bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Moisture-Heat Coupling in the Drying Process of a Multi-Temperature Zone Belt Dryer
Authors: Jia Hepeng , Wu Kai , Wang Yu , Sun Yu
Published: February 2021

The multi-temperature zone distributed drying method solves the problem of uneven drying of the conventional belt dryer. Multi-temperature zone belt dryer is widely used in the drying of aquatic feed products. This paper presents a numerical simulation method for multi-temperature zone belt dryer. The computational fluid dynamics (CFD) was applied to simulate the drying process of materials in a multi-temperature zone belt dryer. The user-defined function (UDF) was used to study the moisture-heat coupling drying process to predict the airflow filed of the multi-temperature zone belt dryer. The results showed that there were vortexes in each drying chamber so that airflow velocity distribution of the material layer was not uniform. However, the multi-temperature zone distributed drying method can maximize the drying efficiency through the bilateral distribution of the air inlet. The temperature distribution in each temperature zone was relatively uniform, and the temperature difference between the two sides of the feed layer was massive. The moisture content of the materials in each temperature zone was very uniform, the drying unevenness was less than 1.0%, and the dryer has excellent moisture content uniformity.
Investigation of Drilling Temperature in Relation to Machining Conditions and Cutting Time
Authors: Seif Charbel Y. , Hage Ilige S. , Baydoun Ahmad M. R. , Hamade Ramsey F.
Published: February 2021

Controlling drilling temperature and thrust forces play a significant role in reducing tool wear and improving machining efficiency. In this work, drilling experiments are set up to measure flank surface temperature via thermocouple sensor wires passed through the coolant holes of 10mm twist drill and brazed to the drill flank surface. The testing setup is an inverted drilling jig where the workpiece (Aluminum 6061-T6 rod) is chucked into the spindle of a vertical machining center. Thrust forces are co-measured using Kistler type 3-component plate dynamometer attached to the table. A design of experiment (DOE) using JMP-SAS/STAT® was adopted for selecting combinations of cutting speed and feed values that cover a wide range.

Drilling temperature rise and thrust forces are found to correlate with cutting conditions of feed (f), maximum cutting speed (V), and drilling depth (Dp). Nonlinear regression analysis produced correlating equations of flank temperature rise and thrust forces to conditions and follow a mechanistic power law of the form a1fa2Va3Dpa4 where a1, a2, a3 and a4 are identified via regression fitting.
On Symmetric Periodic Motions With Different Excitation Periods in a Discontinuous System With a Hyperbolic Boundary
Authors: Luo Albert C. J. , Liu Chuanping
Published: February 2021

In this paper, symmetric periodic motions with different excitation periods in a discontinuous dynamic system with a hyperbolic boundary are presented analytically. The switchability conditions of flows at the hyperbolic boundaries are developed. Periodic motions with specific mapping structures are predicted analytically, and numerical simulations of periodic motions are carried out. The corresponding G-functions are presented for illustration of motion switchability at the hyperbolic boundaries.
Design and Construction of a Four-Stage Travelling-Wave Thermo-Acoustic System for Power Generation
Authors: Ngcukayitobi Miniyenkosi , Tartibu Lagouge , Gqibani Samuel
Published: February 2021

This work describes the design and construction of a four-stage traveling-wave thermo-acoustic system for electricity generation. The thermo-acoustic conversion consists of using a sound-wave for the transfer of heat from a low to high-temperature medium or the use of heat energy to generate a sound wave. Both the absence of moving parts and the simplicity of thermo-acoustic systems make the technology sustainable for converting low-grade waste heat into acoustic power. Many existing studies have pointed out the acoustic-to-electric potential of thermo-acoustic systems. Hence in this work, a thermo-acoustic system has been developed. The traveling-wave system has a total length of 3 560 mm. The distance between each thermo-acoustic engine is 640 mm. Each engine stage had four cartridge heaters used to generate the heat required. A commercial loudspeaker was used to convert sound into electricity. The minimum temperature difference necessary to induce a voltage at the terminals of the loudspeaker was approximately 200°C. The four-stage traveling-wave system generated the highest output voltage of 4.218 V.
Bayesian Optimization of Energy-Absorbing Lattice Structures for Additive Manufacturing
Authors: Hertlein Nathan , Vemaganti Kumar , Anand Sam
Published: February 2021

Additive manufacturing has enabled the production of intricate lattice structures that meet stringent design requirements with minimal mass. While many methods such as lattice-based topology optimization are being developed to design lightweight structures for static loading, there is a need for design tools for achieving dynamic loading requirements. Lattice structures have shown particular promise as low-mass energy absorbers, but the computational expense of nonlinear finite element analysis and the difficulty of obtaining objective gradient information has made their optimization for impact loading particularly challenging. This study proposes a Bayesian optimization framework to determine the lattice structure design that provides the best performance under a specified impact, while managing the structure’s mass. Considering nonlinear effects such as plasticity and strain rate sensitivity, a 2D explicit finite element (FE) model is constructed for two lattice unit cell types under impact, and parameterized with respect to geometric attributes such as height, width, and strut thickness. These parameters are considered design variables in a minimization problem with an objective function that balances part volume with a common injury metric, the head injury criterion (HIC). Penalty values are assigned to designs that fail to absorb the entire impact. Design for additive manufacturing (DFAM) constraints including minimum feature thickness and maximum overhang angle are applied to ensure that the optimal design can be manufactured without subsequent manual refinement or post-processing. The best optimizer hyperparameters are then carried over into larger optimization problems involving lattice structures. Future work could include expanding this framework to allow for lattice structure designs with arbitrary boundaries.
Periodic Motions and Bifurcations of a Periodically Forced Spring Pendulum Varying With Excitation Amplitude
Authors: Guo Yu , Luo Albert C. J.
Published: February 2021

In this paper, the semi-analytical method of implicit discrete maps is employed to investigate the nonlinear dynamical behavior of a nonlinear spring pendulum. The implicit discrete maps are developed through the midpoint scheme of the corresponding differential equations of a nonlinear spring pendulum system. Using discrete mapping structures, different periodic motions are obtained for the bifurcation trees. With varying excitation amplitude, a bifurcation tree of period-1 motion to chaos is achieved through the bifurcation tree of period-1 to period-2 motions. The corresponding stability and bifurcations are studied through eigenvalue analysis. Finally, numerical illustrations of periodic motions are obtained numerically and analytically.
Analytical Modeling of Outward Solidification With Convective Boundary in Cylindrical Coordinates
Authors: Xu Minghan , Akhtar Saad , Zueter Ahmad F. , Alzoubi Mahmoud A. , Sasmito Agus P.
Published: February 2021

Solidification consists of three stages at macroscale: subcooling, freezing and cooling. Classical two-phase Stefan problems describe freezing (or melting) phenomenon initially not at the fusion temperature. Since these problems only define subcooling and freezing stages, an extension to characterize the cooling stage is required to complete solidification. However, the moving boundary in solid-liquid interface is highly nonlinear, and thus exact solution is restricted to certain domains and boundary conditions. It is therefore vital to develop approximate analytical solutions based on physically tangible assumptions, like a small Stefan number. This paper proposes an asymptotic solution for a Stefan-like problem subject to a convective boundary for outward solidification in a hollow cylinder. By assuming a small Stefan number, three temporal regimes and four spatial layers are considered in the asymptotic analysis. The results are compared with numerical method. Further, effects of Biot numbers are also investigated regarding interface motion and temperature profile.
Failure Analysis of Coil Racks in a Batch Annealing Furnace Using Finite Element Methods
Authors: Walla Nicholas J. , You Hua , Zhu Xinyu , Zhou Chenn Q. , Liddick Matthew
Published: February 2021

In this work, a series of finite element method simulations were performed on cooling racks used for the loading and unloading of steel coils in a batch annealing furnace. Normal furnace operations were simulated using ANSYS Thermal FEA and ANSYS Mechanical FEA to reproduce the thermal and structural loads experienced by the racks, as well as additional lifting forces representing removal by forklift after annealing. In addition to warping found due to uneven heating from the radiative elements of the furnace, severe stress leading to failure was identified on the base of the racks from the lifting force. These results correspond with failures seen in the actual units. The simulation data was used for design adjustments to reduce the damage from the above sources.
Freeform 3D-Printing of Pure Ceramics
Authors: Mahmoudi Mohammadreza , Burlison Scott R. , Moreno Salvador , Minary Majid
Published: February 2021

Polymer derived ceramics (PDC’s) offer a unique opportunity to 3D-print ceramics; however, 3D printing of such polymers require it to be combined with specialized light-sensitive agents and layer-by-layer crosslinking using an optical beam due to their low viscosity. Here, three-dimensional printing of ceramics enabled by dispensing the preceramic polymer from a nozzle inside a yield stress fluid is being demonstrated. The printed parts are crosslinked in the same gel. After crosslinking process, the printed parts are taken out of the gel and prepared for high temperature pyrolysis process that converts the cured parts to ceramic. The specially designed gel was three orders of magnitude more viscous than the preceramic polymer at no shear, which provided a stable medium during the whole process for maintaining the shape of the printed material and prevented possible instabilities. The SEM images of the cross section of the specimens showed that the printed material was dense and without any apparent porosity or cracks. Statistical analysis on the mechanical properties of the printed preceramic polymer specimens revealed that the printed specimens had characteristic strength (∼257 MPa).
Damage Detection in Composite Structures via Scanning Laser Doppler Vibrometry Using Linear and Nonlinear Ultrasonic Wave Features
Authors: Cen Mingjing , Shen Yanfeng
Published: February 2021

This study presents the modeling and experimental investigation of damage detection and evaluation methods based on the linear and nonlinear features of ultrasonic guided waves while they interact with possible structural damage sites. Such wave damage interaction features are visualized via the full field imaging capability of SLDV. First, numerical modeling is conducted to develop an in-depth understanding of the mechanism behind the wave damage interactions. A coupled-filed transient dynamic finite element model is constructed with a simulated delamination area. The modeling of Contact Acoustic Nonlinearity (CAN) is realized by defining the contact surfaces at the delamination area. The linear ultrasonic features such as the trapped modes as well as the nonlinear features such as the mixed frequency response are illustrated using the numerical simulation. Based on the numerical study, experimental investigations are further conducted. Experiments are performed to explore linear ultrasonic technique for damage quantification. For the linear case, the detection utilizes a short tone burst in both spatial and temporal domain, generated by a Piezoelectric Wafer Active Sensor (PWAS); the trapped wave energy and a directional vector field technique are adopted to visualize an impact damage in a carbon fiber composite plate. The nonlinear detection methodology combines a continuous resonant low frequency harmonic pumping wave with a high frequency tone burst probing wave, simultaneously generated by two PWAS transducers on both sides of the specimen to take advantage of the mixed nonlinear interactions between the vibroacoustic waves and the structural damage. This study shows that both linear and nonlinear ultrasonic techniques possess great application potential for the damage detection and quantification in composite structures. The paper finishes with summary, concluding remarks, and suggestions for future work.
Simulation and Technology Economic Analysis of Micro Gas Turbine Range-Extended Electric Vehicle
Authors: Xiao Xiangyu , Ji Fenzhu , Zhao Yunhai , Li Yang
Published: February 2021

This paper investigates a 10-kW micro gas turbine (MGT) as range extender (RE) for Range-Extended Electric Vehicles (REEVs). The MGT structure is designed and the simulation model of the MGT with a speed control system is built in MATLAB/Simulink. A novel configuration of the REEV equipped with MGT is presented. Then, a performance simulation model of the REEV is adopted to analyze the technology economic performance of the MGT range extender and the gasoline ICE range extender comparatively. The simulation results show that with a RE of 10 kW, the REEV could have 600 km driving range. In addition, the REEV equipped with the MGT can operate with lower energy consumption and the concentration of NOx, CO emissions are 24% and 9% of the ICE REEV, respectively. Finally, the battery pack energy is optimized to study its impact on fuel economy, which indicates that when the battery pack energy is 20 kW·h, the REEV performs optimal energy consumption and emissions in the example.
Approaches to Initial Gap Modeling in Final Aircraft Assembly Simulation
Authors: Zaitseva Nadezhda , Lupuleac Sergey , Khashba Valeriia , Shinder Julia , Bonhomme Elodie
Published: February 2021

Variation simulation of final aircraft assembly concerning compliance and contact interaction of parts requires the specialized approaches to setting and generation of initial gaps between the joined parts. The initial gap reflects all assembly deviations for the joining parts. In this paper two models for the generation of the initial gap samples are considered: the random field model and the mode-based model. The random field model represents the initial gap as a random field with defined properties. The mode-based model decomposes the initial gap into a series of natural modes of the parts.

Typically for the real assembly processes, there is not enough accessible information about initial gaps. If the measurements are not included in the production process, then the number of measured samples can be small. The goal of this paper is to compare how considered initial gap models cope with the small number of given measurements. The models are examined on the example of wing-to-fuselage assembly process. For the considered process both initial gap models are trained on different amounts of measurements, and generated gaps are applied for the variation simulations. The comparison with measured gaps allows to determine which method is the most suitable during variation simulation with limited measurement data. The performed study shows that the mode-based approach is more accurate for initial gap modeling in case of the small number of available measurements.
A Waveguide Ultrasonic Phased Array Radar for High Temperature Equipment Monitoring
Authors: Yin Xiaowei , Shen Yanfeng
Published: February 2021

This paper proposes a design for monitoring high temperature structures utilizing phased array waveguide transducers, where the active sensing elements work synthetically together to achieve damage detection. The waveguide transducer is comprised of a wave-generation piezo element and a waveguide bar conducting the wave energy into the host structure. A coupled-field local finite element model (FEM) is constructed to grasp an in-depth understanding of the wave generation behavior. Via the harmonic analysis, optimum wave generation frequency and mode type can be analyzed. Thereafter, an array of waveguide transducer elements are attached to the host structure to study their wave manipulating ability. The system works based on the principle of phased array theory; the excitation instant of each element is controlled to form an equiphasic surface. In this way, the wave propagation phenomenon such as focusing and directional steering can be realized. An ultrasonic radar for high temperature working condition can thus be realized. The proposed system possesses great application potential to enhance the performance of Lamb wave SHM and NDE systems for high temperature structures.
Rheological Characterization of Polyethylene Oxide (PEO): An Experimental Steady State and Transient Analysis
Authors: Ahmad Hafiz , Boutaous M'hamed , Xin Shihe , Pabiou Hervé , Siginer Dennis A.
Published: February 2021

In this paper, the rheological characteristics of aqueous PEO (Polyethylene oxide) solution with very high molecular weight 4 × 106 g/mol is investigated. Shear flow measurements were carried out in steady and transient modes. The unique behavior of PEO is found to be heavily dependent on the input shear rate and the mechanism of data generation. Generally, PEO is found to be shear-thinning throughout the experiments, but at the start of the experiments at low shear rates, minimum input shear value also affects the shear-thinning behavior. In this study, we investigate the critical method of applying input shear to the samples in the lower shear rate regime. Surprisingly, different input methods yield different results. Viscosity curves obtained through shear flow experiments are found to be significantly dependent on the input method of shear rate. Experimental measurements were validated by Cross and Carreau-Yasuda models.
Performance Analysis of a Solar-Assisted Organic Rankine Cycle
Authors: Nitsas M. T. , Koronaki I. P.
Published: February 2021

The objective of this paper is the thermodynamic analysis of a solar powered Organic Rankine Cycle (O.R.C.) and the investigation of potential working fluids in order to select the optimum one. A dynamic model for a solar O.R.C. with a storage tank, which produces electricity is developed. The mathematical model includes all the equations that describe the operation of the solar collectors, the storage tank, the Rankine Cycle and the feedback between them. The model runs for representative days throughout the year, calculating the net produced energy as a function of the selected evaporation temperature for every suitable working fluid. Above that, the temporal variation of the systems’ temperatures, collectors’ efficiency and net produced power, for the optimum organic fluid and evaporation temperature are presented.
Numerical Study on the Influence of Microchannel’s Geometry on Sub-Micron Particles Separation Using Acoustophoresis
Authors: Lai Tsz Wai , Fu Sau Chung , Chan Ka Chung , Chao Christopher Yu Hang , Law Anthony Kwok Yung
Published: February 2021

Application of acoustophoresis to cell and particle separation in microchannel filled with fluid medium has been drawing increasing attention in many disciplines in the past decades due to its high precision and minimum damage to the matters of interest. Previous studies on particle separation often rely on the size-dependent feature of the acoustic radiation force (ARF), while the acoustic streaming effect (ASE) is a hurdle as the particle size goes down. Sub-micron particles circulate according to the streaming vortices and become inseparable from the particles settled on the pressure node. Instead of suppressing the ASE, this study intends to utilize the combined effect of ARF and ASE on sub-micron particle sorting by altering the microchannel’s cross-sectional shapes. The roles of ARF and ASE on particles with 0.2um and 2um in radius in various cross-sectional shapes are studied numerically. The studied geometries include 1. rectangular, 2. trapezoidal, and 3. triangular. The results show that changing the cross-sectional shapes affects the acoustic field’s magnitude and distribution, the streaming patterns, the magnitude of streaming velocity, and the movement of sub-micron particles. In non-rectangular microchannel, sub-micron particles circulate towards and settle at the center of the streaming vortices. This phenomenon shows the potential to manipulate the streaming-dominant particles, thereby enhancing the acoustophoretic particle sorting performance.
Molecular Dynamic Simulation Study on Soy Protein As Drug Delivery Vehicle
Authors: Zheng Zhuoyuan , Singh Akash , Li Yumeng
Published: February 2021

Protein-based drug carriers are promising candidates for efficient drug delivery among the available potential colloidal carrier systems, due to their low cytotoxicity, abundance, renewability, diverse functional groups and interactions, and high drug loading capacity, etc. In this study, molecular dynamics (MD) simulations are performed to study the mechanisms of 11S molecule of soy protein as drug delivery vehicle to attach allyl isothiocyanate (AITC) and doxorubicin (DOX) drugs. The intermolecular interactions between protein and drugs are investigated; and the loading capacities of the protein molecules are calculated and compared with experiments. It is found that, for the AITC system, both nonpolar and polar residues of protein have the ability to adsorb AITCs; particularly, the polar residues serve as the primary active sites for the stable attachment of the drug molecules through the electrostatic (dipole-dipole) interactions. For the DOX system, however, the main driving force become the π-π stacking (the van der Waals interactions) among the aromatic rings of DOX and protein. In addition to pristine protein, different denaturation processes are found to be able to increase the exposure of active sites, therefore, enhance the loading efficiency of the protein carriers.
Lyapunov Exponent for a Globoidal Cam With a Roller Follower Mechanism Using Wolf Algorithm
Authors: Yousuf Louay S. , Marghitu Dan B.
Published: February 2021

A globoidal cam and roller follower system is analyzed and discussed for non-periodic motion of the follower. Wolf algorithm is used to calculate the largest Lyapunov exponent. The impact between the cam, follower and the two guides is occurred due to the impulse and momentum phenomenon. The effect of the internal dimension of the follower guide on the non-periodic motion of the follower is considered at distinct angular velocity of the cam. The numerical simulation has been done using SolidWorks software. Follower movement is processed experimentally through an infrared 3-D camera device. Phase plane diagram is used to explain the variation in follower motion. Phase-plane diagram and Fast Fourier Transform (FFT) are used to investigate follower non-periodicity. The follower motion is non-periodic when the orbit of phase-plane diagram diverges with no limit of spiral cycles.
In-Plane Vibration Mode Shapes for Rotating Disks: Exact Solution
Authors: Sarfaraz Ehsan , Hamidzadeh Hamid R.
Published: February 2021

An analytical method is developed for the determination of modal vibration characteristics of high speed rotating annular disks. A systematic approach based on established solutions for the linear in-plane free vibrations of the disks which satisfy the displacement and stresses compatibilities is developed. The disk is considered to be a homogeneous, thin and elastic isotropic, and it is rotating at constant angular speed. The developed analytical solution was obtained by implementing the two-dimensional plane stress theory. In this research, fixed-free and free-free boundary conditions for the annular disks are considered, and natural frequencies, as well as mode shapes of the rotating disks, are computed. The mode shapes are represented by eight functions in polar coordinates. The dimensionless natural frequency parameters are depicted for free vibration of the system for a range of dimensionless rotation speed and radius ratios. Also, the results provide several non-dimensional critical speeds.
Performance of a Modified Ram Pump With Double Inlets: An Innovative Technique to Improve Performance of the Hydraulic Ram Pump
Authors: Sharma Ashokkumar M. , Ragsdale Casey A. , Nwali Uche P. , Pidugu Srikanth B.
Published: February 2021

Hydraulic ram pump offers electricity-free, low-cost and reliable way to supply water to a higher elevation. The goal of this study was to modify the existing hydraulic ram pump system to improve its overall performance. In the present work, the effects of adding a second drive pipe to a common pressure chamber of the existing ram pump unit were studied. Notably, the other components remained the same throughout all experiments. It was hypothesized that the addition of second drive pipe should increase the amount of water delivered by the pump and overall yield a better result in terms of pump’s volumetric efficiency and energy efficiency. Building on previous findings, all testing conducted during our research was completed using an optimal drive pipe inclination angle of 67.5°, with a pipe length of 4.8 ft, and a delivery pipe height of 10′8″. Using these initial conditions, and a single drive pipe, resulted in a maximum efficiency of 8%. Test runs with an additional drive pipe of the same length and inclination and with modifying the waste and check valve showed a considerable increase in the pump’s efficiency, up to 22%. Remarkably, the delivery flow rate increased by as much as 340%.
Nanoscale Interphase Characterization of Agglomerated MWCNT in Composites Connected to Mode I Fracture
Authors: Yekani Fard Masoud , Pensky Alek , Mester Jack
Published: February 2021

The authors investigate the effect of carbon nanotubes (CNT) on the microstructure, nanomechanical properties, and fracture performance of three-phase polymer matrix composites (PMC). Two types of carbon fiber (CF)-Epoxy-CNT composites with different nanofiller distribution were studied at the nanoscale with PeakForce Quantitative Nanomechanical mapping technique (PFQNM) and macroscale with mode I fracture testing to clarify the relationship between nanofiller interphase properties and mode I fracture performance. CNT agglomerates were identified on the polished sample surface in well-dispersed and agglomerated form. AFM data showed the inhomogeneity of nanoscale local mechanical properties in CNT-rich zones. Variation in material properties is attributed to voids, CNT alignment, and changes in density of the matrix and CNT nanoparticles. A higher resolution AFM scanner and Field Emission Scanning Electron Microscopy are necessary to observe nano-scale interphase mechanical properties and CNT orientation, respectively. Mode I interlaminar fracture testing demonstrated the effectiveness of CNT nanoparticles in preventing crack-jump and fiber-bridging effects. GIC for FCNT is 0.345±0.06 N-mm/mm2 at crack initiation, compared to 0.28±0.03 N-mm/mm2 for the plain epoxy reference sample. CNT nanoparticles increase the energy required for interlaminar fracture by promoting crack deflection and strengthening the interphase between CF and epoxy matrix through increased interfacial surface area.
A Virtual Physical Therapy Lab to Simulate a Balance Perturbation Assessment Setup
Authors: Martinez Maya , Shankar Praveen , Marayong Panadda , Krishnan Vennila
Published: February 2021

The paper addresses the development of a virtual physical therapy lab in an immersive CAVE system (Visbox, Inc., IL) to simulate a balance perturbation experiment in a Physical Therapy (PT) setting. The primary goal is to determine if virtual reality (VR) can be effectively used for rehabilitative assessment and training instead of a physical setup. The Balance Perturbation Setup (BPS) includes a seven-and-a-half-foot apparatus with an adjustable-height pendulum and pads attached to its structure for making physical contact with a participant. This pendulum is reconfigurable and can be adjusted to the participant’s height and shoulder width. The released pendulum perturbs the participant’s upper torso at the shoulder level disturbing the upright stability of the participant. The virtual environment developed in this study utilizes Unity 3D and Blender software to recreate the BPS and the environment of the PT lab in the CAVE VR system integrated with a full body motion capture. A haptic vest equipped with tactors is developed to simulate the tactile feedback when the pendulum makes contact with the participant’s upper torso. This virtual lab for balance assessment is expected to be evaluated in a user study for its effectiveness as compared to the physical BPS setup using appropriate kinematic measures and sensors. The virtual lab has the potential to provide an alternate, highly reconfigurable method for physical therapy evaluations leading to rapid development of strategies for individualized care.
Design of a Payload Spin Stabilization System for an All-Rotating Aerial Vehicle
Authors: Swaney Thomas , Shankar Praveen , Prince Tanner , Crisantes Jessica , Chaing Oliver , Ulrich Evan , Oberto Bob
Published: February 2021

This paper details the electrical and mechanical design of a de-spin mechanism for the payload of an all-rotating aerial vehicle. The system is designed to be compatible with the Aeroseed aircraft developed by Aerospace Corporation. The system consists of a motor housing and a de-spun payload plate. The payload plate serves as a mounting surface for the desired de-spun payload, an IMU, an Arduino Nano, and a SD card module. The Arduino receives rotational velocity readings of the payload plate from the IMU and calculates the necessary spin rate to stabilize the rotation. This spin rate is sent through a slip ring to the motor and ESC enclosed within the motor housing, which implement the commands. The electronics on the payload plate are protected by a thin shroud that extends down from the motor housing. A slider mechanism with two degrees of translational freedom serves as the interface between the system and the aircraft and allows for the alignment of their respective centers of rotation. The final design has a total mass of 589.67 g and a height of 109.1 mm.
The Size Distribution of Cellulose Nanocrystals in the Variation of Acid-to-Microcellulose Crystals Ratio and Reaction Time Through Catalyzed Acid Hydrolysis
Authors: Yang Yucheng , Fabian Frank , McKenzie Janice , Hyblova Kristyna , Ma Qin
Published: February 2021

Literature has shown that cellulose nanocrystals (CNCs) which are produced through hydrochloric (HCl) acid hydrolysis catalyzed by inorganic chlorides can enhance the mechanical properties of organic polymers further than CNCs by pure HCl acid hydrolysis. The results have shown that the level of reinforcement may be negatively correlated to the dissociation constant of the inorganic chlorides. However, titanium tetrachloride’s dissociation constant is 1.3, lower than that of ferric chloride, 2.2, which is the lowest dissociation constant among the four inorganic chlorides that have been studied. Therefore, for this study, titanium tetrachloride was investigated along with ferric chloride. The only two variables in this study are reaction time and acid-to-microcellulose crystals (MCCs) ratio. The results of laser diffraction spectroscopy (LDS) show that the resultant solutions exhibit binomial size distributions which contain both MCCs and CNCs. At acid-to-MCCs ratio of 40 for ferric chloride, any increase in reaction time above 1.5 hours did not result in size reduction. The Fourier transform infrared (FTIR) spectroscopy results of CNCs showed that the catalyzed hydrolysis did not change the molecular structure of MCCs. The color of CNCs varies with increasing reaction time, but, based on the FTIR and LDS results, the color is not an indication of CNCs’ size nor their chemical composition.
Research on In-Situ Measurement Technology of NC Machining Based on Line Laser Sensor
Authors: Song Weishu , Ye Peiqing , Zhao Tong , Zhao Zhen
Published: February 2021

In order to improve the machining accuracy of machine tools, it is important to obtain the geometric profile information of the parts after clamping, in order to plan the machining path again. Line laser measurement has the advantages of non-contact and large single measurement area, so it has higher measurement efficiency than traditional contact measurement. However, due to the influence of measurement environment, laser measuring angle, tested workpiece surface quality and other factors, the measurement errors of each point on the laser measuring line are different, so it is important to compensate the error and set the working parameters of the in-situ laser sensor measurement system.

In this study, the influence of the line laser measuring angle factors is researched. The physical model of the laser light path is deduced based on the laser triangulation principle. Then the measuring angle compensation model can be expressed quantitatively. At the same time, the algorithm to obtain the measurement angle based on free-form surface measurement results is used, as it is an important parameter of compensation model in practical application.

On this basis, a set of line laser sensor in-situ measurement process is put forward. The influence of the working environment factors on the stability of line laser in-situ measurement data is explored through experiments, such as tested workpiece surface material and ambient light intensity. The process conforms to the actual engineering requirement and provides experience reference.
STEMpathy Study on Persistence in Mechanical Engineering
Authors: Fertig Jan , Kumpaty Subha
Published: February 2021

Despite widespread targeted efforts at the pre-college level to recruit greater numbers of females and minorities for careers in science, technology, engineering and mathematics (STEM), fewer than 9% of today’s mechanical engineers are female and underrepresented minorities remain under 10%. There is a disproportionately high attrition rate of females and minorities from engineering programs and professions. Female and underrepresented minority mechanical engineering students are discouraged by factors involving: 1) Wider cultural norms and biases (societally pervasive ideas and often discriminatory practices); 2) Social-structural factors that result in differential engineering college preparedness; and 3) Organizational norms and biases within mechanical engineering. At the intersection of these forces is an individual who enters a career to make a difference, but whose fundamental social responsibility goals and leanings are frustrated. This culture alienates many students at a time when prominent engineering organizations like ABET call for greater diversity, empathy and social responsibility. Undergraduates in ten engineering programs at the Milwaukee School of Engineering completed a survey consisting of developed measures of “STEMpathy” (empathy in STEM); equitable treatment across commonly known bases for discrimination; a measure of personal empathy based on Baron-Cohen’s systemizing-empathizing dichotomy; a developed instrument to measure likelihood of persistence; and qualitative questions on reasons for career choice and discriminatory experiences in college. Multiple linear regression analysis supported the hypothesis that persistence likelihood is a function of program STEMpathy and departmental fairness (lack of discrimination) and showed a moderating effect of empathy on program fairness/discrimination. Mechanical engineering was distinguished by low STEMpathy and unique challenges surrounding student persistence.
Experimental Analysis of Venturi-Tube Behavior in Wet Gas Conditions
Authors: Mehlum Olav , Hundseid Øyvind , Bakken Lars E.
Published: February 2021

Subsea wet gas compressors have been successfully in operation for approximately 5 years. Their use has proven to increase the recovery by approximately 10% and achieve a reliability up to 98%. Further developed and operation of subsea wet gas compression require detailed knowledge of compressor operability and how shift in operational conditions affect the compressor system. The compressors ability to handle wet gas is documented in detail for a gas volume fraction limited down to 0.90. The 4–5 last year of operation proves the wet gas concepts capability. As years pass by, well pressure and production rate declines which causes the compressor operation point to shift towards the high head and low flow (surge) area of the characteristics. In addition, compressor inlet transients increase due to pipe surge (slugs), requiring a robust control system to prevent instabilities, e.g. compressor surge. It is therefore vital to understand how the compressor inlet flow device behaves at different wet operation conditions.

The article documents how a standard dry gas venturi tube behave at different wet gas operation conditions. The venturi is designed according to ISO5167-4 for dry gas conditions and is tested at the low-pressure air water compressor test rig at NTNU. The primary objective of the work has been to visualize the wet flow regime through the transparent venturi tube and to document the wet gas flow rate measurements by means of single-phase meters. The venturi tube is tested in a GMF range from 1 to 0.83 at an air volume flow rate of 1.3m3/s.
An Energy Frame of Reference to Assess Vehicle’s Physical Externalities
Authors: Otremba Frank , Romero Navarrete José A. , Lozano Guzmán Alejandro A.
Published: February 2021

Externalities of the road transportation are multidimensional in nature and involve the road-vehicle interaction under different environmental conditions. Estimating the pavement and vehicle damage potentials as a function of the conditions under which such interaction takes place, is important to avoid accelerated or catastrophic damages in these systems. Such an assessing is crucial from the perspective of pricing the effects of the vehicle on the infrastructure and vice versa. The existing models for pricing such interaction, critically depends on gross average statistical models. In this paper, it is proposed a deterministic approach to realize such an assessment, based upon validated approaches for the pavement damage. The simulation scheme considers different degrees-of-freedom vehicle models, and a discrete asphalt pavement, that make possible the simulation of massive traffic situations on realistic road lengths.
Molecular Dynamics Study on Interfacial Fracture of Aluminum Alloy and Epoxy Resin Adhesive Subjected to Cyclic Loading
Authors: Kanamori Kohei , Kimoto Yoshikatsu , Yonezu Akio
Published: February 2021

Direct bonding of metal-resin plays a critical role in jointing of dissimilar materials and the adhesion strength is known to be dependent on strain rate (loading rate) due to the strain rate sensitivity of polymeric resin. This study evaluated adhesion strength and adhesion durability against repetitive loading for the interface between aluminum alloy and epoxy resin. For experiment, a pulsed YAG laser was used to generate strong elastic waves, resulting in interfacial fracture. This method is called Laser Shock Adhesion Test (LaSAT), which enables us to evaluate impact strength of interfacial fracture. This study prepared two types of specimens with different curing temperature (20°C and 100°C). It is found that the specimen with higher temperature curing shows larger adhesion strength. Subsequently, repetitive LaSAT experiments (cyclic loading tests) were conducted to evaluate adhesion durability. This reveals that adhesion strength showed cyclic fatigue characteristics and higher curing temperature improves fatigue strength. To elucidate this mechanism at molecular level, molecular dynamics (MD) simulation was conducted for the interfacial material with epoxy resin. This study created all-atomistic model of Al2O3/epoxy resin interface, and repetitive tensile deformation was applied until delamination. It is found that the number of loading cycles to delamination was increased when the applied tensile stress was lower. It is also found that the 400K curing model showed larger adhesion strength than that of the 300K curing model. This trend is very similar with the results of LaSAT experiments. Our comprehensive study with LaSAT experiments and MD simulations evaluates adhesion strength of Al/epoxy interface and reveals its fracture mechanism.
Optimal Extrusion Die Design for Production of Polymer Tensile Test Specimen
Authors: Andrade Sebastián Acosta , Rigail-Cedeño Andrés , Tapia-Bastidas Clotario V. , Castillo-Orozco Eduardo
Published: February 2021

This work aims to present the design of an extrusion die for the production of polymeric tensile test specimens. Computational Fluid Dynamics is used during the optimization process to minimize the overall pressure drop across the die, achieve uniform exit velocity, low energy consumption, high throughput, and excellent properties of the extruded specimens. A three-dimensional incompressible viscous flow is considered and the Cross model is employed for taking into account the non-Newtonian behavior of the flow. Several geometries are analyzed before devising an optimum shape. The final design includes, in the beginning, a conical flow profile and then it gradually transitions into the rectangular cross-section of the slab. The die land is an elongated flow restriction channel of smaller cross-section, where the material experiences gradually-decreasing pressures along the length of the land and finally converging the molten polymer into a melt laminate at the exit.
Crack Deflection Near a Ply Interface in a Composite Laminate
Authors: Zhuang Linqi , Talreja Ramesh , Maragoni Lucio
Published: February 2021

The deflection of a matrix crack near 0°/90° interface in a cross-ply laminate was studied numerically. In the finite element (FE) model, an initial matrix crack was introduced in the 90° layers away from the 0°/90° interface. The initial matrix crack could be initiated either at the middle of 90° layer or at one side of 0°/90° interface. The 0° layers and a part of the initial matrix crack were modeled using homogenized layer properties to simplify the model. The nonuniformly distributed fibers were modeled explicitly close to the 0°/90° interface in order to study the influence of this nonuniformity on the crack deflection process. The Energy Release Rate (ERR) of debond crack tip was calculated using Virtual Crack Closure Technique (VCCT) to study the debond growth. Maximum principal stress was then adopted to access the debond crack kinking qualitatively. It’s found that when a macro-size matrix crack forms and propagate towards ply interface, the subsequent debonding and debond cracking process in nearby intact fiber shows some distinct differences compared to the same processes at single isolated fiber without considering the interaction with nearby debonded fiber and existing matrix crack. Meanwhile, present analysis shows clear influence of microstructures on the crack deflection process by affecting the fiber/matrix debonding and debond kinking processes.
Composite Core Cross Tube Crushing Analysis
Authors: Jenson Sean , Ali Muhammad , Alam Khairul
Published: February 2021

Thin walled axial members are typically used in automobiles’ side and front chassis to improve crashworthiness of vehicles. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of inclusion of functionally graded cellular structures in thin walled members under axial compressive loading. A compact functionally graded composite cellular core was introduced inside a cross tube with side length and wall thickness of 25.4 mm and 3.048 mm, respectively. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were evaluated. The results showed that the inclusion of composite graded cellular structure increased the energy absorption capacity of the cross tube significantly. The composite graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the cross tube thus delaying local tube wall collapse and promoting large localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that were observed in the empty cross tube under axial compressive loading. The variation in deformation mode resulted in enhanced stiffness of the composite structure, and therefore, high energy absorption by the structure. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.
Ballistic Performance of Sandwich Composite Armor System
Authors: Alam Shah , Shakar Samhith
Published: February 2021

This study focused on the design, modelling and the analysis of the dynamic response of composite armor system, constructed with Kevlar 29 as front skin, Alumina-ceramic filled in x shaped corrugated structure as core and bottom skin Kevlar 29 and T800S, in terms of residual velocity, energy absorption capacity and limiting velocity. The core cell size, height, thickness, skin thickness, etc., will be varied to get their influence on the impact resistance.

The design parameter will be investigated for the sandwich composite armor with various configurations and stacking sequence of Alumina Ceramics, Kevlar 29 and T800S. The sandwich typically consists of front plate, core and backing plate, which will be impacted at different velocities starting at 100m/s till significant armor penetration. The ballistic limit velocity (V50) will be determined from the analysis. The non-linear explicit dynamic analysis and simulation results computed using the software ABAQUS will be validated by experiment. From the data obtained it can be suggested which composite armor has improved impact resistance and performance.