Variable Thickness Research Articles

Analysis of Thickness Variation in 2219 Aluminum Alloy Ellipsoid Shell with Differential Thickness by Hydroforming

The process of spinning and machining for heavy plates has the problems of a large amount of machining, large springback, and easy cracking. Aiming to address these issues, we proposed a deep drawing forming method for a plate with differential thickness to manufacture an integral ellipsoid component with a thin zone in the middle and a thick zone in the periphery. The plate with a differential thickness was initially produced through machining, followed by the execution of deep drawing deformation. During the deformation process of plates with differential thickness, the thin zone is prone to rupture defects. Therefore, a hydroforming method utilizing an elastic auxiliary plate was adopted to solve this problem. Through mechanical analysis and deep drawing experiments, the influences of hydraulic pressure and elastic auxiliary plate on the distributions of thickness and strain were studied, and the influence of friction on hydroforming was analyzed. The results indicate that increasing the hydraulic pressure and setting elastic auxiliary plates can increase the interfacial friction, reduce the thickness thinning rate, and improve the thickness distribution and deformation uniformity within the thin zone. When the hydraulic pressure is 5.2 MPa and the thickness of the elastic plate is 5 mm, the maximum thickness thinning rate of the ellipsoid shell is 8.8%, which is 34% lower than that of the ellipsoid shell obtained via conventional deep drawing.

Manipulating localized geometric characteristics in multistable energy-absorbing architected materials

Optimizing global geometric features of unit cells and their spatial arrangements have been well studied in multistable energy-absorbing architected materials (MEAMs), yet their optimized geometries could lead to highly complex features that require expensive additive manufacturing techniques. In this study, we introduce a generalized design strategy to adjust localized thickness variation of thin curved beams in MEAMs. We numerically identify the optimal non-uniform modulation parameter for maximizing energy trapping capacity across MEAM cells, arrays, and cylinders. Then, quasi-static compression and drop impact tests on MEAM cylinders with non-uniform designs are conducted to prove the proposed method's effectiveness in achieving equivalent energy-absorbing abilities with the same material consumption. Overall, we believe that our easy-to-implement strategy can be applied to any type of MEAM with slender beam elements and embedded into energy-absorbing devices and structures.

The Influence of Variable Thickness in Two Directions on the Stability of Cracked FG Plate on Pasternak Foundation

The Influence of Variable Thickness in Two Directions on the Stability of Cracked FG Plate on Pasternak Foundation

The modeling of acoustic black hole beam by spectral element method

A technique developed in recent decades for the passive control of vibrations and noise is the Acoustic Black Hole (ABH). The structural ABH effect is achieved by incorporating a local modification in the thickness of a thin structure, typically a beam or a plate, with a variation in thickness according to a spatial power law. The combination of the variation in the thickness power law and a local increase in damping, provided by the concomitant application of layers of viscoelastic material, produces a significant reduction in the wave propagation speed and an increase of attenuation properties. As an elastic wave propagates within an ABH, its propagation speed decreases smoothly and continuously, in theoretical case, when the structure's thickness disappears at the end of the ABH, the wave speed drops to zero. For practical applications, ABH is typically combined with dissipative materials to obtain significantly higher structural loss factors. This work aims to establish a numerical approach for modeling and designing a beam-type structural one-dimensional ABH device for vibration control device using the Spectral Element Method (SEM) and verified by the Finite Element Method (FEM). Examples are performed, and the results are compared with those found in the literature.

Digital Twin Model of Paper-Aluminum Laminates for Sustainable Packaging.

The proposed integrated experimental and simulation study focuses on the mechanical behavior and failure analysis of coupled paper-aluminum (paper-Al) laminates for sustainable packaging. The research employs an innovative experimental approach combining uniaxial loading with in situ visualization of sample deformation. The acquired experimental data are utilized to validate a simulation model, ensuring its accuracy and reliability. Parametric studies conducted through the finite element model further enhance our understanding of the mechanical behavior of the coupled laminates. Specifically, the study investigates microscopic mechanisms influencing the overall response of laminates in both the machine direction (MD) and the cross-machine direction (CD), presenting a comparative analysis with traditional aluminum-polyethylene (Al-PE) laminates, which is a prevalent choice in the packaging industry. The findings contribute to a better comprehension of key factors affecting the mechanical behavior of paper-Al laminates, enabling the design of more effective and sustainable solutions for the packaging industry. Results indicate the advantage of increasing the laminate thickness in the MD, demonstrating an enhanced strength. Conversely, the sensitivity of the thickness variation in the CD is found to be less pronounced. Additionally, our investigation highlights the substantial potential of paper-based materials as environmentally friendly alternatives, particularly in contrast to Al-PE laminates. Furthermore, integrating an innovative digital twin model, which combines experimental data and simulation, significantly advances our understanding and application of laminated in the context of paper packaging design.

Study on solidification and heat transfer of billet shell in a new-structure high-speed continuous casting mold

In this work, a three-dimensional finite element model of a newly structured high-speed continuous casting mold was established to study the heat transfer and solidification process of the billet shell. A complete billet shell, from the meniscus to the secondary cooling zone, was obtained through flame cutting. Using both simulations and test verification, detailed analyses were conducted on the temperature field distribution, thickness variation law, and cooling rate law of the billet shell within the mold, revealing its solidification behavior. Additionally, the effects of casting speed, molten steel superheat, and mold taper on the solidification behavior of the billet shell were discussed. Results showed that the simulation data were basically consistent with the test verification results. Within 200 mm from the meniscus, the heat dissipation accounted for three-quarters of the mold's total heat dissipation. The cooling rate at the corners of the billet shell was slightly higher than that at the sides. Between 200 mm and 400 mm from the meniscus, air gaps caused the temperature at the corners of the billet shell to rise. Afterwards, the whole billet shell eventually reached a similar the heat dissipation rates. The thickness of the billet shell increased exponentially within 110 mm from the curved meniscus, and from 110 mm to the exit of the mold, the thickness increased linearly but slowly. The effect of molten steel superheat within a range of 10 °C on billet shell solidification was relatively minor. Increasing the casting speed reduced the billet shell thickness and raised the billet shell surface temperature. However, increasing the taper of the mold had the opposite effect. Both adjustments shifted the gap formation position backward.

Geometrically nonlinear vibrations of plate embedding a large circular acoustic black hole

The concept of acoustic black hole (ABH) designates a decrease in bending stiffness and a localized added damping within a thin structure aiming to localize and efficiently dissipate vibrations. The small thickness results in large amplitude vibrations, which suggests to take into account geometrical nonlinearities. The subject has been previously studied on a beam with a one dimensional ABH. Previous research studied a geometrically nonlinear plate embedding a one dimensional ABH. This study aims at solving the Von Karman equations for a variable thickness plate, via a modal projection using the eigenmodes obtained with a finite element model. The use of a finite element model in this context allows to take into consideration more complex geometries. The methodology is then applied to a rectangular plate embedding a large circular ABH with added damping. The convergence of the nonlinear coefficients is studied and time domain computations show the relative importance of the geometrical nonlinearity.

Comparison of visual acuity outcome and choroidal thickness variation of intravitreal ranibizumab injection for myopic choroidal neovascularization with or without dome-shaped macula

BackgroundTo investigate the visual acuity outcome and choroid thickness (CT) change after intravitreal ranibizumab in highly myopic eyes with or without dome-shaped macula (DSM) in Chinese patients. MethodsThis retrospective, observative study included 80 treatment-naive eyes (80 patients), which received ranibizumab according to the 1+PRN protocol. The best corrective visual acuity (BCVA) and CT change were compared between eyes with or without DSM. ResultsThere was no significant difference between eyes with or without DSM in BCVA and central macular thickness (CMT). The recurrent rate was not different between the two groups during the first year of treatment. The CT was significantly thinner in eyes with DSM than in eyes without DSM before treatment (median 40.00um versus 71.00um), at 1 month after treatment (median 31.00um versus 65.50um), and in the last follow up (median, 32.00um versus 65.00um) (p = 0.0101). Axial length (AL) was longer in eyes with DSM than those without DSM (median, 29.17 mm versus 28.10 mm) before treatment, and in the last follow up (median, 29.44 mm versus 28.20 mm) (p = 0.0055). The CT was significantly correlated with AL (p < 0.0001). ConclusionsNo difference was found in visual outcome between eyes with or without DSM. The visual acuity significantly improved at 1 month after ranibizumab injection and it was recovery sooner in extrafoveal choroidal neovascularization (CNV) group than in subfoveal CNV group. The CT was thinner in eyes with DSM, which was significantly correlated with AL.

B-064 Bovine Serum Albumin Coats Silicon Dioxide More Uniformly Near its Isoelectric Point Based on Atomic Force Microscopy Analysis

Abstract Background Bovine serum albumin (BSA) serves as a blocking agent in in-vitro diagnostic (IVD) applications, with fatty acid stabilized (FAS) and fatty acid free (FAF) BSA as common options. The presence of fatty acids and pH influence the conformation of BSA. While previous studies have explored the individual effects of fatty acids or pH on BSA blocking, limited data exists on their combined impact. This study employs atomic force microscopy (AFM) to investigate how pH and fatty acids jointly affect BSA adsorption onto silica, a surface relevant within diagnostics. Methods AFM, a sensitive microscopic technique, provides topographic images of surfaces with superior resolution compared to optical microscopy. We conducted experiments to assess the adsorption of 1% FAS and FAF BSA on a silica surface at pH 5.2 and pH 7. Evaluation of the coatings involved scratching to assess overall thickness, and roughness, indicating thickness variability. Results Results revealed that both fatty acids and pH play significant roles in shaping the BSA coating characteristics on silica surfaces. In three out of four experimental conditions, the average thickness of the BSA coating ranged between 3-4 nm, except for FAS BSA at pH 7, which exhibited a thicker average coating measuring 5.6 nm. The pH impacted the roughness of the BSA coating. Coatings prepared at pH 5.2 displayed smoother surfaces compared to those at pH 7. Utilizing the root mean square average height variability analysis, there is 95% confidence that the FAF and FAS BSA surfaces at pH 5.2 had a height range between 2.4-4.3 nm and 2.0-4.9 nm, respectively, indicating complete coverage of the silica surface without much height variation. In contrast, the FAF and FAS BSA coatings at pH 7 exhibited a wider range of heights, with 95% confidence intervals spanning from -1.5-8.6 nm and 0.0-11.2 nm, respectively. This variability suggests potential issues including incomplete BSA coverage at the lower range, and steric hindrance at the higher end, highlighting the importance of pH in optimizing BSA coatings for various applications. Conclusions Silica is commonly used in IVD assays, with BSA frequently employed to coat and passivate the surface. Our AFM experiments highlight the impact of pH and fatty acid presence on coating thickness and uniformity. Notably, FAS BSA at pH 7 exhibited the thickest coating; however, its increased roughness may pose challenges in IVD applications due to steric hindrance blocking antibody-antigen interactions. Alternatively, FAF BSA at pH 7 displayed an adequate thickness but also considerable roughness, suggesting potential insufficiencies in surface coverage and passivation. FAS and FAF BSA coatings at pH 5.2 showed relatively consistent thickness, indicating a more uniform surface which may be ideal for IVD coating applications. These AFM experiments were conducted on pure silica surfaces, which may differ from surfaces engineered for IVD. Additionally, both FAF and FAS BSA grades are proven to be effective in IVD applications. Further research employing AFM and other biophysical techniques is warranted to deepen our understanding of pH and fatty acid effects on BSA-surface interactions, aiming to enhance blocking strategies in IVD.

Effect of thin film thickness of ferrofluid on inclined bioconvective flow

This research examines the effect of variable thin film thickness on the bioconvective ferrofluid flow through a rotating sloped surface when a magnetic field (dipole) is present. Similarity transformation is used to standardize the current model's governing equations. By using a finite element method, the normalized nonlinear differential equations are numerically solved. Variable thickness of ferrofluid thin film and bioconvective parameters (bioconvective Lewis number, bioconvective Peclet number, and micro-organism concentration difference) yield the following results: velocity profiles (radial, tangential, and axial), gravity flow (drainage velocity and induced velocity), temperature profile, concentration profile and microorganism profile. In addition, this investigation examines the density of moving microorganisms as well as local heat and mass transport. The temperature, concentration, radial, axial, drainage, induced, and motile microbe velocity are all improved with increasing film thickness. Variable thickness increases local heat transfer whereas increasing Brownian motion and thermophoresis parameters decreases it. This study could be helpful for self-sterilizing applications and biomedical engineering.

CFD studies into frictional effects of ship coatings to enhance condition monitoring & increase efficiency

Abstract Managing biofouling on ship hulls is essential for reducing CO2 emissions in the shipping industry. Biofouling, characterized by the accumulation of organisms on hulls, escalates surface roughness and hydrodynamic drag, subsequently increasing fuel consumption and CO2 emissions. In response, AkzoNobel, Royal Philips, and Damen Shipyards are developing a fouling prevention technology that utilizes Ultra Violet Light Emitting Diodes (UV-LEDs). The use of an array of multiple UV-LED tiles may lead to non-uniformities from gaps between tiles, potentially increasing frictional resistance due to variations in thickness and surface roughness at the tile joints. This study examines the impact of these non-uniformities on skin friction through simulations using the commercial Computational Fluid Dynamics (CFD) software, Star-CCM+. The analysis highlights effective jointing methods that minimize drag forces by optimizing gap-filling techniques, thus comparing favourably to traditional coatings. The findings contribute significantly to advancing a UV-C hull fouling prevention system, promising reduced environmental impacts and enhanced operational efficiency in the shipping industry.

Buckling analysis of PMMA hemispherical pressure shells with thickness variation

The buckling behaviour of polymethyl methacrylate (PMMA) hemispherical pressure shells under uniform external pressure was investigated experimentally and numerically. Six PMMA hemispherical pressure shells were prepared via the free blow-forming process. The geometry and wall thickness of each hemispherical shell were measured. The collapse loads and final failure modes of all shells were obtained via a hydrostatic pressure device. In addition, through optical 3D scanning, a numerical model of the hemispherical shell that reflects the actual geometric imperfection was established and used in the finite element buckling analysis. The numerical results were in agreement with the test results. These findings provide a reference for evaluating the buckling load of PMMA hemispherical shells prepared via the free blow-forming process.

Optimization and characterization of a dose-controllable orodispersible dexamethasone film for personalized medicine

Decadron® tablets are commercially available in 0.5 and 4 mg formulations, often requiring the use of multiple tablets or fractional doses when the required dosage is unavailable. This practice can lead to inaccuracies and handling difficulties associated with tablet splitting and crushing tablets into powder. This study aimed to develop an orodispersible dexamethasone film that would allow precise dose control and overcome these challenges. The film formulation was optimized by dissolving varying amounts of hypromellose, glycerol, and dexamethasone in ethanolic solutions. These solutions were cast and dried at different thicknesses. Statistical optimization using the design of experiments was used to determine the ideal film composition. The optimized films met pharmaceutical standards, with a mass variation ≦ 2 %, thickness variation ≦ 2.5 %, and disintegration time ≦ 20 s. The uniform distribution of dexamethasone within the film enabled easy content control based on the film area. Dissolution testing indicated that the dissolution behavior of the film formulation behaved similarly to commercial tablets for up to 90 min. In conclusion, the developed orodispersible film offers precise dexamethasone dose control and addresses the limitations of tablet splitting, positioning it as a promising candidate for personalized medicine applications.

Data-driven investigation of thickness variations in multilayer thin film coatings

Abstract Design and fabrication of multilayer thin film coatings for photonics applications require careful consideration of various parameters such as layer thickness, refractive indices and number of stacks. A growing trend uses machine learning for efficient navigation in the complex parameter space of photonics applications to efficiently extract valuable insights from the extensive datasets and to predict the optical performance. We developed an approach that combines Monte-Carlo and Finite-Difference Time-Domain simulations to model multilayer thin films. After conducting 95 200 runs, the data were analyzed using Neural Network fitting to explore how thickness variations influence the optical performance. An experiment validation on magnetron sputtered coated samples demonstrates the high accuracy of our method in predicting the optical performance of the thin film stacks (R 2 &gt; 0.99), contributing to the understanding and enhancement of photonics stack properties for diverse optical applications using machine learning approaches.

Thermodynamic and Dynamic Variations in Sea Ice Thickness of the Ross Sea, Antarctica, Driven by Atmospheric Circulation

AbstractAtmospheric circulation has significant impacts on sea ice drifting patterns and mass balance, as wind drag induces pressure ridges and leads on the sea ice surface. In this study, the spatiotemporal distributions of these dynamic sea ice deformation features in the Ross Sea are examined using ICESat‐2 (IS2) ATL10 freeboard data (2019–2022). The temporal variation of the modal sea ice thickness (SIT), caused by thermodynamic ice growth and sea ice advection, varies from 0.7–1.0 m in April to 1.0–1.6 m in July–September and decreases thereafter in the northwest (NW) and northeast (NE) sectors. This temporal variation of modal SIT agrees with the air temperature (correlation coefficients &gt;0.5). The southwest (SW) sector shows a consistently low modal SIT (&lt;1.0 m) because of the production of new ice in polynyas and continuous northward sea ice drift. Meanwhile, the southeast (SE) sector shows the thickest ice in Octobers 2019 and 2020 because of the advection of thick ice from the Amundsen Sea, which was reduced in 2021 and 2022. In terms of dynamic sea ice deformation, the SE sector shows the largest deformation because of the wind‐driven convergence of sea ice movement. However, such intense deformation in the SE sector diminished in 2021 and 2022 due to the dominance of strong southerly wind associated with the Amundsen Sea Low (ASL). This study emphasizes the potential of IS2 sea ice products to assess the role of atmospheric driving forces on thermodynamic and dynamic sea ice changes.

Natural geometrical variations of Italian Phyllostachys edulis bamboo culms for construction purposes

Amid the increasing scarcity of raw materials, utilizing bamboo as a renewable building material offers significant environmental and economic benefits for the European construction sector. However, in Europe, the use of bamboo for construction remains limited due to a lack of studies on geometrical and material characteristics of European-cultivated bamboo species. Although bamboo is not typically grown in Europe, the number of bamboo plantations is steadily increasing in countries like Spain, France and Italy. Bamboos growing in temperate climates, however, are exposed to different environmental conditions during growth compared to bamboos from subtropical and tropical climates, such as those in China or Vietnam. As bamboo’s geometric properties are strongly influenced by the environmental conditions during growth, it is essential to investigate how bamboo culms of the same species grown in Europe compare to those from other regions. The present article reports findings on the geometry and geometric imperfections of 90 four-meter Italian bamboo culms. First, the Italian Phyllostachys edulis bamboo culms examined in this study are briefly introduced. Following, geometric imperfections of bamboo culms are defined, and the geometry measurement concept is presented. Subsequently, variations in internode lengths, diameters, wall thicknesses, ovalities, stem tapers and pre-deflections are described and analyzed. Finally, the findings from the Italian culms are compared with those from Asian Phyllostachys edulis. In summary, this article enhances the understanding of the geometric properties of bamboo grown in Europe, thereby advancing the use of cultivated bamboo culms in Europe and improving the overall understanding of bamboo characteristics across different climatic zones.

Topology transition description of horseshoe vortex system in juncture flows with velocity characteristic lines

Particle image velocimetry and numerical simulation results of juncture flows were analyzed to parametrically investigate topology transition. The vortex system evolutions from non-vortex to multi-vortex with variations in obstacle bluntness, obstacle width, flow velocity and boundary layer thickness are discussed from the perspective of velocity characteristic lines. The velocity characteristic lines of u=0, v=0, and ∇2v=0 are adopted to describe the vortex system evolution. The motions of the characteristic lines with juncture flow parameters are described in detail, and the corresponding reflections of the vortex system patterns are illustrated. A panoramic picture of the development of velocity characteristic lines corresponding to the HSV topology transition from a non-vortex to a multi-vortex system with variations in the juncture flow parameter is established. Two methods for determining the attachment/separation pattern of the most upstream singularity are proposed. One method is based on the number of intersections of the u=0 and v=0 velocity characteristic curve lines, and the other is based on the relative positions of the most upstream feet of the u=0 and v=0 loop curves with both feet attached to the wall.

Morphospace of lanternfish larvae and their interplay with oceanographic conditions from the southeastern Pacific Ocean

Lanternfish larval morphology is highly variable probably due to their adaptations to highly variable environmental conditions throughout ontogeny. To study the morphological variability of the larval stage of lanternfishes, samples were collected from the southeast Pacific Ocean between 2014 and 2022. Of the 24 species, nine belonged to the subfamily Lampanyctinae, two to the subfamily Diaphinae, one to the subfamily Notolychinae, one to the subfamily Gymnoscopelinae and 11 to the subfamily Myctophinae. A principal component analysis indicated the presence of body shapes varying from a slender and curved body, and upper jaw oriented downwards, with relatively rounded eyes, to taxa with robust bodies, particularly both the head and trunk, and elongated eyes in a dorsal-ventral plane (PC1 33%). Also, specimens varied from having short jaw, short snout, and slender body, to specimens with larger jaw (reaching behind the eye) and taller snout and trunk (PC2, 23%). Allometric effects were related to variations in body curvature and thickness (Diaphus theta, 12.9%), the curvature of the body and position of the eyes (Lampanyctodes hectoris, 25.1%), lengthening of the jaw and increase in eye size (Diogenichthys atlanticus, 24.6%), and a narrower body and smaller eyes (Hygophum bruuni, 20.5%). Four of the five subfamilies showed covariation between morphometrics and environmental conditions. Diaphinae, Gymnoscopelinae and Lampanyctinae body shape covaried with mean sea temperature of the water column, while Myctophinae larval shape covaried with mean salinity. In conclusion, this study quantifies shape variations during early lanternfish ontogeny from the southeastern Pacific Ocean, identifying main differences and allometric changes between the subfamilies belonging to Myctophidae, with a covariation between the shape of most lanternfish larvae and the environmental conditions experienced by myctophid early stages.

Subsurface basement structures of Usangu basin, East African rift system, with implications for basin structural configuration and hydrocarbon potential

The Usangu basin is a rift basin developed along the Eastern arm of the East African rift system trending in the NE-SW direction. Although the general structures of the basin have been well studied, the structural configuration of the basin and the spatial and depth variations of sediment thickness are still not well known. This study investigates the structures in relation to basement configuration and the variation of sediment thickness within the basin using the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM), aeromagnetic and gravity data. Results from DEM data indicate a few lineaments on the basin flanks representing the Usangu and Chimala border faults with no structures in the central part of the basin. The aeromagnetic and gravity data highlight three sets of normal and strike-slip faults, most of which trend NE-SW and others NNE-SSW, while a few trend WNW-ESE or NW-SE. Structures on the southwest of the basin reveal complex patterns attributed to the concentration of important tectonic and seismic activities in the study area. The Euler deconvolution and gravity models used to calculate the depth to the basement show that the basement is shallow in the north and south to southwest, and the basin deepens in the northeastern, northwestern and western parts. The findings also reveal that the basin has two grabens, troughs, depression and intrabasinal basement trending in the same direction as the basin configuration. The general thickness of sediments filling the basin ranges from 3 to 4.5 km, with the maximum accumulation of sediments reaching up to 4.8 km in the two depocenters at the south and southwest of the basin. The depth range of the sediments obtained implies that the basin has potential for hydrocarbon exploration with the possibility of natural gas occurrence.

Optimizing single crystal diamond mosaic growth: A study on seed thickness variation and pre-growth treatment

The limitations on the size of single-crystal diamond applications still need to be addressed for practical use. This study systematically investigates the impact of variations in seed crystal thickness and pre-growth treatments on step bonding, defect formation, and stress distribution in the mosaic growth of single-crystal diamond films. The findings suggest that variations in seed crystal thickness within 50 μm result in a smooth mosaic junction and high crystal quality, while a 100 μm variation results in noticeable defects and stress concentrations, hindering adequate bonding. Pre-growth treatment improves crystal quality by reducing polycrystalline formations and stress concentrations. Optical microscopy and Raman mapping confirm that pre-growth treated mosaic regions exhibit smooth steps and seamless bonding, with FWHM values between 3 and 5 cm−1, consistent with the quality of non-mosaic growth regions.