Selection Of Material Parameters Research Articles

A Study on Optimal Opening Configuration for Art Museum Exhibition Space Considering Daylight Performance, Indoor Thermal Comfort, and Energy Consumption

Skylights are an efficient means of daylighting in exhibition spaces, but their design presents significant challenges. Considering that daylight utilization profoundly impacts both the visual and thermal environments while affecting energy consumption, the early application of multi-objective optimization strategies becomes imperative. However, many optimization studies provide numerical references only, without delving into the characteristics of opening distribution. This study introduces an optimized exploration approach for openings based on grid subdivision and material parameter selection, targeting Useful Daylight Illuminance (UDI), Energy Use Intensity (EUI), and Predicted Percentage of Dissatisfied (PPD). Simulations and optimizations were performed using Honeybee and Octopus, focusing on the optimal configurations of four typical skylights in Fukuoka, Japan’s climate. The results demonstrate that this novel optimization approach improves metrics for each case and challenges traditional perceptions of daylight systems. Flexible and diverse opening configurations, formed through irregular layouts and material combinations, help achieve more ideal holistic environmental effects under different climatic conditions. Thus, we should provide these research findings as design guidelines for similar scenarios.

Discussion on Material Testing of Municipal Traffic Engineering

At present, the rapid development of municipal traffic engineering is in line with the high quality development trend and the demand for accurate management. The municipal traffic builders strictly control the quality from the aspects of planning and design, construction management, material testing, measurement and acceptance, among which material testing is an important part. The quality of engineering construction materials directly determines the final quality of engineering construction, so the layout and planning of material control must be done well in the actual implementation process. A preliminary investigation was conducted from the aspects of material classification and detection, material parameter selection, material grading and control, etc., so as to realize the centralized management of the three responsible parties of design, construction and suppliers, further standardize the program and standardization of municipal traffic construction projects, and achieve the goal of excellent construction project quality.

Neural networks determination of material elastic constants and structures in nematic complex fluids

Supervised machine learning and artificial neural network approaches can allow for the determination of selected material parameters or structures from a measurable signal without knowing the exact mathematical relationship between them. Here, we demonstrate that material nematic elastic constants and the initial structural material configuration can be found using sequential neural networks applied to the transmmited time-dependent light intensity through the nematic liquid crystal (NLC) sample under crossed polarizers. Specifically, we simulate multiple times the relaxation of the NLC from a random (qeunched) initial state to the equilibirum for random values of elastic constants and, simultaneously, the transmittance of the sample for monochromatic polarized light. The obtained time-dependent light transmittances and the corresponding elastic constants form a training data set on which the neural network is trained, which allows for the determination of the elastic constants, as well as the initial state of the director. Finally, we demonstrate that the neural network trained on numerically generated examples can also be used to determine elastic constants from experimentally measured data, finding good agreement between experiments and neural network predictions.

Factorial design analytics on effects of material parameter uncertainties in multiphysics modeling of additive manufacturing

A bottleneck in Laser Powder Bed Fusion (L-PBF) metal additive manufacturing (AM) is the quality inconsistency of its products. To address this issue without costly experimentation, computational multi-physics modeling has been used, but the effectiveness is limited by parameter uncertainties and their interactions. We propose a full factorial design and variable selection approach for the analytics of main and interaction effects arising from material parameter uncertainties in multi-physics models. Data is collected from high-fidelity thermal-fluid simulations based on a 2-level full factorial design for 5 selected material parameters. Crucial physical phenomena of the L-PBF process are analyzed to extract physics-based domain knowledge, which are used to establish a validation checkpoint for our study. Initial data visualization with half-normal probability plots, interaction plots and standard deviation plots, is used to assess if the checkpoint is being met. We then apply the combination of best subset selection and the LASSO method on multiple linear regression models for comprehensive variable selection. Analytics yield statistically and phyiscally validated findings with practical implications, emphasizing the importance of parameter interactions under uncertainty, and their relation to the underlying physics of L-PBF.

A computational framework for topology optimisation of flexoelectricity at finite strains considering a multi-field micromorphic approach

This paper presents a novel in-silico framework for the design of flexoelectric energy harvesters at finite strains using topology optimisation. The main ingredients of this work can be summarised as follows: (i) a micromorphic continuum approach is exploited to account for size dependent effects in the context of finite strains, thus permitting the modelling and simulation of flexoelectric effects in highly deformable materials such as dielectric elastomers. A key feature of the multi-field (mixed) formulation pursued is its flexibility as it permits, upon suitable selection of material parameters, to degenerate into other families of high order gradient theories such as flexoelectric gradient elasticity. (ii) A novel energy interpolation scheme is put forward, whereby different interpolation strategies are proposed for the various contributions that the free energy density function is decomposed into. This has enabled to circumvent numerical artifacts associated with fictitious high flexoelectric effects observed in the vicinity of low and intermediate density regions, where extremely high strain gradients tend to develop. (iii) A weighted combination of efficiency-based measures and aggregation functions of the stress is proposed to remedy the shortcomings of state-of-the-art efficiency-based functionals, which promotes the development of hinges with unpractical highly localised large strain gradients. Finally, a series of numerical examples are analysed, studying the development of direct flexoelectricity induced by bending, compression and torsional deformations.

Source of Raw Materials and Its Processing for the Manufacturing of Ptolemaic Faience Bowls from Tell Atrib (Nile Delta, Egypt).

The provenance of siliceous grain material, the basic source of manufacturing faience items, is still a matter of discussion. The study methods applied so far have not brought satisfactory outcomes, and the results are ambiguous and problematic. Archaeological evidence has also not supplied adequate proof for establishing the sites where the source material was obtained and the methods of its preparation. Therefore, we propose an interdisciplinary approach to solve these research problems. We explore selected material of 7 faience bowls precisely dated on the c. 100 years of the Ptolemaic Period in Egypt. The body and glaze of the faience bowls was qualitatively and quantitatively tested with regard to chemical and mineral composition, and selected material parameters. Based on structural-textural analysis, as well as chemical and mineral composition, the source area of the studied raw material and its potential excavation site was determined in the Eastern Desert. The obtained results were compared with locations of mines exploiting gold-bearing quartz veins, functioning in the Ptolemaic Period. Material parameters obtained from image analysis have been applied to reconstruct the processes of crushing and grinding of the quartz material and its further treatment for faience manufacturing. Quartz treatment was analysed with regard to tools and handling processes applied in Ptolemaic mines. We assume that such an approach has given accurate results in determining the provenance of siliceous material used in the Ptolemaic workshops of Athribis. Therefore, in material studies of artefacts produced in the antiquity, it is indispensable to use an interdisciplinary and complex approach, beginning from field studies and ending with detailed laboratory analyses.

The Application of a Hybrid Method for the Identification of Elastic-Plastic Material Parameters.

The indentation test is a popular method for the investigation of the mechanical properties of materials. The technique, which combines traditional indentation tests with mapping the shape of the imprint, provides more data describing the material parameters. In this paper, such methodology is employed for estimating the selected material parameters described by Ramberg–Osgood’s law, i.e., Young’s modulus, the yield point, and the material hardening exponent. Two combined identification methods were used: the P-A procedure, in which the material parameters are identified on the basis of the coordinates of the indentation curves, and the P-C procedure, which uses the coordinates describing the imprint profile. The inverse problem was solved by neural networks. The results of numerical indentation tests—pairs of coordinates describing the indentation curves and imprint profiles—were used as input data for the networks. In order to reduce the size of the input vector, a simple and effective method of approximating the branches of the curves was proposed. In the Results Section, we show the performance of the approximation as a data reduction mechanism on a synthetic dataset. The sparse model generated by the presented approach is also shown to efficiently reconstruct the data while minimizing error in the prediction of the mentioned material parameters. Our approach appeared to consistently provide better performance on the testing datasets with considerably easier computation than the principal component analysis compression results available in the literature.

Material Selection Process for Acoustic and Vibration Applications Using the Example of a Plate Resonator.

In this work, a new method for selecting suitable materials is presented. This method has a high potential for a variety of engineering applications, such as the design of sound-absorbing and vibration-loaded structures, where a large number of different requirements have to be met. The method is based on the derivation of functional dependencies of selected material parameters. These dependencies can be used in parameter studies to consider parameter combinations that lie in the range of real existing and targeted material groups. This allows the parameter space to be reduced, the calculation to be accelerated, and suitable materials to be (pre-)selected for the respective application, which contributes to a more target-oriented design. The method is applied to the example of a plate resonator. For this purpose, a semi-analytical model is implemented to calculate the transmission loss as well as the reflected and dissipated sound power of plate silencers, taking into account the influence of flow velocity and fluid temperature on the performance of plate silencers.

Directly foamed geopolymers: A review of recent studies

Geopolymers have been a frequently studied topic during the last decades due to waste materials utilization, low energy demands, and low carbon dioxide emissions related to their production, which makes them very attractive within the current environmental trends. However, the original idea to use them as a concrete replacement showed to be unattainable in the nearest future, so other alternatives of geopolymers applications are being sought that could exploit the efforts spent and research progress made so far. This review paper summarizes the recent progress in the field of directly foamed geopolymers, as one of the alternatives, focusing on the material base, foaming and stabilization processes, and assessments of selected material parameters, as related to raw materials used and treatment techniques applied. As the main result, several gaps and challenges are identified that deserve more attention and deeper investigations, which can help to move the geopolymer foams closer towards their regular application in civil engineering. A detailed knowledge of hygric parameters and their influence on thermal properties, long-term performance analyses in real-world applications, or extension of the material base to achieve environmental more friendly solutions represent the most topical issues that are supposed to be addressed.

MODELLING OF STEEL-TIMBER COMPOSITE BEAMS: VALIDATION OF FINITE ELEMENT MODEL AND PARAMETRIC STUDY

In this paper, non-linear finite elements models (FEM) of steel-timber composite (STC) beams have been developed and analyzed using ABAQUS software. In the FEM, the loading conditions of STC beams were simulated, and the nonlinear behaviour of the contact interface between the steel and timber components were incorporated adequately into the FEM. For the yield load, the maximum error between the FE results and the experimental results is 14.85%. The maximum average error of the yield deflection is 12.94%. and of the ultimate load is 16.79%. However, the error of key points was less than 17% (within a reasonable range), which proves that the established finite element model, selected material parameters and contact element model can better simulate the bending performance of STC beams. Finally,a parametric study was carried out by using the verified FEM. It is shown that the FEM developed in this study can replicate adequately the load-deflection response, andthe development of stress and plasticity of the bending experiment.Through the parameter study, it can be seen that thedistribution density and mechanical properties of the connection between the glulam and H-section steel can affect the mechanical behavior of the whole STC beams.

Nonlinear dynamic characteristics of a cracked steel pipe wound by carbon fiber reinforced composite

In this paper, the nonlinear dynamic characteristics of a cracked steel pipe wound by carbon fiber reinforced composite are studied. The time-dependent stiffness is introduced to describe the influence of cracks on the dynamic characteristics of the system. The natural frequency of the system is obtained on the improved multi-scale method, and the effect of cracks on the system's stability is discussed. The vibration experiment of the system under stochastic excitation shows that the crack will grow as the stochastic excitation increases. This article provides a basis for material parameter selection of steel pipe wound by carbon fiber reinforced composite.

Controlled Domain-Wall Pair to Skyrmion Conversion in Typical Junction Geometry Useful for Magnetic Memory Devices

One of the important goals of modern spintronics research is to develop energy efficient magnetic memory devices. It has been recently proposed that race track memory based on skyrmion can be used as energy efficient magnetic memory due to the small threshold current required for setting its motion. Here, using micromagnetic simulation, we studied the mechanism of skyrmion creation from a pair of domain walls in a magnetic nano track geometry composed of two narrow channels and a wide channel. Interestingly, by using optimum material parameters, fixed current density, and separation between the narrow channels, we obtained velocity up to ∼450 m s−1 during the skyrmion dynamics. The selected material parameters and geometry allow the stabilization as well as controlled manipulation of topological magnetic texture. Based on these results we propose that the skyrmion based race-track memory with more than one narrow channel in a junction geometry with suitable magnetic parameters relevant for spintronic devices will enable better control of skyrmion dynamics.

WEAR OF RAILWAY TYRE STEELS MODELLING USING ARTIFICIAL NEURAL NETWORKS

In the paper the results of sliding wear tests were used to model the dependence of steel volume loss on railway wheel tyres on selected material parameters and sliding conditions. The material properties included in this modelling were the hardness and chemical composition of the tyre material (specimens) and the hardness of the mating material (counter-specimens). The conditions for sliding were the initial maximum Hertzian pressure and the sliding distance. The tests were carried out in the ring-block system. Artificial neural networks were used for modelling. It was found that the constructed model made it possible to quantify the volume loss from the above–mentioned factors. A clear influence of the pressure, friction distance, and hardness of both cooperating materials on the studied wear was found. The influence of the chemical composition is less noticeable due to the rather narrow range of its allowable changes. The microscopic tests allowed us to identify the main wear mechanisms in the sliding friction of the tested tyre and rail steels.

Quality factor of circular microdiaphragm with surface effects in contact with liquids

This paper reports an investigation of the influences of surface effects and residual stress on the quality factor of a circular microdiaphragm in contact with liquids on one side. Acoustic radiation, as the main source of energy dissipation, can decrease the quality factor of a circular microdiaphragm. An approximate solution for the natural frequency can be obtained based on the Rayleigh–Ritz energy method. The results show that the influence of surface effects on the quality factor is obvious, in particular for thinner microdiaphragms. A stiffened surface decreases the quality factor, while a softened surface increases it. Furthermore, the quality factor increases with increases in the normalized tension parameter k for both stiffened and softened surfaces. If k is greater than 30, the influence of the surface effects on the quality factor must be considered. The results can provide effective guidance for the determination of dimensions and selection of material parameters in designing microdiaphragm resonant sensors.

Mechanistic modeling and simulation of a batch vertical stirred mill

Vertical stirred mills are now widely used in the minerals industry and the increasing variety of models from different manufacturers and number of new units installed worldwide are evidence of the growing interest in them. With so many options available, it becomes ever more difficult at the design stage of a plant to choose the most appropriate mill for a given application. The present work takes advantage of a mechanistic mill model originally developed for ball mills and the discrete element method (DEM) to simulate breakage in a vertical stirred mill. Data from a batch mill, in which two materials were tested (copper ore and limestone), served as the basis for fitting selected material parameters, whereas the remainder were used as default. Mill power has then been predicted using the discrete element method and deviations smaller than 3.5% were found between predictions and measurements. On the basis of these, the model has demonstrated to provide valid predictions from comparisons to size distributions at a fixed grinding time for different stirred speeds and percentages of solids.

Coupling between topology optimization and digital image correlation for the design of specimen dedicated to selected material parameters identification

The work addresses the optimization of specimen geometry in the context of parameter identification from full-field measurements. For this purpose, we propose to use topology optimization tools in order to maximize the sensitivity of the measured displacement field to sought parameters, under volume fraction constraints and without any a priori information on the specimen shape. The associated cost function is conveniently defined from sensitivity fields which are directly available from the identification procedure. In addition, further analyzes are conducted in order to fully set the theoretical and numerical aspects of the methodology, and enhance both stability and convergence properties. Numerical experiments illustrate the interest of the proposed approach, while its validation is performed from a real identification test using a specimen with optimized topology.

A multivariate regression parametric study on DEM input parameters of free-flowing and cohesive powders with experimental data-based validation

One of the key challenges in the implementation of discrete element method (DEM) to model powder’s flow is the appropriate selection of material parameters, where empirical approaches are mostly applied. The aim of this study is to develop an alternative systematic numerical approach that can efficiently and accurately predict the influence of different DEM parameters on various sought macroscopic responses, where, accordingly, model validation based on experimental data is applied. Therefore, design of experiment and multivariate regression analysis, using an optimized quadratic D-optimal design model and new analysis tools, i.e., adjusted response and Pareto graphs, are applied. A special focus is laid on the impact of six DEM microscopic input parameters (i.e., coefficients of static and rolling friction, coefficient of restitution, particle size, Young’s modulus and cohesion energy density) on five macroscopic output responses (i.e., angle of repose, porosity, mass flow rate, translational kinetic energy and computation time) using angle of repose tests applied to free-flowing and cohesive powders. The underlying analyses and tests show, for instance, the substantial impact of the rolling friction coefficient and the minor role of the static friction coefficient or the particle size on the angle of repose in cohesive powders. In addition, in both powders, the porosity parameter is highly influenced by the static and rolling friction coefficients.

Hydrogen storage adsorbent systems acceptability envelope

A methodology was developed to determine the range of coupled material parameters and operating conditions that allow an adsorbent based hydrogen storage system to meet performance targets. The range of acceptable parameters forms a multi-dimensional volume, or envelope. For this reason, the methodology is referred to as the Adsorbent Acceptability Envelope. The model evaluates the performance of the overall storage tank, comprised of the adsorbent material, the heat transfer system and the pressure vessel. Two cases were analyzed, both based on the flow-through cooling approach providing the cooling power required to charge hydrogen, with results presented and discussed. The first application (the forward problem) analyzed the gravimetric and volumetric performance of MOF-5® based hydrogen storage beds, under various operating conditions. Results demonstrated that the system can reach a gravimetric capacity of approximately 4 wt% and volumetric capacity of about 20 g/L within 200 s during the absorption process. The second application (the inverse problem) identified the range of selected material parameters, required to meet the U.S. Department of Energy targets for gravimetric and volumetric capacity. Results showed that the most important parameters are the maximum capacity and the density of the material. Adsorbents having a density on the order of twice that of nominal powder form MOF-5® can meet the 2020 DOE targets (i.e. system gravimetric capacity of 0.045 kgH2/kgSystem and system volumetric capacity of 0.030 kgH2/LSystem). A density of about 3–4.5 times the nominal value is required to meet the DOE 2025 targets (i.e. system gravimetric capacity of 0.055 kgH2/kgSystem and system volumetric capacity of 0.040 kgH2/LSystem). Likewise, a material with a maximum adsorption capacity approximately equal to three times that of nominal MOF-5® can meet the 2020 DOE targets, while a maximum capacity about 4.5 times the nominal value is required to meet the 2025 DOE targets.

Parametric analysis of composite sinusoidal specimens under quasi-static crushing

ABSTRACTThis paper aims to build the finite element model of the composite sinusoidal specimens and to carry out the parametric analysis. In this paper, the damage behaviour and the energy-absorbing results of composite sinusoidal specimens have been studied by quasi-static crushing experiments. The failure mechanisms of specimens under quasi-static crushing is further analysed. A numerical simulation has been performed by using the finite element model code LS-DYNA. The numerical results, in terms of load -displacement data, have been compared against experimental data, and good agreement has been found. Moreover, a sensitivity study has been carried out by varying material properties in order to assess their influence on the numerical results, and the material parameter selection scheme is optimised based on the constructed corresponding response surfaces. The results show that the response surface model has passed the test of goodness of fit, and the optimisation method can effectively assist the finite element modelling, and greatly decrease the numbers of trial and error.

Effect of the excavation clearance of an under-crossing shield tunnel on existing shield tunnels

The excavation by earth pressure balance (EPB) shield could cause stress fields varied, which is harmful to adjacent existing structures. Thus the effect of excavation clearance of the EPB shield on the settlement of existing structures should be taken into account. The transit tunnel from Meicun to Shangmeilin of Shenzhen Metro Line 9 constructed by the EPB shield with mid-shield-grouting was investigated. The deformation of existing tunnel is analysed by three-dimensional (3D) finite element methods (FEM). It is found that the settlement of overburden soil is obviously influenced by the structure of the existing tunnels through the plastic development of the soil. The rate of settlement is remarkable when the shield effect zone approaches the existing tunnels so that timely mid-shield grouting is an efficient method of controlling the settlement induced by the excavation clearance. However, the grout used in this method should be with the properties of short hardening time, large elastic modulus and low shear strength. Different standards of settlement control should be employed with respect to different underground tunnels, in which minimum elastic modulus of the filler that is usually determined by fitting function. This can be taken as a guide rule of the selection of material parameters in the project. The simulation results are in good agreement with the settlements measured for the existing tunnels and the ground surface. The parameter sensitivity analysis by means of the Spearman’s correlation coefficients shows that the elastic modulus of filling material significantly influences on the settlement of the existing tunnels and the ground surface.