bluuebunny/crossref_metadata_2025_split huggingface dataset:
Manufacturing Error Detection in Plate and Cylindrical Composite Structures
Authors: Talebi Cihan , Acar Bülent , Özgen Gökhan O. 
Published: February 2021

Abstract
Due to their superior weight to strength ratio of composites to common metallic structures, composite technology is widely used in aerospace industry. Assessment of damage in composites has gained interest after a large number of accidents caused by unanticipated damages in the composite structures. Many different structural health monitoring applications were developed over the years due to the fact that composite materials may inherit damage from within, not always visible from surface. The most common types of errors encountered in the industry are due to misaligned fibers, a mix-up in ply order, and delaminations: all presenting changes in the vibro-acoustical performance of the composite structure. This paper discusses the change in the dynamic properties of a composite structure contains a manufacturing error such as a ply lay-up error, and a ply angle error. Both plate and cylindrical structure types were considered for the stated error types. Effect of symmetric errors, unsymmetrical and unbalanced errors, and mid-plane errors were considered in the case of ply orientations, and dynamic stiffness matrix was used to identify the error. Identification of the structure’s layup properties and manufacturing error identification is employed. From the measured modal properties of the structure, a back-tracking strategy was used to generate the ply lay-up of the composite structure. Prepreg plates of a single carbon fiber system and filament wound hybrid cylinders consisting of glass and carbon fibers were manufactured for testing. Modal tests on plates and cylindrical composite structures were performed and compared with the analysis. A good match between the finite element model and experiment was shown in natural frequencies and mode shapes.
Solar Tracking Using Linear Actuator
Authors: Betai Jay Dipak , Zhou Hong 
Published: February 2021

Abstract
Solar trackers make solar panels perpendicular to solar ray to enhance solar power reaping. The relative motion between Sun and Earth has two degrees of freedom. Sun travels from east to west during daytime and also moves north and south due to Earth’s tilt. However, Sun’s daily north-south move is much smaller than its east-west move. Sensor-based solar trackers make solar panels perpendicular to solar ray based on sensor information. Although the existing sensor-based solar trackers increase solar power reaping from solar panels significantly, they also consume considerable power by driving solar trackers. Sensorless solar trackers make solar panels perpendicular to solar ray based on calculated solar location. The performance of sensorless solar trackers is not affected by bad weather. This paper is on sensorless solar trackers. Single-axis solar trackers have one degree of freedom solar tracking motion. They can catch Sun’s daily east-west movement effectively. The Sun’s small north-south movement can be covered for single-axis solar trackers by monthly or seasonal adjustment of their orientations. This research is focused on single-axis sensorless solar trackers that are driven by linear actuators. The advantages of linear actuator driven solar trackers are their self-locking function and high load carrying capacity. Their challenges include limited solar panel motion range, potential interference between an oscillating solar panel and its fixed supporting ground link, and high motor power consumption for solar tracking. The research of this paper is motivated by surmounting the challenges facing sensorless single-axis linear actuator driven solar trackers. In this research, linear actuator driven solar trackers will be designed and analyzed. The models of the designed solar trackers will be developed. The kinematic and dynamic performances of the modeled solar trackers will be analyzed and simulated. The results of this research will provide some guidelines for developing linear actuator driven solar trackers.
Multibody Dynamic Model of a Double Nut Preloaded Ball Screw Mechanism With Lubrication
Authors: Bertolino Antonio Carlo , Mauro Stefano , Jacazio Giovanni , Sorli Massimo 
Published: February 2021

Abstract
Ball screws have been investigated by several researchers from a theoretical point of view because the intrinsic complexity of experimental investigation of these mechanisms. Most of the models developed so far have been developed in quasi-static conditions ignoring inertia terms and time variability of operating conditions. A detailed multibody dynamic model of a double nut preloaded ball screw is presented in this paper, taking into account the full dynamic of each subcomponent as well as the mutual interactions. A 3D contact model is introduced, considering Hertzian normal contact and a simplified friction model based on grease lubrication. This model takes into account the time variability of the operating conditions and it is suitable to be used for prognostic and model-based design approaches. The results of dynamic simulations in presence of backlash are presented to highlight the model’s capabilities.
Modelling of Energy Accumulation in Belt Conveyor Systems Under Faulty Conditions
Authors: Bertolino Antonio Carlo , Lombardi Gabriele , Mauro Stefano , Sorli Massimo 
Published: February 2021

Abstract
The consideration of potential energy stored in a system is paramount to carry on safe maintenance operations of mechanical system. In particular, this paper concentrates on the elastic energy accumulation occurring in a belt conveyor system ensuing a seizure of one of the pulleys owing to, for example, dirt and spilled bulk material accumulation in the belt inlet zone. The hazard of considering the system completely discharged just because the electrical supply cut off and the effect of such an energy storage are investigated by means of a lumped mass dynamic mathematical model. It allows time variable operating conditions to be considered, as well as starting and stopping phases transients. Standard maintenance operations are simulated, and the effect of stored energy sudden release investigated.
Directed Graphical Model for Real-Time Process Monitoring in Additive Manufacturing
Authors: Clemon Lee 
Published: February 2021

Abstract
An important challenge for additive manufacturing and 3D printing processes is accurate and repeatable deposition quality. Current approaches are unable to handle variable process parameters and input material quality. Accurately controlling material properties requires predicting material state changes. This work proposes a model using statistical learning techniques in conjunction with iterative material study to identify and compute the sources of defects and local material properties. The model makes use of the element-by-element fabrication and time-series material changes of additive manufacturing. The deposition of a part is segmented into volume elements, called voxels. Each deposited voxel is treated as an independent sample of the process parameter effects. The time series of deposition is treated as a Markov Chain, with the control parameters and measurable emissions as known quantities. The state of the material is a hidden variable. The hidden variable is approximated using material models and post-fabrication testing results to train the distribution embedded in the Markov Chain. The results indicated that a physics-based material state transition matrix in conjunction with final material properties and time-series of physical emissions can give insight into process variability and control errors. These results have wide ranging implications as a computationally efficient means of iterative process improvement for additive manufacturing, designing new control strategies, and revealing the real-time state of voxels as they are deposited. This approach moves closer to a predictive model that includes current information on the state of the process to update the prediction.
Regional and Layer Distribution of Residual Stresses in an Unloaded Aortic Medial Wall
Authors: Tamura Atsutaka , Matsumoto Koki 
Published: February 2021

Abstract
The mechanical and structural characteristics of aortic media have profound effects on the physiology and pathophysiology of an aorta. However, many aspects of the aortic tissue remain poorly understood, partly due to the intrinsic layered wall structure and regionally varying residual stresses. Our recent works have demonstrated that a mechanical interaction between the elastic lamina (EL) and smooth muscle layer in the aortic media can be computationally reproduced using a simplified finite element (FE) model. However, it is questionable whether the simplified FE model we created was representative of the structure of a real medial wall and its modeling technique would be applicable to develop a more sophisticated and structure-based aortic FE model. This study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state and successfully reproduced transmural variation in EL waviness across the aortic wall. We also aimed at confirming the inner and outer layers of the medial wall are subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. Moreover, the computed residual stresses were found to be within the reasonable range of the predicted values, 1–10 kPa, supporting the validity of our modeling approach. Although further study is required, the information obtained here will greatly help improve the understanding of basic aortic physiology and pathophysiology, while simultaneously providing a basis for more sophisticated computational modeling of the aorta.
Puncture Impact Behavior of Glass Plate Fitted With a Polymeric Film
Authors: Kojima Tomohisa 
Published: February 2021

Abstract
Glass plates are used extensively as windows in structures, cars, and airplanes. However, because it is a brittle material with low practical strength, improving its resistance to puncture impact loading is important for safety and security. Although it is known that fitting a polymeric film to the glass plate is an easy and effective way to reinforce it against impact loads, the effect of the film fitting has not enough been evaluated quantitatively. In this study, puncture impact behavior was investigated with a glass plate fitted with a polymeric film. When the general puncture impact testing method is applied to a glass plate, the measured load profile would be intensely oscillated by resonance. Therefore, in this study, the modified testing method utilizing the steel incident bar was adopted. By dropping the steel weight, impact loads were applied to the glass plate with the film through the steel incident bar. The applied impact load was estimated from the strain gauge outputs at the incident bar. The stress distribution and crack propagation in the thickness direction of the specimen were observed using the photoelastic method and shadowgraph method with the high-speed video camera. The numerical analysis model capable of reproducing the experiment was built. The obtained load-displacement curves did not include vibrations because of resonance. By the method used in this study, it is possible to quantitatively evaluate the effect of film-fitting on the glass plate.
Spin Accelerating Mechanism for Gyroscopic Wave Energy Converter
Authors: Toyoshima Akio , Hosaka Hiroshi 
Published: February 2021

Abstract
Many wave energy converters have been developed so far, but there are still many engineering problems to be applied to fishery buoys. Gyroscopic generators that use a rotating mass is characterized by the possibility of downsizing, but since low speed precession rotation is used to generate power, efficiency is so low that they do not work in the size of 1 m3. In this study, a new mechanism is proposed which consists of bevel gears, two clutches and gimbals to accelerate spin by transmitting precession torque mechanically to the spin shaft in order to realize high efficiency power generation by high speed spin rotation. Gear-driven gyroscopic generator using this mechanism which has higher efficiency and longer lifespan than former generators is expected to be applied to the power source of the small ocean monitoring buoys for efficient fisheries. A gyroscopic power generator using the accelerating mechanism with flywheel of diameter of 300 mm was designed, and the accelerating mechanism of the generator was manufactured. An experiment was conducted in which a rotating vibration of 0.5 Hz was applied to confirm the effectivity of the mechanism. The spin speed increased from 35.6 rpm to 225 rpm due to the precession torque. Designed generator is expected to output power of 3 W from this result.
Fluid-Structural Dynamic Characterization of a Membrane Wing in a Gust Environment
Authors: Pulok Mohammad Khairul Habib , Chakravarty Uttam K. 
Published: February 2021

Abstract
Unmanned aerial vehicles are applicable in a lot of areas including weather condition monitoring, surveillance, and reconnaissance. They need further development in design, especially, for the turbulent atmospheric conditions. Smart materials are considered for wing manufacturing for gust alleviation whereas membranes are found suitable for such applications, and therefore, analyzing aerodynamic properties of the membrane is important. Wind gusts create an abrupt atmospheric situation for unmanned aerial vehicles during the flight. In this study, a continuous gust profile and two types of stochastic gust models, i.e., Dryden gust model and von Karman gust model are developed to study the effects of gust load on a flexible membrane wing. One of the promising ways to reduce the effects of the gust is by using an electroactive membrane wing. A fluid-structure-interaction model by coupling the finite element model of the membrane and computational fluid dynamics model of the surrounding airflow is generated. Aerodynamic coefficients are calculated from the forces found from the numerical results for different gust velocities. A wind-tunnel experimental setup is used to investigate the aerodynamic responses of the membrane wing. Dryden gust model and von Karman gust model are found comparable with a minimum variation of magnitude in the gust velocity profile. The coefficients of lift and drag fluctuate significantly with the change in velocity due to wind gust. A validation of the fluid-structure-interaction model is performed by comparing the numerical results for the lift and drag coefficients with the experimental results. The outcome of this study contributes to better understand the aerodynamics and maneuverability of unmanned aerial vehicles in the gust environment.
Nano-Scale Wettability of Free-Standing Capped Carbon Nanotube Arrays
Authors: Ouzounian Miray , Hu Travis Shihao 
Published: February 2021

Abstract
Countless organisms in nature have adapted high-aspect-ratio micro-/nano-fibrillar arrays on their functional surfaces for achieving special and often optimized functionalities using earthly abundant materials. At the core of nanoscience and nanotechnology, rationally mimicking nature offers a promising route to create multifunctional superstructures that capture organisms and biological materials’ intriguing responsive and self-adjusting properties. Prior work has demonstrated that hierarchical vertically aligned multi-walled carbon nanotube (VA-MCNT) arrays can achieve ten folds of adhesive force comparing to the fibrillar structures of the gecko toe pads. However, little is known with regard to their wettability at the ultimate atomistic level, and how this may influence the adhesive performance and/or self-cleaning capabilities, despite water condensation and bridging are common phenomena at this length scale. In present study, molecular dynamics (MD) simulations were performed using Large-Scale Atomic / Molecular Massively Parallel Simulator (LAMMPS). Results indicate that commonly believed hydrophobic defect free CNTs (i.e., carbon sp2 hybridization without any dangling bonds) become super-hydrophilic at this length/temporal scale. The critical factors that influence the number of H-Bonds in water are: i) tube-tube spacing; and ii) shape/size and position of the water nanodroplet; and iii) how many droplets exists and how many nanotubes are bridged by the droplets. Chirality has little effect on the water interfacial behaviors. Future work will focus on the effect of water condensation and bridging on the adhesive and self-cleaning properties of carbon-based bio-inspired fibrillar dry adhesives considering defects and saline water.
Development and Characterization of Fly Ash Nanoparticles Reinforced Epoxy Resin Composite for Acoustic Applications
Authors: Ukoba Kingsley , Popoola Samuel , Israel Olatunde , Imoisili Patrick , Jen Tien-Chien 
Published: February 2021

Abstract
Noise is an unwanted sound; requires reduction and control through the use of absorptive materials. This is imperative due to the adverse effect noise poses to human health, knowledge dissemination, and tranquility which is increasing daily due to industrialization and heightened allied activities. The use of natural and synthetic reinforced composites in noise pollution control is an emerging area of research. This study aims to develop and characterize fly ash nanoparticles reinforced epoxy resin composite for acoustic applications. Samples were prepared with fly ash nanoparticles reinforcement at 5%, 10%, 15%, 20%, and 25% and investigation of noise reduction coefficient (NRC), porosity and mechanical properties (hardness, impact, flexural strength) of samples were done. Cenospheres were obtained when fly ash particles were characterized separately with the aid of sieve analysis and x-ray fluorescence analysis. The cenospheres are hollow spherical and lightweight, inertfiller material. Correlation between porosity of the samples and their sound absorption properties was observed and showed that as porosity increased, the NRC values increased and as the porosity decreased the NRC values decreased. It was also observed that heat of polymerization, fly ash nanoparticles structure and air bubbles during sample preparation (mixing) influenced the porosity values which in turn influenced the NRC values of the composite. There was also a steady decrease in mechanical properties, as reinforcements were added (5%, 10%, 15%, 20%, and 25%), this was attributed to the high surface areas and shape of reinforcement added.
Finite Element Analysis of Installation Failures in Engine Cylinder-Liners
Authors: Paruchuru Satya Prasad , Maturi Pramila Rani , Nuthalapati Jashwitha 
Published: February 2021

Abstract
There exist concerns regarding the failures that occur during the installation of thin cylinder-liners of engines at the authorized and unauthorized service centers. Analyzing the probable causes from the points of view of the design, manufacturing, and authorized and unauthorized installation procedures define the problem. The problem involves the simulation of the process of press-fitting the liner into the cylinder bore. A choice of finite element analysis using commercially available software ANSYS helped the analysis of the probable causes of failure. Estimation of the probable loads experienced by the cylinder-liners during the procedures that exist in the installation-process paved the way to the definition of loads that prevail in the problem of relevance. Prediction of the nature of contacts that prevail in the current problem and the impact of the application of the loads enabled the definition of constraints for the simulation procedures. Reference material properties chosen in the conservative sense modeled the problem realistically. The evolution of the recommendations for the manufacturing and installation of thin cylinder-liners concluded the study.
A CFD Approach for the Simulation of an Entire Swash-Plate Axial Piston Pump Under Dynamic Operating Conditions
Authors: Milani Massimo , Montorsi Luca , Muzzioli Gabriele , Lucchi Andrea 
Published: February 2021

Abstract
The paper proposes a CFD approach for the simulation of a swash-plate axial piston pump including the full 3D geometry of the real component.
Different meshing techniques are integrated in order to reproduce all the internal motions of the pump. The overset mesh procedure is used to simulate the dynamic evolution in regions’ shape and the variable orientation between parts in the piston-slipper ball joints while the alternating motion of the piston is accounted for by sliding interfaces with the neighboring regions.
The multiple dynamics of the different moving elements are implemented in terms of superposing motions in order to reproduce the real position time histories as a function of the rotational speed and the swash plate inclination angle.
The proposed numerical model includes all the leakages that characterize the coupling of the many components of the pump and nominal values are assumed (i.e. 10μm) throughout the entire simulation.
A pressure-dependent fluid density approach is adopted to improve the performance prediction of the pump under real operating conditions. Moreover, the turbulent behavior of the flow is addressed by means of the two equation k-omega SST model.
Therefore the proposed modeling approach highlights the capabilities to address any type of swash-plate axial piston pump in order to simulate the entire machine under dynamic operations; the numerical results are discussed in terms of flow ripple, pressure distribution and fluid-dynamic forces.
Comparison of UGV Position Estimation Equipped With GNSS-RTK and GPS Using EKF
Authors: Ismail Hesham , Althani Thani , Anzil Mohammed Minhas , Subramaniam Prashanth 
Published: February 2021

Abstract
Site assessments for bifacial Photovoltaic (PV) installation are quite challenging to conduct manually due to the area size and the extreme temperature conditions at desert sites. We designed and built an autonomous Unmanned Ground Vehicle (UGV) fitted with a Global Navigation Satellite Network-System Real-Time Kinematic (GNSS-RTK) positioning device, an Inertial Measurement Unit (IMU), encoder to improve and aid site assessments in desert condition. Sandy terrains deserts are challenging for UGV’s because they increase the likelihood of wheel slippage due to reduced traction. Sensor details such as IMU, GNSS-RTK, and encoder should be taken into consideration to account for the errors that the desert terrains pose. This study compared the Extended Kalman Filter (EKF) for standard GPS & GNSS-RTK to verify which performs better for the UGV’s position estimation. The estimated UGV’s position from the kinematics model and EKF are validated using a drone camera system that uses an image processing technique to verify the UGV’s position with the help of the visible reference cones. Throughout the experiments, the GNSS-RTK performed better than GPS. Also, the EKF performed as well as the GNSS-RTK by trusting it more than the encoder/gyroscope reading.