bluuebunny/crossref_metadata_2025 huggingface dataset:
Damaged Apple Detection Using Artificial Intelligence
Authors: Gurupatham Sathish K. , Bailey Caleb
Published: February 2023

The field of mechanical engineering is evolving with latest technologies such as artificial intelligence. the blend of AI technologies such as deep convolutional neural network (DCNN), convolutional neural network (CNN), artificial neural network (ANN) which contributes more to control the process parameters, process planning, machining, quality control and optimization for a better product or system. The implementation of AI in mechanical engineering applications results in minimizing the rejection of machine components which helps the whole process to be economical with better quality outputs. Considering the stiff competition among the manufacturers in the market, increasing the production rate while maintaining stringent quality control is a big challenge. In this perspective, artificial intelligence is gaining popularity in production lines to maintain a high quality for the products. A CNN is a deep learning algorithm, that is analogous to that the connectivity pattern of neurons in the human brain, has become popular and effective to image classification problems recently. It takes in the image of the object and assigns importance to various aspects/objects in the image so as to differentiate one from the other. In fruit-sorting process, manual classification is time-consuming, expensive, and requires experienced experts whose availability is often limited. To address these issues, various machine learning algorithms have been proposed to support the automated classification of fruits. In this paper, to classify “regular apples” and “damaged apples”, deep learning algorithm is applied. The pre-trained, deep learning models namely, VGG 16, ResNet50, Inceptionv3, Mobilenet_v2 along with a basic sequential convolutional model are applied to differentiate the damaged apples from regular ones and their performance variation is also analyzed. For this work, the data set containing damaged and regular apples was garnered from various local stores and farms. The data set consisted of 400 color images of both regular and damaged apples. Though the number of samples is smaller, the above-mentioned deep learning models demonstrated to overcome this deficit. For the training of model, 80% of the total sample (280) images were utilized while 20% and 10% of the sample (80 & 40) were applied for the validation and testing the model. The results show more than 90% accuracy for all the models except ResNet 50. The performance of these models can be improved even further by increasing the size of data set by adding more fruit images through better training of the models. Our experimental study demonstrates the application of artificial intelligence through four different transfer learning techniques works well for deep neural network-based fruit classification. It minimizes the labor and human errors involved in the fruit-sorting process which results in saving money and time.
Methods for Evaluating the Effect of Slack Rope Condition in a Nuclear Material Handling Equipment
Authors: Gupta Deepak K. , Kanakasabai Pugazhendhi
Published: February 2023

Electric overhead & gantry multiple girder cranes with top running bridge & trolley used at nuclear facilities are typically designed in the US per the American Society of Mechanical Engineers Nuclear Operating Guide-1 [1] (NOG-1) Standard which is approved by the US Nuclear Regulatory Commission (NRC). Per NOG-1, seismic qualification of the material handling equipment is a major design consideration based on the equipment’s safety classification. Nuclear material handling devices typically use steel wire ropes to hoist the critical load. Seismic events can cause excessive vibrations in the crane and the critical load that is hoisted by the crane hook leading to a potential slack rope condition, which is an important safety consideration per NOG-1.

The work presented in this paper compares two analyses methodologies — the linear response spectrum analysis and the non-linear time-history analysis — as it pertains to slack ropes. A simplified crane finite element model with linear springs representing the ropes is employed for the linear response spectrum analysis. A similar crane finite element model with tension only springs representing the ropes is employed for the non-linear time-history analysis. Equivalent sets of response spectra and five time-history input data are utilized. The aim of this paper is to investigate if the linear response spectrum analysis always yields conservative results for the slack rope condition as compared to the non-linear time-history analysis, and if so, the expensive non-linear time-history analysis required per NOG-1 for the slack rope condition can be avoided without compromising safety.
Numerical and Experimental Qualification of Seal Integrity of Rotary Shouldered Connections Under Combined Loads
Authors: Song Fei , Du Michael , Li Ke
Published: February 2023

The bottom hole assembly (BHA) of a drill string consists of various components and tools such as a drill bit, a mud motor, a directional drilling tool, measurement-while-drilling tools, and logging-while-drilling tools. It operates at the bottom of the wellbore and physically drills the formation. A rotary shouldered threaded connection is composed of a pin element and a box element and serves as a critical component to screw the tools and subs used on the BHA together. Functionally, the rotary shouldered connection upon makeup must be able to maintain sealability between internal and annular pressures at the seal face, while transmitting torque and withstanding bending loads when drilling through a curved well section. Leaks of these connections while drilling can be catastrophic. The drilling and measurement tools could be flooded with invasion of drilling mud into the inside, which could result in severe damage of the expensive measurement devices, sensors, and electronics inside the tools as well as a significant amount of nonproductive time. Hence, sealability assurance of the connections subjected to combined loads in difficult drilling conditions is essential for qualification of advanced rotary shouldered connections.

In this study, a numerical model based on three-dimensional finite element analysis (FEA) of the threads is developed for numerically qualifying the seal integrity of the connection. Specifically, the FEA model can describe the nonlinear interactions between the pin and box threads and on the seal face subjected to combined loads of preload, pressure, and bending. The resulting contact pressure distribution on the seal face predicted by the FEA model can be utilized as a performance metric for evaluating the risk of leaking. A full-scale sealability test rig with three-point bending configuration is also developed for validating the prediction from the numerical model. In the test, the test sample is held at its two ends onto a rigid beam with holding chains. A remotely controlled hydraulic jack is placed between the beam and the connection to generate the bending moment. It is observed in the test that the pressure drop after shutting down the pump is less than 1% within the last 15 minutes and there is no fluid leaking out of the connection after the pressure is released, which favorably agrees with the FEA prediction. Once validated, the numerical modeling method has been successfully applied to virtually qualify the sealing capacity of advanced rotary shouldered connections of various sizes without performing physical tests, which has resulted in a tremendous amount of cost and time savings for advanced rotary shouldered connection development.
Inclusion of Continuous Annuities in Engineering Economics Instruction
Authors: Armstrong Aaron
Published: February 2023

Practicing engineers are often required to conduct financial analyses of engineering projects and related business ventures. The financial impacts of engineering work often involve repeated payments spread out over time rather than simple single transactions. Usually these payments occur monthly, quarterly, biannually, or annually. However, with advances in transactional and computational capability, systems with increasingly frequent payment structures are becoming more common. The greater efficiencies gained with these more frequent payment structures have led to the possibility of using continuous payment streams where the payment amount and time between payments goes to zero. This paper advances the case for the inclusion of this material in undergraduate engineering economics courses and presents an introduction to the topic and suggested methodology for how it can be integrated and presented in such a curriculum. The inclusion of this material in these courses will improve the effectiveness of engineering economic analysis of current transactional systems as well as to potentially advance the use of continuous annuities in professional engineering-related commerce.
Development of a Haptic Glove for the Index and Middle Fingers of the Right Hand With Force Feedback
Authors: Caballero Moreno Jhon A. , Roa Prada Sebastián
Published: February 2023

Due to the growth in the amount and types of information that surrounds us, it is important to explore other areas and ideas and ways to interact with information. Haptic systems with their tactile, kinesthetic and motor capabilities, together with the associated cognitive processes, present a bidirectional channel of information to our brain. This channel provides a way to interact with the information with which a large number of applications can be generated. Haptics covers many disciplines; Therefore, a wide variety of applications is generated that includes those areas of human needs such as products, manufacturing, education, health, among others. For teleoperation and virtual reality applications, force feedback is important for the user, since due to this it can improve the interaction between the user’s real environment and the virtual environment.

For this reason, the human hand is capable of obtaining information while executing complex tasks. This has a variety of functions among the most important are the sensory and motor functions. That is why there is an interest in creating a haptic device for the hand.

Haptic research and technology have created and evaluated different prototypes with their characteristics and capabilities for the use of virtual environments, some of which are currently marketed. In this way, different applications of this technology have been made in areas such as: graphical interface, medicine, games, engineering, telerobotics, simulators and medical rehabilitators. Focusing on the haptic interface for the upper limbs with force feedback, the process of integrating exoskeletons and haptic interface is a great advance to be able to transmit force to the joints of the hand.

Traditional methods for the rehabilitation of patients with motor disabilities in the upper limbs are slow, costly and in many cases ineffective, considerably reducing their quality of life. Therefore, it seeks to develop a low-cost haptic force feedback technology with its three main elements: a haptic device, a computer where a virtual environment (interface) is generated, and a human operator that closes the loop, which complements the recovery of these patients and thus achieve better results. Previous studies that integrate 3D printing technologies, virtual reality (VR), microcontrollers and actuation through tensors demonstrate the successful development of different prototypes with similar characteristics, although most of them are expensive. For the development of the prototype, the V methodology was used, performing instrumentation, interface-prototype connection and force feedback tests. The integration of these subsystems after the tests, result in a final prototype of the haptic glove for two fingers (index and middle) of the right hand, managing to generate feedback forces on the user based on the information provided by the interface, complying with the characteristics of being a functional and low-cost glove.
Body Armor - Current and Potential Materials
Authors: Thakkar Nishant , Piovesan Davide , Steinbrink Scott
Published: February 2023

Military forces have faced the ballistic threat in many forms for hundreds of years, ranging from spears to bomb fragmentation. Soldiers have historically worn body armor to protect themselves on the battlefield. The goal of modern lightweight body armor development has always been to develop lighter and stronger materials so that performance can be improved while reducing weight and making the mobility of the personnel easy. Body armor ballistic testing follows strict guidelines provided by the National Institute of Justice (NIJ) in the United States of America. According to the new testing standards, innovative products are being released. This review elaborates on various materials and composites that are being used in the making of body armor that eventually help eliminate the threats from high-velocity bullets, shell fragments, and knives. In this paper, the science of body armor materials is quickly reviewed with emphasis on current knowledge of relevant energy-absorbing mechanisms in fibers, fabrics, polymeric laminates, and ceramics. The drive to create lightweight and comfortable armor systems for military personnel has led to the development of various composite materials. The paper reviews the major features of materials used in body armor and focuses on the development of intriguing new potential materials.
Ultrasonic Characterization of AlSi10Mg Specimens Printed By Direct Energy Deposition Technology
Authors: Chukovenkova Mariya , Zagrai Andrei , Halliday H. Scott , Toddy Joshua , Murphy Nylana J.
Published: February 2023

Additive manufacturing (AM) process has different parameters, their combination, and powder composition which could affect the mechanical properties of printed material. The layer by layer manufacturing approach influences microstructure of the material, and hence, the anisotropy of the mechanical properties. Also, defects such as porosity or cracks could be caused by non-optimized printing parameters.

In order avoid wasting of sample while inferring mechanical properties of the printed material, it beneficial to utilize the nondestructive evaluation (NDE) methods. Implementation of NDE methods for additively manufactured parts plays a great role in evaluating and ensuring the reliability of the printed part.

In this work, ultrasonic technique was utilized to determine the elastic properties and anisotropy of additively manufactured AlSi10Mg and conventionally fabricated Al 6061 samples.

An ultrasonic measurement approach which allowed for the accurate measurement of the material properties was established and implemented. Longitudinal and shear transducers were used and the sound speed was calculated by analyzing the position of the arrived pulses in the pulse-echo configuration. Elastic properties were calculated from the longitudinal and shear sound speeds and measured density. Also, the correlation between elastic properties and sample’s location within the printed block, and spatial distribution of the elastic properties were explored.
An Experimental Investigation on the Stability of Gel-Like Carbon Dot Based Nanofluids
Authors: Mollick Rahat , Hentges Nicholas , Parveg A. S. M. Sazzad , Zhou Yiqun , Leblanc Roger M. , Ratner Albert
Published: February 2023

Highly photoluminescent gel-like carbon dots (G-CDs) have interesting applications in the fields of bio-sensing, thermofluids, and as photocatalysts to reduce water contaminants. G-CDs have been shown to be nontoxic and environmentally benign while exhibiting interesting characteristics as fluid additives. For additives like G-CDs to be effective, they need to stay suspended in the liquid medium. If they settle to the bottom, the positive benefits are lost, and the high-density lower region can experience adverse effects due to excessive particle loading. Many existing techniques are available to analyze suspension stability. However, most of these techniques are expensive and/or require specialized equipment. Moreover, these methods can be invasive and ultimately end up disturbing the suspension. Furthermore, these methods often focus on understanding the relation between colloidal stability and surface charge development through measuring the zeta potential, an indicator which is reported to be unsuitable while working with higher concentrations of nanomaterial in the colloidal suspension. To overcome the deficiencies of the traditional zetametry experiments, a novel, non-contact, non-invasive, quantitative, and economical experimental setup was deployed in this work to investigate the stability of G-CD nanofluids. The G-CD concentration is kept constant at 3wt%. Decane and small amount of water is used as dispersion media for the nanofluid in this study. Four different water concentrations of 1.5 wt%, 1 wt%, 0.75 wt% and 0.375 wt% are tested in this work. The results show the technique is both effective and inexpensive.
Vibration Control of a Cantilever Beam Using Reduced Model
Authors: Kamalirad Amir Mohamad , Fotouhi Reza , Taghizadeh Mitra
Published: February 2023

One of objectives of the research work here is to actively control vibration of a flexible manipulator’s end-effector. Another objective is to reduce computational cost to control vibration. When the manipulator is in lock configuration, it can be considered as a cantilever beam with base motion. In this paper, finite-element analysis (FEA) is used to obtain natural frequencies (eigenvalues) and mode shapes (eigenvectors) for a cantilever beam. The eigenvectors are translated into uncoupled state space equations, based on balanced realization and Match-DC-Gain model reduction algorithm. Linear quadratic regulator is employed for full and reduced models of the beam. Contribution of this research is on verifying analytical approach (reduced model) with numerical model (FEA). Contribution also includes computational efficiency of the model reduction. Simulation results for vibration suppression of the cantilever beam are obtained and compared with two different models.
Phase-Field Modelling for Crack Evolution of PBX Under Thermomechanical Loadings
Authors: Long Xu , Zhu Jiaqi , Su Yutai , Siow Kim S. , Chen Chuantong
Published: February 2023

Polymer-bonded explosive (PBX), also known as plastic-bonded explosive, is a typical kind of explosive powder with the synthetic polymer bonded together explosive composite materials. It has excellent explosion performance and thus is widely applied in the military and civilian industries. The PBX mechanical properties exhibit high sensitivities to the action of various types of loads, which is closely related to microscopic damage mechanisms within the material. The applied loads vary considerably, with amplitudes ranging from a few MPa to as high as several tens of GPa and durations lasting from the order of μs to ms. The cracking evolution is essential to the PBX applications in a strict control manner. However, PBXs are dangerous energy-bearing materials, and the mechanical experiments to measure their mechanical properties are costly and also challenging. Therefore, theoretical analysis and numerical simulation are anticipated to explore the sensitivities of PBX mechanical properties and also the influence of crack evolution. This paper will simulate numerically the process of work done of PBX explosive gas by fracture phase-field method, which reveals the typical microscopical mechanism of crack evolution and establish a computational model for crack propagation under the coupled thermomechanical effects.
Ammonia for Industrial Combustion
Authors: Londerville Steve , Whelan Matt , Baukal Charles , Gueniche Ali , Haag Michel , Newman Paul
Published: February 2023

Many companies are investigating switching from conventional fossil fuels to “green” fuels such as hydrogen to reduce CO2 emissions. This assumes hydrogen is made by an environmentally-friendly method such as electrolysis using renewable energy. However, there are concerns with hydrogen. For example, it leaks very easily, is extremely flammable, and is more difficult to transport than other fuels.

A potential solution is to use ammonia as an alternative method of supplying hydrogen to a combustion process, assuming it is made in an environmentally-friendly manner. Like H2, ammonia also does not produce any carbon-containing pollutants such as carbon monoxide, carbon dioxide, or soot. It has transport properties like propane, so it is easier to contain and transport than hydrogen.

However, there are some concerns with ammonia. It is a caustic and hazardous chemical with a pungent odor so it must be handled accordingly. It has the potential to generate very high levels of NOx which means a post-treatment system like an SCR may be required. Existing burners may need to be modified or replaced.

While ammonia is a potentially important future green fuel, there are concerns that require attention and further research. This paper compares methane, hydrogen, and ammonia combustion and discusses the advantages and disadvantages of ammonia in particular.
Variation of Sound Directivity From a Supersonic Nacelle
Authors: Sugar Mitchell L. , Slaboch Paul E.
Published: February 2023

The effects of aircraft flight speed and fan face pressure variations on sound propagation from an axisymmetric commercial supersonic engine inlet were studied using numerical methods. A computational fluid dynamics (CFD) model of the inlet was constructed in Ansys Fluent. The results of this model were then used as inputs for the aeroacoustic solver, ACTRAN, and used to calculate far field radiated noise. Using this process, a parametric study was conducted varying two parameters: the approach Mach number from 0.35 to 0.55 in increments of 0.0125, and the fan face back pressures from −10 kPa to −40 kPa in increments of 1 kPa. It was found that variations in free stream Mach number resulted in approximate variations of 2 dB on radiated acoustics while variations in fan face pressure resulted in up to 5 dB of change. These variations were found to be frequency dependent with the largest variations happening over a frequency range of approximately 3 kHz to 5 kHz and again from 6 kHz to 8 kHz. These results indicate combinations of flight speed and fan pressure to avoid in flight to reduce overall noise reaching the ground.
Prediction of Sectional Collapse of Thin-Walled Structure Under Pure Bending by Nonlinear Composite Beam Theory
Authors: Jiang Fang , Yu Wenbin
Published: February 2023

Brazier [1] found that when one dimension of the beam cross-section was relatively smaller than the others, large in-plane displacements over the cross-section might occur, even though the strains could remain very small. Under this circumstance, the so-called Brazier effect refers to the cross-sectional ovalization, which leads to nonlinear bending buckling and collapses. This paper extends the Variational Asymptotic Beam Sectional Analysis (VABS) theory to consider finite cross-sectional deformations. The three-dimensional (3D) continuum is reduced to a one-dimensional (1D) beam analysis and a two-dimensional (2D) cross-sectional analysis featuring both geometric and material nonlinearities without unnecessary kinematic assumptions. The present theory is implemented using the finite element method (FEM) in the VABS code, a general-purpose beam cross-sectional analysis tool. An iterative method is applied to solve the finite warping field for the classical-type model using the Euler-Bernoulli beam theory. The deformation gradient tensor is directly used to deal with finite deformation, various strain definitions, and several types of material laws regarding nonlinear elasticity and progressive damage. Numerical examples demonstrate the capabilities of VABS to predict the sectional collapse of thin-walled structures under pure bending.
Thermal Analysis of a Fiber Optic Cable for a Vertical Farming Application
Authors: Cesmeci Sevki , Islam Mohammad Towhidul , Horowitz Stephen
Published: February 2023

Feeding the existing 7 billion and ever-growing population around the world urges farmers to adopt alternative ways. Research indicates that the demand for alternative farming will only increase as fertile lands become scarcer each and every year. Emerged from this need, “agritecture,” often called vertical farming, has attracted a great deal of attention recently. Vertical farming is centered around growing plants by adopting methods like hydroponic, aeroponic, or aquaponic and staking the layer vertically up to the sky or going deep in the ground. Lighting is the integral component of the vertical farming systems, which can be natural or artificial and should be provided at a specific intensity and spectrum. The world is already in need of energy to tackle the soaring energy demand due to the rising population and industrialization. Researchers have been trying to utilize alternative sources, and the heat and illumination of the sunlight is always the widespread field of interest. In vertical farming, using hybrid solar lighting can also be an appealing approach. However, the fiber optical cable is one of the critical components of this system, which is used to transmit the light to the luminaire. Since this cable plays a vital role in transmitting the power, the exposure of the surface of the cable to different rays from the directed sunlight is of primary concern to avoid any thermal failure. If not designed properly, the temperatures at the inlet of the fiber optical cable can reach to very high values, resulting in both physical and chemical changes in the cable, and in some cases, local burnings. A literature survey revealed that there are only a few studies that dealt with the thermal management of fiber optical cables. In this study, we analyze the thermal behavior of fiber optical cables for a vertical farming application, which was supported by the United States Department of Agriculture SBIR Phase I program. To do that, we adopted a Finite Element Analysis (FEA) based approach. Before carrying out the full simulations, the simulation methodology was verified by replicating an existing study in the literature. Once confirmed, a full parametric sweep analysis was conducted to see the effects of material and geometric properties of the fiber optical cable on the temperature increase at the inlet. This study is novel in the sense that there are no prior studies that targeted the effects of material and geometric properties on the thermal behavior of the fiber optical cables so the users could make the appropriate choices for the cable selection or could custom design their cables for specific lighting conditions. The results were presented and discussed, and future research directions were indicated.
Spatial Pendulum TMD With Two Tuning Frequencies
Authors: Mohamed Waled T. A. , Kashani Ahmad
Published: February 2023

Some structures have different natural frequencies in the two lateral X and Y-directions. Tuned damping of such structures require using either a) the less attractive option of two regular PTMDs each tuned to one of the natural frequencies of the structures’ lateral modes or b) one pendulum TMD with two different tuning frequencies (one for each lateral directions), necessitating two different swinging lengths. Pendulum TMDs with two different tuning frequencies in the two lateral X and Y directions, are realized by constraining the swinging length of the pendulum in one direction but not in the other direction. Such two degree-of-freedom pendulum tuned mass damper, is called Bi-PTMD.

In this work, the dynamics of a two degree-of-freedom pendulum tuned mass damper (Bi-TMD) appended to a structure with two low-frequency, lateral degrees of freedom (representing the first two modes of a tall structure) is studied and the nonlinear differential equations of motion are derived using the Lagrangian mechanics approach. The equations of motion are simplified using small angle and slow motion assumptions.

The system of nonlinear differential equations are numerically simulated in Matlab/Simulink environment and the responses of the structure without and with the pendulum Bi-TMD to a number of different perturbations in the lateral directions are evaluated. The numerical model is verified by comparing its simulation results with the outcomes of SimScape Multibody physical model of the same system.
Hysteresis Effect of Tangential Force Field on Deformation of Single Cell Migrating Between Different Micro-Striped Topography Patterns
Authors: Hashimoto Shigehiro , Yonezawa Hiroki , Kishimoto Kazuya
Published: February 2023

The hysteresis effect of the tangential force field (perpendicular to the cell major axis) on cell activity (deformation, migration) has been studied in vitro. Cell orientation was aligned by microtopography patterns (striped ridgelines; height 0.7 μm, width 3 μm, spacing 3 μm) on the scaffold plane. Three compartments with different angles (0 degrees, 45 degrees, and 90 degrees) between the longitudinal direction of the ridges and the direction of the tangential force field were designed. Osteoblasts (MC3T3-E1; osteoblast precursor cell line derived from mouse calvaria) were used in the experiment. After applying a tangential force field for 5 hours, the position and contour of each cell was tracked by time-lapse microscopic images for 48 hours. Experimental results show that the tangential force field perpendicular to the cell major axis affects subsequent action (deformation, migration) of cells. The effect is maintained for 48 hours even if the cell moves to different areas of the topography pattern.
Experimental Research on the Corrosion and Heat Transfer Characteristics of HCl-H2O Vapors Outside a 3-D Finned Tube
Authors: Huang Ying , Chen Yuxuan , Zhang Weilong , Ding Yudong , Liao Qiang , Cheng Min
Published: February 2023

Hydrochloric acid (HCl) corrosion in the overhead condensation system of crude distillation units is a common occurrence in refinery worldwide. The HCl corrosion can not only reduce the heat transfer performance of the heat exchanger, but also lead to the thinning of the heat exchanger wall, and even cause perforation and leakage. Therefore, it is necessary to study the corrosion and heat transfer characteristics of the heat exchanger under this condition, in order to improve the heat transfer performance and safety. In this paper, a 3-D finned tube with high heat exchange efficiency was used to study the corrosion and heat transfer characteristics with the moist air containing HCl outside it. The effects of different H2O volume fraction and HCl volume fraction on the HCl dew point of the 3D finned tube were studied. The corresponding HCl dew point prediction formula was fitted by the experimental data. In addition, the heat transfer characteristics of 3-D finned tube with HCl-H2O vapors outside was studied. The experimental results showed that the HCl dew point increased with an increase of the H2O volume fraction and HCl volume fraction. Furthermore, for the 3-D finned tube, the heat transfer coefficient increased with an increase of the H2O volume fraction and HCl volume fraction. In addition, when the H2O volume fraction was 10%, the 3-D finned tube had 87.2%–95.4% higher heat transfer coefficient and 91.3%–97.1% higher heat transfer rate compared with the smooth tube.
Failure Investigation of Secondary Superheater (SSH) Tube Boiler in the Coal Switching Case
Authors: Hermawan Rachmat , Rooscote Didi , Kustiawan Agung Sidang , Nugraha Herry
Published: February 2023

Failure in the boiler tube is one of the major causes of the force outages in a coal-fired power plant. This paper presents a failure investigation on the high-strength alloy ASME SA213 T91 superheater tube of a 600 MW class coal-fired power plant due to coal switching. The research investigated the fuel quality and the materials using the material characterization method and mechanical testing. The potential slagging and fusibility were found based on coal properties. A wide-open rupture with thick and blunt edges is exposed in the tube failure. Several steps for failure investigation were performed. Microstructures of the failed tube show numerous creep voids estimated < 2.5 microns and decomposed into spheroids as evidenced by a decrease in the hardness number 165 HV nearest location of failure. Exposure to high temperatures in the long-term causes the formation of an oxide scale layer on the fireside tube. The thickness of the oxide scale on the inner side tube > 600 microns also accelerates tube failure and shortened creep life is shown by a time rupture value from 16.29 to 0.26 hours with higher operating hoop stress near to failure location. Changes in fuel characteristics are indicated by the value of fusibility of 1190°C and slagging index of 0.473 which can worsen the condition of overheating from the increase in metal temperature. Higher flue gas temperatures due to the coal switching characteristic and higher metal temperatures of tubes above 570°C were identified as the cause of overheating. The finding confirmed that the superheater tube failed by long-term overheating.
Biaxial Stress Inversion in Plate-Like Structures Based on Acoustoelastic Guided Waves
Authors: Zhao Chunyu , Chen Xin , Li Jian , Liu Yang
Published: February 2023

The nondestructive evaluation of stress using guided waves through the acoustoelastic effect has significant importance for the safety of the structure. In this paper, a Semi-Analytical Finite Element (SAFE) method is used to develop the acoustoelastic theory of guided waves propagating in plate-like structures with arbitrarily shaped cross-sections. Based on the anisotropy of the material induced by the axial force, a method for in-situ detection of biaxial stress through multi-angle dispersion change was developed. The inversion algorithm was validated by data of the SAFE method and the Sweeping Frequency Finite Element Modeling (SFFEM) method, respectively. The inversion results of S0 mode under this method are mainly studied, which can achieve accurate stress in-situ detection of the plate-like structure, and the Root Mean Square Error (RMS) can reach below 1%.
Particle Flow and Packing Behavior of Electron Beam Melting Ti-6Al-4V Powder Under Atmospheric and Vacuum Conditions
Authors: Kelley Garrett , Mamidala Ramulu
Published: February 2023

Electron beam melting (EBM) is a powder bed fusion process capable of manufacturing metallic components out of a variety of alloys. The process is unique in that it relies on the generation of a uniform, densely packed powder bed under vacuum conditions at high temperatures. Therefore, understanding the behavior of the powder subjected to the build environment is crucial to developing the process further.

This study presents a method for comparing the flowability, angle of repose, and packing arrangements of non-virgin Ti-6Al-4V powder under atmospheric and vacuum conditions. The two-dimensional particle packing behavior was acquired during the filling of a container constructed from microscope slides and double-sided adhesive. Data on the Newton or “kissing” number was then analyzed using optical microscopy. To facilitate identical measurements within a vacuum environment, a device was designed to initiate flow within a vacuum chamber using a photoresistor switch and “mechanical finger”. The results show that vacuum environments have negligible effect on powder behavior. These results are important in understanding the connections between benchtop measurements and how they correlate to powder performance within the build chamber. While not explicitly tested, the potential effects that temperature has on powder flow performance will also be discussed.
Analytical and Computational Modeling of FRP-Metal Joints Made by Ultrasonic Additive Manufacturing
Authors: Zhao Ningxiner , Guo Hongqi , Headings Leon M. , Dapino Marcelo J.
Published: February 2023

Previous research has developed a process for producing strong fiber reinforced polymers (FRP)-metal joints via ultrasonic additive manufacturing (UAM), and structural tests have been conducted to characterize the mechanical properties of the joints. In this research, an analytical model and a finite element analysis (FEA) model are developed for UAM-produced FRP-metal joints to provide better joint design and application insights. The analytical model applies both the thick-wall cylindrical pressure vessel theory and Tsai-Wu failure criterion to characterize the stress condition in the embedded fibers and the failure mode when tension is applied to the joint. Comparing the analytical model and experimental results of two different sample configurations, the model is able to predict the peak load of the joint with given material properties and joint geometries. Based on the analytical model, an FEA model is built using LS-DYNA to simulate the tensile testing of FRP-metal joint using shell mesh by homogenizing the hybrid portion of the joint. The stress maps obtained from the FEA model for two joint designs show similar distributions when compared to measured digital image correlation (DIC) strain maps, indicating that the failure modes match the experimental results. The FEA simulation results agree well with the experimental result for peak load and displacement at fracture, with an error of less than 5%.
Integration of Minivalves With RNA Amplification Device for Simultaneous Detection of SARS-CoV-2 and Influenza Viruses
Authors: Alipanah Morteza , Manzanas Carlos , A. Lednicky John , Wu Chang-Yu , Fan Z. Hugh
Published: February 2023

We report a point-of-care (POC) device for simultaneous detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A viruses. The device carries out sample preparation using ball-based valves for sequential delivery of reagents. A microfluidic paper-based analytical device (μPAD) in the detection unit enables RNA isolation and enrichment, followed by reverse transcription loop-mediated isothermal amplification (RT-LAMP) and colorimetric detection. The device integrates all the necessary steps for the sample preparation, including virus lysis, RNA enrichment and purification of two virus samples. The device enabled simultaneous detection of SARS-CoV-2 and Influenza A N1H1 viruses in 50 min., with limit of detection of 2 and 6 genome equivalents (GEs), respectively. The device was also capable of detecting environmental sample of the two viruses.
Quadcopter Control Using Single Network Adaptive Critics
Authors: Velazquez Alberto , Xu Lei , Sardarmehni Tohid
Published: February 2023

In this paper, optimal tracking control is found for an input-affine nonlinear quadcopter using Single Network Adaptive Critics (SNAC). The quadcopter dynamics consists of twelve states and four controls. The states are defined using two related reference frames: the earth frame, which describes the position and angles, and the body frame, which describes the linear and angular velocities. The quadcopter has six outputs and four controls, so it is an underactuated nonlinear system. The optimal control for the system is derived by solving a discrete-time recursive Hamilton-Jacobi-Bellman equation using a linear in-parameter neural network. The neural network is trained to find a mapping between a target costate vector and the current states. The network’s weights are iteratively trained using the least-squares approximation method until the maximum number of iterations or convergence is reached, and training begins at the final time and proceeds backward to the initial time. The trained neural controller applies online optimal feedback control that tracks a trajectory, minimizes control effort, and satisfies the optimality condition. The SNAC method provides a controller that can handle all initial conditions within the domain of training and all times less than the training’s final time.
Performance Advantage Evaluation of Air-Oil Heat Exchanger Based on Variable Cycle Engine in Flight Mission
Authors: Huang Congcong , Xu Guoqiang , Wen Jie , Li Mengchen , Zhuang Laihe
Published: February 2023

Adding an air-oil heat exchanger to the aero-engine is beneficial to improve the cooling quality of turbine cooling air, while its influence mechanism during the whole flight envelope is still ambiguous. This paper evaluates the performance advantages of the air-oil heat exchanger by building a comprehensive performance simulation model integrating variable cycle engine (VCE), air-oil heat exchanger, and blade temperature evaluation model. The results show, based on typical flight tasks: adding a heat exchanger without changing the cycle parameters reduces the engine’s overall performance, but the blade thermal environment improves, and the temperature drop of the cooling air can reach 45–214K under various operating conditions. Adding a heat exchanger and adjusting bleed air ratio or turbine inlet temperature can increase thrust obviously. For these two parameters, adjusting turbine inlet temperature can gain more enhancement in aeroengine performance. The increase in thrust is no less than 15% in take-off, climbing, and air combat conditions when high thrust is needed, effectively improving the climbing rate, service limit, and maneuverability of the assembled aircraft. Based on the flight envelope: the influence of flight environment on the two modes of VCE is consistent, the cooling air temperature and blade surface temperature are higher in the high-Ma region. Moreover, from the perspective of the engine’s internal thermal environment, double bypass mode is more suitable in low-altitude and low-speed regions, while single bypass mode is more fit in high-altitude and high-speed regions. Furthermore, the heat exchanger can effectively improve the thermal environment of hot-end components in the high-Ma region, ensuring the engine runs in safe conditions. In conclusion, this study points out the performance advantages of air-oil heat exchangers on VCE, which could help solve thermal problems in future advanced engines.
A Sequential Structural Optimization Framework to Design Compliant Constant Force Mechanisms
Authors: Ou Haihua , Johnson Shane
Published: February 2023

Compliant constant force mechanisms (CFMs) output a constant force over a large range of displacement input and offer tremendous energy storage compared to mechanisms/material with linear or hardening responses. In this study, we present a graph-based sequential structural optimization framework to design CFMs with high energy storage capacity. In the framework, the constant force behavior with a zero preload is defined to be ideal, as this behavior offers the maximum energy storage given a force and displacement limit. A graph-based topology selection, followed by shape optimization is conducted to select designs with energy storage most similar to the energy of the ideal constant force relation. During the graph-based topology selection, the possible topologies are exhaustively listed, and then ranked based on their performance in energy storage capacity. The better performing topologies are selected as the initial shape of the following shape optimization. We present two design cases obtained from this framework. The obtained CFM designs through this framework has a higher energy similarity index compared to typical designs from literature (0.95 vs. 0.90) and they are experimentally validated. The constant force mechanisms developed through this study can be further applied in different robot/human-environment interfaces that benefit from both mitigating impact force and increasing energy storage.
Experimental and Numerical Investigation of the Influence of Crack Front Orientation in Mode 1 Plane Strain Fracture Toughness of a Vero Material System via Poly Jet Additive Manufacturing
Authors: Khapper Vishwanath , Mohan Ram V.
Published: February 2023

Polyjet printing, a multi-jet Additive Manufacturing technique, has been used to fabricate 3-Dimensional structures for various polymeric material systems. This technique uses a layer-by-layer deposition method and allows for the fabrication of parts with different material compositions and varying thermomechanical properties. The current research investigates the influence of process-induced variation on Mode 1(K1C) fracture toughness of the Vero material system. Compact Tension (C-T) specimens with crack fronts parallel and perpendicular to the print direction were fabricated. The orientation of the crack front relative to the print and build directions influenced the Mode I fracture toughness values. When the crack front was parallel to the print plane, K1C decreased by 49.54%, G1C decreased by 41.56%, and peak load intensity decreased by 52.76% compared to the perpendicular crack front orientation. C-T samples were modeled in CAD to correlate with the experimental results and then analyzed in the Ansys workbench. The FEA yielded a Mode 1 fracture toughness value of 2.48 MPa m0.5 for a perpendicular configuration of the crack front and a fracture toughness value of 1.15 MPa m0.5 for a parallel configuration of the crack front. The Representative Volume Element method is used for a composite containing the Vero material system as a matrix and carbon nanofibers as reinforcement. Carbon nanofibers are integrated using a customized material configuration, and their influence on fracture is studied. A tailored network perpendicular to the crack front in a 3D printed C-T specimen stiffens the specimen. In contrast, a tailored network parallel to the crack front has a relaxing impact, indicating that an additively created part may be prone to softening under certain conditions.
Creasing Damage Analysis in Corrugated Packages Using Beam Lattice Models With Joints Stiffness Degradation
Authors: Tahir Saad , Qaiser Zeeshan , Ou Haihua , Ur Rehman Tanzeel , Johnson Shane
Published: February 2023

Corrugated packages are widely used for the distribution and storage of consumer goods. These containers experience high compressive forces in stacking, and the boxes fail due to buckling and creasing in the panels. Crease lines increase the consumer product rejections as the product is thought to be damaged with the package. With increased online shopping, these problems result in higher monetary losses for the companies and increased material waste. Lattice modeling, a method to represent continuums using beams or springs, provides new opportunities to describe post-buckling creases via beam joint stiffness reduction. This may be accomplished by inducing moment releases at the lattice joints upon failure. Lattice modeling has been used to model orthotropic material properties, but not to model nonlinear orthotropic behavior or creasing. The goal is to develop a modeling method to predict the creasing failure modes and the applied force magnitudes at the onset of creasing damage for corrugated paper packages with nonlinear orthotropic properties. This manuscript modifies the analytical beam-lattice models from literature to describe nonlinear (bi-linear) orthotropic paper, and analyze corrugated board lattices via classical lamination theory. The research employs an adjusted transformed cross-section method to represent the liners and homogenized fluting. To model failure, the computational framework replaces the original rotational constraints between beams with rigid connector elements, and reduces the lattice joint rotational stiffness to zero based on a pre-defined critical connector moment or critical stress criteria. The critical stress for failure is obtained by capturing crease line formation during non-standard edge compression tests (ECTs) in the container’s loading direction. The model is then validated via box compression tests (BCTs) of regular slotted containers (RSCs). The lattice model predicts the crease lines origin and progression as well as an accurate peak BCT load. The proposed framework may be used to alter corrugated box design to reduce failures and hence the consumer rejections. This will help lower the related financial losses and address sustainability concerns.