bluuebunny/crossref_metadata_2025 huggingface dataset:
Actuation Behaviors of Flexoelectric and Light-Activated Shape Memory Polymer on Rings
Authors: Li Hongjie , Fan Mu , Deng Yan , Wang Dan , Tzou Hornsen
Published: February 2024

Some vibration problems caused by the low stiffness and light weight of large aerospace structures hinder precision operation. To enhance the environmental adaptability of the structure and improve its performance of the structure, sensors, actuators, and controllers are integrated with the structure, and signal processing and electronic circuit systems are combined to form a smart structure system. Smart materials and structures usually exhibit multi-field coupling behavior. Among them, flexoelectric materials have gradient coupling characteristics, that is, the linear coupling between electric polarization and strain gradient and between polarization gradient and strain. Flexoelectric materials are more sensitive to changes in bending strain or structural curvature. Therefore, the flexoelectric actuator is very important for controlling the deformation and vibration of the bending structure. A light-activated shape memory polymer (LaSMP) exhibits coupling behavior. Under ultraviolet (UV) light illumination, the Young’s modulus of LaSMP changes greatly and the material returns to the initial state. Based on its shape memory properties, LaSMP actuators can be used to actuate and control thin shell structures. Ring structure can be applied to torpedo, missile and underwater vehicle shell joints, etc. In this work, an atomic force microscope (AFM) probe is placed on the top of a flexoelectric patch to induce an inhomogeneous electric field. A LaSMP has dynamic Young’s modulus and strain under the illumination of UV lights. Therefore, both the flexoelectric actuator and LaSMP actuator can be used to actuate structures. This work aims to study the actuation behavior of the flexoelectric and LaSMP actuators on rings. The membrane forces and bending control moments and their induced components are defined respectively in the transverse/circumferential directions. In case studies, the circumferential distribution of the induced membrane force and bending control moment is analyzed first. The membrane force induced component and the bending control moment induced component, together with the total effect, are studied. Then, the induced microscopic transverse/circumferential actuation behavior is evaluated. Finally, the effects of bending and membrane of the flexoelectric actuator are compared. The results suggest: (a) the membrane force and bending control moment induced by the flexoelectric actuator concentrate near the AFM probe location, while the membrane force and bending control moment induced by the LaSMP actuator distributes throughout the LaSMP patch; (b) the overall actuation behavior of the flexoelectric actuator can be regarded as a drastic sharp bending effect near AFM probe location; and (c) the LaSMP actuator shrinks in the circumferential direction under UV light.
Study of the Effect of Toolpath and Machining Parameters on Sphericity, Surface Finish, and Dimensional Tolerance of Polymer Acetabular Cups
Authors: Becerra-Becerra Ernestina , Vidal-Lesso Agustin , Saldaña-Robles Alberto , Reveles-Arredondo Juan Francisco
Published: February 2024

The study of cutting parameters, machining strategies, effects of the cutting tool on precision and final surface quality, are necessary to extend the useful life of prosthetic elements allowing to delay joint replacement. In this work, an experimental study of CNC milling machining of an internal liner acetabular cup with a diameter of 28 mm for hip prosthesis was carried out. The investigation was carried out through a Taguchi L9 design of experiments, analyzing the influence of 4 machining parameters with 3 levels and 2 replicates. The used tool is a ball mill with a diameter of 10 mm. The factors studied were the effect of the toolpath (vertical-horizontal parallel, spiral-radial, vertical-spiral parallel), depth of cut (0.5, 1.0, and 1.5 mm), spindle speed (146.6, 178.02, and 209.43 rad/s) and stepover (0.05, 0.075 and 0.15 mm) over average roughness, sphericity, nominal diameter tolerance and machining time. The smallest mean roughness (0.6436 μm) was obtained considering a vertical-spiral parallel strategy, a depth of cut of 0.5 mm, a spindle speed of 209.43 rad/s, and a cutting stepover of 0.075 mm. Our finding suggests that the cutting parameters proposed through the design of experiments of this work can help to obtain the desired surface finish in acetabular liner components by machining, in accordance with the international standard ISO 7206-2.
Modeling and Implementation of a Flamelet Based Model With Presumed Shaped Probability Distribution Function Integration in Fortran for Non-Premixed Flame Dynamics
Authors: Hasan Md Kamrul , Haque Md Azazul , Mahamud Rajib
Published: February 2024

Numerical modeling of combustion dynamics for various applications is a complex problem that involves flow-chemistry interaction and requires the implementation of efficient numerical schemes. Computational modeling of turbulent combustion is essential in predicting different combustion attributes like flame stability and heat release. Despite being a reasonable alternative to the experimental data, the modeling approach also requires tremendous computational resources. Various strategies have been introduced over the year to minimize computational time. This study reports on a Fortran-based Computational Fluid Dynamics (CFD) code to investigate non-premixed flame applications, utilizing a fourth-order accurate compact finite difference scheme. The CFD code incorporates the flamelet model combined with the Navier-Stokes (NS) equations to solve for various variables, including velocity, pressure, temperature, mixture fraction, mixture fraction variance, and scalar dissipation rate. Flamelet model uses laminar flame components in turbulent flame, where the laminar flamelet characterizes the local structure at each point on the flame front. The reactant fluxes depend on the gradients of flow velocity and are controlled by the scalar dissipation rate. The flamelet model and the β(beta)-pdf integration for species transport and temperature distribution are incorporated into the code. The laminar diffusion flame provides unique relationships for all thermochemical variables (such as temperature, species concentrations, and heat release rate) in terms of the mixture fraction. These relationships can be averaged for the non-premixed flame using an assumed probability distribution function of the conserved scalar. The steady-state flamelet libraries are generated from a zero-dimensional chemical kinetics solver with dependencies on mixture fraction and scalar dissipation rate.
Comparison of Control Strategies for Temperature Control of Buildings
Authors: Salcan-Reyes Gabriela , Cajo Ricardo , Aguirre Adriana , Espinoza Víctor , Plaza Douglas , Martín César
Published: February 2024

In this paper, a classic controller such as PID and more advanced controllers such as fractional order model predictive control (MPC) were designed and compared for the temperature control of buildings. In a previous study by the authors, fractional calculus was incorporated into the design of the weighting factors of a classic MPC. The designed fractional order MPC outperformed the classic MPC. In this work, based on the same building model, and specifications, such as settling time, overshoot, and steady-state error, we designed traditional discrete PID controllers with anti-reset windup. Then, an improved FOMPC was compared with these two PID controllers and classic MPC. As a result, a numerical analysis of some indices shows that the FOMPC performs better than the designed PIDs in performance but with slightly more control effort. Also, it is shown that a meticulously tuned PID controller produces similar results to a FOMPC when designed appropriately.
3D Printed Diffraction Gratings by Two-Photon Polymerization
Authors: Hua Junyu , Shan Yujie , Wu Shaocheng , Mao Huachao
Published: February 2024

Diffractive optical elements (DOEs) are important optics that can manipulate the light by diffraction, which could be used in optical systems where compactness and lightweight matter. As one of the typical DOEs, diffractive gratings have widely application and their fabrication requires high precision and a clean environment. In this paper, we designed and fabricated diffraction gratings with different dimensions for visible light using the two-photon polymerization technique. The optical path differences and distances between diffraction fringes were measured and compared with the theoretical ones. The results showed that the precision across the printing direction was good while the height differences in the printing direction were around 20% smaller than the designed ones. Another problem was that the gratings were printed by small blocks and the borders of the blocks could serve as secondary gratings to generate smaller diffraction fringes, which need to be fixed for future fabrication of precise gratings and other complex DOEs by two-photon polymerization.
Toward Position Approximation Using Asynchronous Multi-View Cameras: A 2D Investigation With Probabilistic Considerations
Authors: Civetta Christopher A. , Kutzer Michael D. M.
Published: February 2024

Multi-view position recovery is common in the field of computer vision and applications range from commercial motion tracking to three-dimensional (3D) reconstruction of static environments. For these applications, one of two key assumptions is commonly assumed true: (1) camera information is synchronized across two or more offset cameras, (2) the environment being viewed is static. This work considers a simulation study of multi-view position approximations of a moving target in two dimensions (2D). The position is recovered using two or more 2D pinhole cameras. In this use case, images from cameras are asynchronous with respect to one another and extrinsic measurements. In simulations, the recovered target position varies widely from the true target position and uncertainty is injected using Monte Carlo methods to approximate a single probability distribution representing the target’s uncertain position in space. Results show a probability distribution that reasonably approximates the target’s true position in 2D space given sufficiently accurate extrinsic information.
Development of Robotic Hand With Novel Soft 3D Printed Actuators
Authors: Patel Kishan , Magee Kyra , Hoover Bill , Yu Jason , Ashuri Turaj , Amiri Moghadam Amir A.
Published: February 2024

Soft robotics has emerged as a promising technology in the Biomedical field and the development of prostheses. These devices use flexible materials such as silicone, rubber, and other polymers to create lightweight and adaptable structures that mimic a human hand’s complexity and dexterity. Their soft and flexible nature offers a unique advantage over traditional rigid robotic systems, allowing for safer and more efficient environmental interaction. One of the most crucial elements of a soft robotic hand is the soft actuators, which enable a soft robotic system to interact with the environment, enabling various motions using its deformable structure. While soft actuators offer many advantages over traditional rigid actuators, their use has potential downsides such as limited strength and durability, precision, speed, and control. This paper offers a solution that addresses the downsides mentioned by developing a robotic hand prosthesis using novel 3D-printed soft actuators. These novel actuators are designed to mimic human fingers while increasing control and speed compared to current soft actuators while keeping costs down.
CFD-Based Ventilation Assessment of a University Building With an Integrated Windcatcher in Egypt
Authors: ElDakroury Moataz , Goubran Sherif , Abdelaziz Omar
Published: February 2024

Windcatchers have gained renewed interest owing to the increasing demand for energy-efficient ventilation strategies that can provide satisfactory indoor air quality conditions. Previous studies have demonstrated the positive potential of windcatchers in improving indoor air quality (IAQ), ventilation rates, and occupant comfort in enclosed spaces, such as small rooms. However, the impact of windcatchers on the overall ventilation performance of an entire building under realistic climatic conditions has not been systematically investigated. The present study, therefore, aims to bridge this gap by investigating the indoor air velocity of a real-world windcatcher located on top of an atrium in the main building of the School of Sciences and Engineering (SSE) on the premises of the American University in Cairo campus (New Cairo). A detailed Computational Fluid Dynamics (CFD) model was developed to simulate the operation of the windcatcher and the natural ventilation inside the building beneath it under a neutral atmospheric boundary layer (ABL) condition. Additionally, climatic data from a nearby automatic weather station were used to avoid using unrealistic conditions for simulations that may introduce uncertainties. The results show that the proposed windcatcher improves the ventilation of the atrium and connected corridors compared to cases with no windcatcher attached.
Performance of a Forward Feed Multi-Effect (MED-FF) Thermal Desalination System With Feed Preheating
Authors: Qudah Azeez , Hasan Abdulsalam , Antar Mohamed A.
Published: February 2024

The Multi-Effect Forward Feed Desalination System (MED-FF) is an effective technology for large-scale seawater desalination. The addition of the thermal vapor compressor (TVC) enhances the system’s performance ratio. According to recent studies, the best placement for the TVC is in the middle. In the present study, a new component has been installed on the system, which is the brine preheater. This component works as a preheater for the feed before it flows into the first effect. The performance of the MED-FF plant with no feed preheater is compared with the proposed layout with the preheater. Results reveal that the performance has significantly improved through energy recovery, reflected in an 8% increase in the performance ratio, along with notable cost savings of 3.73% in distilled water production and energy fuel savings of 5.95% in the boiler consumption. The effect on the total heat transfer surface area and specific flow rate of cooling water is also taken into consideration.
Water-in-Diesel Emulsion: Torque, Fuel Consumption and Emission Analysis
Authors: Oliveira Pedro , Brójo Francisco
Published: February 2024

Water-in-diesel emulsions (WiDE) as an alternative fuel are becoming more and more an option to fight global fossil fuel consumption and emissions restrictions without the need of engine modifications. This work aims to compare water-emulsified diesel fuel with European commercially available diesel (EN590) when it comes to engine performance and emissions. A mixture of diesel, 8% (m/m) of distilled water, and surfactant was performed in laboratory by mechanical homogenization and later tested in a Lombardini LDW 502 diesel engine connected to an eddy current dynamometer and an emission gas analyzer. The tests were performed at 50%, 75%, and 100% engine loads at different engine speeds (rpm).

The results suggest that adding water as a dispersed phase in the fuel allows to obtain better thermal efficiency and overall lower emissions of nitric oxide (NO) and carbon dioxide (CO2) when compared to traditional diesel. The micro-explosion phenomenon and lower temperatures in the exhaust gases can explain these occurrences.
Thermal Management System for Lithium-Ion Batteries Using Phase Change Material, Heat Pipes and Fins
Authors: Sharifi Nourouddin , Roesler Dylan , Gold Audrey , Shabgard Hamidreza
Published: February 2024

This work presents a comparative study on different cooling strategies for an 18650 lithium-ion battery both experimentally and numerically. Passive and hybrid cooling techniques that consist of heat pipes (HPs) and fins integrated with a phase change material (PCM) are investigated. The experimental setup consists of a vertically oriented cylindrical enclosure with an inner and outer housing. The annulus space between the inner and outer housings are occupied with a PCM, Fin-PCM, and HP-Fin-PCM and are enumerated as PCM-only, Fin-PCM, and HP-Fin-PCM configurations, respectively. A cartridge heater is inserted inside the inner housing concentrically to generate a pseudo battery, which mimics the heat generated by the battery. An air flow channel is designed for HP-Fin-PCM configuration. Temperatures at various locations of the setups are measured and compared for different heater powers. It is concluded that the HP-Fin-PCM configuration is the most effective in reducing the battery surface temperature, followed by the Fin-PCM, and the PCM-only configuration. A transient three-dimensional numerical model using ANSYS-FLUENT software is also developed and used to provide details into the physics of the problem, and to enable optimization studies. The phase change in the conjugate numerical model is accounted for by the enthalpy-porosity technique. The computational results reasonably agreed with the experimental data.
An Iterative Actuation Method for Master-Slave Telemanipulation by Humanoid Robot Arm
Authors: Barlow Ethan , Arif Tariq M. , Bentley Parker , Hiatt Hudson , Call Chase
Published: February 2024

Master-slave telemanipulation of a humanoid robot arm is one of the challenging and intuitive control tasks that is being studied to achieve human-like competency in remotely operated collaborative robots. Traditional inverse kinematics-based manipulation typically produces highly complex and non-unique solutions and has the risk of running into singularity conditions for a higher degree of freedom manipulator. On the other hand, pendant-based teaching manipulation is suitable for only predefined trajectories. As the use of telemanipulation is increasing in collaborative robots to support better human-robot interactions, it is becoming critical to explore alternative novel, simple, and innovative manipulation strategies. In this study, we propose an iterative search-based efficient actuation method for the telemanipulation of collaborative master-slave robot arms. The forward kinematic model used in the iterative algorithm is developed using Denavit-Hartenberg parameters, and a manipulation platform with data glove is designed to map the position and orientation of the master arm. Using the iterative algorithm, on average, the end-effector of the robot arm can be within 18.5 mm of required positions in a 106 mm3 sub-workspace (0.63% error). Our study also presents a series of experimental executions on hardware, iterations, and errors to demonstrate the performance and capabilities of the proposed algorithm.
Acoustic Cloak Design via Gradient-Based Optimization
Authors: Avina Angel , Gerges Samer , Amirkulova Feruza A. , Du Winncy
Published: February 2024

An acoustic cloak [1] is a metamaterial device that can bend acoustic waves around their interior and hide any object inside from an incident acoustic field. The current methods of designing acoustic cloaking devices involve traditional methods such as direct computer simulation, topology optimization, stochastic optimization, gradient-based optimization (GBO), and more recently data-driven machine learning models. This project focuses on implementing GBO strategies to optimize an objective function of interest, improving our models developed earlier [2, 3] to reduce the cost of design and improve the efficiency of cloaking devices. Acoustic cloak design is achieved by minimizing the total scattering cross section (TSCS) for a set of cylindrical rigid scatterers.
Modeling Underwater Propulsion of a Helical Drive Using Computational Fluid Dynamics for an Amphibious Rover
Authors: Donohue Brigid , Beknalkar Sumedh , Bishop Riley , Bryant Matthew , Mazzoleni Andre
Published: February 2024

The Multi-terrain Amphibious ARCtic explOrer (MAARCO) rover is an amphibious arctic rover designed to explore arctic regions in otherwise unsafe or restricted environments. The MAARCO rover consists of a propulsion system with two helical drives made up of hollow cylinder ballasts wrapped in auger or screw shaped blades that provide thrust to propel the vehicle as the drives rotate. Computational fluid dynamic methods provide a better understanding of the helical drives properties effects on hydrodynamic forces. In this paper, the computational fluid dynamic simulations are performed in ANSYS Fluent to observe the hydrodynamic properties of a helical drive. The drag and thrust on the helical drives are simulated for various helical drives with different blade heights and pitch lengths to determine general trends and characteristics of helical drives in water to optimize the vehicle’s abilities to navigate underwater. The helical drive drag is simulated using bluff body drag simulations with a prescribed velocity. The helical drive thrust is simulated using a multi-reference frame (MRF) mesh model with a frame motion replicate flow rotating around a stationary helical drive at a prescribed angular velocity. A convergence study was conducted to test different meshes and turbulence models to determine the most accurate drag and thrust simulation methods. The results demonstrate the effects the blade height and pitch length have on the helical drive thrust and drag properties, while maintaining a constant ballast diameter. From these results a helical drive design can be determined to optimize the net force and therefore the overall vehicle performance.
Design and Construction of a Terrestrial Testing Rig for Experimental Characterization of Multi-Terrain Screw-Propelled Vehicle Dynamics
Authors: Lynch Ryan , Beknalkar Sumedh , Bishop Riley , Crow Arin , Donohue Brigid , Pacheco-Cay Cristian , Smith Alaina , Mazzoleni Andre , Bryant Matthew
Published: February 2024

Helical drives (sometimes known as Archimedes’ screws) are a class of propulsion mechanism with the potential for application in amphibious, multi-terrain robotic ground vehicles such as Arctic rovers. Despite their simplistic construction, consisting of a screw-like rotating drum with a helically wound blade, their propulsion dynamics are complex and not well understood. There is a need for an experimental testing environment capable of controlling and recording the variables that characterize the dynamics of this terrestrial propulsion mechanism in order to experimentally validate dynamic and energetic modelling. Such variables include displacement, velocity, and acceleration of the mechanism in question in the x, y and z directions, as well as terramechanical properties such as substrate moisture content, subsequent density, and particulate size. This environment would also ideally be designed with modularity in mind in order to easily adapt to multiple different test conditions and terrestrial propulsion mechanisms. This paper describes the design of the experimental testing rig created to serve the above-described purpose. The apparatus is tested with an example of a helical screw drive at three different rover weights. Results of an initial test are shown, and the trends shown in the x position (longitudinal travel), z position (vertical travel), and effective pitch length are discussed.
Thermal Orbital Spacecraft Analysis of an Additively Manufactured Deployable Radiator Oscillating Heat Pipes (AMDROHP) CubeSat
Authors: Miesner Spencer , Shibata Gabriella , Bautista Neyda , Wolk Kieran , Furst Ben , Daimaru Takuro , Sunada Eric , Roberts Scott , Bellardo John , Kuo Jim
Published: February 2024

As small spacecraft technologies develop, thermal management devices need to meet the growing demands of high-powered electronics. Currently being developed to meet this demand in CubeSats is the Additively Manufactured Deployable Radiator Oscillating Heat Pipes (AMDROHP). AMDROHP seeks to implement the high thermal conductivity and two-phase technology of Oscillating Heat Pipes into a unique deployable radiator design for a 3U CubeSat, taking advantage of additive manufacturing capabilities. While much consideration has been put into designing the AMDROHP on its own as a heat exchanger, there is also the need for it to be evaluated thermally at a system-level with the rest of the CubeSat while in orbit. In this study, thermal orbital spacecraft simulations, through the Thermal Desktop software, were performed to analyze how AMDROHP thermally integrates and interacts with the rest of the CubeSat and evaluate the survivability of temperature-sensitive components on the spacecraft. The simulations in this study included an 11th-orbit beta angle sweep for a tumbling orientation of the spacecraft in Low Earth Orbit (LEO). These simulations were performed with two AMDROHP devices in the CubeSat bus, each under a direct 25W heat input and performing with a thermal conductance of 6 W/K, which corresponds to the projected performance of the AMDROHP device while in operation. In this paper, the Thermal Desktop model of the AMDROHP CubeSat includes all major physical components, connections, heat loads, and thermal and optical materials. Then, steps are taken to improve the computational speed of the model. Furthermore, the means of addressing the modeling of the complex two-phase behavior of the OHP is outlined. Then, a number of test cases considering various operating conditions were simulated. From these simulations, orbital temperatures of sensitive components, primarily electronics, were collected and analyzed to find the minimum and maximum operating temperatures across all potential orbits. These temperatures were then evaluated to determine the component’s survivability in a worst-case scenario in orbit. From the results, it was found that, with the projected conductance of AMDROHP, all components operate under safe temperature conditions for any beta angle while in Low Earth Orbit. The evaporator is consistently the hottest component of the spacecraft and electronics boards all maintain survivable temperatures and are not at risk of over or underheating, even at worst case temperatures for all orbits tested. Based on the results and analysis of this conceptual study, it is suggested that AMDROHP will perform as an effective management device for small satellites.
Numerical Investigation of Steady Blowing on Active Drag Reduction of a Truck Model
Authors: Zhang Cheng , Ge Haiwen , Bakhoum Ezzat
Published: February 2024

Large trucks are an important way of transporting goods worldwide. Aerodynamic drag is responsible for a large portion of the energy consumption in trucks, hence there are increasing interests in reducing the aerodynamic drag to achieve better fuel efficiency. Many active and passive flow control strategies have been proposed to reduce the aerodynamic drag of trucks. The effects of steady blowing on drag reduction of the Ground Transportation System (GTS) truck model are studied using an Improved Delayed Detached Eddy Simulation (IDDES) model, with a Shear Stress Transport (SST) k-ω model in the boundary layer. A bounded central difference scheme is used for the momentum equation, and a second-order upwind scheme is used for the k and ω equations. A bounded second order implicit scheme is used for time marching. For the baseline case, the predicted pressure coefficient and drag coefficient are in good agreement with the experimental data. The locations of the vortices in the wake along a vertical streamwise cut and a horizontal stream-wise cut are also in reasonable agreement with the experimental data. In addition to the baseline case, cases with steady blowing introduced from four slots at the edges of the truck base are also considered. The blowing velocities have a component in the streamwise direction, and another component perpendicular to the streamwise direction and pointing to the center of the truck base, forming a 45° angle with the streamwise direction. Cases with three different blowing velocity magnitudes (10m/s, 50m/s, and 100m/s) are reported. It has been found that the length of the recirculation zone, as well as the locations and sizes of the vortices in the wake have changed due to steady blowing for the 50m/s and 100m/s cases. Compared to the baseline case, cases with steady blowing velocity magnitudes of 10m/s, 50m/s, and 100m/s have a drag reduction of 2.41%, 8.84%, and 9.24%, respectively. However, taking into account the power consumed to produce the steady blowing, the blowing efficiency for the three cases are 2.40%, 7.34%, and −2.76%, respectively. Among the three cases considered here, the 50m/s case is the most efficient in reducing the aerodynamic drag. On the other hand, the 100m/s case actually increases power consumption by 2.76%.
A Study on Surface Texture and Wettability of Femtosecond Laser Treated Aluminum Alloy
Authors: Angell Dakota , Wang Xinya , Song Xiaoxu , Lei Shuting
Published: February 2024

This study aims to investigate the effects of femtosecond laser treatment on surface texture and wettability properties of an aluminum alloy, AL6061, with the primary goal of creating a superhydrophobic surface. A central composite design is used for the laser surface texturing design of experiments. Surface texture is examined using SEM to detect minuscule changes on the morphology. A 3D optical profiler extracts topographical data from the surface. A contact angle goniometer based on the sessile drop method is used to measure the contact angle of the textured samples. The response surface method is used to build a second-order polynomial model for the contact angle and obtain optimal parameters to maximize the contact angle. This research shows that laser surface texturing can generate a wide range of surface profiles and roughness values with geometric features ranging from hundreds of μm to submicron. All three laser parameters (pulse energy, pulse duration, pulse repetition rate) affect surface roughness and contact angle to some degree. To quantify the relationship between the contact angle and laser parameters, a response surface model for Al6061 is identified and used to find the optimal conditions of E = 214 μJ, tp = 10 ps, and fp = 2427 Hz with a predicted maximum contact angle of 161°. A confirmation experiment produces a contact angle of 168°, in good agreement with the predicted value.
Spin Forming Simulation and Forming Defect Analysis of Thin-Walled Deep Conical Parts
Authors: Zheng Jiabin , Shu Xuedao , Lu Qinying , Li Zixuan , Xu Haijie , Len Junkun
Published: February 2024

Aluminum alloy is widely used in various thin-walled deep conical parts due to its strong corrosion resistance, high specific strength and good plasticity. In this paper, the deep cone 1100 aluminum alloy parts are spun by the preform scheme. This scheme combines the advantages of multi-pass stamping and spinning, and can reduce the number of spinning passes of deep cone parts to four passes, which significantly improves the production efficiency. In this paper, Simufact software is used for simulation experiments. Different spinning schemes and different spinning parameters are imported into finite element software for simulation analysis, and finally different simulation results are obtained. The results show that for the workpiece on the preform, it is feasible to use the scheme of one-pass die-fitting spinning. In the spin forming of the final die, if the scheme of single pass die forming is adopted, the waist of the workpiece has the risk of cracking, and the wall thickness distribution of the whole workpiece is uneven. The final product is formed by four passes spinning, and the wall thickness of the product is uniform and the quality is reliable. This paper provides a new processing scheme for the actual production of thin-walled deep tapered aluminum alloy parts, which can effectively solve the problems of many molds in stamping forming and complex roller trajectory in spin forming, and significantly improve the production efficiency.
Smart Patterning for Topological Pumping of Elastic Surface Waves
Authors: Wang Shaoyun , Hu Zhou , Wu Qian , Zhu Rui , Huang Guoliang
Published: February 2024

Topological pumping supplies a robust mechanism to steer waves across a sample without being affected by disorders and defects. For the first time, we demonstrate the pumping of elastic surface waves, achieved by a smart patterning of a surface that creates a synthetic dimension, which is explored by the wave as it is launched perpendicularly to the steering direction. Specifically, we design and fabricate an elastic medium decorated with arrays of pillar-type resonators whose eigenmodes are located below the sound cone, together with coupling bridges edged according to a specific algorithm. We establish a connection between the collective dynamics of the pillars and that of electrons in a magnetic field by deriving an accurate tight-binding model and developing a WKB-type analysis suitable for such discrete aperiodic systems with spatially slow-varying couplings. This enables us to predict topological pumping pattern, which is numerically and experimentally demonstrated by steering waves from one edge of the system to the other. Finally, the immune character of the topologically pumped surface waves against disorder and defects is evidenced. The principle of surface patterning together with the WKB-analysis could provide a powerful new platform for surface wave control and exploration of topological matter in higher dimensions.
PVC-Based Materials for Thermoformed Tactile Diagrams: Assessment and Characterization
Authors: S. Ganesh , Ahuja Ramya , Goel Priyank , Sapra Pulkit , Rao P. V. Madhusudhan
Published: February 2024

Tactile diagrams are embossed diagrams on a sheet that visually challenged people explore through touch. One of the common processes to prepare these diagrams is by vacuum thermoforming. These diagrams help non-sighted people to explore pictorial contents such as maps, books, charts, and artworks. The identification of suitable and affordable polymeric material for preparing thermoformed tactile diagrams has not been explored much by researchers. The present research attempts to investigate alternate material for this purpose which meets three essential requirements: affordability, manufacturability, and perceptibility. Four different Polyvinyl Chloride (PVC) -based materials have been selected and studied as a part of this work. Initial studies show that PVC-based materials are more suitable for tactile diagrams because of their cost, low density, and, more importantly, stretchability at higher temperatures. All four materials are characterized using techniques such as Fourier-transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), and Differential scanning calorimetry (DSC) to know the exact compositions of materials. Characterization studies show that an essential ingredient, namely PVC content, typically varied from 70% to 90%. All the substrates were used to prepare tactile diagrams by thermoforming and to conduct user feedback experiments to study the readability, clarity of edges, sheet quality, and surface finish. The study carried out as a part of this work demonstrates that thermoforming of tactile diagrams may be carried out successfully on all four substrates with some limited number of adjustments in processibility to accommodate for the differences in these materials. These new materials will facilitate the production of thermoformed diagrams in an affordable manner and make them available to a large population of visually challenged.
Influence of Heat Treatment on the Microstructural Properties of Wire Arc Additively Manufactured Inconel 625 Alloy
Authors: Thangapandian N. , Manivannan R. , Shanmugam Ragavanantham , Vivekananda A. S. , Rangarajan V.
Published: February 2024

In this research, Wire arc additively manufactured IN625 alloy was subjected to different heat treatments and compared with the unheated alloy. All three samples were solution treated to a temperature of 980 °C followed by furnace cooling. S1 and S2 denote the solution-treated sample with a soaking period of 30 min and 1 hour respectively, whereas, S4 represents the sample which is aged for 8 hours at 720 °C respectively after the 1-hour solution treatment. The columnar and dendritic structures were visible in the parent additively manufactured (S1) specimen. These structures cannot be seen in the wire, which is used as the feed material for WAAM. The microstructure of the solution heat-treated specimen (S2) was seen with clear grain boundaries and precipitates. The micrograph confirms the uniform grain structure and more dispersed precipitates when compared to the unheated specimen. Though the average grain size remains the same, there were visible coarse grains in the 1-hour aged sample when compared to the 30-minute aged sample. The microhardness of the different heat-treated samples was measured using a Rockwell hardness tester to study the influence of heat treatment. The results revealed that the heat treatment significantly improved the hardness of the specimen.
Waterjet Process Parameters Optimization
Authors: Alsayyed Basel , Malm Frederick O.
Published: February 2024

Abrasive Water Jet Machining (AWJM) is a non-conventional machining process widely used in modern manufacturing industries due to its versatile cutting capabilities. The optimal performance of AWJM depends on the appropriate selection of process input parameters, which include water pressure, abrasive mass flow rate, material thickness, and cutting feed. However, the impact of material thickness variation on the AWJM process has been overlooked in previous research studies. To address this research gap, this study aims to investigate the effect of material thickness variation on the performance of AWJM and incorporate it as a factor in the process input parameters. The study methodology will employ the Taguchi orthogonal array and Analysis of Variance (ANOVA) to determine the optimal levels of process parameters for aluminum 6061 T65. The Design of Experiment (DoE) model will be set up based on the four input factors and their levels. Experiments will be conducted using the A-0612 WARDJet machine to achieve the best quality characteristics regarding the material removal rate (MMR) and the surface roughness Ra for different materials. By considering material thickness as a factor in the analysis of responses, this study seeks to enhance the understanding of the interrelationship between process input parameters and material thickness variation in AWJM. The study findings are expected to provide valuable insights to improve process efficiency and effectiveness, leading to better-quality outcomes in modern manufacturing industries.
Parameter Analysis of Spherical Pulsation Damper Using ANSYS Fluid-Solid Interaction
Authors: Butler Finnley , Duan Shawn
Published: February 2024

Various devices have been developed for the reduction of pulsation-induced vibrations, such as diaphragm chamber systems or gas bladders, non-intrusive fluid wave actuators and fluid filled, also known as reflection-type, dampeners. However, these devices are not suitable in a hydraulic system powered by a triplet piston pump. For example, pulsation dampeners incorporating gas bladders are effective, but there are many drawbacks. Loss of gas charge, incorrect gas charge or volume/mass ratio, elastomeric rupture, narrow range of pressure operation and pump speeds, routine maintenance, ineffective location, and branch connection instead of in-line configuration are all integrity issues which the industry faces. In addition to having a structural integrity issue, branch connected devices do not perform as efficiently as in-line devices. If a pulsation dampener is responsible for safeguarding critical equipment or systems, premature rupture of a gas bladder can be catastrophic.

This paper introduces a spherical pulsation dampener which is used to reduce harmful pulsations induced by a triplet piston pump in fluid power systems. The damper is composed of an inlet, a distributing plate with nozzles, a spherical housing, a receiving plate with orifices, and an outlet. The damper can be welded in-line and reduce 75% of pulsation-induced vibrations. The paper presents how fluid-solid interaction (FSI) and transient structural modules of ANSYS will be used to model and simulate the spherical pulsation damper. Developing a compatible system coupling module is necessary to generate models cognizant of time and computing expenditure. The preparatory build model is used to study mechanisms of pulsation reduction in the spherical damper and to analyze the correspondence of key damper parameters to the effectiveness of pulsation reduction. A CAD model of the pulsation damper is built in Autodesk Inventor, with a control volume of the fluid in the damper indicative of proper boundary condition. The model will then be imported into ANSYS, with fluid-solid interaction and transient structural modules, to study fluid flow fields and understand the governing mechanisms for reducing the pulsation induced by a triplet piston pump. Furthermore, a study will be carried out to analyze how the design of key parameters, such as the diameters of the inlet and the outlet nozzles, the axial distance between the distribution plate and the receiving plate, and the radius of the spherical housing, experience fundamental repercussions in pulsation reduction. The results of this work will be partially useful for engineers to design an efficient spherical pulsation damper, and supplement individual requirements to match up a triplet piston pump with a spherical pulsation damper effectively.
Development of Interactive Teaching Aid Material for Engineering Courses
Authors: Higby Dustin , Pashah Sulaman
Published: February 2024

Teachers’ clarity is the most essential factor in student learning. In addition to the teaching approach, teaching material is necessary for clearly presenting complicated engineering topics. Smart classrooms with multimedia support are conducive to covering complex engineering topics in less time. Nevertheless, the graphics are generally in static image format (from textbook publishers as instructor resources). Therefore, the entire image is displayed with a single click. Despite being time effective, this approach is not helpful from a student’s learning point of view because the essence of developing the concept from scratch is lost. PowerPoint provides various graphic and visual tools to develop detailed graphical illustrations using simple drawing objects and animation tools. Converting an image into a combination of drawing objects has the advantage of creating the illustration from scratch using animation tools stepwise rather than displaying the entire image at once. The other benefits include using multi-colors for improved visuals and a better understanding of a complicated graphical illustration or concept. Nonetheless, two-dimensional illustrations cannot represent three-dimensional configurations and motion simulations. This issue can be addressed by interactive three-dimensional illustrations and carefully planned motion animations. The illustrations are, however, not readily available and must be developed by the instructor. Development of interactive illustrations and animations requires considerable time and effort, in addition to knowledge of the software to be used to create such material. This work presents interactive illustrations for an enhanced learning experience for mechanical engineering courses at Texas A&M University Texarkana.
Stochastic Stability of a Torsional-Flutter Energy Harvester in Thunderstorm-Like Winds: Duffing vs. Hybrid Duffing – Van Der Pol Restoring Force Mechanisms
Authors: Caracoglia Luca
Published: February 2024

Wind energy harvesters are usually designed to operate in the low wind speed range and for medium scale applications, as a complement to standard, large horizontal-axis wind turbines. A torsional-flutter-based apparatus has been proposed by the author to extract wind energy. The apparatus is composed of a non-deformable, flapping blade-airfoil. A nonlinear torsional spring mechanism (Duffing model), installed at equally spaced supports, enables limit-cycle, post-critical vibration.

In this study a new model is proposed by replacing the Duffing restoring force mechanism by a hybrid Duffing – van-der-Pol one that couples a cubic torsional spring with amplitude-dependent damping. The apparatus is designed to be used in an area where thunderstorm-like flows may be present. The flow model accounts for both non-stationary turbulence and a slowly varying mean outflow, replicating intensification and decay of a thunderstorm.

Mean-square stability is studied through Moment Lyapunov Exponents. Stability limits are computed numerically through Monte Carlo solution of the numerical model. Various configurations are examined.
Variable Radius Fillet Shape Analysis to Minimize Stress Concentration Effects: Learning From Trees for Sustainable Design
Authors: Warner Mark , Vargas-Silva Gustavo , Jawaharlal Mariappan
Published: February 2024

Abrupt changes in geometry create stress concentrations, which are highly localized stresses causing failure at these locations. Engineers create fillets, and round-off sharp corners to reduce these stresses. Stress concentrations occur in the natural world, and the objective of this paper is to understand how trees handle areas of high stresses, learn from nature, and are used for engineering design inspiration. The main areas of the tree where high stress concentration occurs are the trunk base, where the trunk meets the ground above surface, and the branch base, where tree branches intersect with the trunk. Although extensive work has been done on the trunk base of trees, little work has been done on the branch base.

In this paper, the effectiveness of the natural curvature where branches intersect with the trunk is analyzed. The tree used in this scheme comes from the species Pinus Taeda (a.k.a. Loblolly Pine). The natural tree fillet was compared with both circular fillets and shapes developed using the Method of Tensile Triangles, a graphical way to create an optimized fillet design in nature. The comparison was carried out by using Finite Element Method (FEM). Static bending studies were done on both 2D and 3D models comparing various fillet geometries and stresses.
The Effect of Pulsed Power During Electrochemical Surface Modification on the Wettability of Aluminum and Titanium Alloy
Authors: Petrenko Anton , B. Kamaraj Abishek
Published: February 2024

Aluminum and especially titanium alloy are increasingly being used to replace traditional metals in many new applications due to their high strength-to-weight ratio and biocompatibility. Surgical implants need to have a hydrophilic nature when tissue growth is desired, while they need to be hydrophobic if tissue/microbial growth is not expected. Thus, there is a need to control the wettability of these metals. This study used a sodium chlorate electrolyte to control the wettability of 1-inch by 3-inch aluminum and titanium alloy samples using an electrochemical surface modification (ECSM) process. Duty cycle, frequency, and ECSM duration were modified while voltage was held constant at 10 V. Duty cycles of 25%, 50%, 75%, and 100% (or direct current) and frequencies of 1 kHz and 100 kHz were used. The time of processing was changed to allow the samples to have an equal active time with 2000, 1000, 667, and 500 seconds for 25%, 50%, 75%, and 100% duty cycles, respectively. A first principles-based theoretical model was developed in this study to predict the pulse power setting needed to achieve the desired wettability in the samples by measuring the sample mass before and after ECSM. The model was validated with experimental results. The surface’s wettability switched from superhydrophilic to hydrophilic after the sample was heated in a furnace. Both the metals showed a change in contact angle behavior after evaporation of the residual water. This study allows for the use of ECSM as a technique to modify the surface of implants with controlled wettability for improved osseointegration.