Variable Thickness Research Articles

A numerical study on the warm deep drawability of polypropylene under differential heating conditions

AbstractWarm deep drawing of polypropylene blanks to form flat‐bottom cylindrical cups under differential heating conditions is numerically investigated using finite element analysis. Differential heating involves heating only the flange area of the blank to an elevated temperature while the punch area of the blank remains at 25°C. The effects of initial flange temperature, blank diameter, blank holder force, punch corner radius and die corner radius on the depth of draw are studied. Comparisons are made between depths of draw obtained in differential heating and homogeneous heating in which the entire blank that includes its flange as well as punch areas is heated to the same temperature. It is shown that significantly higher draw depths can be obtained with differential heating for the cups with sharp punch corner radius of 3 mm and lower. Variations in thickness, temperature and plastic strain in the deep drawn cups, punch forces, and failure modes are also determined.Highlights Differential blank heating gives higher draw depths with sharp punch radius. Draw depth increases with increasing die corner radius. Draw depth increases with increasing temperature differential. Draw depth increases with decreasing blank diameter and blank holder force. In differential heating, blanks fail at die corner instead of punch corner.

Gender-based risk analysis of vehicle control loss due to localized water puddles: an analytical approach

Adverse weather conditions significantly increase the risk of traffic accidents, yet most studies focus on uniform conditions across all tires. This study investigates the impact of asymmetric drag forces when only one tire encounters a local water puddle, causing potential vehicle control loss. Using analytical methods, we calculate drag forces and their transmission to the steering wheel, accounting for variations in water film thickness, vehicle speed, and driver gender. The results indicate that female drivers face higher risks of control loss, with critical speeds decreasing as water film thickness increases. The study highlights that localized water puddles, especially at low speeds and water depths exceeding 3 cm, pose significant risks. These findings can inform road safety guidelines and vehicle design standards to mitigate accident risks in adverse weather conditions.

Hollow-type plasma absorption probe for measurement of electron density in low pressure plasmas: A sheath thickness–insensitive technique

Abstract We propose a hollow plasma absorption probe (PAP) designed to improve the accuracy of electron density measurement in low-pressure plasmas regardless of the sheath thickness on the planar probe surface. This improvement is achieved through an artificial hollow space acting as a thick sheath to bring the resonant absorption frequency (f_PAP) from the hollow PAP close to the surface wave resonant frequency (f_SWR), insensitive to variation in sheath thickness. Electromagnetic simulations confirmed the efficiency of the hollow design, showing a minimized discrepancy between f_PAP and f_SWR even with the thin sheath. Optimal configurations with a coaxial core diameter of 5 mm and a hollow depth of 5 mm were found and tested in plasmas ranging from 〖5×10〗^8 cm^(-3) to 〖5×10〗^10 cm^(-3). Comparative experiments employing a planar cutoff probe to directly measure f_pe demonstrated good agreement between the electron density derived from the hollow PAP and from the planar cutoff probe, compared to that from a conventional planar PAP.

Recurring volcanism in New England region focused by a region of thin lithosphere

The Appalachian Orogen experienced extensive volcanism through the early Paleozoic, as well as around ∼200 Ma. Unlike most of the northern Appalachians, the New England region saw repeated episodes of volcanic activity between 293 and 120 Ma. An anomalous region in the upper mantle beneath New England underlies these distinct volcanic rocks. Low values and lack of anisotropy in seismic velocity imply elevated temperature and suggest sub-vertical flow in the upper mantle. Our new constraints on the depth to the lithosphere-asthenosphere boundary (LAB) show that thinned lithosphere underlies the region of localized repeated anorogenic volcanism in New England. The upper mantle directly beneath the shallow LAB is not unusually warm, while surrounding regions have significantly lower temperatures. Changes in the type of igneous rocks erupted between 150 and 120 Ma, from kimberlites in Ontario to felsic plutons in New England, correlate with variations in lithosphere thickness and imply that these variations existed by 125 Ma. It is also plausible that thin lithosphere is inherited from the time of Appalachian collisions at ∼450 Ma. Our overall conclusion is that the region of presently thin lithosphere beneath New England is unusual and has focused volcanic activity within it since ∼300 Ma.

Numerically predicting deflections of mat-sand interaction model under gravity loadings

This research proposes a novel mat-sand interaction model to evaluate limiting values of sand elastic modulus and super-imposed gravity load for a specific mat thickness to control vertical deflection of mat by using BNBC 2020 prescribed allowable deflection limit. For this reason, the linear elastic analysis is performed by using finite element-based software ETABS v.18.1.1, whereas the impact of sand on the mat is transferred by springs. The difference in results between present and previous studies is obtained to be 1.76%, which may indicate good accuracy of verification of the proposed model with the field study data. The difference in mat vertical deflections between two consecutive sand elastic moduli is obtained to be 7.1%, and it is found to be 32.8% in the case of the mat thickness variations. So, the difference in the case of the sand elastic modulus is reduced by 78.4% compared to the mat thickness. The limiting value of imposed gravity load is found to be 60 kPa for 150 mm mat thickness with a range of sand elastic modulus of (5–25) MPa. Similarly, it is obtained to be 120 kPa in the case of the 200 mm mat thickness for 5 MPa elastic modulus of sand. These findings may help engineers to select suitable mat thickness with corresponding sand elastic modulus and super-structure gravity load.

ATLAS-MAP: An Automated Test Station for Gated Electronic Transport Measurements.

The diversification of electronic materials in devices provides a strong incentive for methods to rapidly correlate device performance with fabrication decisions. In this work, we present a low-cost automated test station for gated electronic transport measurements of field-effect transistors. Utilizing open-source PyMeasure libraries for transparent instrument control, the "ATLAS-MAP" system serves as a customizable interface between sourcemeters and samples under test and is programmed to conduct transfer curve and van der Pauw methods with static and sweeping gate voltages. Zinc oxide transistors of variable thickness (5, 10, and 20 nm) and channel size (50 μm to 3 mm, of equal length and width) were fabricated to validate the design. Standardization of testing procedures and raw data formatting enabled automated data analysis. A detailed list of parts and code files for the system are provided.

Copper Precursor-Driven Variations in Structural, Optical and Electrical Properties of SILAR-Deposited CTS Thin Films

Abstract This pioneering study elucidates, for the first time, the profound impact of copper precursors (copper acetate, copper sulfate, and copper chloride) on the structural, optical, and electrical properties of Copper Tin Sulfide (CTS) thin films synthesized via successive ionic layer adsorption and reaction (SILAR) deposition. Comprehensive characterization using X-ray diffraction (XRD), cross-sectional scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and electrical and optical measurements revealed significant variations in crystallite size (59.3-76.4 nm), film thickness (1.235-4.75 µm), and conductance (3.7-6.4 × 10-11 S). Notably, copper chloride-derived films exhibited enhanced surface morphology, maximum bandgap energy (3.7 eV), and highest conductance, with displaying unique optical properties, including zero transmittance below 300 nm, low absorption above 300 nm, and a balanced absorption profile, making them ideal for photovoltaic cells, optical sensors, and UV-blocking applications. These results demonstrate the critical influence of copper precursors on CTS thin film properties, paving the way for tailored material design and enhanced device performance, with significant implications for the development of efficient and sustainable photovoltaic technologies.

Augmented reality for rhinoplasty: 3D scanning and projected AR for intraoperative planning validation

AbstractRhinoplasty is one of the major surgical procedures most popular and it is generally performed modelling the internal bones and cartilage using a closed approach to reduce the damage of soft tissue, whose final shape is determined by means of their new settlement over the internal remodelled rigid structures. An optimal planning, achievable thanks to advanced acquisition of 3D images and thanks to the virtual simulation of the intervention via specific software. Anyway, the final result depends also on factors that cannot be totally predicted regarding the settlement of soft tissues on the rigid structures, and a final objective check would be useful to eventually perform some adjustments before to conclude the intervention. The main idea of the present work is the using of 3D scan to acquire directly in the surgical room the final shape of the nose and to show the surgeon the differences respect to the planning in an intuitive way using augmented reality (AR) to show false colours directly over the patient face. This work motivates the selection of the devices integrated in our system, both from a technical and an ergonomic point of view, whose global error, evaluated on an anthropomorphic phantom, is lower than ± 1.2 mm with a confidence interval of 95%, while the mean error in detecting depth thickness variations is 0.182 mm.

Trichoscopic Hallmarks in Non-cicatricial and Cicatricial Alopecia in Indian Population: A Narrative Review

Context: Trichoscopy is a non-invasive, bedside diagnostic tool used to classify alopecia. It is instrumental in distinguishing between non-cicatricial (non-scarring) and cicatricial (scarring) alopecia, aiding in disease classification, prognosis, and treatment decisions. This modality reduces the need for skin biopsies by identifying specific trichoscopic patterns that correlate with disease activity, severity, and potential for hair regrowth, especially in cicatricial alopecia. It also helps select biopsy sites in diagnostically challenging cases. Objectives: The review discusses trichoscopy of various forms of non-scarring and scarring alopecia. Methods: The authors searched the literature on non-cicatricial and cicatricial alopecia and their clinical and trichoscopic characteristics in various research databases. Results: Non scarring alopecia includes androgenetic alopecia (AGA), female pattern hair loss (FPHL), telogen effluvium, alopecia areata (AA), tinea capitis, trichotillomania (TTM), and tractional alopecia. In AGA and FPHL, trichoscopy identifies hair thickness variability and signs like yellow dots and vellus hair, which aid in assessing disease severity and surgical candidacy for hair transplants. Alopecia areata shows unique trichoscopic features like exclamation mark hairs and yellow dots, which help gauge disease activity. Tinea capitis and TTM also display distinct trichoscopic markers, facilitating accurate diagnosis without invasive biopsies. In scarring alopecias such as discoid lupus erythematosus (DLE), lichen planopilaris (LPP), and frontal fibrosing alopecia (FFA), trichoscopy reveals inflammation-related features like Perifollicular hyperkeratosis, erythema, and the absence of follicular ostia, guiding treatment and biopsy decisions. It helps distinguish FFA from conditions like AGA and AA by showing characteristic features like concentric Perifollicular erythema and loss of vellus hair. Morphea and pseudopelade of Brocq each display hallmark trichoscopic features. Morphea, in its early stages, responds well to immunosuppressive treatments, whereas pseudopelade of Brocq, being an end-stage condition, shows limited responsiveness to medical interventions. Conclusions: Overall, this review article emphasizes the importance of trichoscopy as a bedside tool for narrowing differential diagnoses and guiding clinical management in various types of alopecia. It highlights the need for ongoing knowledge of trichoscopic signs to facilitate prompt diagnosis and tailored treatment for both non-scarring and scarring alopecia.

Large Deflections, Loss of Stability and Over-Critical Behavior of Sloping Panels and Arches of Variable Thickness on an Elastic Base

The problem of large deflections of a flat arch in its plane (or an infinitely long panel) loaded with transverse loads is considered. A variational approach has been applied to solve it. The resolving nonlinear equations are reduced to finding the deflection and longitudinal force, which is considered constant along the length of the arch due to its flatness. An approximate solution method is proposed by decomposing the displacements into a Fourier series. The peculiarity of the approach used is that in order to pass the limit points, it is not necessary to use special algorithms such as the continuation method by parameter. It also allows you to trace the process of supercritical deformation of the arch. The proposed approach allows us to consider problems for arches of variable thicknesses, located on elastic supports, on an elastic base with a variable bed coefficient and various loads. Therefore, it is also convenient in problems of finding, for example, the optimal thickness distribution under restrictions on critical loads, on rigidity stiffness and on maximum compression or tension stresses. The results of numerical calculations are presented. The convergence is studied of the solution depending on the number of terms of the series, into which the desired deflection decomposes. A good agreement with the known analytical results is obtained earlier by solving the equilibrium equations of the arch element and panel in the case of simple types of loading. At the same time, even in more complex cases of loading and supercritical bending of an arch without an elastic base, the results are obtained when holding three, four and five members of the Fourier series, the maximum deflections and critical loads differed by no more than 2.5%. On the basis of numerical experiments, the features of the arch behavior caused by the rearrangement of geometry during loading are revealed. The processes of stability loss of the arch and its supercritical behavior are investigated. The effect of symmetric deformation in the case of kinematic loading is found, namely, it is revealed that at a certain value of the concentrated force, an infinite number of equilibrium forms are possible. Arches on an elastic base, as well as with variable thickness are considered (the results are presented in the form of load–displacement diagrams and in the form of pictures of deformed arch shapes). An interesting effect has been revealed based on numerical experiments. It turned out that the increase in thickness when moving away from the supports does not change the nature of the load–displacement diagram, i.e., with some load, a slap occurs. On the contrary, a decrease in thickness when moving away from the supports leads to a flattening of the diagram, and after a certain thickness value in the center, its further decrease leads to the fact that the arch does not occur.

Colorimetric changes of zirconia-reinforced lithium disilicate with varied thicknesses under UV aging conditions

Background. Zirconia-reinforced lithium disilicate (ZLD) is a promising material for esthetic dental restorations due to its strength, translucency, and color stability. However, its durability under accelerated aging conditions needs further investigation. The present in vitro study evaluated the effect of UV accelerated aging on the translucency and color stability of ZLD at varying thicknesses, using IPS e.max Press (LD) as a reference. Methods. Seventy-two samples were divided into two groups: high translucent (HT) Vita Ambria (ZLD) and IPS e.max Press (LD) (n=36, each). Each group was further subdivided into four thicknesses: 0.5, 1.0, 1.5, and 2.0 mm (n=9). The samples were fabricated, polished, and subjected to UV weathering for 384 hours, simulating one year of clinical service. Translucency and color changes were assessed using a spectrophotometer. Data were analyzed using SPSS 20, with independent t-test, paired t-test, and one-way ANOVA at a significance level of P≤0.05. Results. Vita Ambria exhibited significantly higher translucency before and after aging compared to IPS e.max press at all thicknesses (P=0.000). In both materials, translucency decreased when the thickness increased (P=0.000), observed before and after UV aging. Vita Ambria also displayed a greater color change (ΔE=2000) compared to IPS e.max press across all thicknesses (P=0.000). Conclusion. ZLD exhibited higher translucency than LD before and after accelerated artificial aging, indicating that the accelerated aging process adversely impacted the optical properties of the tested material. However, LD demonstrated superior color stability.

Design of an Underactuated, Flexure-Based Gripper, Actuated Through a Push–Pull Flexure

Abstract The design of grippers for the agro-industry is challenging. To be cost-effective, the picked object should be moved around fast requiring a firm grip on the fruit of different hardnesses, shapes, and sizes without causing damage. This article presents a self-adaptive flexure-based gripper design optimized for high acceleration loads. A main novelty is that it is actuated through a push–pull flexure that is loaded in tension when the gripper closes, allowing it to handle high actuation forces without the risk of buckling. To create a robust gripper that can handle relatively high loads, flexures are used that are reinforced and have a thickness variation over the length. The optimal thickness distribution of these flexures is derived analytically to facilitate the design process. The derived principles are generally applicable to flexure hinges. The resulting advanced cartwheel flexure joint, as used in this gripper, has a 2.5 times higher support stiffness and a 1.5 times higher buckling load when compared to a conventional cartwheel joint of the same size and actuation stiffness. The PP-gripper is numerically optimized for a high pull-out force, using analytical design insights as a starting point. The gripper can grip circular objects with radii between 30 and 40 mm. The pull-out force is 21.4 N, with a maximum actuation force of 100 N. Good correspondence is found between the geometric design approach, the numerically optimized design, and the results of the experimental validation.

Prediction of Reservoir Properties Using the RDQ Crossplot Workflow

We present the Rotated Distance and Quadrant (RDQ) Crossplot, an innovative alternative to the conventional amplitude versus offset (AVO) analysis using amplitude versus gradient (AB) crossplots. This new display is made possible through integration of the Distance and Quadrant (DQ) trace attribute, and offers significant advantages over traditional methods. The RDQ Crossplot reduces shale datapoint overprinting on wet and gas sand clusters, better separates lithology and pore fluid points, and analyzes all seismic trace samples. Unlike AB crossplots, which require specialized processing and conversion of seismic amplitudes, the RDQ workflow uses readily available near and far partial-stack seismic sections as input, expediting the AVO analysis. An AVO catalog of well log suites and their synthetic modeled seismic traces are used to develop and test new theories, revealing linear trends in RDQ Crossplot displays that correlate to variations in thickness, porosity, lithology, and pore fluid. A new seismic trace attribute, DQOpx, is derived from the RDQ Crossplot and used to better delineate fluid types and augment lithology predictions. We demonstrate a DQOpx seismic display for a dim spot, AVO Class 1 sand model, revealing a hydrocarbon fluid contact not visible on stack seismic sections. Additionally, a Signed Half Isochron preconditioning filter is introduced to distinguish between sand and shale lithologies. The RDQ workflow and Crossplot represent a significant advancement in seismic AVO interpretation and reservoir characterization, allowing for earlier integration of geology, petrophysics, and basin properties.

ФОРМОУТВОРЕННЯ НАМОТУВАННЯМ КОМПОЗИТНОГО ПЕРЕДНЬОГО ГОРИЗОНТАЛЬНОГО ОПЕРЕННЯ ЛЕГКОГО ЛІТАКА

A process has been developed for modeling the trajectory of laying reinforcing material (RM) during the formation of composite aerodynamic surfaces (AS). The work provides a brief description of the types of structures of aircraft of complex shape according to the criterion of the possibility of manufacturing by the winding method, in which certain types of surface shapes are highlighted according to the condition of determining the laying trajectory and developing a winding control program (WCP) for CNC machines. It is shown that the process of developing technology for manufacturing structures such as aerodynamic load-bearing surfaces has significant differences from the process of developing technology for axisymmetric products. The general technique for determining the trajectory of laying reinforcing material is shown and new approaches to specifying the reinforcement pattern are described. The general methodology for calculating the WCP for winding the AS is described. Calculation of the movements of the working parts of a winding machine (WM) includes several subtasks: choosing the order of passage of individual turns of the RM, calculating the movements of the working parts of the WM when laying each turn, and determining the program for transition from turn to turn. It is shown that the most important stage in the development of general-type AS winding technology is the choice of a winding scheme that determines the structural-force diagram (SFD) of the structure. For this purpose, the concept of the limiting point of winding has been introduced. The winding pattern of any type of product can be described by an array of coordinates of boundary points and reinforcement angles. An algorithm for calculating the trajectory of RM placement on the surface of the mandrel is presented. The features of choosing the order of passage of turns are described. The order in which the turns pass affects the number of weaves in the structure of the composite material obtained during the winding process and the strength of the product. The optimal order of passing turns according to the strength criterion is determined experimentally through repeated development tests. The features of choosing programs for transition from turn to turn are described. The algorithm of actions of the WM during the transition from one turn to another - the transition program consists of two programs: the program for entering the turn and the program for exiting the turn. The algorithm of transition programs depends on the chosen order of turns and in each specific case depends on the design features of the product. To test the developed methodology, a test calculation of the front horizontal tail of a light aircraft was carried out. As a result of the work done, it was possible to solve the problem of modeling the RM laying trajectory for bodies of complex shape with a fixed type of section, manufactured by the winding method from a polymer composite material (PCM). This technology can be used to produce aircraft structures such as “wing”, “fuselage” of an airplane, helicopter, and the like. Thus, the possibility of winding a general type AS has been proven using the example of the horizontal front tail of a light aircraft. The range of production of wound products has expanded - bodies with an arbitrary convex section and a straight generatrix. A technology has been developed for manufacturing from PCM by winding non-axisymmetric aerodynamic power structural elements such as aircraft wings, helicopter blades, air and water propellers. A surface reinforcement scheme has been found that makes it possible to obtain a variable wall thickness with its decrease from the root to the end rib. The trajectories of laying reinforcing material on a surface with an arbitrary convex section and the movement of working parts for a three-axis winding machine are determined. The developed calculation method can be used to create various aerodynamic structural elements with positive surface curvature from PCM by winding. The use of advanced high-performance technology for automated winding of reinforcing fiber material provides a significant reduction in labor costs in the manufacture of these units, reducing their prices compared to the prices of existing metal and composite aircraft of comparable size and equipment

Influence of the manufacturing strategy on the microstructure and mechanical properties of Invar 36 alloy parts manufactured by CMT-WAAM

AbstractThe influence of the manufacturing strategy of Invar 36 alloy parts manufactured by Directed Energy Deposition by Arc (DED-Arc) also known as wire and arc additive manufacturing (WAAM) using cold metal transfer (CMT) technology has been investigated. This study focuses on the influence of applying different deposition strategies on the resulting microstructure and mechanical properties. As manufacturing costs and time are critical issues which determine the business case in WAAM applications, it is important to use the smallest possible amount of feedstock material. Therefore, different manufacturing strategies are used to obtain the variable wall thicknesses required for each part preform using WAAM as a manufacturing route. Differences in manufacturing temperature and thermal history due to different deposition strategies have been recorded. Deep microstructural analysis in as-built condition revealed that granular alignment and the crystallographic texture obtained differ between deposition strategies studied. This is the reason why there are differences in the mechanical properties, such as yield strength, ultimate tensile strength, elongation, and hardness, of the different strategies analyzed. The results revealed that the higher strength is obtained in three overlapped weld beads for the walls (514 and 581 MPa in building direction and perpendicular direction, respectively), compared to single weld bead wall (481 and 489 MPa), circular single weld bead wall (460 and 484 MPa), and meandering weld bead wall (467 and 439 MPa). The opposite is true for elongation, which is a typical correlation between strength and ductility in Fe-based alloys, having the highest elongation in the meandering weld bead wall (26 and 30%) and circular single weld bead (30 and 27%) compared to single weld bead wall (27 and 23%) and three overlapped weld bead wall (23 and 20%). It can therefore be concluded that an Invar 36 alloy part manufactured by CMT-WAAM with different strategies will have different mechanical properties, having a difference in ultimate tensile strength of 54 MPa and 142 MPa, and in elongation of 7% and 10% in building direction and perpendicular direction, respectively, between the most and the least resistant zone.

Variation of Packing Densities and Liquid Film Thicknesses in Alkali Solution and Water in Natural Pozzolan Calcium Hydroxide Pastes and Mortars

The characteristic properties of concrete depend on the quality of mortar. In order to improve the properties of hardened concrete, the mortar needs to have good performance. The property of mortar is affected by wet packing density, liquid film thickness, type and quality of binder, gradation of fine aggregates, and binder-to-fine-aggregate ratio. The commonly used alkali solutions to produce polymer mortar and concrete are cursed by carbon dioxide emissions. This study used alkali solution and water to investigate the variation of packing densities and film thicknesses on paste and mortar mixes. of natural pozzolan and calcium hydroxide at a ratio of 75P25CH and standard sand. The standard proctor compaction tools and procedures were adopted to attain the maximum values of packing density of 0.937 for mortar mixed with alkali solution, 0.919 for mortar mixed with water, 0.906 for paste mixed with alkali solution, and 0.829 for paste mixed with water. For the case of film thicknesses, the optimum values obtained were 0.548 μm for mortar mixed with alkali solution, 0.248 μm for mortar mixed with water, 0.398 μm for paste mixed with alkali solution, and 0.09 μm mixed with water. The results indicate that alkali solution produced higher packing density and liquid film thickness than water for both paste and mortar, and the packing density and liquid film thickness increase with the increase of the number of compacting blows with 9 blows to 36 blows. The study recommends the establishment of standard compaction effort and procedure.

Trends and drivers of hypoxic thickness and volume in the northern Gulf of Mexico: 1985-2018.

Hypoxia is a major environmental issue plaguing the commercially and ecologically important coastal waters of the northern Gulf of Mexico. Several modeling studies have explored this phenomenon, but primarily focus on the areal extent of the mid-summer hypoxic zone. Research into the variability and drivers of hypoxic volume and thickness is also important in evaluating the seasonal progression of hypoxia and its impact on coastal resources. In this study, we compile data from multiple monitoring programs and develop a geospatial model capable of estimating hypoxic thickness and volume across the summer season. We adopt a space-time geostatistical framework and introduce a rank-based inverse normal transformation to simulate more realistic distributions of hypoxic layer thickness. Our findings indicate that, on average, there is a seasonal lag in peak hypoxic volume and thickness compared to hypoxic area. We assess long-term trends in different hypoxia metrics (area, thickness, and volume), and while most metrics did not exhibit significant trends, mid-summer hypoxic thickness is found to have increased at a rate of 5.9 cm/year (p<0.05) over the past three decades. In addition, spring nitrogen load is found to be the major driver of all hypoxia metrics, when considered along with other riverine inputs and meteorological factors in multiple regression models. Hypoxic volume, which was also often influenced by east-west wind velocities, was found to be more predictable than hypoxic thickness.

Investigation of mechanical responses of flexo-magnetic variable thickness nanoplates resting on elastic foundations, taking into account geometrical imperfections

Investigation of mechanical responses of flexo-magnetic variable thickness nanoplates resting on elastic foundations, taking into account geometrical imperfections

An Artificial Neural Network Prediction Model of GFRP Residual Tensile Strength

This study uses an Artificial Neural Network (ANN) to examine the constitutive relationships of the Glass Fiber Reinforced Polymer (GFRP) residual tensile strength at elevated temperatures. The objective is to develop an effective model and establish fire performance criteria for concrete structures in fire scenarios. Multilayer networks that employ reactive error distribution approaches can determine the residual tensile strength of GFRP using six input parameters, in contrast to previous mathematical models that utilized one or two inputs while disregarding the others. Multilayered networks employing reactive error distribution technology assign weights to each variable influencing the residual tensile strength of GFRP. Temperature exerted the most significant influence at 100%, while sample dimensions had a minimal impact at 17.9%. In addition, the mathematical model closest to the proposed was the Bazli model, because the latter depends on two variables (thickness and temperature). The ANN accurately predicted the residual tensile strength of GFRP at elevated temperatures, achieving a correlation coefficient of 97.3% and a determination coefficient of 94.3%.

Using X-ray Microscopy to Probe Failure Mechanisms in Anode-free Cells: An Industry Perspective

To meet the energy demands of future electric vehicle technologies, batteries with ever-increasing energy densities are desired. One promising technology is an anode-free lithium metal battery (AFLMB) cell, where lithium ions are deposited directly on the anode current collector, resulting in more energy dense cells relative to the current state-of-the-art lithium-ion battery cell. Nevertheless, anode-free cells are prone to early capacity degradation and cell failure. To better understand the degradation mechanisms in these devices, we present a methodology for assessing microstructural changes in battery cells that can be easily implemented within existing battery manufacturing facilities. We employed X-ray tomographic imaging and analyses on small format, AFLMB pouch cells. Anode thickness variations were characterized non-destructively by housing the pouch cells in fabricated pressurized jigs during both cycling and tomographic imaging. Additionally, we present a technique to measure cathode porosities and tortuosities at the end-of-life (EOL) with higher resolution X-ray imaging. The proposed methodology is able to accurately reproduce known microstructural behaviors in AFLMBs. At the anode, significant thickness changes are observed because of continuous electrolyte degradation and solid electrolyte interphase growth. At the cathode, large porosity changes are detected at the EOL, potentially owing to NCM (LiNixCoyMnzO2) particle cracking.