Strip Of Material Research Articles

A computational approach for phase-field model of quasi-brittle fracture under dynamic loading

AbstractA computational model is formulated for studying dynamic crack propagation in quasi-brittle materials exposed to time-dependent loading conditions. Under such conditions, inertial effects of structural components play an important role in modelling crack propagation problems. The computational model is proposed within the theory of regularised cracks which uses a damage-like internal variable. Here, fracture considers phase-field damage which gives rise to a material degradation in a narrow material strip defining the regularised crack. Based on the energy formulation using the Lagrangian of the system, the proposed computational approach introduces a staggered scheme adopted to solve the coupled system and providing it in a variational form within the time stepping procedure. The numerical data are obtained by quadratic programming algorithms implemented together with a finite element code.

Random Dynamic Responses of Two Parallel Interfacial Cracks Between A Functionally Graded Material Strip And Two Dissimilar Elastic Strips

Abstract An analytical approach is presented in this article for the random dynamic study of two parallel interfacial cracks in a functionally graded material (FGM) strip that is bonded between two distinct elastic strips. One of the parallel cracks is placed at the interface of the elastic strip I and the FGM strip, and another is at the interface of the FGM strip and elastic strip II. A stationary stochastic process of time is used to model the dynamic loadings that are applied to the crack faces. To find the solution, the FGM strip is splited into a number of sub-strips, and using an average method, the material properties of each sub-strip are reduced to random variables. A fundamental problem is formulated to find the solution. The boundary conditions are reduced to a set of singular integral equations employing the Fourier sine, Fourier cosine, and Laplace transforms, which are solved by using the Collocation method. Further, the analytical expressions of dynamic stress intensity factors (DSIFs) about the crack tips in the time domain are obtained with the help of the Improved Dubner and Abate's method. Finally, the Monte Carlo method is used to obtain the mathematical expectation and standard deviation of DSIFs. The outcomes of the present study are also verified. The unique aspect of this study is the pictorial illustration of mathematical expectation and standard deviation as functions of the number of sub-strips, functionally graded parameter, thickness of the strips, and length of parallel interfacial cracks.

Self-assembled dipeptide grafted nanohybrid material strips for reliable spectroscopic and electrochemical recognition of tryptamine

According to the World Health Organization (WHO), foods high in tryptamine may cause foodborne diseases and abnormal activity in the central nervous system (CNS). The real-time monitoring of tryptamine levels is an emphasized topic among scientific community. In the present work, we report a cost-effective fluorescent paper strips-based methodology impregnated with self-assembled dipeptide-modified (DM1) zinc oxide (ZnO) i.e.DM1@ZnO for the real-time monitoring of tryptamine levels. It is based on an organic-inorganic nanohybrid material of self-assembled N-functionalised dipeptide molecule coated over the surface of ZnO thus tailoring its properties for the detection of tryptamine employing spectroscopic and electrochemical methods. The designed material exhibited a noteworthy response towards tryptamine irrespective of the presence of other biogenic amines (BAs). It selectively displayed blue fluorescence under the 365 nm UV light. On top of that, the detection of tryptamine was also corroborated by its transition to 2-oxytryptamine, as deduced from its electrochemical route. Thus, the proposed paper strip-based methodology unbolts a realistic platform for the efficient recognition of varying levels of tryptamine thus tackling the prima facie reasons for foodborne diseases.

ВАРІАНТИ ВИКОРИСТАННЯ ВЛАСТИВОСТІ УНІФІКАЦІЇ ПРИ ВИБОРІ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ РІШЕНЬ З’ЄДНАНЬ “МЕТАЛ+КОМПОЗИТ”

Possibility of unification property realization in application to variants of structural-technological solutions of “metal+composite” joints.It is drawn that this property is important for up-today vehicle engineering structures at different goals of its manufacturing. It is shown that there are three possible options can be revealed in metal-composite heterogenous joints realization: with monolithic, cylindrical and sheet transversal fastening connections.Possibility of application sheet transversal fastening elements produced on metal strips is considered exactly. Also, possibility of implementation strips of different materials and thickness is analyzed.The property of unification is most fully manifested at the stages of design, technological preparation of production and production itself. Variants of technological processes for manufacturing sheet fasteners on metal strips using stamping methods or laser cutting are proposed. An analysis of the advantages and disadvantages of these technical processes showed that the most rational method is stamping with bending.Options for route technical processes for forming transversal connections on metal tips using sheet reinforcing elements are proposed.Options for equipment are proposed, with the help of which serial production of teeth on metal strips is possible. It should be noted among these equipment options metal stamps for stamping teeth and using an electro-hydraulic device for bending them.Examples of implementation of design and technological solutions with sheet micro-elements in the manufacture of high-pressure vessels and in the strengthening of bolted joints are given.

Multi-Mode Damage and Fracture Mechanisms of Thin-Walled Tubular Parts with Cross Inner Ribs Manufactured via Flow Forming.

In order to study the multi-mode damage and fracture mechanisms of thin-walled tubular parts with cross inner ribs (longitudinal and transverse inner ribs, LTIRs), the Gurson-Tvergaard-Needleman (GTN) model was modified with a newly proposed stress state function. Thus, tension damage and shear damage were unified by the new stress state function, which was asymmetric with respect to stress triaxiality. Tension damage dominated the modification, which coupled with the shear damage variable, ensured the optimal prediction of fractures of thin-walled tubular parts with LTIRs by the modified GTN model. This included fractures occurring at the non-rib zone (NRZ), the longitudinal rib (LIR) and the interface between the transverse rib (TIR) and the NRZ. Among them, the stripping of material from the outer surface of the tubular part was mainly caused by the shearing of built-up material in front of the rollers under a large wall thickness reduction (ΔT). Shear and tension deformation were the causes of fractures occurring at the NRZ, while axial tension under a large TIR interval (l) mainly resulted in fractures on LIRs. Fractures at the interface between the TIR and NRZ were due to the shearing applied by rib grooves and radial tension during the formation of ribs. This study can provide guidance for the manufacturing of high-performance aluminum alloy thin-walled tubular components with complex inner ribs.

Polarization of Compton-Scattered Prompt Gamma-Ray Technique for HEU Detection at 186 keV

Prompt gamma-ray polarization is a practical method for detecting highly enriched uranium (HEU) in concealed sources. It also provides information on their geometry, magnetic fields, and radiation mechanisms. However, prompt gamma-ray polarization measurements have rarely been applied in nuclear nonproliferation areas to detect HEU. In this study, the feasibility of detecting the characteristic energy peak of 186 keV, which is associated with the asymmetry of the activation mechanism and the detection of energy-dependent polarization from concealed HEU sources, was evaluated using the Compton scattering approach. A Monte Carlo N-particle transport code simulation was used to realize the activation mechanism of HEU via two 1.4-mm strips of converter material [i.e., cesium lead tribromide (CsPbBr3)], transported by secondary scattered gamma rays during the three-stage process of Compton scattering, polarization, and detection. This paper presents the mathematical model, the physics of Compton scattering, and the polarization mechanism for the detection technique. In this case, the physics is relevant to both processes in which the emitted secondary scattered gamma rays undergo initial orthogonal polarization. Specifically, to meet the objective of testing the technical protocol for the enhanced detection of energy peaks associated with HEU, particularly 186 keV, simulations were conducted to quantify the HEU volume and neutron source strength in the MCNP data card to perform error analysis. The detector system had the potential to acquire good resolved photopeak with a 4.5% relative error or less, with a 1 Ci source activity, and a peak-to-background ratio of 1.15. This resolution took 163 s for high-purity germanium detection, which is comparable to current methods used for material detection placed within 100 to 900 s to completion. The small error difference was due to the attributes of the phenomenal enhancement properties of cesium tribromide and polarimetry. The identified photo peaks included K-shell X-rays from 235U, 61 keV from fission, 511-keV annihilation, and the peak of interest at 186 keV. The result from spectral analyses showed clear signatures related to pure and adulterated HEU. HEU detection with the low neutron yield and the easiness of shielding the yield of the HEU sample showed that the HEU characterization was feasible when shielded, with the highest success rate under both enhancement approaches. The optimization and scale-up of this technique are expected to enhance its applications in a large-scale HEU detection design.

Hydrogen gas sensor based on self-heating effect of SnO2/Pt thin film with ultralow power consumption

Self-heating of sensing elements on gas sensors is an effective solution to avoid using external heaters. In this paper, a self-heated hydrogen gas sensor is presented. The sensor was created using the DC sputtering method, which involved fabricating it on a thermal-insulating Kapton flexible substrate. This process utilized a thin film of SnO2 with thick 50 nm that was modified with nanoclusters of Pt, serving as the sensing material. The SnO2/Pt material film was analyzed for microstructure and composition by SEM, XRD, and XPS analysis. Infrared images show that the self-heating effect is mainly concentrated in the strip of gas-sensitive material. It showed many good performances, such as high sensitivity (able to detect down to 50 ppm of H2), good selectivity (poor response to CO, NH3, H2S, and NO2), the sensor's performance is little changed by environmental humidity, and low power consumption (89 μW at 5V). The sensor is also stable and low-cost, suitable for portable H2 detection devices due to its low generated heat and small size.

A new deformable self-clinching fastener

This work proposes a novel deformable self-clinching fastener for producing hidden lap joints suitable for both structural and electric power distribution applications. The fastener, characterized by an axisymmetric concave shape, is employed to fabricate hybrid busbar joints between electrically conductive strips of different materials and thicknesses. The self-clinching process with the new deformable fastener involves machining dovetail holes in both conductors and applying a squeezing force to the fastener to create a form-closed mechanical joint. The work encompasses both experimental investigations and numerical modeling using finite element analysis and is carried out on unit cells made from aluminum and copper conductors, which are representative of the joining process. The investigation evaluates force requirements, conducts destructive testing, and performs thermo-electric characterization of the new joints to conclude on the suitability of the new deformable self-clinching fastener for electric power distribution applications. Results indicate that while copper fasteners necessitate greater squeezing forces, they offer superior mechanical and thermo-electrical performance compared to aluminum fasteners in hybrid busbar joints.

Sperm morphology of Tingidae Laporte, 1833 (Miroidea: Cimicomorpha).

Here, we describe for the first time the sperm morphology of Tingidae (Heteroptera). They are small insects presenting lacy patterns on their pronotum and hemielytra and are exclusively phytophagous, with many economically important species. We studied five species of the tribe Tingini (Tinginae): Teleonemia scrupulosa, Vatiga illudens, Gargaphia lunulata, Leptopharsa sp., and Corythucha arcuata. Their spermiogenesis process is similar to other Heteroptera, with some differences in the formation of the centriole adjunct. This structure extends in the anteroposterior spermatid axis, flanking the nucleus, possibly contributing to nucleus remodeling and sperm elongation. The mature sperm of Tingidae is also similar to that of other Heteroptera, with features that corroborate the group's monophyly. Our data support previous results for their sister family, Miridae, which exhibits some characteristics exclusive to this taxon, not present in Tingidae or other Heteroptera. They also support the sister relationship of the genera Gargaphia and Leptopharsa and suggest closer relationship between Vatiga and Corythucha. Overall, this study sheds light on the sperm ultrastructure of Tingidae and provides information for understanding the evolution and diversity of Heteroptera. RESEARCH HIGHLIGHTS: The spermiogenesis process and mature sperm are similar to other Heteroptera The centriole adjunct is derived from a strip of a pericentriolar material extending from the centriole Tingidae and Miridae are distinguishable using sperm morphology.

Numerical simulations of a magnonic reservoir computer

A numerical model for a spin wave delay-line active ring resonator is presented. Spin wave dynamics along a one-dimensional strip of magnetic material are modeled using the nonlinear Schrödinger equation. The equation is solved numerically in Fourier space using the fourth-order Runge–Kutta method and yields qualitative agreement with experimental measurements of spin wave dynamics in two different regimes. The model provides a useful tool for performing experiments based on neuromorphic computing and logic gates in traveling spin wave devices.

Shape of contact between deformable material and elastic rollers

The study is devoted to the analysis of the contact shape in a symmetrical roll module for the case when changes in the thickness of the material and the roller coating at each point of the contact zone occur in the vertical direction of the strip of material. A mathematical model of the shape of contact between a deformable material and elastic rollers is developed. Particular types of mathematical models of the contact shape are obtained in cases where the material being processed is absolutely elastic, elasticviscous, and plastic. It was revealed that the shape of the contact depends primarily on the geometric and deformation properties of the strip of material being processed and the roller coating, and the deformation rate.

Relation of the stress state in the contact zone and the forces acting in the roller mechanisms

Mathematical models were developed to study the distribution pattern of shear and friction stresses in the roll contact zone. These models establish a relationship between the stress state in the contact zone, the forces acting on the roller mechanisms, and the shape of the roll contact curve in driven and free rollers. The distribution of normal stresses determines the distribution of shear stresses along the contact curve, the compliance of the material strip and the roller coating, and the forces acting on the roller mechanism.

A Device Model for Achieving Sizable and Tunable Tunneling Magnetoresistance Using Two‐Dimensional Materials InX (X = O, Se) without Hetero‐Interface

AbstractThe two‐dimensional (2D) materials InX (X = O, Se), experimentally available thus far, can become a ferromagnetic half metal under hole doping, though the charge neutral states of them are nonmagnetic semiconductors. Based on such an electronic characteristic, a theoretical model of magnetic tunnel junction (MTJ) is proposed composed only of one of the 2D InX. In doing so, the two semi‐infinite pieces of 2D InX in the half‐metallic state is assumed as the opposite electrodes which are separated by a strip of the same material but in its nonmagnetic state. Owing to the 2D nature of InX, the half metal electrodes of the InX device induced by hole doping can be achieved by using split gating technique. The numerical simulations identify a proper hole doping concentration, at which 100% tunneling magnetoresistance (TMR) ratios can be realized, accompanying an appreciable conductance of majority spin electron under parallel magnetization configuration. Under a finite bias voltage, the TMR ratio remains high. Therefore, the proposed device model is an ideal candidate for future spintronics applications. It enables electrical control of TMR and circumvents the detriment of hetero‐interface disorder inevitable in conventional MTJs.

Experimental and simulation study on surface material stripping of glass fiber reinforced composites by baking soda abrasive jetting technology

Glass fiber reinforced composites (GFRP) working in a specific environment require regular inspection and maintenance. It is necessary to remove the surface material of fiber reinforced composites to check the fracture of fibers and the damage to matrix that binds fibers in this process. In this paper, the baking soda abrasive jetting was utilized to strip the surface material of glass fiber reinforced epoxy resin (GFREP). The stripping effects of baking soda abrasive jetting technology under different jetting parameters (fiber orientation, jet angle, jet pressure) were explored, and the optimum stripping conditions were determined as parallel to the fiber, 30°, 0.4 MPa. Compared with the chemical stripping method (phenol-dichloromethane), baking soda abrasive jetting can better retain epoxy resin between glass fibers. The LS-DYNA was applied to simulate the erosion process of a single abrasive particle under the optimum stripping condition. The plastic deformation of the matrix and the slight bending deformation of the glass fiber under abrasive impact were observed.

A Computational Approach for Analysis of Scattering Characteristics for Strips of Resistive Material

A Computational Approach for Analysis of Scattering Characteristics for Strips of Resistive Material

Rectifying Strip Patterns

Straight flat strips of inextensible material can be bent into curved strips aligned with arbitrary space curves. The large shape variety of these so-called rectifying strips makes them candidates for shape modeling, especially in applications such as architecture where simple elements are preferred for the fabrication of complex shapes. In this paper, we provide computational tools for the design of shapes from rectifying strips. They can form various patterns and fulfill constraints which are required for specific applications such as gridshells or shading systems. The methodology is based on discrete models of rectifying strips, a discrete level-set formulation and optimization-based constrained mesh design and editing. We also analyse the geometry at nodes and present remarkable quadrilateral arrangements of rectifying strips with torsion-free nodes.

Laser-induced Bragg resonances in ferrit/semiconductor heterostructure

The paper reports on laser-induced Bragg resonances in the spectrum of magnetostatic waves in a heterostructure based on a ferrite film [yttrium iron garnet (YIG)] with periodic strips of semiconductor material (Si) on the surface. Laser irradiation of such a structure leads to the formation of Bragg bandgaps due to the modulation of the Si conductivity on the YIG surface, and the magnitude modulation increases with increasing laser radiation intensity. It is shown that an increase in laser radiation intensity also leads to an increase in the depth and frequency shift of the bandgaps.

A Simplified Method for the Preparation of Highly Conductive and Flexible Silk Nanofibrils/MXene Membrane.

Silk nanofibers (SNF) have great applications in high-performance functional nanocomposites due to their excellent mechanical properties, biocompatibility, and degradability. However, the preparation of SNF by traditional methods often requires the use of some environmentally harmful or toxic reagents, limiting its application in green chemistry. In this paper, we successfully prepared SNF using natural silk as raw material and solvent stripping technology by adjusting the solvent concentration and solution ratio (the diameter of about 120 nm). Using the above SNFs as raw materials, SNF membranes were prepared by vacuum filtration technology. In addition, we prepared an SNF/MXene nanocomposite material with excellent humidity sensitivity by simply coating MXene nanosheets with silk fibers. The conductivity of the material can approach 1400.6 S m-1 with excellent mechanical strength (51.34 MPa). The SNF/MXene nanocomposite material with high mechanical properties, high conductivity, and green degradability can be potentially applied in the field of electromagnetic interference (EMI) shielding, providing a feasible approach for the development of functional nanocomposite materials.

Experimental Investigation on Effect of Temperature on FDM 3D Printing Polymers: ABS, PETG, and PLA

Four-dimensional printing is a process in which a 3D-printed object is intentionally transformed in response to an external stimulus such as temperature, which is useful when the final geometry of a 3D-printed part is not easily manufacturable. One method to demonstrate this is to print a part made of thin strips of material on a sheet of paper, heat the part, and allow it to cool. This causes the part to curl due to the difference in the thermal expansion coefficients of the paper and plastic. In an attempt to quantify the effect of different temperatures on various materials, samples of three common 3D printing filaments, acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PETG), and polylactic acid (PLA), were heated at different temperatures (85 °C, 105 °C, and 125 °C) for intervals of 15 min and then allowed to cool until curling stopped. This heating and cooling cycle was repeated three times for each sample to determine if repeated heating and cooling influenced the curling. Each sample was filmed as it was cooling, which allowed the radius of curvature to be measured by tracking the uppermost point of the part, knowing the arc length, and calibrating the video based on a known linear length. After three cycles, all three materials showed a decrease in the radius of curvature (tighter curl) as heating temperature increased, with PLA showing the trend much more predominantly than ABS and PETG. Furthermore, for PETG and PLA, the radius of curvature decreased with each cycle at all temperatures, with the decrease being more significant from cycle 1 to 2 than cycle 2 to 3. Conversely, ABS only shared this trend at 125 °C. The findings of this work can provide guidelines to users on the temperature dosage for the mass manufacturing of complex geometries such as packaging, self-assembly robots, and drug delivery applications.

Structural buckling analysis of pre-twisted strips

This article focuses on the buckling response of columns formed by pre-twisting a flat, narrow and straight material strip of a rectangular cross section. The experimental analysis accomplished for birch plywood strips covers twisting up to 90 degrees. The corresponding computational analysis covers the twisting process (geometrically nonlinear analysis) and the subsequent compression (linear buckling analysis, including the residual stresses from the twisting process) and includes comparisons for 3D solid and 2D shell finite elements within orthotropic linear elasticity. A further finite element analysis provides findings up to twisting angles of 400 degrees and includes nonlinear post-buckling analyses for the compression subsequent to twisting, in addition to the linear buckling analyses. These sets of analyses reveal some new findings regarding this classical problem. Most importantly, there are four characteristic twisting angles which are associated to mode jumps in buckling, to a plateau in the curve relating the critical load and the twisting angle and, finally, to a loss of stability during the twisting process. The influence of the twisting-induced stresses on the buckling response is investigated as well.