Material Parameters Research Articles

Ultrahigh-contrast plasmonic mode conversion in coupled graphene waveguides by manipulating the graphene chemical potential and the gyration

We investigate ultrahigh-contrast plasmonic mode conversion in a coupled graphene waveguide structure with manipulated gyration and graphene chemical potential by using both analytic theory and numeric simulations. The ultrahigh contrast is supported by a magnetic resonance at the expense of high sensitivity on the design and material parameters and the operation frequency. The analytical study reveals that the ultrahigh contrast mode conversion can be preserved by adjusting the gyration and the chemical potential in the deviation of structural and material parameter values due to imperfect fabrication and harsh environment and for tuning its operation frequency over a broadband frequency range. We derive explicit analytical results for the resonance gyration and chemical potential that answer to those questions how to manipulate the gyration and the chemical potential according to the design and material parameters and the operation frequency. Numerical simulations demonstrate the robust and broadband tunable plasmonic mode conversion preserves the contrast higher than 103 (99.9%) for different design and material parameter values over a one-octave-spanning broadband frequency range. In practice, the chemical potential and the gyration can be manipulated by controlling the gate voltage of the graphene and the external magnetic field, respectively. Our findings can be of great importance in the design of high-integration nanophotonic circuits and for probing of ultrafast magnetization dynamics. Published by the American Physical Society 2024

Rapid Prototyping for Accelerated Establishment of Film Processing‐Performance Relationships in Silicon Phthalocyanine OFETs

AbstractUnderstanding the complex relationships underlying the performance of organic electronic devices, such as organic field‐effect transistors (OFETs), requires researchers to navigate a multi‐dimensional parameter space that includes material design, solution formulation, fabrication parameters, and device geometry. Herein, a recently developed materials acceleration platform is demonstrated, named the RoboMapper, to perform direct on‐chip fabrication of OFETs by ultrasonic meniscus printing using silicon phthalocyanine (SiPc) derivatives as the semiconductor. OFETs using bis(tri‐n‐butylsilyl oxide) SiPc ((3BS)2‐SiPc) exhibited the best device performance characterized by the highest electron field‐effect mobility (µe). Through optical microscopy and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS), the favorable performance of (3BS)2‐SiPc is attributed to the specific film morphology and molecular packing achieved with optimal print conditions. Investigating the impact of deposition parameters reveals the crucial role of solvent evaporation rate and print speed in achieving high‐quality film formation. Overall, optimal fabrication conditions for (3BS)2‐SiPc devices include slow print speeds and fast evaporating solutions achieved by using a mixture of co‐solvents and an elevated substrate temperature. The results of this work reveal distinct relationships between deposition conditions, film properties, and device performance for each SiPc derivative and emphasize the necessity of high throughput experimentation to comprehensively understand process‐performance relationships in organic semiconductors.

Minimization of melt-pool field variables fluctuation during selective laser melting of Ti6Al4V alloy through computational investigation

Abstract The optimization of selective laser melting (SLM) process parameters for a new material through experiments is a time-consuming and challenging process. Computational approaches, on the other hand, offer an economical and relatively faster approach to effectively predict the influences of process factors on the behaviors of the field variables of SLM process. In this work, multiphysics models built using COMSOL software were used to carry out optimization of SLM-Ti6Al4V processes through a single-level setup method followed by a parametric sweep optimization (PSO) approach. The simulated results of the melt pool field variables obtained from both approaches were compared. In the PSO approach, the melt pool velocity was found to have 14.3% higher flow and 78.8% reduction in the transient velocity fluctuation amplitude within the melt pool region. The average transient temperature of the melt pool region was found to have 5.9% increase and 36.4% reduction in the average fluctuation amplitude along the solidus and peak points, respectively. On the other hand, the associated temperature gradient was found to have a fluctuation amplitude reduction of 15.3% at the maximum side of the melt pool region. Finally, the optimal solutions of the melt pool field variables obtained from the PSO were compared with published data to verified the approach. The reductions in temperature and thermal gradient results were found by 18.3% and 28.5% respectively in the melt pool region of the current SLM-Ti6Al4V process and, hence, validating the predictions of the PSO technique.

Development of a simple test to quantify the consolidation properties of liquefied granular materials

AbstractLiquefaction can have devastating consequences by causing increased mobility of debris flows, tailings dam breaches, and settlement following seismic shaking. Observations on the consolidation behaviour of liquefied soils in 1-g or centrifuge shake table tests have permitted significant advancements in analytical and numerical methods to predict the rate and magnitude of consolidation settlement. However, advanced consolidation models introduce material parameters which are currently difficult to define quickly and at low cost. The objective of this paper is to demonstrate the development of a simple, low-cost test that can be used to quickly estimate the spatially and temporally varying coefficient of consolidation, which controls post-liquefaction settlements. Using the proposed simple setup, experiments were conducted on four uniformly graded sands of varying grain size and on one well-graded mixture. A range of analytical and numerical approaches from literature were assessed for their ability to back-analyse the observed pore pressure dissipation and settlement. Estimated values for the coefficient of consolidation were comparable between models and estimates of surface settlement matched well the experimental results. The simplicity of the proposed test combined with its low-cost and mobile nature, raise significant possibilities for quick estimations of the evolution of the coefficient of consolidation post-liquefaction.

Determining reaction rate parameters for an energetic material through inverse multi-scale analysis of shock-to-detonation transition

Determining reaction rate parameters for an energetic material through inverse multi-scale analysis of shock-to-detonation transition

Nonuniform Temperature Compensation in Ultrasonic Guided Wave Pipeline Health Monitoring Using Local Phase Matching

Faced with a complex working environment, pipelines are prone to nonuniform temperature variations, which cause nonuniform phase changes in the guided wave signals during structural health monitoring, thereby increasing the difficulty of monitoring. To address this, a simulation model is established in this paper to analyze the effects of temperature on material parameters and the variation patterns of guided wave signals. A nonuniform temperature compensation method based on local phase matching is proposed. The algorithm first uses cosine similarity to find the locally best-matched signal segments between the monitoring signal and the baseline signal. Then, an indicator is introduced to quantify the differences between these best-matched signal segments, with the maximum difference considered to be the damage index. Three heating experiments on pipelines with nonuniform temperature fields ranging from 24 °C to 80 °C demonstrate that the proposed method can effectively overcome the resulting phase deviations while achieving high detection accuracy and a reduction false positives. Additionally, the method shows high resolution in detecting defects in both temperature-varying and non-temperature-varying regions.

Mathematical Model of Copper Nanofluid Flow Past a Spherical Enclosure

The study examined mathematical models for describing the behavior of copper nanoparticles in water base fluid. Coupled hydrodynamic governing equations of momentum, energy and concentration were non dimensionalized and solved using installed Laplace transform technique in Mathematica 12.3. The solution obtained were used to analyze the effect of the material parameters on the concentration, temperature and velocity profiles of the copper nanofluid. Results of the study using graphs reveal that an enhancement of the nanoparticle size results in a depreciation of the concentration of the copper nanofluid and escalate the temperature and velocity profiles of the copper nanofluid. Also, the twin effect of an increase in Thermophoresis and Brownian motion bring about a decrease in the concentration of the nanofluid and an increase in the temperature and velocity of the nanofluid. An increase in the radiation parameter, enhanced the temperature of the nanofluid and depreciate the concentration and velocity of the nanofluid while an increase in the magnetic Hartmann number inhibits the velocity of the nanofluid, while an enhancement of the Lewis and Prandtl numbers led to a depreciation of the concentration, an increase in the temperature is observed, for the velocity, it is enhanced by sharp increase in the lewis number and accordingly depreciates by an increase in the Prandtl number. The Reynolds number increase also escalates the velocity profile of the copper nanofluid. Generally, it was observed that the copper nanofluid in some cases react abnormally in the presence of some material parameters under investigation which is a reflection of its characteristics.

Using muscle-tendon load limits to assess unphysiological musculoskeletal model deformation and Hill-type muscle parameter choice.

Musculoskeletal simulations are a useful tool for improving our understanding of the human body. However, the physiological validity of predicted kinematics and forces is highly dependent upon the correct calibration of muscle parameters and the structural integrity of a model's internal skeletal structure. In this study, we show how ill-tuned muscle parameters and unphysiological deformations of a model's skeletal structure can be detected by using muscle elements as sensors with which modelling and parameterization inconsistencies can be identified through muscle and tendon strain injury assessment. To illustrate our approach, two modelling issues were recreated. First, a model repositioning simulation using the THUMS AM50 occupant model version 5.03 was performed to show how internal model deformations can occur during a change of model posture. Second, the muscle material parameters of the OpenSim gait2354 model were varied to illustrate how unphysiological muscle forces can arise if material parameters are inadequately calibrated. The simulations were assessed for muscle and tendon strain injuries using previously published injury criteria and a newly developed method to determine tendon strain injury threshold values. Muscle strain injuries in the left and right musculus pronator teres were detected during the model repositioning. This straining was caused by an unphysiologically large gap (12.92 mm) that had formed in the elbow joint. Similarly, muscle and tendon strain injuries were detected in the modified right-hand musculus gastrocnemius medialis of the gait2354 model where an unphysiological reduction of the tendon slack length introduced large pre-strain of the muscle-tendon unit. The results of this work show that the proposed method can quantify the internal distortion behaviour of musculoskeletal human body models and the plausibility of Hill-type muscle parameter choice via strain injury assessment. Furthermore, we highlight possible actions to avoid the presented issues and inconsistencies in literature data concerning the material characteristics of human tendons.

A Thermal Impedance Model for IGBT Modules Considering the Nonlinear Thermal Characteristics of Chips and Ceramic Materials

The traditional method of calculating junction temperature does not consider the dependence of a material’s thermal conductivity on temperature, in which the thermal conductivity changes with temperature. However, with an increase in junction temperature, the temperature sensitivity (TS) will have a more significant impact on the actual temperature of chips. This study established an improved IGBT equivalent thermal impedance model that considers the nonlinear characteristics of the TS of chips and ceramic materials. The Fourier series analysis method was used to obtain the heat flux density curve, and then the heat diffusion angles of each layer were solved. Moreover, iterations were performed until the thermal conductivity and temperature of the chip and ceramic layers matched the nonlinear characteristics of the TS. When the power loss was less than 200 W, the maximum error of the junction temperature calculated by the proposed method considering TS was 3%, while the maximum error of the method without considering TS was 9.5%. Compared with the finite element simulation, the proposed method has a faster solving speed and high accuracy. The proposed method only requires the input material parameters, size parameters, and boundary conditions to solve the junction temperature, which has strong practicality and high accuracy.

DETERMINATION OF TECHNOLOGICAL CHARACTERISTICS OF PRESSABILITY

This article deals with the results of technological tests of pressability (Erichsen's - IE index and capping - limit drawing ratio (LDR)). It also presents on which material parameter (ductility, strain hardening exponent, coefficient of normal anisotropy...) should be given more emphasis when choosing a steel sheet, if stretching stress (uniaxial tension, biaxial tension) dominates during the production of stampings, or if dominates the “pull-pressure” technique (pulling out from under the flange).

On the Peculiarities of Wire-Feed Electron Beam Additive Manufacturing (WEBAM) of Nickel Alloy–Copper Bimetal Nozzle Samples

In order to gain insight into the unique characteristics of manufacturing large-scale products with intricate geometries, experimental nozzle-shaped samples were created using wire-feed electron beam additive technology. Bimetal samples were fabricated from nickel-based alloy and copper. Two distinct approaches were employed, utilizing varying substrate thicknesses and differing fabrication parameters. The two approaches were the subject of analysis and comparison through the examination of the surface morphology of the samples using optical microscopy, scanning electron microscopy, and X-ray diffraction analysis. It has been demonstrated that the variation in heat flux distributions resulting from varying the substrate thicknesses gives rise to the development of disparate angles of grain boundary orientation relative to the substrate. Furthermore, it is demonstrated that suboptimal choice of the fabrication parameters results in large disparities in the crystallization times, both at the level of sample as a whole and within the same material volume. For example, for the sample manufacturing by Mode I, the macrostructure of the layers is distinguished by the presence of non-uniformity in their geometric dimensions and the presence of unmelted wire fragments. In order to characterize the experimental nozzle-shaped samples, microhardness was measured, uniaxial tensile tests were performed, and thermal diffusivity was determined. The microhardness profiles and the mechanical properties exhibit a higher degree of strength than those observed in pure copper samples and a lower degree of strength than those observed in Inconel 625 samples obtained through the same methodology. The thermal diffusivity values of the samples are sufficiently close to one another and align with the properties of the corresponding materials in their state after casting or rolling. The data discussed above indicate that Mode II yields the optimal mechanical properties of the sample due to the high cooling rate, which influences the structural and phase state of the resulting products. It was thus concluded that the experimental samples grown by Mode II on a thinner substrate exhibited the best formability.

The Mechanical Properties of Aged PA-12 FS3300PA Powder: Influence of Layer Thickness, Sintering Orientations, and Laser Power

Abstract This research investigates the influence of layer thickness, laser power, and sintering orientation on the mechanical properties of aged Polyamide-12 (PA-12) FS3300PA using the Selective Laser Sintering (SLS) 3D printing method. Specimens were sintered with three different layer thicknesses, laser powers, and sintering orientations using SLS. The study also aimed to examine the resulting powder morphology, mechanical properties, and tensile fracture behaviors of the aged (more than eight continuously sintering cycles) and virgin FS3300PA powders. The specimens divided into ten groups: nine groups of aged powder and one group of virgin powder as a benchmark. The nine groups of aged powder were sintered with three different layer thicknesses (0.07 mm, 0.12 mm, and 0.15 mm), laser powers (65W, 70W, and 75W), and orientations (YZY 0⁰, YZY 90⁰, and XYY 0⁰). The selections of these laser power and layer thickness values for the sintering setting are due to machine and material parameter limitation. The results from these parameters then compared with those of the virgin powder, which sintered using the parameters provided by the manufacturer, in terms of powder morphology, mechanical properties, and tensile fracture behaviours. Observation made using scanning electron microscope (SEM) revealed that there were not many changes in shape, size, and distribution between the virgin and aged powder, but slightly larger sizes and the presence of cracks found in the aged powder. The tensile strength, elongation at break value, and Young’s modulus all shared a similar trend, increasing with higher laser power but decreasing with increased layer thickness. Regarding the fracture morphologies, the number of pores and dimples decreased with increased laser power but increased with thicker layer thickness. There was also the occurrence of un-molten powder, especially in specimens sintered at the YZY 90⁰ orientation with lower laser power and thicker layer thickness.

Global reliability sensitivity analysis of cradle-type double rotary table

The rotary table is a crucial component of the machine tool, and its accuracy and reliability have an important impact on the machining accuracy and machining efficiency of the machine tool. In this paper, a global reliability sensitivity analysis method of the rotary table is proposed considering the random uncertainty for material parameters of each component. Firstly, the mechanical model of the rotary table is established based on the finite element method. Subsequently, the functional relationship between the parameters of each component and the deformation of the rotary table is reconstructed using the adaptive Kriging surrogate model. Finally, a global reliability sensitivity analysis of the rotary table is performed based on the Bayesian formulation. The results show that the proposed global reliability sensitivity analysis method of the rotary table demonstrates satisfactory efficiency and can provide theoretical guidance for the design and optimization of the rotary table.

Exploring Sb2S3 as a hole transport layer for GeSe based solar cell: A numerical simulation

Abstract Germanium selenide (GeSe) and antimony sulfide (Sb2S3) both are technological intriguing semiconductor material for green and economical photovoltaic devices. In this study, GeSe and Sb2S3 have been utilized as the absorber layer and hole transport layer, respectively, to constructed a heterojunction thin film solar cell consisting of FTO/TiO2/GeSe/Sb2S3/Metal. The GeSe and Sb2S3 are binary compounds and can adopt the same film deposition method, for instance, thermal evaporation, which is expected to improve process compatibility and to reduce production costs. The TiO2 (electron transport layer) and Sb2S3 can form small spike-like conduction band offset and valence band offset with the GeSe, respectively, which possesses potential to suppress carrier recombination at the heterointerfaces. Subsequently, the effects of main functional layer material parameters, heterointerface characteristics and back contact metal work function on the performance parameters of the proposed solar cell were simulated and analyzed using wxAMPS software. After numerical simulation and optimization, the proposed solar cell can reach an open circuit voltage of 0.872 V, a short circuit current of 40.72 mA·cm-2, a filling factor of 84.16%, and a conversion efficiency of 28.35%. According to the simulation results, it is anticipated that the Sb2S3 can serve as a hole transport layer for GeSe based solar cell and enable device to achieve high efficiency. Simulation analysis also provides some meaningful references for the design and preparation of heterojunction thin film solar cells.

Utilizing physics‐augmented neural networks to predict the material behavior according to Yeoh's law

AbstractThis article discusses physics‐augmented neural network approaches in the field of hyperelastic material modeling. Physical conditions such as objectivity, material symmetry, or a stress– and energy‐free reference configuration are considered in the construction of the neural networks. In addition, a new approach for stress normalization is proposed. The neural network is used to learn the behavior of Yeoh's constitutive model with sparse data. Finally, the trained networks are incorporated into a three‐dimensional finite element framework and compared with the classical material model in terms of accuracy. The paper demonstrates the ability of physics‐augmented neural networks to model hyperelastic materials using a small amount of data that could be generated by experiments. Compared to the classical constitutive laws of Yeoh's model, our trained material showed no material instabilities that could occur due to poorly chosen material parameters.

Regulating Entanglement Networks of Fibrillatable Binders for Sub-20-µm Thick, Robust, Dry-Processed Solid Electrolyte Membranes in All-Solid-State Batteries.

Despite significant advancements in all-solid-state batteries (ASSBs), the reliance on thick solid electrolyte (SE) membranes hinders their commercial viability. Although the dry process using polytetrafluoroethylene (PTFE) binder is proposed for thin SE membranes, a comprehensive understanding of the correlation between PTFE fibrillation and SE membrane quality remains lacking. Here an important guidance is provided for producing durable SE membranes that can be reduced to sub-20-µm thickness by regulating the entanglement networks of PTFE. While establishing fabrication parameters; shear time and shear temperature, a dominant effect of the number-average molecular weight (Mn) on PTFE fibrillation is revealed for the first time. Moreover, the degree of PTFE fibrillation is quantified using systematic X-ray diffraction (XRD) analysis. The SE membrane utilizing the high-Mn PTFE binder that achieves a maximum fibrillation degree (≈98%) and thus forms highly entangled fibrous PTFE network interweaving SE particles, exhibited superior toughness. Consequently, the 18 µm thick SE membrane with 0.5wt% high-Mn PTFE shows a considerably higher areal conductance. The ASSB using this durable, ultrathin SE membrane outperforms its counterparts that used flimsy SE membranes or pure SE pellets. Finally, uniquely thin ASSBs demonstrate significantly improved cell-level energy densities, showcasing the promising potential for practical ASSB fabrication.

Safety and Effectiveness of Triple-Antenna Hepatic Microwave Ablation

Microwave ablation is becoming a standard procedure for treating tumors based on heat generation, causing an elevation in the tissue temperature level from 50 to 60 °C, causing tissue death. Microwave ablation is associated with uniform cell killing within ablation zones, multiple-antenna capability, low complication rates, and long-term survival. Several reports have demonstrated that multiple-antenna microwave ablation is a promising strategy for safely, rapidly, and effectively treating large tumors. The key advantage of multi-antenna tumor microwave ablation is the creation of a large, well-defined ablation zone without excessively long treatment times or high power that can damage healthy tissue. The strategic positioning of multiple probes provides a fully ablated volume, even in regions where individual probe damage is incomplete. Accurate modeling of the complex thermal and electromagnetic behaviors of tissue is critical for optimizing microwave ablation because material parameters and tissue responses can change significantly during the procedure. In the case of multi-antenna microwave ablation, the calculation complexity increases significantly, requiring significant computational resources and time. This study aimed to evaluate the efficacy and safety of liver percutaneous microwave ablation using the simultaneous activation of three antennas for the treatment of lesions larger than 3 cm. Based on the known results from a single-probe setup, researchers can estimate and evaluate various spatial configurations of the three-probe array to identify the optimal arrangement. Due to the synergistic effects of the combined radiation from the three antennas, the resulting ablation zone can be significantly larger, leading to better outcomes in terms of treatment time and effectiveness. The obtained results revealed that volumetric damage and the amount of damaged healthy tissue are smaller for a three-antenna configuration than for microwave ablation using a single-antenna and two-antenna configurations.

New method for predicting the free vibration characteristics of composite laminates based on generalized cell and spectral‐Tchebychev methods

AbstractThis paper presents a new method for analyzing the free vibration characteristics of composite laminates under arbitrary boundary conditions by integrating the generalized method of cells (GMC) and the Two‐Dimensional Spectral‐Tchebychev (2D‐ST) method. First, a meso‐macro correlation matrix is constructed based on the GMC, and the macroscopic performance parameters of the composite laminates are predicted. Then, virtual boundary springs are introduced to simulate the arbitrary boundary conditions, and the energy equation of the laminate is derived based on the first‐order shear deformation theory (FSDT) and Hamilton's principle. Furthermore, an approximate displacement function of the laminate is derived by using the 2D‐ST Tchebychev polynomials, and the Gauss‐Lobatto points are selected for meshless discretization of the structure to obtain the discretized characteristic equation, which is solved to obtain the free vibration frequency of the laminate. Based on Matlab programming, the free vibration frequencies of the laminate under different conditions are calculated, and the convergence, accuracy and computational efficiency of the calculation method are discussed, and the effects of boundary conditions, stacking angle, geometrical parameters, and material parameters on the free vibration frequencies of the laminate are analyzed. The numerical results show that the method has the advantages of fast convergence, high accuracy and high efficiency, and the method can be convenient and fast for parametric studies.Highlights The free vibration characteristics of composite laminates are studied. Combining generalized cell method with spectral‐Tchebychev method. The method has the characteristics of fast convergence, high accuracy and high efficiency. A parametric study is conducted on the free vibration of laminated panels.

Multitask scheduling on cloud additive manufacturing using NSGA-II

Purpose: Cloud manufacturing (CM) represents a new manufacturing paradigm that integrates distributed resources to provide on-demand services. The high consumer demand from various locations, coupled with the customizability and complexity of manufacturing, complicates task scheduling. In this context, 3D printers are crucial as innovative manufacturing technologies with significant potential in producing complex and custom products. Scheduling in CM falls under the non-deterministic polynomial time-hard category, where tasks must be scheduled and distributed rapidly. Considerations of distance, minimization of delays, and makespan become critical variables that must be considered. This research aims to schedule and distribute tasks in CM using the non-dominated sorting genetic algorithm II (NSGA-II) to minimize delays, reduce makespan, and decrease costs.Methodology: NSGA-II is employed to tackle the complexities of scheduling in CM. The strength of NSGA-II lies in its ability to determine optimal and efficient solutions for multiobjective problems. Tasks originating from requests at various locations are adjusted based on material parameters and dimensions and then distributed to providers while considering aspects such as makespan, delay minimization, and cost.Findings: The optimization results using NSGA-II demonstrate effective and efficient task distribution to providers. Across the four tested task distribution scenarios, the average computational time required was 5.59 seconds. Pareto analysis indicates a trade-off between various objective functions. Solutions with short distances tend to have increased maximum time and delays.Originality/value: NSGA-II is effective for task distribution with multiobjective considerations. Not all three objective functions can be optimized simultaneously, given the trade-offs between distance, maximum time, and lateness. The priority of the objective functions should be determined to achieve optimal results. If minimizing lateness is most important, the focus should be on points with low lateness values. Further development can be done by modifying the Pareto front to make data-driven decisions that consider these trade-offs.

Three-Layered Annular Plate Made of Functionally Graded Material Under a Static Temperature Field

The presented problem considers the static temperature analysis of a three-layered, annular plate with heterogeneous facings made of material with radially variable parameters. They are defined by the accepted exponent functions. The plate is composed of thin metal facings and a thicker foam core. The plate is loaded with a flat temperature field with a gradient directed across the plate radius. Using the approximation finite-difference method, the eigen-value problem is solved in order to calculate the temperature differences between plate edges, which cause a loss of plate stability. Taking into account the different material and geometrical parameters, the critical temperature state parameters are evaluated. The meaning of the mixed system of parameters connected with the plate shape geometry, dimensions of the plate-transversal structure, and with the gradation of the material in the radial direction on the thermal response of the composite plate have been found. Numerous results of numerical calculations show the responses of the examined composite plate with facings made of the heterogeneously directed material.