Geometry Shape Research Articles

Tire-Pavement Interaction Noise: Recent Research on Concrete Pavement Surface Type and Texture

Several solutions have been proposed for quieter riding surfaces, including porous pavements, tining, and grinding. This paper deals with certain aspects of a recent large-scale research that has been carried out to examine the influence of cement concrete pavement surface type and texture on noise generation. One pavement surface type (Enhanced Porosity Concrete – EPC), and one surface texturing method (transverse tining) is dealt with in detail in this paper. Experimental studies to ascertain the physical (porosity and pore size), mechanical (strength), and acoustical (acoustic absorption using impedance tube) properties of EPC are discussed. It is shown in this paper that, with careful selection of aggregate gradation and cementing materials content, it is possible to generate a system of optimally-sized pores in the material to maximize acoustic absorption. Mathematical modeling of noise to evaluate the influence of transverse tine geometry (depth, width, and shape) on noise reduction characteristics is explained in the second part of this paper. A mathematical model has been used to determine the stress distribution between the concrete pavement and the tire. The stress distribution model is used to describe the stress and ultimately noise generated by various geometries of tining patterns. Experiments on Tire-Pavement test apparatus are also discussed.

Numerical analysis on heat transfer enhancement of Al2O3 and CuO-water nanofluids in annular curved tubes

The present investigation presents numerically the thermo-hydraulic performance of annular curved tubes in the turbulent flow region. The three-dimensional (3D) computational fluid dynamic (CFD) model was developed by using a commercial ANSYS 14.5 package to get additional insights on the thermo-hydraulic performance on a level of detail that is not always available in experiment results. The turbulent k-ε realize model was employed to examine the effect of Al2O3-water and CuO-water nanofluids on the heat transfer and fluid flow characteristics at different key design parameters. Three coil geometry shapes (including helical, spiral, and conical), five annular cross-section shapes (including circular, elliptical, square, rectangular, and triangular), and three cross-section areas were also investigated in this study. The numerical simulations were carried out at Reynolds numbers of 4700 to 26,700 and nanofluid volume concentrations, φ of 1%, 3%, and 5%, with constant wall temperature (CWT) heat transfer boundary conditions. The result showed that the addition of Al2O3 (45 nm) and CuO (29 nm) nanoparticles to water improves the heat transfer coefficient by 48.8%, 25.7%, and 8.4% and 37.1%, 20%, and 8.7%, respectively, at φ of 5%, 3%, and 1%, while the penalty of pressure drop is approximately negligible. The heat transfer rate per unit pumping power for helical design achieved 21.6% and 5.34% higher than conical and spiral designs, respectively, for the same curvature ratio, cross-section area, and coil length. Also, the circular shape achieved a higher heat transfer enhancement than elliptical, square, rectangular, and triangular shapes by 4%, 14.6%, 17.8%, and 30.1%, respectively. The maximum thermo-hydraulic performance index reached 1.68 and 1.58 for both Al2O3-water and CuO-water nanofluids, respectively, at φ of 5%.

Effects of Cover-Plate Geometry on the Mechanical Behavior of Steel Frame Joints with Middle-Flange and Wide-Flange H-Beams

This study investigates the mechanical behavior of cover-plate reinforced connections in steel frames with I-section columns and middle- or wide-flange H-beams, addressing gaps in current design standards. Finite element analyses validated by experimental data were employed to explore the effects of cover-plate geometry—shape, length, and thickness—on seismic performance. Results demonstrate that cover plates improve load-bearing capacity and ductility by relocating plastic hinges outward from joint regions. Specifically, cover-plate connections increased ductility by 25%, yield moment by 15%, and initial rotational stiffness by 7% compared to non-reinforced connections. The shape of the top cover plate had minimal impact on mechanical behavior. The cover-plate length and thickness significantly influenced seismic ductility and load-bearing capacity. The cover-plate thickness should be at least 0.3 times the beam flange thickness (not less than 6 mm) while ensuring the combined thickness of the cover plate and beam flange does not exceed the column flange thickness. These recommendations address the conservatism of existing standards, balancing material efficiency and seismic performance. Optimal cover-plate lengths of 0.7 to 0.9 times the beam depth were also identified. These findings provide practical guidelines for designing resilient steel frame connections in seismic regions.

Influence of Powder Feed Density on Mechanical Properties and Microstructure in L-DED Additive Manufactured STS316L

Laser Directed Energy Deposition (L-DED) is a notable additive manufacturing method in which metal powder is sprayed through a nozzle and then consolidated layer by layer using a laser. Unlike other additive manufacturing processes, DED has fewer constraints on the size of the fabricated parts, making it advantageous for the production of large-scale components. However, the use of DED in additive manufacturing requires careful optimization of various process parameters, including laser power, powder feed rate, nozzle scanning speed, and deposition path, as these parameters significantly influence the geometry and properties of the fabricated parts. Recent studies have extensively investigated the microstructure and properties of parts fabricated via DED at different energy densities, but research on variables related to powder feed is still lacking. In this study, using Powder Line-Density (PLD) as a parameter, changes in bead geometry, microstructure and mechanical property followed by variation in powder feed density while conducting DED additive manufacturing with STS316L were observed. Controlled by powder feed rate and scanning speed, the Powder Line-Density was utilized for 1-line deposition with STS316L alloy powder, enabling the observation of bead geometry and melt-pool shape during the deposition process. Additionally, square-shaped specimens were manufactured via DED with controlled Powder LineDensity to observe the resulting microstructure and mechanical properties. It was observed that, even for the same energy density, specimens exhibited distinct grain morphologies, microstructure, and mechanical properties depending on the Powder Line-Density, with a particularly significant change in anisotropy. This highlights the importance of powder feed density as a key variable alongside energy density to optimize DED additive manufacturing processes. The findings of this study are expected to contribute to the control of anisotropy and strength of fabricated components in metal additive manufacturing processes by the regulation of powder feed density.

The Role of Geometry on the Ease of Solidification Inside and Out of Cylindrical Nanopores.

We investigated the role of a nanoporous particle on the formation of macroscopic solid in the framework of equilibrium thermodynamics and from the free-energy perspective. The model particle has cylindrical pores with equidistant circular openings on the particle surface. We focused on two potentially limiting steps: (i) the solid nucleation from liquid inside a single pore and (ii) the bridging of multiple pores on the particle surface. We examined the nucleation near the liquid-vapor meniscus inside a pore by considering different solid-vapor and solid-pore wall contact angles, as well as the liquid-vapor meniscus angles. For bridging, we quantified the effects of the proximity of neighboring pores and the number of participating pores where we considered two or three pores, placed two different distances apart, and three contact angles of the solid with the particle surface. Except in special cases where an analytical solution could be developed, we determined the equilibrium nucleus and bridge shapes numerically using the Surface Evolver code. The geometry of these equilibrium shapes was the key for correctly calculating the energy barriers. Our results indicate that the meniscus angle can be an important factor in reducing the barrier for nucleation if the internal angles of the solid nucleus satisfy a certain criterion. For the solid growth out of the pores, we found that the barriers were significantly lower in the presence of multiple, closely packed pores compared to the growth from a single pore. This paper is deliberately written with no reference to material properties or a specific process to highlight the generality of geometry-controlled barriers. A direct application where our findings can be particularly valuable is the ice formation in clouds, which is the subject of intensive research in atmospheric sciences for its role in influencing precipitation patterns and hence the climate.

Tolerance allocation of mechanical assemblies including thermal deformation: A machine learning – based method

Tolerance allocation is one of the prominent tools to achieve the optimal manufacturing cost and the best performance for mechanical assemblies. Variations in dimensions and geometry shape due to different working temperatures for various components within an assembly can make initially assigned tolerances ineffective. Therefore, it is necessary to consider the component’s deformation caused by thermal gradients during the tolerance design. In this paper, a new method is presented for optimal tolerance allocation of mechanical assemblies under thermal deformation. First, the system’s temperature working conditions and tolerance design goals are specified, followed by the finite element simulation of the assembly at the desired working temperature. Then, the assembly equation is determined according to the complexity of the problem by using analytical methods and some machine learning (ML) algorithms such as XGBoost. The optimal tolerance design is formulated into a constrained multi-objective optimization problem. Then, to obtain the Pareto front of optimal tolerances, the multi-objective optimization is solved by the NSGA-II algorithm. Finally, to illustrate the capability of the proposed method, two case studies are considered, and obtained results from the presented method and conventional approaches are compared.

Optical Visualization of Stretchable Serpentine Interconnects using Chiral Liquid Crystal Elastomers.

The shapes and structures of stretchable interconnects are pivotal in determining their functionality, allowing them to withstand bending, stretching, and twisting while maintaining their operational integrity. However, all stretchable interconnects are subjected to dynamically changing, non-uniform strains during mechanical deformation. Therefore, achieving an accurate understanding of stretchable interconnect properties, including tracking and analyzing these dynamic, non-uniform strains in real-time, remains a challenging endeavor. Herein, a method for analyzing the strain behavior of stretchable interconnects using a chiral liquid crystal elastomer (CLCE), which exhibits immediate structural color changes of nano periodic molecular arrangement in response to dynamic stretching deformations, is presented. Beyond the uniform color change of simple CLCE, by further engineering the modulus and shape geometry of the serpentine CLCE, an intuitive strain capturing visualization of dynamically changing serpentine structures is performed. Moreover, by expanding the serpentine CLCE into a 2×2 array, the real-time strain distribution of the stretchable interconnects under various multi-stretching properties (uniaxial and biaxial) is investigated. This optical visualization provides an accurate and precise understanding of the structure of stretchable interconnects under dynamic stretching conditions and is a promising breakthrough to enable enhanced design and optimization of stretchable serpentine structures for broadband stretchable applications.

An Adaptive Metal-Organic Framework Discriminates Xylene Isomers by Shape-Responsive Deformation.

The separation of xylene isomers, especially para-xylene, is a crucial but challenging process in the chemical industry due to their similar molecular dimensions. Here, a flexible metal-organic framework, Ni(ina)2, (ina = isonicotinic acid) is employed to effectively discriminate xylene isomers. The adsorbent with adaptive deformation accommodates the shapes of isomer molecules, thereby translating their subtle shape differences into characteristic framework deformation energies. Through a combination of multiple local flexibility behaviors, Ni(ina)2 exhibits guest-specific structural transformations that energetically favor para-xylene over other isomers. Single-crystal X-ray diffraction, in situ powder X-ray diffraction, and theoretical investigations validate this "adaptive fitting" mechanism, where the degree of structural deformation scales with the mismatch between the molecular shape and pore geometry. As a result, Ni(ina)2 achieves exceptional para-xylene selectivity in both liquid and vapor phase separations, maintaining a high para-xylene purity and productivity. This work demonstrates a novel strategy of exploiting framework flexibility to address challenging molecular separations and provides fresh insights into the design of selective adsorbents.

A Flexible Mold for Facade Panel Fabrication

Architectural surface panelling often requires fabricating molds for panels, a process that can be cost-inefficient and material-wasteful when using traditional methods such as CNC milling. In this paper, we introduce a novel solution to generating molds for efficiently fabricating architectural panels. At the core of our method is a machine that utilizes a deflatable membrane as a flexible mold. By adjusting the deflation level and boundary element positions, the membrane can be reconfigured into various shapes, allowing for mass customization with significantly lower overhead costs. We devise an efficient algorithm that works in sync with our flexible mold machine that optimizes the placement of customizable boundary element positions, ensuring the fabricated panel matches the geometry of a given input shape: (1) Using a quadratic Weingarten surface arising from a natural assumption on the membrane's stress, we can approximate the initial placement of the boundary element from the input shape's geometry; (2) we solve the inverse problem with a simulator-in-the-loop optimizer by searching for the optimal placement of boundary curves with sensitivity analysis. We validate our approach by fabricating baseline panels and a facade with a wide range of curvature profiles, providing a detailed numerical analysis on simulation and fabrication, demonstrating significant advantages in cost and flexibility.

Modeling of laser beam absorption on rough surfaces, powder beds and sparse powder layers

The energy transfer from a laser beam source to material surfaces with arbitrary geometrical features and variable surface roughness is the crucial step in many high-end engineering applications. We propose two models capable of predicting this energy transfer, applicable in different scenarios. The first is a high-fidelity numerical framework for the simulation of laser beam interaction with rough surfaces, which includes meshed geometry of arbitrary shape and material Lagrangian particles. The method discretizes the laser source as a collection of photon-type immaterial Lagrangian particles (Discrete Element Method) and is able to capture the effects of multiple reflections, angle-dependent reflectivity, and polarization change. Simulations were performed on a geometry reconstructed from a rough copper sample to reveal the impact of the polarization effects. This method is generally applicable to any surface where the effects of inelastic light scattering are not expected to play a significant role. The second model is a novel phenomenological correlation specifically designed to predict the effective reflectivity of sparse powder layers, which occur for example when metal vapor is recondensed and redeposited on the substrate during laser welding. The correlation is compared to the predictions obtained from the simulation framework and has been favorably compared to experimental data in a separate publication.

Three-Layered Annular Plate Made of Functionally Graded Material Under a Static Temperature Field.

The presented problem considers the static temperature analysis of a three-layered, annular plate with heterogeneous facings made of material with radially variable parameters. They are defined by the accepted exponent functions. The plate is composed of thin metal facings and a thicker foam core. The plate is loaded with a flat temperature field with a gradient directed across the plate radius. Using the approximation finite-difference method, the eigen-value problem is solved in order to calculate the temperature differences between plate edges, which cause a loss of plate stability. Taking into account the different material and geometrical parameters, the critical temperature state parameters are evaluated. The meaning of the mixed system of parameters connected with the plate shape geometry, dimensions of the plate-transversal structure, and with the gradation of the material in the radial direction on the thermal response of the composite plate have been found. Numerous results of numerical calculations show the responses of the examined composite plate with facings made of the heterogeneously directed material.

Experimentation and FE analysis of low carbon steel-based laser welded tailored blanks in case of single point incremental forming

This study explores the formability of laser-welded tailored blanks in the context of single-point incremental forming (SPIF), a flexible and dieless manufacturing process. Two approaches, variation in materials and thicknesses, were used to fabricate tailor-welded blanks (TWB) with CRCA and DD steel sheets. The quality of the weld was evaluated by metallographic studies and tensile tests. The ductility of the welded joint was reduced by 81%, and the hardness was increased by 133% compared to the base metal. SPIF was employed using a hemispherical tool to form a ‘D’ shape geometry on fabricated TWBs. Fracture was observed only at the weld line, irrespective of thickness and material combination in the TWB. The forming height achieved from the SPIF of TWBs was reduced by 24% and 34% for both differences in thickness and material when compared to their corresponding base metals. Finite Element simulations were performed in Abaqus software using a dynamic explicit approach employing von Mises and Hill48 yield functions. Further, the FE model was validated by comparing the thickness and surface major/minor strains at the same forming height as observed from the experiments. Reduced formability and no weld line movement were the main observations made in this study, and the same was manifested by the FE simulation.

Control of Acoustic Tone Formation using Shape Geometry Modifications and Jet Blowing in a Cavity experiencing Supersonic Flow

Acoustics tones have caused significant damage to sensitive electronic equipment and aircraft respectively. The effects become severe in cavities experiencing turbulent flows and could lead to human fatalities. Studies have compared the effects of cover plate (CP) and jet-blowing (JB) systems in suppressing the propagation of these undesirable effects. The sound pressure levels (SPL) were observed to decrease by 10% and 3% in the former and latter respectively. This study critically examines the combined effect of CP geometry modifications, jet orifice positions as well as integration with other established flow control techniques (FCT) with the possibility of achieving further attenuation in the system. Geometric sizes of the CP are set to 20%, 25% and 30% of the cavity length, with a length-to-depth ratio (l/d) of 5.07 and simulated in a flow field with a Mach number of 1.5. Also, four orifices for jet blowing are varied on the cavity leading and trailing edge wall. The trailing edge modification and trailing edge curvature are also implemented on the cavity. The k-ꙍ turbulence model and second-order discretization method are used to perform the computation. Results show that the trailing edge region produced the largest pressure fluctuations. Also, it was observed that longer cover plates (0.3l) permit the formation of self-oscillating frequencies as the flow field is brought closer to the trailing edge. However, the further inclination of the trailing wall will ensure prompt evacuation and dissipation of the flow turbulence energy. At the trailing edge, the jet-blowing control technique successfully attenuated approximately 10dB in SPL, though a significant amount of turbulence was introduced into the system. Overall, the trailing edge modification, inclined cover plate with a 0.25l and jet blowing on the trailing and leading edges produced an approximate 27.5% reduction in acoustic tone suppression.

Knowing Geometric Shapes Through Block Play Activities for Group B Children at Tk Belimbing Raya Kepahiang

The purpose of this research is: To analyse geometry shapes through block games in Group B children at Belimbing Raya Kindergarten Kepahiang. this research is a qualitative approach. The subject of this research is 5 teachers of Belimbing Raya Kindergarten Kepahiang.The method used in this research is descriptive method. Qualitative data analysis is the process of systematically searching and compiling data obtained from interviews, field notes and other materials so that it is easy to understand and of course can be informed to others. Data analysis techniques used in this study are Interactive models. introduction of geometric shapes. Most of the children of PAUD Belimbing Raya have been able to distinguish the shape of a triangle although there are still some children who have not been able to mention the shape of a triangle

A New Method for Determining the Safety Distance Between Irregular Karst Cave and Circumferential Shield Tunnel

ABSTRACTWhen a shield tunnel passes through a karst area, the water‐filled cave can easily make the surrounding rock metamorphic, resulting in water inrush, ground collapse, and shield machine failure and other engineering hazards. Natural cavities have a significant degree of geometric irregularity due to groundwater alteration and soluble rock erosion. Considering the difficulties in describing the shape of a natural irregular cavity, circular, rectangular, and elliptical geometries have been simplified in most related studies. Based on the upper bound theorem of limit analysis, we established a three‐dimensional failure model including the karst caves located directly above and below the circumferential side of the tunnel. Then, we deduced the corresponding analytical solution of the critical safety distance (CSD). Furthermore, the effects of rock mass parameters, cave parameters, and geometric parameters on the CSD were analyzed. Then we designed the numerical simulation considering the irregular geometry shape at the circumferential side of tunnel using the Fourier descriptors. In addition, we estimated the CSDs for two failure models using the revised dichotomy and failure criterion. The findings demonstrated a quantifiable association between CSD and Fourier descriptors of irregular cave shape, resulting in the development of a CSD prediction model. These test results can provide a theoretical foundation and direction for predicting water inrush caused by the constrained irregular cave.

Numerical and experimental frequency analysis of damaged fiber‐reinforced metal laminated composite

AbstractThis research numerically evaluated the eigenvalue responses of the damaged fiber metal laminate (FML) structure. The current numerical model is delved into including crack‐type damage effect on the structural integrity/ stiffness via frequency response. In this regard, a complete mathematical model of FML has been derived through higher‐order shear deformation kinematics for computational purposes. The mathematical model is converted to computer code in the MATLAB platform to predict the eigenvalue responses of FML components with and without damage. The damage influences are considered via circular meshing of finite element steps associated with the isoparametric element (nine nodes and nine degrees of freedom for each node). The solution consistency is checked via convergence, and the results are compared with data available in the open domain. Further, an experimental test is carried out to improve confidence using an in‐house test rig. The experiment was conducted by varying the length of the FML in 0.1 m increments. The results showed good agreement between the numerical and experimental data, with the lowest deviation being 0.29% and the highest 8.97%. The developed numerical model is extended to analyze the influences of design parameters such as geometry shape, aspect ratio (a/b), thickness ratio (a/h) ratio, curvature ratio, and fiber layup sequence on the natural frequency response.

Sorghum segmentation and leaf counting using in silico trained deep neural model

AbstractThis paper introduces a novel deep neural model for segmenting and tracking the number of leaves in sorghum plants in phenotyping facilities. Our algorithm inputs a sequence of images of a sorghum plant and outputs the segmented images and the number of leaves. The key novelty of our approach is in training the deep neural model. Manual annotations are tedious, and we have developed a procedural three‐dimensional (3D) sorghum model that provides detailed geometry and texture to generate photorealistic 3D models. The overall shape of the sorghum leaf geometry is determined by its skeleton, and it is detailed by a procedural model that varies its curvature, width, length, and overall shape. The color is determined by using a Monte Carlo path tracer. We mimic the illumination of the phenotyping facility and use reflectance and transmittance on sorghum surfaces to determine the color of the leaves. The 3D procedural model allows us to generate photorealistic and segmented images that we use to train a deep neural model. Our segmentation provides a mean intersection over union score of 0.51, resulting in leaf counting accuracy within the 90% confidence interval for the human counts.

3D FEM forming simulation optimization and experiment on bevel thread-forming screw

Abstract This study adopts 3 forming passes and 1 thread rolling process as the multi-pass schedule of bevel thread-forming screw. The finite element simulation software is used to simulate the plastic behaviour of forming and thread rolling processes. The geometry shapes, the part dimensions of each pass, the effective stress, the effective strain, the forming force and the die stress of each pass can be reached via FEM simulation. Moreover, especially Taguchi method for the maximum force pass is conducted to optimize the forming processes. Considering 4 control factors such as A: head arc radius (rH), B: flange thickness (t), C: corner radius (r), and D: frictional factor(m) and 3 levels to establish the orthogonal array table for optimum forming force, the influence rank and the optimal parameters combination are obtained to carry out the realistic experiment for confirming the feasibility of FEM simulation optimization. In a word, the influence rank of control factors: flange thickness (t) > head arc radius (rH) > corner radius (r) > frictional factor (m), and the optimal parameters combination is A3B3C3D1 (rH=42 mm, t=1.3 mm, r=0.7 mm, and m=0.12).

A Modular Neural Motion Retargeting System Decoupling Skeleton and Shape Perception.

Motion mapping between characters with different structures but corresponding to homeomorphic graphs, meanwhile preserving motion semantics and perceiving shape geometries, poses significant challenges in skinned motion retargeting. We propose M-R 2 ET, a modular neural motion retargeting system to comprehensively address these challenges. The key insight driving M-R 2 ET is its capacity to learn residual motion modifications within a canonical skeleton space. Specifically, a cross-structure alignment module is designed to learn joint correspondences among diverse skeletons, enabling motion copy and forming a reliable initial motion for semantics and geometry perception. Besides, two residual modification modules, i.e., the skeleton-aware module and shape-aware module, preserving source motion semantics and perceiving target character geometries, effectively reduce interpenetration and contact-missing. Driven by our distance-based losses that explicitly model the semantics and geometry, these two modules learn residual motion modifications to the initial motion in a single inference without post-processing. To balance these two motion modifications, we further present a balancing gate to conduct linear interpolation between them. Extensive experiments on the public dataset Mixamo demonstrate that our M-R 2 ET achieves the state-of-the-art performance, enabling cross-structure motion retargeting, and providing a good balance among the preservation of motion semantics, as well as the attenuation of interpenetration and contact-missing.

Multi-shell bowl-like carbon microspheres for lightweight and broadband microwave absorption

Carbon materials have made significant progress in the field of microwave absorption (MA), but achieving wide effective absorption bandwidth (EAB) at low filler content still remains a great challenge. In this work, we design multi-shell bowl-like mesoporous carbon microspheres (MBMCs) by a facile hard template method for efficient MA. It is demonstrated that the spacing between inner and outer shell and second shell thickness play a vital role on the configuration of carbon microspheres. By controlling the second addition of silica template, the microstructure of carbon microsphere evolves from spherical to bowl shape geometry. Expanded shell spacing is beneficial for forming bowl-like microsphere. The dielectric loss and MA properties are highly associated with the configuration of MBMCs. Well-proportioned MBMCs with appropriate shell spacing present wide EAB of 7.3 GHz under a low filling ratio of 12 wt.%. This work paves a new way to broaden EAB and lower filling content of carbon materials via asymmetric multilayer microstructure design.