Material Parameters Research Articles

The Factorial Fundamental Frequency Explicit Formulas for Homogenous Rectangular Thin Plates with Four Free Edges

PurposeThis study aims to investigate fundamental modal solutions for rectangular thin plates with four free edges: (1) to provide a novel criterion for fundamental mode identification, and (2) to derive high accurate explicit formulas for calculating the fundamental frequency.MethodTo achieve the study objectives, an investigation into the fundamental mode space was conducted, varying structural and material parameters including the plate’s dimensions (a, b), thickness (h), and Poisson’s ratio (ν). A novel, explicit criterion for fundamental mode identification was formulated, incorporating a six sigma tolerance tailored for specific aspect ratios. Ordinary least squares (OLS) multiple linear regression methodology was integrated within a dedicated process to identify optimal factor combinations for factorial frequencies based on 56 features. This methodology allowed for the derivation of factorial frequency formulas as a function of a, b, h, and ν, providing explicit expressions for calculating the fundamental frequency.ConclusionThe study concludes that the global fundamental mode shapes of rectangular thin plates with four free edges are primarily governed by the aspect ratio a/b, Poisson’s ratio ν, and the thickness-induced shearing effect h on both dimensions. The derived explicit formulas for calculating the fundamental frequency exhibit exceptional accuracy, with a maximum error of −0.217% compared to extensive finite element analysis results, surpassing current state-of-the-art accuracy. This work presents physically meaningful, explicit formulations and introduces a novel perspective in plate and shell research, particularly relevant in scenarios with adjacent free edges and similar global modes.

Dynamic Properties and Vibration Response of Polymer Matrix Composites: Mechanisms, Influences, and Applications in Engineering

ABSTRACTPolymer matrix composites (PMCs) are critical materials in vibration‐intensive applications, including aerospace, automotive, naval, and sports sectors, where understanding their dynamic behavior is essential for reliable performance. This study comprehensively reviews PMCs' dynamic properties, focusing on their vibration response and damping characteristics. It explores the influence of material parameters, such as matrix composition, fiber orientation, stacking sequence, and nanoparticle incorporation, on natural frequencies and damping ratios. Experimental techniques like dynamic mechanical analysis and fast Fourier transform, alongside computational and analytical methods, including finite element analysis and classical theory, are utilized to evaluate these properties. Key findings reveal that natural fibers like kenaf and hamp enhance damping for eco‐friendly applications, while synthetic fibers and nanoparticles, such as multi‐walled carbon nanotubes, improve frequency response but may reduce damping. The effects of temperature sensitivity and chemical treatments are also discussed, emphasizing their role in optimizing vibrational performance. Analytical models and numerical simulations validate these findings, providing insights into structural design. This work bridges knowledge gaps by integrating experimental and theoretical approaches and offers practical strategies for developing lightweight, vibration‐resistant PMCs tailored for critical engineering applications. Future research should focus on optimizing material–environment interactions for advanced applications.

Computational and experimental mechanical characterization of a novel corneal implant for the treatment of keratoconus

Aims/Purpose: Current treatment options of keratoconus have several limitations. These limitations have been addressed by developing a novel nitinol GROSSO® implant, that restores the physiological curvature of the cornea by virtue of a dome‐shaped design. Its minimally invasive implantation requires accurate assessment of the mechanical properties, investigated here both experimentally and computationally.Methods: Bending of two opposite edges of the implant is necessary for its implantation in the intracorneal pocket. Bending was conducted experimentally at 37°C using a DMA Q800 (TA Instruments) with a thermal chamber and a cell load of 18 N to obtain force‐displacement curves. A computational model of the real implant was reconstructed from microcomputed tomographic acquisitions (Phoenix v|tomo|x m, resolution: 1μm). The mechanical behaviour of the implant was modelled by implementing a superelastic constitutive law with material parameters obtained from experimental tensile tests of the nitinol, which also determined the plastic permanent deformation value. Finite element analysis of the bending simulation was performed in Abaqus (Dassault Systèmes Simulia Corp.) to obtain the bending force (BF) and assess the absence of permanent deformation.Results: A good agreement between the experimental (0.09 N) and computational tests (0.08 N) in terms of BF was observed. The computational simulation highlighted that the maximum principal strain value during bending was 10.8%, i.e. below the limit strain for plasticity of 12%.Conclusions: The GROSSO® implant can be safely bent during implantation with minimal effort, as the force applied does not exceed 0.1 N. The ongoing validation of the computational model will enable a cost‐effective prediction of macro‐scale mechanical properties and compliance with relevant standards and regulatory requirements. Additional critical scenarios and the remodeling effect imposed by the implant on corneal tissue will be the subject of future investigations.

Joint intelligent optimization design of the active region and electron blocking layer for AlGaN-based deep ultraviolet LEDs

Aiming to enhance the internal quantum efficiency (IQE) of AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs), the active region based on the V-shaped quantum well (QW) and the electron-blocking layer (EBL) structure are jointly optimized using intelligent algorithms in this work. This method focuses on maximizing the IQE of the DUV LEDs by optimizing the geometric and material parameters of multiple QWs (MQWs) and EBL. It is demonstrated that the DUV LED with an optimized structure exhibits smaller band edge tilt for improved wave function overlap in QWs and more effective carrier blocking for reduced electron overflow compared to that with a conventional structure. The results show that, by optimizing the active region and EBL structure using the proposed method, the IQE and maximum radiation intensity of the AlGaN-based DUV LED are enhanced by 38% and 41% at 200 A/cm2 injection current density, respectively.

Experimental and numerical analysis of Carbon/Glass fiber reinforced thermoplastic wind turbine blade prepared by VARIM

Abstract The output of wind energy, a vital renewable resource, has increased from 94 GW to 591 GW globally in the last ten years. Weight and cost are important considerations in wind turbine blade (WTB) design, as rotor blades make up 40%–80% of the overall weight, to fulfill the growing need for energy. Even though thermosetting composites are frequently used to make blades, they have several drawbacks, most notably that they cannot be recycled. As more blades approach the end of their lives and become unreformable once cured, recycling and disposal become more difficult, and environmental concerns increase. The main objective of the present work is to manufacture thermoplastic composites reinforced with fibers using the Vacuum Assisted Resin Infusion Moulding (VARIM) technique and assess their mechanical characteristics. The finite element analysis of the WTB incorporates the material parameters calculated for the thermoplastic resin. Test coupons are produced by shaping thermoplastic resin and fiber reinforcement using VARIM. The mechanical characteristics, including flexural and impact strength, are then assessed utilizing destructive testing techniques. Thermoset resins have good flexural properties while thermoplastic resins have better impact properties. The wind turbine blade (WTB) is simulated in ANSYS ACP based on the designated stacking sequence and fiber orientation. Static structure analysis is performed for the thermoplastic and thermosetting composites under various operating circumstances. Identification and analysis of the critical section susceptible to mechanical failure are conducted under different loading conditions, and the obtained outcome is verified. Based on the results, it is concluded that thermoplastic composites are viable materials for manufacturing wind turbine blades.

Thermal and solutal performance analysis featuring fully developed chemically reacting micro-rotational convective flow in an open-ended vertical channel

Thermal and solutal performance analysis featuring fully developed chemically reacting micro-rotational convective flow in an open-ended vertical channel

A time-domain finite element formulation of the equivalent fluid model for the acoustic wave equation

Sound-absorptive materials such as foam can be described by the equivalent fluid (EF) model. The homogenized fluid’s acoustic behavior is thereby described by complex-valued, frequency-dependent acoustic material parameters. When transforming the acoustic wave equation for the EF model from the frequency domain to the time domain, convolution integrals arise. The auxiliary differential equation (ADE) method is used to circumvent the direct calculation of these convolution integrals. The wave equation and the coupled set of ordinary ADEs are solved in the time domain using the finite element (FE) method. The approach relies on approximating the complex-valued frequency response functions of the inverse equivalent bulk modulus and density by a sum of rational functions consisting of real and complex poles. The order of the rational function approximation defines the number of additionally introduced auxiliary variables per nodal degree of freedom. The presented FE formulation includes a narrow-band non-reflecting boundary condition (NRBC) for normal incidence. The implementation in openCFS shows optimal temporal and spatial convergence for a semi-infinite duct based on the analytic plane wave solution for harmonic excitation. The simulation of a pressure pulse propagating in an infinite EF domain with a scatterer demonstrates the capability for multidimensional, actual transient problems.

Machine learning driven measurement of high-aspect-ratio nanostructures using Mueller matrix spectroscopic ellipsometry

Accurate fabrication of high-aspect ratio (HAR) structures in applications from semiconductor devices to x-ray observatories is essential for their optimal performance because their performance directly depends on their structure. High-efficiency critical-angle transmission (CAT) gratings enable high-resolution x-ray spectroscopy in astrophysics, but their performance is only ideal when certain performance-critical parameters, like the bar tilts introduced during deep reactive-ion etching, are tuned to precise values. Traditional measurement methods like small-angle x-ray scattering (SAXS) are accurate, but limit the development of robust control algorithms to nudge performance-critical parameters toward favorable values because they are slow and often destructive. We present a fast, accurate, nondestructive measurement method using Mueller matrix spectroscopic ellipsometry and machine learning. Given a HAR structure, we train on rigorous coupled-wave analysis simulation data to predict Mueller matrix spectra from input performance-critical parameter values. We then invert this forward problem by freezing our network weights, measuring experimental Mueller matrix spectra, and vanilla gradient descending on performance-critical parameters to values that correspond to the input Mueller matrix spectra. Introducing machine learning to invert the forward problem reduces computation time, and experimental results demonstrate close agreement between our method’s determined tilt and SAXS measurements. Our accurate, fast measurement method paves the way for the development of robust control algorithms that adjust fabrication parameters in response to measurement, ensuring optimal performance in not only CAT gratings but also HAR structures embedded in applications from semiconductor to microelectromechanical systems fabrication.

The effect of travertine waste on the strength and insulation properties of foam concrete

Abstract Incorporating waste additives into foam concrete mixtures is a promising route to develop environmentally-friendly concrete production with tailored thermos-mechanical properties. In this paper, the effects of various fabrication parameters of foam concrete, including the type of waste additive, water/binder ratio, density of mixture, and incorporation of glass fibers were investigated. Foam concrete samples were fabricated using fly ash and travertine wastes, and the variations in their compressive strength, and thermal conductivity using various concrete mixture designs were measured. The obtained results show that foam concrete with fly ash additive tends to have higher compressive strength and thermal conductivity than foam concrete with travertine waste. However, the latter exhibits better thermal insulation properties, which tend to improve by adding glass fibers. This work defines the outlines for exploring the use of harmful wastes in fabricating foam concrete. It offers guidelines for developing improved foam concrete mixtures with tailored thermos-mechanical properties.

Rapid Separation of Representative Monomer Compound Rutin From Natural Product by Molecularly Imprinted Macroporous Adsorption Resin.

Monomer compounds from natural products are the major source of active pharmaceutical molecules, which provide great opportunities for discovering of new drugs. However, natural products contain a large number of rather complex compounds. It is difficult to obtain high-purity monomer compounds from complex natural products. Herein, we developed molecularly imprinted macroporous adsorption resins (MIRs-PDA) for the selective adsorption of target monomer compounds from natural products. The response surface methodology was employed to optimize the fabrication parameters. The separation performance of MIRs-PDA for the representative monomer compound rutin was thoroughly studied. We found that MIRs-PDA presented large adsorption capacity (107.82mg/g), high selectivity (selectivity coefficient was 2.90), good repeatability, and reusability. MIRs-PDA can reach 78.5% equilibrium adsorption capacity in 20min, showing quick binding kinetic behavior. Furthermore, MIRs-PDA showed good selective and specific adsorption performance for rutin from a representative real sample of Fagopyrum tataricum extract solution. The study of the adsorption mechanism showed that the adsorption of rutin on MIRs-PDA was spontaneous and thermodynamically feasible. The kinetic parameters adapted well to the pseudo-second-order kinetic model, and there existed equivalent binding sites in MIRs-PDA. The MIRs-PDA show promising application prospects for the separation of monomer compounds in natural products.

Impact of material property variations and sensor positioning on the coating thickness determination of steel sheets using eddy current testing

Purpose This paper aims to investigate the reliable thickness, and more generally, the geometric and material parameter determination of thin electrically conductive and diamagnetic coatings on conductive and ferromagnetic substrates, e.g. steel, using eddy current testing (ECT). Design/methodology/approach The analytical model of an ECT coil arrangement known from the literature is analyzed to evaluate the numerical simulation performed by a Finite Element (FE) program. The latter is used to investigate the influence of the sheet edge on the measurement result. Finally, a measurement setup is presented and the unknown geometric and material parameters are estimated from measurement data of different sample sheets at different air gaps. Findings Generally, valid mesh rules are found for a very accurate FE analysis of eddy current problems with large air gaps. The influence of large air gaps on the parameter estimation is emphasized. Moreover, the formulated hypotheses can be widely confirmed by measurements. Research limitations/implications In this paper, electrical steel sheets coated with a conductive oven-cured ink are used. This sample configuration creates a discrete transition between the substrate and the coating as present in the analytical modeling approaches. Furthermore, the ferromagnetic substrate’s nonlinear B-H curve is not considered in the analytical model so far. Originality/value The analytical model is known from the literature. However, real practical measurements have not been carried out with the discussed setup. Furthermore, well-known literature on eddy current measurements usually only considers constant and very small air gaps.

VIRTUAL FIT EVALUATION FOR OPTIMIZATION OF GARMENT COMPONENT’S PARAMETERS

Apparel fit is influenced by body proportion, fabric, and design parameters, but much of the fit evaluation is carried out in a static model, which leads to time consumption and higher development costs. In this work, an attempt has been made to quantify the fit objectively for a basic crewneck T-shirt for men’s wear made of cotton and cotton-lycra blended single jersey knitted fabric. A parametric avatar model was created, and virtual patterns were developed by changing the design parameters at three levels in the CAD platform. The fit is objectively quantified as strain and ease in different garment fit zones of the body. Virtual 3D fit software evaluates the fit zones of the garment by incorporating the low-stress mechanical properties of the knitted fabrics into an avatar model. There is a significant influence on pattern parameters and material compositions; cotton-lycra garments reveal lower ease at various fit zones.

Stress distribution around a circular hole in transversely isotropic elastic bodies whose material moduli depend on density

In this paper, we study the stress distribution around a circular hole in transversely isotropic elastic bodies, whose material moduli depend on density under small deformations. Two special constitutive relations are considered within the framework of implicit elasticity to describe the nonlinear stress–strain response of such bodies. We studied the stress concentration problem in a thin plate under uniaxial tension. The constitutive relations presented herein exhibit stiffening or softening mechanical response under tension and compression depending on the values of the material parameters. While the stress distribution at the circumference of the hole resembles that of a classical linearized elastic body, the peak value of the normalized hoop stress at the hole is not constant and varies as a function of the applied stress. Furthermore, we perform a parametric study to understand the influence of different material parameters on the stress distribution around the hole.

Failure analysis and size optimization of CFRP composite single-lap bonded joints based on the influence of multiple parameters

This paper had conducted tensile shear tests on single-lap joints (SLJs)bonded structures of carbon fiber reinforced resin matrix (CFRP) composite laminates with different overlap lengths, overlap widths, overlap model, adherend material, and adhesive layer thicknesses under two environments: room temperature dry state (RTD) and elevated temperature wet state (ETW). The failure modes were observed, and load–displacement curves were obtained. The microscopic morphology of the fracture surface was observed by scanning electron microscope (SEM). At the same time, a finite element simulation model was established to simulate the damage initiation and evolution process between layers and in the adhesive layer, and analyze the distribution laws of peel stress and shear stress in the adhesive layer. Through the combination of test data and simulation results, the influences of geometric parameters, material parameters and environmental parameters on the structure were explored, and the joint failure mechanism was revealed. Finally, the ACO-BP neural network was used to optimize the geometric parameters through test data. The research results showed that the geometric parameters of the structure mainly affect the bearing capacity and failure type. Reducing the overlap length and increasing the overlap width within a certain range can weaken the peeling phenomenon, so that a smaller overlap area has a higher shear strength. The material parameters of the adherend mainly affect the stress distribution law and stress transfer process of the adhesive layer in the overlap area. The joint mainly bore shear stress and peel stress, and shear stress is the main cause of damage initiation. When the types of adherend materials are different, the stress distribution law shows obvious asymmetric offset. The lap model mainly affects the location distribution of the failure area, and the environmental parameters mainly affect the area proportion relationship of various fracture forms in the mixed failure mode.

Translucency of New Lithium Disilicate Ceramics After Ageing and Immersion in Coffee Solution

Aim To evaluate translucency parameters of different lithium disilicate glass-ceramic materials after thermocycling and coffee staining. Material and method Three different rectangular-shaped specimens were prepared using three distinct 1.2 mm thick lithium disilicate glass ceramics (IPS e.max CAD, LD_C; Cerec Tessera, LD_A; Initial LiSi Block, LD_F) by using a precision cutting device. All specimens were standardised by polishing with abrasive silicone paper. Thereafter, the specimens were subjected to thermal cycling (5000 cycle, 5-55 C, 30 sn dwell time) and then immersed in coffee solution for 30 days. The colour coordinates of each sample before and after ageing were recorded, and the relative translucency parameter (RTP) was calculated using the CIEDE 2000 formula. The results were then subjected to statistical analysis by one-way ANOVA and a post hoc Tukey test. Results There was a significant difference between the groups in terms of RTP both before and after staining (p

Multi‐objective optimization of coaxial cables with foamed LDPE/HDPE dielectric layers: Correlating process parameters with foam structure and impact on piezoelectric and electrical properties

AbstractPolymeric foams are one of the new candidates for use in the dielectric layer of coaxial cables to improve their piezoelectric and electrical properties. These properties are affected by the structural properties, which depend on material and processing parameters. In this research study, first, the effect of cell size, cell density, and expansion ratio was theoretically studied on the piezoelectric and electrical properties. Then the effect of talc content, processing temperature, and cooling method was investigated on the structural, piezoelectric, and electrical properties of the produced coaxial cables. The examinations revealed that the increase in cell size, cell density, and expansion ratio increases the piezoelectric coefficient and velocity of propagation and decreases attenuation. According to the analysis of variance results, the talc content parameter was the most effective parameter on cell size, cell density, and piezoelectric coefficient with the contribution of 72%, 83%, and 69%, respectively. Also, the processing temperature parameter was the most effective parameter on the expansion ratio and electrical properties with the contribution of 42%, and 41%, respectively. Finally, the produced sample with talc content of 2 wt%, processing temperature of 125°C, and cooling method by water was introduced as the optimum sample by the multi‐objective optimization.Highlights Production of foamed dielectric layers in extrusion process of coaxial cables. Effect of cell structure on piezoelectric and electrical properties. Effect of process on structural, piezoelectric and electrical properties. Optimization of structural, piezoelectric, and electrical properties. Optimum conditions: 2 wt% of talc, temperature of 125°C, and water cooling.

Comparative study when modeling and multi-objectif optimization of machining parameters during turning Polyoxymethylene polymer using DFA, GRA and TOPSIS technics

This paper examines the effect of the material and machining parameters on cutting force, and surface roughness when turning polyoxymethylene POM C using a carbide tool. Turning experiments were conducted based on the Taguchi orthogonal matrix L16, taking into account cutting speed, cutting feed and cutting depth as input process parameters. Multi-objectif optimization was achieved through DFA, GRA, and TOPSIS methods. Results proved that both GRA and TOPSIS techniques provided a similar optimal parametric condition, namely a Vc = 500 m/min, a f = 0.08 mm/rev and a ap = 1 mm. On the other hand, the DFA method gives the following optimal parameters: Vc = 345.04 m/min, f = 0.09 mm/rev and ap = 1 mm. Experimental approach illustrates the feasibility and effectiveness of these proposed methods GRA and TOPSIS for multi-objectif optimization by contributing to the DFA method.

Clay 3D printing: Exploring the interrelations of materials and techniques

This research aims to design an algorithm for optimizing clay 3DP. The algorithm's inputs are defined by combining the results of previous research and specific clay information selected from different regions of Anatolia, utilizing the design of experiment methodology. The design parameters include angle, profile and height; printing parameters include compressor pressure, speed, and layer height; and material parameters are assessed through drop spike, tube pressure, and flow rate tests. Once the inputs and their computation ranges were defined, the algorithm was tested with various inputs and corresponding physical prints to evaluate its recommendation capability. The test prints demonstrated that the printing suggestions made by the algorithm for design, printing and material parameters were suitable for the given parameter inputs. With its current state, the research is not an expert tool for recommendation but a base of a more complex framework for further research.

Nonclassical and Nonlinear Stability Analysis of Viscous Fluidic Piezoelectric Biomedical Nanosensor

In this paper, nonlinear vibration and stability analysis of viscous fluidic piezoelectric biomedical nanosensor (VFBNS‎) based on cylindrical nanoshell is investigated using the electro-elastic Gurtin–Murdoch surface/interface (S/I) theory. This piezoelectric nanoresonator is simultaneously subjected to visco-pasternak medium, electrostatic and harmonic excitations. The Hamilton’s principle, the assumed mode method combined with Euler – Lagrange and also Complex averaging method combined with arc-length method are used to achieve the governing equations, boundary conditions and also the effect of different material, structural and excitations parameters on dimensionless natural frequency (DNF) (undamped and damped , critical fluid velocity, nonlinear vibration and stability analysis of piezoelectric biomedical nanosensor. It is shown that the fluid velocity has major unpredictable effects on parametric studies of the system and one should precisely consider their effects. Also, it is concluded that ignoring the surface /interface effects leads to inaccurate results in vibrational response of the VFBNS‎. By changing the surface/interface parameters, the system stiffness is changed leading to nonlinear behavior of the system, which can be more or less pronounced compared to the case without the S/I effects accounted for. The obtained results of this study are useful for designing of nano/micro electro mechanical system and other nano-/micro-smart structures.

Development of thermal model of an oil-filled transformer in Ansys environment

The paper deals with modelling of thermal modes of an underground substation using the Ansys software environment. The main attention is paid to the oil-filled transformer TRDN-63000/110, for which a simplified geometric model was created in the Design Modeler module. The thermal processes were modelled in Ansys Steady-State Thermal using a triangular mesh and adjusting material parameters such as thermal conductivity and cooling medium properties. The study analysed the transformer's operating modes: short circuit, no-load, and transient states. In the short-circuit mode, the modelling results showed that when using transformer oil, the maximum temperature of the active part is reduced to the range of 67–91 °C, which is significantly lower than in the case of air cooling, when the temperature exceeded the permissible values (225 °C). In the no-load mode, the maximum temperature of the transformer was only 35 °C, which indicates the effectiveness of oil cooling even at minimal power loads. Particular attention is paid to the study of the dependence of the maximum temperature of the transformer core on the density of heat fluxes in different operating modes. It is shown that the maximum temperature is directly proportional to the load and heat flux density, and the highest heat transfer intensity is observed near the windings. The obtained results allow us to assess the efficiency of heat dissipation of the transformer and its impact on the heat balance of the substation premises. The modelling data can be used to improve the design of transformers, optimise cooling systems and ensure reliable operation of power equipment in underground substations. This study emphasises the importance of using modern numerical methods to analyse the thermal characteristics of transformers and adapt them to difficult operating conditions.