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This review paper covers a topic of significant importance in micro- and nano-systems development and manufacturing, specifically the residual stresses in deposited thin-film material layers and methods to control or mitigate their impact on device behavior. A residual stress is defined as the presence of a state of stress in a thin-film material layer without any externally applied forces wherein the residual stress can be compressive or tensile. While many material properties of deposited thin-film layers are dependent on the specific processing conditions, the residual stress often exhibits the most variability. It is not uncommon for residual stresses in deposited thin-film layers to vary over extremely large ranges of values (100% percent or more) and even exhibit changes in the sign of the stress state. Residual stresses in deposited layers are known to be highly dependent on a number of factors including: processing conditions used during the deposition; type of material system (thin-films and substrate materials); and other processing steps performed after the thin-film layer has been deposited, particularly those involving exposure to elevated temperatures. The origins of residual stress can involve a number of complex and interrelated factors. As a consequence, there is still no generally applicable theory to predict residual stresses in thin-films. Hence, device designers usually do not have sufficient information about the residual stresses values when they perform the device design. Obviously, this is a far less than ideal situation. The impact of this is micro- and nano-systems device development takes longer, is considerably more expensive, and presents higher risk levels. The outline of this paper is as follows: a discussion of the origins of residual stresses in deposited thin-film layers is given, followed by an example demonstrating the impact on device behavior. This is followed by a review of thin-film deposition methods outlining the process parameters known to affect the resultant residual stress in the deposited layers. Then, a review of the reported methods used to measure residual stresses in thin-films are described. A review of some of the literature to illustrate the level of variations in residual stresses depending on processing conditions is then provided. Methods which can be used to control the stresses and mitigate the impact of residual stresses in micro- and nano-systems device design and fabrication are then covered, followed by some recent development of interest.

• Efforts to enhance PMFC performance are reviewed. • Both exciting advancements and current limitations are discussed. • An innovative strategy of multi-scale simultaneous optimization is proposed. Paper-based microfluidic fuel cell (PMFC) has attracted great attention in the microfluidic fuel cell field in recent years. It utilizes the spontaneous capillary flow of reactant solutions in paper-based porous substrate to achieve passive transportations of fuel and oxidant, solving the fluid driving issue encountered in traditional microfluidic fuel cells and thus having broad application prospects in medical detection, wearable devices, micro sensors, environmental monitoring, and many other fields. However, the commercialization of this technology is impeded by the low output performance caused by the limited mass and energy transfer in PMFCs. To enhance the mass and energy transfer in PMFCs, numerous research studies have been conducted via experimental optimization of the cell materials and structures. Numerical analyses focusing on the structure–activity relationship of PMFCs were also performed recently. To provide a comprehensive and thorough review about the efforts devoted to improving performance of PMFC, research papers relevant to PMFC since its invention in 2014 have been extracted in this work and significant works were filtered to highlight the exciting advancements. The experimental studies were classified and discussed based on the key components involved in the PMFC system, followed by a critical review of the limited computational models. Potential directions for future research were also provided, aimed at overcoming the current technological challenges in PMFCs. Importantly, an innovative strategy of multi-scale simultaneous optimization of the cell properties is proposed considering the typical multi-scale feature of the PMFC system, which could inspire the designing of advanced cell materials with optimal multi-scale structures for applications of PMFCs. [ABSTRACT FROM AUTHOR]

This review paper covers a topic of significant importance in micro- and nano-systems development and manufacturing, specifically the residual stresses in deposited thin-film material layers and methods to control or mitigate their impact on device behavior. A residual stress is defined as the presence of a state of stress in a thin-film material layer without any externally applied forces wherein the residual stress can be compressive or tensile. While many material properties of deposited thin-film layers are dependent on the specific processing conditions, the residual stress often exhibits the most variability. It is not uncommon for residual stresses in deposited thin-film layers to vary over extremely large ranges of values (100% percent or more) and even exhibit changes in the sign of the stress state. Residual stresses in deposited layers are known to be highly dependent on a number of factors including: processing conditions used during the deposition; type of material system (thin-films and substrate materials); and other processing steps performed after the thin-film layer has been deposited, particularly those involving exposure to elevated temperatures. The origins of residual stress can involve a number of complex and interrelated factors. As a consequence, there is still no generally applicable theory to predict residual stresses in thin-films. Hence, device designers usually do not have sufficient information about the residual stresses values when they perform the device design. Obviously, this is a far less than ideal situation. The impact of this is micro- and nano-systems device development takes longer, is considerably more expensive, and presents higher risk levels. The outline of this paper is as follows: a discussion of the origins of residual stresses in deposited thin-film layers is given, followed by an example demonstrating the impact on device behavior. This is followed by a review of thin-film deposition methods outlining the process parameters known to affect the resultant residual stress in the deposited layers. Then, a review of the reported methods used to measure residual stresses in thin-films are described. A review of some of the literature to illustrate the level of variations in residual stresses depending on processing conditions is then provided. Methods which can be used to control the stresses and mitigate the impact of residual stresses in micro- and nano-systems device design and fabrication are then covered, followed by some recent development of interest. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The influence of the material properties of a pre-stressed cylinder containing a compressible inviscid fluid on the dispersion of axisymmetric quasi-Scholte waves is studied. It is supposed that the inhomogeneous pre-stresses in the cylinder are caused by the fluid pressure acting on the internal face surface of the cylinder before the wave propagation. The motion of the cylinder during wave propagation is described by the so-called three-dimensional linearized equations of the theory of elastic waves in bodies with initial stresses, and the flow of the fluid, by the linearized Euler equations. For solving the corresponding eigenvalue problem, the discrete–analytical solution method is employed and the related dispersion equation is solved numerically. The dispersion curves containing the first roots of the dispersion equation refer to quasi-Scholte waves, which play an important role in helping to understand the solid–fluid dynamic interaction. A study of the influence of the cylinder material properties on the character of these curves is the main novelty of the present paper. The numerical results are presented and discussed on. For this purpose, steel, aluminum, lucite, and soft rubber are selected as cylinder materials, and water is chosen as the fluid. It is established, in particular, according to the numerical results, that an increase in the shear wave velocity in the cylinder material causes an increase in the propagation velocity of quasi-Scholte waves. [ABSTRACT FROM AUTHOR]

The knee is the most complex joint in the human body, including bony structures like the femur, tibia, fibula, and patella, and soft tissues like menisci, ligaments, muscles, and tendons. Complex anatomical structures of the knee joint make it difficult to conduct precise biomechanical research and explore the mechanism of movement and injury. The finite element model (FEM), as an important engineering analysis technique, has been widely used in many fields of bioengineering research. The FEM has advantages in the biomechanical analysis of objects with complex structures. Researchers can use this technology to construct a human knee joint model and perform biomechanical analysis on it. At the same time, finite element analysis can effectively evaluate variables such as stress, strain, displacement, and rotation, helping to predict injury mechanisms and optimize surgical techniques, which make up for the shortcomings of traditional biomechanics experimental research. However, few papers introduce what material properties should be selected for each anatomic structure of knee FEM to meet different research purposes. Based on previous finite element studies of the knee joint, this paper summarizes various modeling strategies and applications, serving as a reference for constructing knee joint models and research design. [ABSTRACT FROM AUTHOR]

Implementation of existing stress–strain models for cold-formed steel requires the input of key material parameters determined from corner coupon tests on cold-formed portions. This paper proposes various approaches that can accurately describe the stress–strain responses of cold-formed steel by using corner material properties if known, or by using parent material properties and the corner geometry after cold-forming in the absence of corner material properties. First, a comprehensive database of coupon test results of cold-formed steel is assembled. A total of 483 corner coupon test results with 236 full stress–strain curves are collected from 31 sources, covering a large range of steel grades with nominal yield strength varying from 235 to 960 MPa. The applicability of existing empirical models for determination of the enhanced yield strength, ultimate strength, and ultimate strain is carefully evaluated. New predictive expressions for the required input parameters (namely, 0.01% or 0.05% proof stresses for the use of the two-stage Ramberg-Osgood model, and the strain hardening exponent for the use of one-stage material model) are subsequently derived. Prediction performances of the two-stage Ramberg-Osgood model and the one-stage material model are then evaluated against experimental stress–strain curves under different availabilities of primary material parameters. According to the proposed approaches, the minimum required input parameter to utilize these models is only the yield strength of cold-formed steel or, alternatively, the yield strength of the parent metal and corner geometry after cold-forming. The developed models are proved to be accurate in predicting the monotonic stress–strain response (up to the ultimate point) of cold-formed steel, and they are suitable for use in parametric studies and advanced modeling of cold-formed structures. [ABSTRACT FROM AUTHOR]

Since China's inheritance, the history of the long river has left a brilliant cultural treasure. As a witness of history, they reflect the process of human activities. With today's rapid development, the protection of cultural relics is gradually deepening. Stone coated cultural relics are the most inheritance. However, the body material of stone carut articles is extremely fragile under the influence of time and environment. It is necessary to make it easy to continue to keep; it is necessary taking the necessary protection measures. But currently used protective materials have certain defects more or less. This paper is based on this, with the purpose of extending the life of the cultural relics; it proposed the use of nanomaterial Ti02 modified common protection materials WD-10. It performed comparison by adding different concentrations of Ti02, and the microsurrant rock obtained by the ground is used as a sample to detect its protection effect. And it has achieved appropriate ratios to enhance protection performance. The experimental results of this paper showed that the concentration of Ti02 was a modification result of the modification of the concentration, and the performance was most excellent. The value in the detection of the moist angle is 80% or more and excellent ultraviolet aging properties. [ABSTRACT FROM AUTHOR]

Recent studies show that zinc oxide (ZnO) nanostructures have promising potential as an absorbing material. In order to improve the optoelectronic properties of the initial system, this paper considers the process of adsorbing multilayer graphene-like ZnO onto a Si (111) surface. The density of electron states for two- and three-layer graphene-like zinc oxide on the Si (111) surface was obtained using the Vienna ab-initio simulation package by the DFT method. A computer model of graphene-like Zinc oxide on a Si (111)-surface was created using the DFT+U approach. One-, two- and three-plane-thick graphene-zinc oxide were deposited on the substrate. An isolated cluster of Zn3O3 was also considered. The compatibility of g-ZnO with the S (100) substrate was tested, and the energetics of deposition were calculated. This study demonstrates that, regardless of the possible configuration of the adsorbing layers, the Si/ZnO structure remains stable at the interface. Calculations indicate that, in combination with lower formation energies, wurtzite-type structures turn out to be more stable and, compared to sphalerite-type structures, wurtzite-type structures form longer interlayers and shorter interplanar distances. It has been shown that during the deposition of the third layer, the growth of a wurtzite-type structure becomes exothermic. Thus, these findings suggest a predictable relationship between the application method and the number of layers, implying that the synthesis process can be modified. Consequently, we believe that such interfaces can be obtained through experimental synthesis. [ABSTRACT FROM AUTHOR]

This paper defines the tensile properties of a successfully worn 3D-printed transtibial socket. The socket was printed from a proprietary polypropylene filament and FDM 3D-printing process. Fused disposition modeling involves producing successive cross-sectional layers on top of one another and welding them together. Because of this, a notch is formed between the printed layers. As part of this investigation, tensile test specimens were die-cut perpendicular to the material direction and tested according to ASTM D638—Standard Test Method for Tensile Properties of Plastics. From the measured load–elongation data, stress–strain curves and the corresponding material properties were determined, including modulus of elasticity E, Poisson's ratio ν, yield strength Sy, and ultimate strength Su. The average values for each of these material properties were 955 MPa, 0.35, 11.4 MPa, and 16.3 MPa, respectively. In addition to defining tensile properties, this work demonstrated a viable methodology for characterizing the as-built material behavior of 3D-printed sockets. [ABSTRACT FROM AUTHOR]

In the bridge structure, the main bearing element is the spans, which are directly subject to random and continuous loads, environmental influences, ageing, etc. These factors are easy to lead to material deterioration. Therefore, this study proposes a novel approach to investigate the mechanical properties of the material. The span of the bridge is the selected structure for investigation. This study focuses on the general evaluation of mechanical factors consistent with reality, so the following main factors are to be carried out. First, the viscoelastic model of material will be applied to set up and solve the governing differential equation of the beams with material characteristics involving the elastic modulus (E) and the viscous coefficient (C). The viscoelastic model is different from the traditional elastic model due to its non-linearity, reflecting the actual state of the structure. Second, the random vibration signal-based Loss Factor function (LF) calculation using the Power Spectral Density (PSD) to detect changes in structures. LF is a feature representing changes in material properties, including elasticity and viscosity, and is suitable for many types of bridge structures. Also, the paper uses Cubic Interpolation (CI) to generate a surface representing the LF distribution. This interpolation results in surfaces with respect to the LF values distributed by frequencies and spectral amplitudes. Finally, the LF distribution-based material investigation using Convolutional Neural Network (CNN) is proposed with high performance and accuracy. This study applies the proposed method to several bridges in Ho Chi Minh City, Vietnam. It demonstrates that LF is highly suitable for bridge health monitoring. [ABSTRACT FROM AUTHOR]

A supercritical suspended abrasive water jet with dual inputs of pressure and heat is proposed to improve the cutting performance of the conventional suspended abrasive water jet in deep-sea environments. The paper studies the flow and kinetic characteristics of the supercritical suspended abrasive water jet. The CFD simulation method is proposed to investigate these characteristics by integrating a programmed database of supercritical water material properties with Ansys Fluent. The simulation and comparison show that abrasive particle density, abrasive particle size, inlet pressure, and water temperature affect the acceleration process of the abrasive particles. At the nozzle outlet, the velocity of the abrasive particles reaches over 95% of the supercritical water velocity. With the proposed supercritical abrasive water jet, the jet velocity is increased by 192.2% to 402.40 m/s compared to the conventional suspended abrasive water jet, reducing the amount of water used by 67.7% at a specified temperature of 773.15 K. Correspondingly, the medium kinetic energy is increased by 177.7% and the medium kinetic energy ratio is 2.78. The particle kinetic energy is increased by 723.2% and the particle kinetic energy ratio is 8.23. [ABSTRACT FROM AUTHOR]

This paper researches the free vibrations and corresponding material parameters of a functional gradient graphene platelets-reinforced composite (FG-GPLRC) cantilever torsional plates with both pore and graphene variations in the transverse direction. Utilizing the feature of closed-cell cellular solids, the mixture rule, and the modified Halpin–Tsai model, the material parameters of the composite are determined for different volume fractions of component materials. Then, using the classical plate theory (CLPT), the Rayleigh–Ritz technique and polynomials, the dynamic equation that can be used to obtain the free vibration mode shapes and frequencies of the rotating cantilever torsional plate is given. Comparison studies with the previous calculation results from available literature and the finite element (FE) models of cantilever plates are conducted, and the correctness of the present theoretical formulation and numerical calculation is verified. Finally, the effects of graphene platelet (GPL) distribution, porosity distribution (PD), GPL content, rotational speed, and average geometric size of GPL on free vibrations of the system are studied in depth. [ABSTRACT FROM AUTHOR]

As a wind blade is getting larger, its structural behavior becomes more complex and thus the risk of blade structural failure becomes higher. Generally, structural integrity is proved through blade testing with contact measurement devices such as strain gauges. However, contact measurement can only measure the physical quantities from installation points and requires lengthy cables to transmit the electrical signals to a data acquisition system, which can cause signal noise and add unnecessary weight. Recently, noncontact measurement techniques such as digital image correlation (DIC) have been widely used in various industries to process images captured from cameras and generate full-field strains and displacements without any mechanical connections such as cables. In this study, the application of three-dimensional DIC to wind blades was investigated; in addition, the material properties of glass-fiber-reinforced plastics used in blades for the measurement of the first frequency were also studied. Tensile testing was performed using coupons equipped with strain gauges and speckle patterns. In addition, a small blade from a 10 kW wind turbine was utilized to measure the first flapwise frequency using DIC and modal tests; the results showed a 2.1% difference between the two different measurements. This research showed that the DIC technique could be an alternative replacement for the traditional measurement technique upon further validation tests. [ABSTRACT FROM AUTHOR]

Designing an electromagnetic device, as with many other devices, is an inverse problem. The issue is that the performance and some constraints on the inputs are provided but the solution to the design problem is non-unique. Additionally, conventionally, at the start of the design process, the information on potential solutions needs to be generated quickly so that a designer can make effective decisions before moving on to detailed performance analysis, but the amount of information that can be obtained from simple analysis tools is limited. Machine learning may be able to assist by increasing the amount of information available at the early stages of the design process. This is not a new concept, in fact it has been considered for several decades but has always been limited by the computational power available. Recent advances in machine learning might allow for the creation of a more effective "sizing" stage of the design process, thus reducing the cost of generating a final design. The goal of this paper is to review some of the work in applying artificial intelligence to the design and analysis of electromagnetic devices and to discuss what might be possible by considering some examples of the use of machine learning in several tools used in conventional design, which have been considered over the past three decades. [ABSTRACT FROM AUTHOR]

Probabilistic approaches provide a more realistic look into assessing structures under fire conditions and overcome some limitations observed in the more traditional (deterministic) approaches. These approaches have also been introduced to the fire engineering domain, for example, fire probabilistic risk analysis and probabilistic structural fire engineering. In order to perform probabilistic‐based analysis, temperature‐dependent probabilistic models for material properties are needed. This paper presents a methodology to develop temperature‐dependent probabilistic models for the thermal and mechanical properties for commonly used construction materials, including normal‐strength, high‐strength, and high‐performance concrete and mild, high‐strength, and cold‐formed steels. The presented approach analyzes a comprehensive list of surveyed experimental data at different temperature groups, tests the goodness of fit for a number of distributions, and derives a continuous function to quantify temperature‐dependent parameters of the distribution. In addition, the newly derived models are also compared against those adopted by fire codes, and standards and others derived using machine learning. The newly developed models will complement existing efforts to facilitate probabilistic performance‐based structural fire engineering. [ABSTRACT FROM AUTHOR]

The split Hopkinson pressure bar (SHPB) is a commonly used technique to measure the stress-strain of materials at high strain rate. Using the strain records in the input and output bars, the average stress-strain and strain rate in the sample can be calculated by SHPB formulas based on the one-dimensional wave propagation theory. The accuracy of a SHPB test is based on this assumption. In this paper, first a laser measuring system is designed, implemented, and calibrated in order to obtain the dynamic properties of different materials using split Hopkinson pressure bar test. In this method which is a non-contact one, the displacements of bar/sample interfaces are measured directly using a laser extensometer technique, by using the provided equations, in addition to the strain, the stress of the tested sample can be calculated. Moreover, the operation of the method is evaluated using numerical simulation. Aluminum 7075 and copper C10200 samples were studied to evaluate the implemented measurement method. The comparison with other measurement methods shows good agreement of numerical and experimental results. Moreover, since the one-dimensional wave propagation is not used directly in this method, we show the proposed method can be used even with shorter pressure bars which can reduce the cost of manufacturing and maintenance of the SHPB apparatus. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is rapidly expanding to all research areas due to its multiple advantages, such as the freedom and flexibility in achieving any geometry. By using AM as a fabrication technique, the design process has almost no limitations, blending considerably well with the irregular geometries that may result from topology optimization, which can produce optimal material configuration. Therefore, Topology Optimization can combine greatly with Additive manufacturing. A suitable AM method concerning geometry, speed and shape is Wire Arc Additive Manufacturing (WAAM). In this paper, a hollow square t‐joint is modelled and evaluated by the application of two optimization methods with various parameters to find an optimal geometry; numerical analysis (FEM) on non‐optimized and optimized models; and experimental assessments on non‐optimized and optimized printed t‐joints to validate the entire process. [ABSTRACT FROM AUTHOR]

Cross-section behaviour for cold-formed high strength steel (HSS) irregular hexagonal hollow section (IHexHS) stub columns under combined compression and bending is studied and presented in this paper. Finite element models were developed and validated using the existing experimental data collated from the previous research. Upon the validated finite element models, extensive parametric studies were subsequently carried out to generate more numerical data covering a wider range of cross-section dimensions, steel grades and load combinations from pure compression to pure bending. The obtained numerical results were utilised to assess the accuracy and the applicability of the current design codes, such as Eurocode of EN 1993-1-12 (EC3) and the North American code of ANSI/AISC 360-16 (AISC) for cold-formed HSS IHexHS stub columns under combined loading. It was demonstrated that the existing design codes can be safely applied and can be extended for cold-formed HSS IHexHS stub columns design under combined loading. In cross-sectional resistance predictions, conservative results were provided from the existing design codes. The over-predictions were primarily due to the neglect of the strain hardening and plate element interaction. The end points used in the interaction curves of EC3 and AISC adopt an idealised elastic-plastic material model to derive the corresponding resistance in cross-sectional level. The employment of Continuous Strength Method (CSM) leads to improved accuracy in cross-sectional resistance prediction with updated end points in the interaction curve. More consistent and reliable predictions were revealed by carrying out reliability analysis in accordance with EN 1990. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In induction heating processes, knowledge of the charge material parameters, i.e., thermal conductivity and volumetric heat capacity, as well as resistivity and magnetic permeability, is important both at the stage of preparatory process simulations and during their implementation. The paper presents a measurement method for estimating the thermal diffusivity, volumetric heat capacity, and resistivity of the charge material as a function of temperature on a single measuring setup, using a generator for induction heating as the source of signals. The method is based on the study (for forced temperature levels) of the temperature responses of cylindrical samples of the test materials and the voltage induced in the designed measuring coil after short- or long-term step excitation impulses. The presented approach enabled the dedicated computer-controlled system to obtain the initial values of the searched parameters with an accuracy of several percent. The procedure constitutes an introductory step in the simultaneous determination of a set of searched characteristics, and, by performing measurements, significantly narrows the range of variability in the decision variables of the optimization process. [ABSTRACT FROM AUTHOR]

This paper depicts characteristics of degradation of walls of bioreactors made of polymethylmethacrylate (PMMA) which was used to culture algae. The degradation processes take place stimulated by lighting of external surface and interaction with cultured species on internal surface. Results presented are representative for degradation of a bioreactor tube after the 4-year cultivation of Chlorella sp. Microscopic observations, roughness and transmission tests showed that changes have occurred on the inner surface. The result of use is a decrease in transmission and an increase in roughness. Microscopic observations showed that particles remained after culture, especially in cracks. [ABSTRACT FROM AUTHOR]

The tissue-engineered blood vessel (TEBV) has been developed and used in cardiovascular disease modeling, preclinical drug screening, and for replacement of native diseased arteries. Increasing attention has been paid to biomechanical cues in TEBV and other tissue-engineered organs to better recapitulate the functional properties of the native organs. Currently, computational fluid dynamics models were employed to reveal the hydrodynamics in TEBV-on-a-chip. However, the biomechanical wall stress/ strain conditions in the TEBV wall have never been investigated. In this paper, a straight cylindrical TEBV was placed into a polydimethylsiloxane-made microfluidic device to construct the TEBV-on-a-chip. The chip was then perfused with cell culture media flow driven by a peristaltic pump. A threedimensional fluid–structure interaction (FSI) model was generated to simulate the biomechanical conditions in TEBV and mimic both the dynamic TEBV movement and pulsatile fluid flow. The material stiffness of the TEBV wall was determined by uniaxial tensile testing, while the viscosity of cell culture media was measured using a rheometer. Comparison analysis between the perfusion experiment and FSI model results showed that the average relative error in diameter expansion of TEBV from both approaches was 10.0% in one period. For fluid flow, the average flow velocity over a period was 2.52 cm/s from the FSI model, 10.5% higher than the average velocity of the observed cell clusters (2.28 mm/s) in the experiment. These results demonstrated the facility to apply the FSI modeling approach in TEBV to obtain more comprehensive biomechanical results for investigating mechanical mechanisms of cardiovascular disease development. [ABSTRACT FROM AUTHOR]

Fatigue models using the strain-life method do not show exact conformity with the empirical results. Therefore, the use of the mean-stress correction approach is to be evaluated, with a particular focus on mild and higher-strength steel. The influence of the ductility parameters will be studied. A potential favorable development of structural steels with regard to ductility will be checked. The paper will focus on two types of structural steel: S355 and S700. Initially, the mechanical properties of the steel test specimens were measured via a tensile testing rig. In addition, a fatigue test was carried out by applying various mean-stresses. Surface roughness was measured at the notch and introduced into the initial model. The strain amplitudes were determined using the Ramberg-Osgood and Masing material models. Subsequently, a curve fitting was applied to the strain-life data for the fatigue ductility exponent. The multiparameter model was fitted with only one parameter. The resulting model showed a good fit between the strain-life curve and the test results. During the course of the optimization, the error and the scatter were calculated separately for steel types S355 and S700. Based on the ductility exponent, a favorable behavior of the materials was determined. [ABSTRACT FROM AUTHOR]

The present paper, provides a study of conducting experimental investigations (based on the ISO standards), in the context of determining material properties (mechanical and strength parameters) in the case of thin-walled composite structures – made of carbon-epoxy composite. Tests were carried out on 5 different types of test specimens (in accordance with the standards), with a minimum of 9 specimens per each type of test. The tests provided high repeatability of results, and the large number of test specimens per each test made it possible to precisely average the test results in terms of determining the necessary material properties. The tests were carried out using a Zwick Z100 universal testing machine (UTM), under room temperature conditions, using two types of test heads that allow static experimental tests. The results presented in this paper constitute a prelude to research within the framework of the project from the National Science Centre (Poland) with the number 2021/41/B/ST8/00148. The paper presents the initial stage of the implementation of the aforementioned project – which was the determination of material parameters of the composite material from which the target thin–walled composite structures with closed sections were made. The purpose of this paper was mainly to present a methodology for the determination of material parameters describing a composite material (laminate), in order to allow subsequent implementation of the determined properties into numerical models. [ABSTRACT FROM AUTHOR]

Thin fiber-shaped pneumatic artificial muscle (PAM) can generate contractile motions upon stimulation, and it is well known for its good compliance, high weight-to-power ratio, resemblance to animal muscle movements, and, most importantly, the capability to be integrated into fabrics and other textile forms for wearable devices. This fiber-shaped device, based on McKibben technology, consists of an elastomeric bladder that is wrapped around by a braided sleeve, which transfers radial expansion into longitudinal contraction due to the change in the sleeve's braiding angle while being inflated. This paper investigates the effect of material properties on fiber-shaped PAM's behavior, including the braiding yarn and bladder's dimensional and mechanical properties. A range of samples with combinations of yarn and bladder parameters were developed and characterized. A robust fabrication process verified through several calibration and control experiments of PAM was applied, which ensured a more accurate characterization of the actuators. The results demonstrate that material properties, such as yarn stiffness, yarn diameter, bladder diameter, and bladder hardness, have significant effects on PAMs' deformation strains and forces generated. The findings can serve as fundamental guidelines for the future design and development of fiber-shaped pneumatic actuators. [ABSTRACT FROM AUTHOR]

Design verifications of buildings are usually carried out supported by a finite element analysis (FEA), for which, however, there are only a few and almost exclusively non-binding application rules. Within the Cluster of Excellence Integrative Computational Design and Construction for Architecture (IntCDC) at the University of Stuttgart, Guidelines for a Finite Element-Based Design of Timber Structures have been developed. The scope of the guidelines is daily engineering practice, expert engineering applications and product development and certification. Essential parts of the guidelines are design procedures, modelling (including geometrical, material and imperfection modelling), analysis, model verification and validation and design. The content and application of the guidelines are described and illustrated in this paper using two benchmarks. These two benchmarks, which are based on experimental investigations, deal with the elastic material modelling of glulam made of beech laminated veneer lumber (beech LVL) and dowel-type connections for beech LVL members. The experimental basis of the benchmarks is described. With the experiments for the benchmarks, all Poisson's ratios and the complete elastic material stiffness matrix of beech LVL are determined by means of an optical measuring system. The experimentally determined stiffnesses of the investigated dowel-type connections in beech LVL are compared with normative values. Based on the experiments, a numerical model is developed in RFEM (Dlubal). [ABSTRACT FROM AUTHOR]

The knee is the most complex joint in the human body, including bony structures like the femur, tibia, fibula, and patella, and soft tissues like menisci, ligaments, muscles, and tendons. Complex anatomical structures of the knee joint make it difficult to conduct precise biomechanical research and explore the mechanism of movement and injury. The finite element model (FEM), as an important engineering analysis technique, has been widely used in many fields of bioengineering research. The FEM has advantages in the biomechanical analysis of objects with complex structures. Researchers can use this technology to construct a human knee joint model and perform biomechanical analysis on it. At the same time, finite element analysis can effectively evaluate variables such as stress, strain, displacement, and rotation, helping to predict injury mechanisms and optimize surgical techniques, which make up for the shortcomings of traditional biomechanics experimental research. However, few papers introduce what material properties should be selected for each anatomic structure of knee FEM to meet different research purposes. Based on previous finite element studies of the knee joint, this paper summarizes various modeling strategies and applications, serving as a reference for constructing knee joint models and research design.

Copyright of Japanese Journal of Cognitive Psychology is the property of Japanese Society for Cognitive Psychology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A comprehensive approach to understand the mechanical behavior of materials involves costly and time-consuming experiments. Recent advances in machine learning and in the field of computational material science could significantly reduce the need for experiments by enabling the prediction of a material's mechanical behavior. In this paper, a reliable data pipeline consisting of experimentally validated phase field simulations and finite element analysis was created to generate a dataset of dual-phase steel microstructures and mechanical behaviors under different heat treatment conditions. Afterwards, a deep learning-based method was presented, which was the hybridization of two well-known transfer-learning approaches, ResNet50 and VGG16. Hyper parameter optimization (HPO) and fine-tuning were also implemented to train and boost both methods for the hybrid network. By fusing the hybrid model and the feature extractor, the dual-phase steels' yield stress, ultimate stress, and fracture strain under new treatment conditions were predicted with an error of less than 1%. [ABSTRACT FROM AUTHOR]

The construction industry is one of the main sources of greenhouse gas emissions, and portland cement production is responsible for approximately 8% of anthropogenic CO2 emissions. Microbially induced calcium precipitation (MICP) has the potential to partially replace cement or modify the properties of materials that would otherwise not find use in construction, for example, in concrete recycling. MICP might be an environmentally friendly method to improve the properties of recycled aggregates and form conglomerates from the finest fractions. In this paper, factors influencing MICP's ability to solidify recycled concrete fines are thoroughly investigated. Calcium carbonate precipitate crystals produced by the bacterium Sporosarcina pasteurii were analyzed using scanning electron microscopy and energy dispersive spectroscopy. [ABSTRACT FROM AUTHOR]

In recent years, metal additive manufacturing developed intensively and became a relevant technology in industrial production of highly complex and function integrated parts. However, almost all additively manufactured parts must be post-processed in order to fulfil geometric tolerances, surface quality demands and the desired functional properties. Thus, additive manufacturing actually means the implementation of additive-subtractive process chains. Starting with the most relevant additive processes (powder-based PBF-LB, LMD-p and wire-based WAAM and LMD-w/WLAM), considering intermediate process steps (heat treatment and shot peening) and ending up with post-processing material removal processes (with defined and undefined cutting edges), this paper gives an overview of recent research findings with respect to a comprehensive scientific investigation of influences and interactions within the additive-subtractive process chain. This includes both the macroscopic geometric scale and the microscopic scale of the material structure. Finally, conclusions and future perspectives are derived and discussed. [ABSTRACT FROM AUTHOR]

This paper reports an enhancement of the nonlinear conductivity, thermal and mechanical properties of micro-silicon carbide/silicone elastomer (m-SiC/SE) composites by adding nano-aluminum nitride (n-AlN) for power module encapsulation applications. The electrical properties (such as nonlinear conductivity characteristics and transient permittivity obtained from polarization current, and trap distributions obtained from thermally stimulated depolarization current) and material properties (including thermo-gravimetric analysis, coefficient of thermal expansion (CTE), and thermal conductivity, tensile strength, strain at break and Young’s modulus) of the pure SE, m-SiC/SE microcomposites, m-SiC/n-AlN/SE hybrid composites are investigated. The effect of the m-SiC fillers and n-AlN fillers on physicochemical properties of the SE matrix is analyzed by FT-IR spectroscopy and crosslinking degree. The measured nonlinear conductivity and transient permittivity are used for electric field simulation under DC stationary and square voltages. It is found that the addition of n-AlN fillers in the SE hybrid composite improves the nonlinear conductivity characteristics and mitigates the electric field under DC stationary and square voltages, compared to the SE microcomposite. Furthermore, the m-SiC/n-AlN/SE hybrid composite has a higher thermal degradation temperature, thermal conductivity, tensile strength, Young’s modulus, and crosslinking degree than the SE microcomposite, whereas their CTE and strain at break are lower. It is elucidated that the m-SiC/n-AlN/SE hybrid composite with enhanced nonlinear conductivity and material properties is a promising packaging material for high-voltage power modules. [ABSTRACT FROM AUTHOR]

The small punch test (SPT) can be very convenient to obtain mechanical properties due to its unique advantages from small-volume samples, and has gained wide popularity and appreciation among researchers. In this paper, the SPT test and finite element (FE) simulations were performed for three alloys, and the yield stresses (σYS) and ultimate tensile strengths (σUTS) from the uniaxial tensile test (UTT) were correlated with the yield force (Fy) and maximum force (Fm) of the small punch test (SPT) before and after compliance calibration. Finally, the effect of specimen size on the SPT curves was discussed. The results showed that the deviation between SPT test and FE simulation was due to the loading system stiffness, which was confirmed by the loading system compliance calibration test. The SPT curves before and after calibration have less influence on the empirical correlation results for σUTS, while the correlation results for σYS depend on the method used to determine Fy in the SPT curve. Finally, the simulation results indicated that the effect of specimen size on the force–displacement curve in the SPT is slight. This work also provides a reference for subsequent researchers to conduct empirical correlation studies using different specimen sizes. [ABSTRACT FROM AUTHOR]

Summary: Fire models, or other fire safety engineering tools, may require that input data be supplied for characterizing the ignition of combustible solids. This may be done in ad hoc manner and result in poor realism for modeling the ignition process. Extensive research on the ignition of solid materials has been done in recent decades, notably in characterizing the ignition time as a function of incident heat flux. This paper summarizes the highlights of what has been learned during such research. It then offers the user algorithms that may prove useful in the development or advancement of fire models. The suggested methods can also be valuable to performing simple (i.e., spreadsheet‐based) analysis of ignition data in order to extract effective thermophysicochemical properties of tested materials. Procedures for both thermally thick and thermally thin solids are presented. The previously developed procedures for a constant heating flux are extended to a time‐varying heat flux, with the latter based on the Duhamel superposition principle. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a progressive technology which holds promise for manufacturing of heat resistant super alloys. One of the most productive methods is wire arc additive manufacturing (WAAM). In this article, an alternative WAAM strategy is investigated. Experimental clads and material tests were performed to evaluate the material properties obtained through a cold metal transfer (CMT) discontinuous WAAM of Inconel 625 alloy. Using the modern terminology of Fronius Gmbh this method is called CMT cycle step. The difference is that it is automatically controlled by the welding source. CMT discontinuous WAAM has lower productivity and a higher consumption of shielding gas. However, it excels in low heat input and precise material cladding in comparison with a standard CMT continuous WAAM. It enables fabrication of finer details even on thin-walled components or in sections with problematic heat dissipation. Samples manufactured using this strategy were also compared with samples manufactured through a standard CMT continuous WAAM. Two sets of manufactured samples were thus tested. The following material tests were performed: (i) metallographic analysis, (ii) x-ray tomography, (iii) SEM analysis, (iv) hardness, (v) tensile strength (20 °C, 650 °C) and (vi) pin-on-disc (20 °C, 650 °C). The results show that the CMT discontinuous WAAM led to improved material properties in the Inconel 625 samples. Ultimate tensile strength improved by 15% at 20 °C and by 4% at 650 °C. Wear resistance at 650 °C was about two times higher. This paper concludes that the CMT discontinuous WAAM for Inconel 625 is definitely suitable for manufacturing of complex shapes, fine details and thin-walled components. [ABSTRACT FROM AUTHOR]

Nonlinear thermal frequency characteristics of multidirectional doubly curved, functionally graded (FG) panels are examined numerically in the current paper using the finite element method. The material properties of the FG panel are computed using individual temperature-dependent properties of the FG constituents and by using Voigt's micromechanical model in conjunction with different types of material distribution patterns. Also, two types of porosity distributions through the panel thickness are considered in the present work. Higher-order shear deformation theory kinematics and Green-Lagrange nonlinearity are used to create a mathematical model. The graded panel's governing equation is obtained and solved using Hamilton's principle and the direct iterative method. The stability and correctness of the proposed model have been checked via a convergence and validation study. Several numerical examples are solved and discussed in the paper to show the efficacy of the proposed model. [ABSTRACT FROM AUTHOR]