Characteristics Of Various Materials Research Articles

Friction Stir-Based Techniques: An Overview

AbstractFriction stir-based techniques (FSTs), originating from friction stir welding (FSW), represent a solid-state processing method catering to the demands of various industrial sectors for lightweight components with exceptional properties. These techniques have gained much more attraction by providing an opportunity to tailor the microstructure and enhance the performance and quality of produced welds and surfaces. While significant attention has historically been directed towards the FSW process, this review delves into the working principles of FSTs, exploring their influence on mechanical properties and microstructural characteristics of various materials. Additionally, emphasis is placed on elucidating the advancement of hybrid FSW processes for both similar and dissimilar metal components, aimed at enhancing welding quality through meticulous control of grain textures, structures, precipitation, and phase transformations. Finally, the review identifies current knowledge gaps and suggests future research directions. This review paper synthesises academic literature sourced from the Web of Science (WoS) and Scopus databases, supplemented by additional sources such as books from the last 15 years.

Materials, Structure, and Interface of Stretchable Interconnects for Wearable Bioelectronics.

Since wearable technologies for telemedicine have emerged to tackle global health concerns, the demand for well-attested wearable healthcare devices with high user comfort also arises. Skin-wearables for health monitoring require mechanical flexibility and stretchability for not only high compatibility with the skin's dynamic nature but also a robust collection of fine health signals from within. Stretchable electrical interconnects, which determine the device's overall integrity, are one of the fundamental units being understated in wearable bioelectronics. In this review, a broad class of materials and engineering methodologies recently researched and developed are presented, and their respective attributes, limitations, and opportunities in designing stretchable interconnects for wearable bioelectronics are offered. Specifically, the electrical and mechanical characteristics of various materials (metals, polymers, carbons, and their composites) are highlighted, along with their compatibility with diverse geometric configurations. Detailed insights into fabrication techniques that are compatible with soft substrates are also provided. Importantly, successful examples of establishing reliable interfacial connections between soft and rigid elements using novel interconnects are reviewed. Lastly, some perspectives and prospects of remaining research challenges and potential pathways for practical utilization of interconnects in wearables are laid out.

Improving energy harvesting through femtosecond laser surface modification of PVDF/ZnS composite nanofibrous nanogenerators for electronic applications

Surface modification in ceramic/polymer composites holds paramount importance for electronic devices applications. Laser is a versatile and flexible device for modifying the surface characteristics of various materials. Here, we propose a novel approach to enhance the energy harvesting efficiency of polyvinylidene fluoride (PVDF) and zinc sulfide (ZnS) composite nanofibrous membranes through femtosecond laser surface modification. The electrospinning technique is used to produce nanofibers with a high β-phase content in a single step. The PVDF membrane was further enriched with ZnS nanoparticles to enhance the β-phase content. The membranes were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Electron Energy Loss spectroscopy (EELS), and Fourier-transform infrared spectroscopy (FTIR) to characterize their morphological and chemical properties. Femtosecond laser was employed to induce controlled surface modifications, resulting in hierarchical microstructures and surface functionalization. The results showed patterned tracks on the fiber surface while preserving its inherent nature. To validate its utility as an energy harvesting device, the membrane's capability was assessed by measuring the open circuit voltage. The results revealing average output voltages for nanogenerators treated with laser fluences of 0.5 J/cm2, 0.7 J/cm2, and 0.9 J/cm2 are 15.6 V, 25 V, and 17 V, respectively. The maximum output voltage is observed for a laser fluence of 0.7 J/cm2, attributed to the deeper structure created, increasing the surface area of contact and deformation in the structure. This work offers promising avenues for enhancing energy harvesting efficiency and expanding the scope of electronic devices such as sensors and actuators.

Investigating Material Performance in Artificial Ankle Joints: A Biomechanical Study

This study delves into an in-depth examination of the biomechanical characteristics of various materials commonly utilized in the fabrication of artificial ankle joints. Specifically, this research focuses on the design of an ankle joint resembling the salto-talaris type, aiming to comprehensively understand its performance under different loading conditions. Employing advanced finite element analysis techniques, this investigation rigorously evaluates the stresses and displacements experienced by the designed ankle joint when subjected to varying loads. Furthermore, this study endeavors to identify the vibrating frequencies associated with these displacements, offering valuable insights into the dynamic behavior of the ankle joint. Notably, the analysis extends to studying random frequencies across three axes of motion, enabling a comprehensive assessment of directional deformities that may arise during joint function. To validate the effectiveness of the proposed design, a comparative analysis is conducted against the star ankle design, a widely recognized benchmark in ankle joint prosthetics. This comparative approach serves dual purposes: confirming the accuracy of the findings derived from the salto-talaris design and elucidating the relative efficacy of the proposed design in practical application scenarios.

Adaptive Machining Method for Helical Milling of Carbon Fiber-Reinforced Plastic/Titanium Alloy Stacks Based on Interface Identification.

CFRP/Ti stacks composed of carbon fiber-reinforced plastic composites (CFRP) and titanium alloys (Ti) are widely used in aerospace fields. However, in the integrated hole-making process of CFRP/Ti stacks, the machining characteristics of various materials are significantly different, and constant machining parameters cannot simultaneously meet the high-quality machining requirements of two materials. In addition, errors exist between the actual thickness of each material layer and the theoretical value, which causes an impediment to the monitoring of the machining interface and the corresponding adjustment of parameters. An adaptive machining method for the helical milling of CFRP/Ti stacks based on interface identification is proposed in this paper. The machining characteristics of the pneumatic spindle and the interface state in the helical milling of CFRP/Ti stacks are analyzed using self-developed portable helical milling equipment, and a new algorithm for the real-time monitoring of the machining interface position and adaptive adjustment of the machining parameters according to the interface identification result is proposed. Helical milling experiments were carried out, the results show that the proposed method can effectively identify the position of the machining interface with good identification accuracy. Moreover, the proposed parameter-adaptive optimized machining method for CFRP/Ti stacks can significantly improve hole diameter accuracy and machining quality.

Corrugated veneer joinery and construction material and its sound insulation properties

The article presents a new joinery and construction material made of corrugated veneer. The material under consideration can be used to create lightweight internal enclosing structures of residential premises (interior partitions) and for interior decoration. Within the framework of this study, the tasks related to the determination of sound insulation properties and characteristics of a new joinery and building material and the search for ways to improve its design are considered. The analysis of the regulatory requirements for interior partitions of residential premises and the requirements of standards for the experimental determination of the degree of isolation of air noise by enclosing structures in field conditions is carried out. Methods for determining the sound insulation properties and characteristics of various materials and structures, as well as equipment used for research, have been studied. An experimental installation has been developed to evaluate the effectiveness of insulation from air noise of samples of the proposed joinery and construction material. Samples of the material necessary for the experiment were made, and an experiment plan was drawn up. It has been established that the highest efficiency of isolation from air noise is achieved in the high frequency range from 4800 dB and above. In the area of low and medium frequencies, the sound insulation of the material under study is not effective enough, which requires the use of additional sound insulation layers. The assessment of ways to improve carpentry and construction material to improve its sound insulation properties in the low and medium frequencies has been carried out.

Mineral Additives in Concrete Durability: A Comprehensive Review

The body of literature on concrete using mineral admixtures covers a number of review studies on the durability characteristics of various materials used in concrete, such as fly ash (FA), rice husk ash (RHA), ground granular blast furnace slag (GGBS), fly ash (SF), and met kaolin (MK) are reviewed in this work. The features that are related to durability have been evaluated, and they include permeability, resistance to chloride ion penetrations, abrasion, fire resistance efflorescence. Incorporating mineral admixtures in concrete affects various properties. Concrete's permeability decreases and its ability to resist chloride ion penetration rises when admixtures containing a greater alumina content are used. Use of mineral admixtures enhances compressive strength and enhancing abrasion resistance. Moreover, highly reactive mineral admixtures mitigate efflorescence. Notably, while heating PFA concrete improves fire resistance, it reduces overall durability. SF concrete, on the other hand, behaves similarly to standard concrete but can be more brittle. MK concrete exhibits increased strength at 200°C, but its durability and strength decline at higher temperatures compared to other concrete types.RHA pozzolans can replace OPC up to 15% by weight after curing for up to 200 days without lowering the concrete's compressive strength.

Understanding Atomic Structure in Solid by Using the X-ray Diffraction

In solid-state physics research, the spacing and arrangement of atoms play a crucial role in determining the properties of solids. Therefore, it is essential to analyze the structural characteristics in order to understand new physical phenomena within solids. X-ray characterization is considered a highly important technique in the field of material characterization, as it provides information about atomic-scale features. In Korea Institute of Science and Technology (KIST), extensive researches are conducted on the structural characteristics of various materials and the corresponding physical phenomena. To efficiently operate, manage, and further develop advanced analytical methods, the centralized X-ray characterization instrument facility was established in the Analysis and Data Center at KIST in January 2013, named ‘X-ray Open Lab.’ In this special issue, we would like to introduce X-ray diffraction (XRD) technique and their principle, which is the most widely utilized analysis equipment among the analytical instruments available at the X-ray Open Lab.

Possibilities of Using Low-Density C–C Composites for Thermal Protection of Small Unmanned Aerial Vehicles

Abstract The study demonstrates the possibilities of using, as well as the features associated with the use of, unmanned aerial vehicles (UAVs) for military and peaceful purposes. Information is provided on the need to use components that would contribute towards ensuring thermal protection against modern laser weapons. The requirements for such materials are given, according to the field of application of the UAV. An analysis of the available materials that can be used to create thermal protection of UAVs against laser weapons is provided. The thermophysical characteristics of various materials are presented. The work presents technological features of production and properties of low-density carbon–carbon composite materials (CCCM). It is proposed to consider the prospects of using CCCM materials for not only the UAV structural components but also other purposes.

Two-Dimensional Materials Applied in Membranes of Redox Flow Battery.

Redox flow batteries (RFBs) are one of the most promising techniques to store and convert green and renewable energy, benefiting from their advantages of high safety, flexible design and long lifespan. Membranes with fast and selective ions transport are required for the advances of RFBs. Remarkably, two-dimensional (2D) materials with high mechanical and chemical stability, strict size exclusion and abundantly modifiable functional groups, have attracted extensive attentions in the applications of energy fields. Herein, the improvements and perspectives of 2D materials working for ionic transportation and sieving in RFBs membranes are presented. The characteristics of various materials and their advantages and disadvantages in the applications of RFBs membranes particularly are focused. This review is expected to provide a guidance for the design of membranes based on 2D materials for RFBs.

Fabrication of white light emitting diodes via high yield surface passivated carbon quantum dots doped with terbium.

Exploiting the unique characteristics of various materials to create novel hybrid materials opens up innovative possibilities for cutting-edge applications across numerous fields. Here, we have synthesized novel surface functionalized photoluminescent carbon quantum dots (CQDs) doped with a rare-earth element (Tb3+) for white light emitting diodes. High quantum yield CQDs were produced utilizing Plumeria leaves as a precursor using a one-step hydrothermal approach, and further, its optical characterization was thoroughly investigated. Herein, the functionalized CQDs demonstrate excitation-independent electroluminescence performance. The UV-LED chip and functionalized CQD were combined to create a device that emits cold white light with Commission Internationale de L'Eclairage coordinates of (0.33, 0.34), a corresponding correlated color temperature of 4995 K and color rendering index of 84.2.

The Making of Bikini Glass in Bida, Nigeria: Ethnography, Chemical Composition, and Archaeology

This paper discusses the process, prospects, and challenges of making bikini glass in Bida (Nupeland), central Nigeria. The Masagá glassmakers of Bida provide the ideal case study for investigating the production of bikini. Nineteenth-century Arab and European writings have described glassmaking in Nupeland; however, with the exception of the study carried out by Peter Robertshaw and his colleagues in 2009, there is no work that identifies the raw materials and formula used to produce bikini glass. Our recent ethnographic work at Bida provided the opportunities to collect raw glass, beads, and unfused raw material for bikini glass as well as vitrified furnace wall fragments for analysis. We present results of binocular observation and chemical compositional analysis conducted on the raw materials, glass products, and furnace remains to understand the mineralogical and chemical characteristics of various materials connected with the production of bikini. From the manufacture of glass to that of glass ornaments, bracelets, and beads, the documentation of the work of Masagá glassmakers provides new data for the history of glass and its techniques. This information is relevant for understanding glassworking in the past. The paper also addresses issues relating to migration, technology transfer, and culture contact between Nupeland and its neighbors in the Lower Niger region. It argues that the investigation of the production of bikini glass in Bida is essential for expanding our knowledge of the archaeology of glassmaking and glassworking in Sub-Saharan Africa and beyond.

Modeling of Pool Fire Risk in a Chemical Warehouse

Background: Pool fire is a phenomenon caused by the leakage of flammable materials on the ground leading to serious hazards, irrespective of its consequences. The proximity and high volumes of chemicals in warehouses require that the characteristics of various materials in warehouses be taken into account for calculating the chain effects of the pool fire. Methods: One of the effective parameters in expanding the impact of pool fire chain is heat flux value. There are different models for calculating and predicting it. In this study, two approaches of computational fluid dynamic (CFD), fire-driven fluid flow, fire dynamics simulator (FDS), and solid flame model were used to predict heat flux values. Results: In both models, the calculated heat flux was used to evaluate the effects on humans (first-degree burns, second-degree burns, and deaths) and the materials. The CFD results were compared with the results of the solid flame model, which indicated that there was little error in the predicted heat flux values. Conclusion: The results of this study can be used to better understand the effects of pool fire on chemical warehouses, and provide appropriate control measures to prevent such accidents in warehouses.

Evaluation of the possibility of using pulp to improve the characteristics of various materials

The article presents the results of the analytical review of the work on the possibility of using cellulose to improve the physical and chemical characteristics of various materials, including paper, cardboard, plastic and others. Unique chemical and physical properties of nanocellulose are shown.

DETERMINING THE THERMO PHYSICAL CHARACTERISTICS OF VIBRATION DRYING OBJECTS

Crop products require good moisture content for successful storage. The drying process is mainly used for this purpose. For its successful design and implementation it is necessary to have information about the physical and mechanical properties of the material, including thermo physical characteristics. It is for the successful implementation of the process of post-harvest processing of pumpkin seeds were planned and conducted experimental studies. Analysis of previous studies to determine the thermo physical characteristics of various materials, including plant products, showed that in most cases one series of experiments to determine three main indicators - heat capacity, thermal conductivity and thermal conductivity of products. Unfortunately, there is no universal method and installation for determining the required indicators, so in our research we used the original installation, the principle of which is based on the use of non-stationary heating patterns of two semi-bounded rods, where the source of heat is constant power. The theoretical basis of the implemented method is the solution and analysis of the thermal equation with the corresponding boundary conditions. Intermediate equations were obtained from which the values of thermal conductivity and thermal conductivity for each series of experiments were found by the graph-analytical method of solution. The value of heat capacity of the material was determined from the well-known formula of the ratio of these three indicators. As a result of research and processing of the obtained data, the dependences of the thermo physical properties of the material on its humidity were determined, which are presented in graphical and analytical form. The obtained dependences confirmed the results of researches of some authors on the presence of inflection in the graph of thermal conductivity which is explained by the transition of moisture from free to bound state.

The use of modern work methods with information in teaching the strength of materials

The article presents an analysis of the modern work methods inclusion with educational and scientific information into the “Resistance of materials” course educational process. Over the course of five years, the author has tested the information search technic, students work organizing technic with educational and scientific literature in different formats, cooperation technic, self-presentation technic to involve students in active work on the theoretical material study necessary for every engineer. The educational process, organized using a blended learning technic encouraged students to work independently, adhering to the discipline studying plan in the semester. Modern technologies for working with information are based on working with scientific electronic libraries, educational platforms, and online scientific publications. Mind mapping technology allows you to optimize the theoretical material studying time. An independently executed mind map helps the student to understand and remember the procedure for calculating structural elements, to systematize the strength characteristics of various materials. Classwork and self-guided work in mini-groups allow students to form a communication culture. Students learn to prove their opinions on professional topics, show respect for others' opinions, and evaluate various situations that arise in the process of teamwork. Collaboration technic encourages learners to assign tasks and roles. Students who work in the executor role and the lead role, acquire the collective presentation skill while defending laboratory work. In the transition to individual educational trajectories, it is necessary to combine various educational technologies for the successful universal and general professional competencies acquisition by students. Various modern digital resources should be included in the educational process for checking purposes of the strength, structural elements, and mechanisms stiffness, and stability problems solution.

Prediction of tool wear in CFRP drilling based on neural network with multicharacteristics and multisignal sources

Carbon fiber-reinforced polymer (CFRP) drilling is a typical process in the aircraft industry. Because the components of CFRP are different and uneven, it is difficult to extract tool wear characteristics from the machining signals, which are composed of the processing characteristics of various materials and the tool state characteristics. The aim of this work is to present a new comprehensive approach based on multicharacteristics and multisignal sources to predict the tool wear state during CFRP drilling through a combination of a backpropagation (BP) artificial neural network (ANN) model and an efficient automatic system depending on the sliding window algorithm. It was verified that the peak factor and Kurtosis coefficient of different signals and the energy value of the d5 layer of the thrust force signal and the d3 layer of the vibration signal after wavelet decomposition were related to tool wear. Among them, the energy value of the d3 layer of the vibration signal was selected as the wear indicator and was able to describe the state of the tool during the CFRP drilling process regardless of the drilling conditions and individual tool differences. A confirmatory drilling experiment using 6-mm-diameter polycrystalline diamond twist drilling under different processing parameters was conducted to verify the ANN model based on multicharacteristics and multisignal sources. A lower feed speed and a higher cutting speed were both highly correlated with the VB value of flank wear. Drill wear accelerated because of the occurrence of adhesive wear when the number of drilled holes reached around 90. The accuracy of the neural network model is 80–87% when using the value of only one characteristic but clearly increases based on multicharacteristics and multisignal sources in real time, indicating that the BP ANN model has higher accuracy in predicting the tool state in CFRP drilling through the sensor signal fusion method.

Key Technique Study of Stability Control of Surrounding Rock in Deep Chamber with Large Cross-Section: A Case Study of the Zhangji Coal Mine in China

This paper is a case study on the key technique of stability control of surrounding rock in the deep chamber with large cross-section in Zhangji Coal Mine of China. Many investigations and field experiments were performed to reveal the surrounding rock failure mechanisms of the chamber. It was found that the large cross-section, high in situ stresses, large rock zone and construction disturbance were the main causes of the chamber instabilities. For the original supporting scheme, the numerical simulation was adopted to analyze the surrounding rock stress and displacement during excavation and support. There are stress concentrations and large displacement at the junction of the chamber, shaft lining, and machine roadway. The maximum displacements are 74.7 mm in horizontal, 105.9 mm roof fall and 29.2 mm floor heave in vertical. Based on the simulation results, the supporting structure optimization design of the chamber has been completed. The primary supporting structure is composed of the bolt, steel mesh, shotcrete and anchor. The secondary supporting is concrete lining with double-layer reinforcement and an inverted arch. The shallow and deep lagging grouting technique was adopted for reinforcing rock. The three-dimensional steel grid inverted arch lining was developed independently. The indoor model test showed that the inverted arch lining can take advantages and characteristics of various materials through unique spatial network design, which improved the whole bearing capacity. A field experiment of convergence and reinforcement stress monitoring was conducted. The field measurement data showed that the maximum displacement of two sides and roof were 60 mm and 42 mm at 200 days, respectively. The reinforcement stresses of supporting structure were far less than the yield strength, which had a higher safety stock. This successful case study demonstrated that the optimized supporting structure is reasonable and the deformation of surrounding rock has been effectively controlled.

Effects of Material Properties on Angular Distortion in Wire Arc Additive Manufacturing: Experimental and Computational Analyses

In wire arc additive manufacturing (AM), as in arc welding, arc heat thermally deforms substrates and articles. For industrial applications, deformation characteristics of various materials must be understood and appropriate materials and methods of reducing deformation must be devised. Therefore, angular distortions of different materials were investigated through bead-on-plate welding and finite element analysis. A model that simplifies temperature-dependent properties was developed to establish relationships between thermomechanical properties and angular distortion. A simplified model of temperature-dependent properties was used, and angular distortion characteristics were extensively investigated for different material properties and heat inputs. Coefficient of thermal expansion, density, and specific heat all notably affected angular distortion depending on heat input conditions. Results showed that during wire arc AM, flatness of both substrates and articles could vary depending on material properties, heat input, substrate thickness, and bead accumulation. Study findings can provide insight into deformation characteristics of new materials and how to mitigate thermal distortions.

ЕКСПЕРИМЕНТАЛЬНЕ ВИЗНАЧЕННЯ ЕНЕРГЕТИЧНИХ УТОМНИХ ХАРАКТЕРИСТИК СПЛАВУ Д16Т (2024) МЕТОДОМ ВІЛЬНИХ КОЛИВАНЬ

In the process of studying fatigue characteristics of materials, components, assemblies and entire structures, as well as the prediction of durability, it is necessary to know the energy fatigue characteristics of various materials. These parameters include α – a fatigue failure parameter and W-1– irreversibly dissipated energy per loading cycle at stresses equal to the fatigue limit based on N = 107 cycles. The logarithmic damping decrement shows the fraction of irreversibly scattered energy when the oscillations decay from the total elastic energy of the oscillations. It has been proven that for metals fatigue failure is a constant "dangerous" energy. This paper describes the experimental determination of these energy characteristics for one of the most common materials in aviation, D16T (2024). By measuring the logarithmic damping factor in the fatigue test process, the dissipated energy is found over the loading cycle. Tests are conducted at two different loading levels. This allows to obtain a system of two equations to determine the two energy characteristics α and W-1.