production waste are driving the need for predictive modelling of the blade infusion process. Such simulations are reliant upon Darcy’s Law for the description of fluid flow through porous materials and therefore depend greatly on the permeability properties of the blade preform materials. The characterisation of fabric permeability, although unstandardised, has been well studied in recent years as the focus of numerous international benchmarking efforts. However, the effective permeability properties of infusion consumables, core materials, and pre-cast elements are not so well defined or validated, despite their significance on infusion behaviour. Hence, the great variety of preform materials, stacking configurations, geometric features, and transition regions in wind turbine blades present considerable challenges in terms of permeability characterisation and subsequent modelling. This article reviews some of the challenges, opportunities, and alternatives for characterising permeability in common blade preform materials, along with examples of how these properties have been applied in numerical models to better simulate the resin infusion manufacturing process for wind turbine blades.

Machine learning aided uncertainty analysis on nonlinear vibration of cracked FG-GNPRC dielectric beam

Functionally graded graphene nanoplatelet reinforced composite (FG-GNPRC) have shown significant potential for the development of high-performance and multifunctional materials and structures. Conducting an accurate analysis of the nonlinear vibration of FG-GNPRC dielectric beams can accelerate their application in various engineering fields. To investigate the nonlinear vibration of FG-GNPRC dielectric beams, the effective material properties of a cracked composite beams are evaluated using effective medium theory (EMT) and the rule of mixture. Three ML models adopted in this work, i.e., artificial neural network (ANN), random forest (RF), and AutoGluon (AG), are used to capture the complex relationship between the systematic inputs (i.e., parameters for materials and structure, the attributes of electrical field, etc.) and frequency ratio of the cracked FG-GNPRC beams. Moreover, shapley additive explanations (SHAP) is employed for the analysis of the nonlinear vibration of FG-GNPRC dielectric beams considering the influence of multi-factor coupling and uncertainties. The SHAP analysis suggests that the uncertainty of structural parameters has the greatest impact on the nonlinear vibration of FG-GNPRC dielectric beams, particularly when the structure is subjected to a voltage of 40 V.

Static analysis of shear-deformable aircraft wings using a multilayered functionally graded material model

This study presents a comprehensive investigation of the static analysis of a shear-deformable aircraft wing made of functionally graded materials (FGMs). A finite element-based multilayered FGM model is employed for this purpose. In order to ensure the safe structural design of the aircraft wing, it is crucial to analyze the transverse displacement of the wing under various loading conditions. The presented model employs a power-law distribution based on the rule of mixture to derive the effective material properties of the FGM wing. The analysis focuses on three standard FGM aircraft wing profiles, namely NACA 0009, NACA 2424, and NACA 4415, which are representative of commonly used geometries in aircraft design. Additionally, the study explores the effects of volume fraction index, loading conditions, boundary conditions, and aspect ratio on the static analysis of the shear-deformable FGM aircraft wing. These parameters play a significant role in shaping the static behavior of the wings and offer valuable insights into the design of FGM aircraft wings.

Numerical vibroacoustic analysis of multi-layered composite structure under hygrothermal loading using coupled FEM-IBEM micromechanical model

The vibroacoustic responses of multi-layer composite shallow shell panels subjected to harmonic mechanical excitation in hygrothermal environment is numerically investigated. A homogenized micromechanical finite element (FE) based on the higher-order mid-plane kinematics replicating quadratic function as well as the through the thickness stretching effect together with the indirect boundary element (IBE) scheme has been first time employed. The isoparametric Lagrangian element with zero-order Hermitian interpolation function (10 degrees of freedom per node) is used for structural model discretization to attain the hygro-thermo-elastic natural frequencies via Hamilton’s principle. The uniqueness of the model is the incorporation of the effective material properties under combined hygrothermal loading via a micromechanics approach. An IBE method is then implemented to attain structure-surrounding coupling and the Helmholtz wave equation is solved to compute the sound radiation responses. The effectiveness of the model is tested by converging it with the similar analytical/numerical results as well as the experimentally acquired data for vibrational as well as acoustic responses. The present scheme is further hold out for solving diverse numerical illustrations. The geometrical parameters, volume fraction of fiber, layup, and support conditions alongside the hygrothermal load is found to have significant influence on the hygro-thermo-acoustic characteristics. The functional inferences will assist in designing the imminent multi-layered structures that serve under the influence of severe hygrothermal loading during high-performance engineering applications.

Nonlinear vibration study of a rotor blade based on a novel non-polynomial function

This work investigates the nonlinear free vibration of a turbomachinery blade, which is idealized as a rotating, conical, twisted shell of varying thickness reinforced with graphene platelets. Using the von Karman type of nonlinearity, the dynamic equilibrium equation for the twisted panel is obtained and solved by finite element method. The impact of the centrifugal force caused by rotation is taken into account, but the effect of the Coriolis force is neglected. The functionally graded twisted tapering conical shell has two alternative ways in which graphene platelets (GPLs) are reinforced in the thickness direction. The rule of mixture and the modified Halpin-Tsai model are used to compute the effective material properties of the twisted shell. The strain displacement relation is based on a new non-polynomial shear deformation theory. The parametric analysis performed at the endshows that nonlinear frequency increases when twist angle, rotational speed, tapper ratio, and weight fraction of GPLs increase. It is also observed that mode shapes are severely impacted by twist angle and rotational speed.

Finite element analysis of natural frequencies of the FGM porous cooling plate with cutouts: A multilayered FGM approach

This study comprehensively investigates the natural frequency analysis of a shear-deformable functionally graded porous plate with cutouts, utilizing an FE-based multilayered FGM model. Analyzing natural frequencies is vital to prevent catastrophic failure in porous plates, particularly in cooling plates. Cutouts in cooling plates enhance heat dissipation, improve airflow or fluid contact, reduce weight, customize battery layouts, optimize structural integrity, simplify installation, and enable precise thermal management in critical areas. The present study employs an FE-based multilayered FGM model that considers three distinct porosity distributions (even, uneven, and sinusoidal) and incorporates a power law distribution based on a modified rule of mixture to derive the effective material properties of the FGM porous plate. Furthermore, this investigation comprehensively explores the influences of variables such as volume fraction index, thickness ratio, porosity distribution, and porosity index on the natural frequency analysis of shear-deformable FGM porous plates with cutouts, encompassing both conventional and unconventional boundary conditions. This extensive examination elucidates the collective impact of these variables on the vibrational behavior of FGM plates featuring cutouts. These parameters significantly impact the vibration behavior of the FGM plate with cutouts. The results affirm the efficacy of the presented model in analyzing intricate FGM structures.