bluuebunny/crossref_metadata_2025 huggingface dataset:
Experiments on Imperfect Lubrication
Authors: Hersey M. D. , Staples C. W.
Published: January 2022

This brief paper is based upon a full report of certain experiments conducted for the ASME Research Committee on Lubrication. The experimental work comprised friction measurements under imperfect lubrication conditions up to loads of 10,000 psi or more. Eight lubricants were compared whose viscosity-pressure characteristics were known. A Kingsbury oil-testing machine was used, with bearing surfaces designed to eliminate hydrodynamic action so far as possible.

A condition of mixed lubrication prevailed, in which rapid wear of brass on steel occurred simultaneously with hydrodynamic effects. All tests were run well to the left of the familiar minimum point on the coefficient-of-friction diagram. Three methods of plotting the data were tried: (a) The direct plot of friction per unit area against load per unit area, holding the speed and viscosity constant; (b) a conventional plot of the coefficient against Z1N/P, where Z1 is the viscosity at atmospheric pressure, N the speed, and P the load per unit of projected area; and (c) a modified diagram in which each of the foregoing curves is replaced by a family of curves with different values of the pressure-viscosity parameter. This parameter, the product of load per unit area by the pressure coefficient of viscosity, helps to explain earlier discrepancies and to set up a better correlation.

The usual contrast between friction of fatty and mineral oils was confirmed, and it was concluded that boundary lubrication and wear are accompanied by hydrodynamic action on a microscopic scale.
Cavitation and Nuclei
Authors: Knapp Robert T.
Published: January 2022

Contrary to the general impression, water and other common liquids, when pure, have high tensile strength. Cavitation would be impossible at the highest velocities currently encountered. In practice all liquids appear to cavitate as soon as the pressure tends to drop below the vapor pressure, thus implying that liquids have no tensile strength. This discrepancy is explained by the presence of “weak spots” whose characteristics have as yet only been inferred.

This paper presents the results of an experimental investigation of the weak spots present in ordinary water. The results are consistent with the model of the nucleus proposed by Harvey, but are apparently inconsistent with other models currently found in the literature.

After summarizing the results of the experimental program, the paper concludes with a series of implications concerning the engineering significance of the nuclei in industrial liquids.
An Investigation of Effective Thermal Conductivities of Powders in Various Gases
Authors: Deissler R. G. , Boegli J. S.
Published: January 2022

An experimental study was made to determine the effective thermal conductivities of magnesium oxide, stainless steel, and uranium oxide powders in various gases. The gases included air, helium, argon, nitrogen, neon, and various mixtures of these gases. The variables investigated included temperature level, gas pressure, porosity, gas conductivity, and solid conductivity. A reasonably good correlation of the data was obtained by using the dimensionless groups effective thermal conductivity over gas conductivity, solid conductivity over gas conductivity, and porosity of the powder, although the effective conductivity may also be a function of the shape and arrangement of the particles. A solution for spheres in cubical array was obtained by relaxation and was in reasonable agreement with the data for porosities in the neighborhood of that for the spheres.
Oil-Whip Resonance
Authors: Hull E. H.
Published: January 2022

A series of oil-whip resonances has been demonstrated by applying a rotating force to a shaft running in a hydrodynamically lubricated bearing. These resonances appear at the ratios of shaft speed to exciting-force frequency of approximately 2 which is normal oil whip, 3, 4, 6, 8 …. and −2, −4, −6 … . The locus of the shaft center at these resonances traces a trochoid containing a number of loops related to the ratio of shaft speed and force frequency. Inside loops are formed at positive frequency ratios, outside loops at negative ratios. A qualitative explanation of the formation of these resonance figures is offered.
Possible Similarity Solutions of the Laminar, Incompressible, Boundary-Layer Equations
Authors: Hansen A. G.
Published: January 2022

A review of research on the problem of obtaining similarity solutions of the three-dimensional, laminar, incompressible, boundary-layer equations is presented along with a general method of analysis for treating the problem. Restrictions on main flow velocity components and co-ordinate systems which lead to similarity solutions are tabulated. Finally, a discussion is given of the practical application of similarity solutions and the problems which remain to be solved.
Application of the Griffith-Irwin Theory of Crack Propagation to the Bursting Behavior of Disks, Including Analytical and Experimental Studies
Authors: Winne D. H. , Wundt B. M.
Published: January 2022

This paper presents the results of bursting tests of large, bored, and effectively notched disks removed from long rotor forgings. Most of the tests were conducted at room temperature. For the particular disk geometry employed, the net average tangential stress at bursting speed was as low as 25,000 psi for brittle behaving materials and as high as 77,000 psi for materials approaching ductile behavior. These correspond to 26 per cent and 92 per cent of yield strength, respectively. The Griffith-Irwin theory of crack propagation is adapted to the calculation of Gc, fracture toughness, from notched-disk bursting-test results. It is shown that Gc from disk tests agrees with Gc obtained from slow notched-bend tests, and therefore appears to be a property of material, largely independent of specimen size. The actual magnitude of Gc permits the classification of forgings by the degree of their susceptibility to brittle fracture in the presence of discontinuities. Gc and the ratio Kys of room temperature bursting strength to yield strength are found to correlate well with the material Charpy V-notch fracture appearance transition temperature. As the latter is reduced, Gc and Kys are increased.
An Indirect Method for Determining Accelerations in Complex Mechanisms
Authors: Goodman Thomas P.
Published: January 2022

In complex mechanisms such as the six-bar, two-pivot linkage (Fig. 2) the graphical construction for determining accelerations can be simplified by starting from a point on the mechanism other than the point whose acceleration is known. Arbitrary values of velocity and acceleration can be assumed for the starting point, and the accelerations of other points can be obtained graphically on the basis of this arbitrary assumption. The accelerations so found can be converted into the actual accelerations in the mechanism by means of a simple formula which is derived in the paper.

This indirect method of determining accelerations facilitates the analysis of compound mechanisms which consist of two or more mechanisms connected in series. The method also provides a useful check on values of accelerations which have been obtained by other methods.
Three-Dimensional Laminar Boundary Layer in Curved Channel With Acceleration
Authors: Senoo Yasutoshi
Published: January 2022

A theory is developed for two families of three-dimensional laminar boundary layers; namely, for the boundary layer on the plane end wall of a concentric circular-arc channel having a particular family of accelerated or decelerated main flows and for the boundary layer on the parallel plane end walls of a curved channel with logarithmic spiral side walls. A turbine nozzle was approximated by a channel with logarithmic spiral side walls for analysis, and the theoretical prediction of boundary layer on the end wall was compared with the experimental data with fair agreement across the nozzle and along the center line of the nozzle.
Well Trajectory Optimization With an Emphasis on Anticollision Design
Authors: Cao Jie , Wiktorski Ekaterina , Sui Dan
Published: January 2022

Well trajectory design and optimization are essential parts in well planning before drilling. The main objective of the design is to find an optimal trajectory for efficient and safe drilling. Meanwhile, the anticollision of well trajectory must be considered with offset wells in the same area. In general, optimal wellbore trajectory design includes some essential criteria, for example, shortest possible path, minimum tortuosity, collision avoidance, and most extended possible contact with the reservoir. This article presents a central part of plan phase represented by a trajectory planning and optimization module with a focus on anticollision design. The trajectory is optimized based either on minimization of wellbore length and dogleg severity or on the maximization of well-reservoir contact subject to strict anticollision constraint and other associated constraints or their combinations to some extent. The anticollision model considers industry standard bit error sources and their interactions and propagation along the well trajectory, and results in the separation factor as an constraint for trajectory optimization. The introduction of anticollision models to the trajectory optimization techniques has real potential in drilling design. Besides saving time and effort by providing engineers with multiple options, the well design with anticollision considerations ensures the well path safety while searching for optimal well trajectory. The presented work has a good potential in well planning as a viable method to keep drilling operations’ safe and efficient.
Analysis of Measured and Predicted Turbine Maps From Start-Up to Design Point
Authors: Scotti del Greco Alberto , Biagiotti Sara , Michelassi Vittorio , Jurek Tomasz , Di Benedetto Daniele , Francini Stefano , Marconcini Michele
Published: January 2022

This paper describes a coupled experimental and computational fluid dynamics (CFD) campaign conducted on a 1.5 intermediate turbine stage in the full range of operating conditions, from start-up to design point under variable expansion ratio and physical speed. The test maintains engine similitude conditions and allows direct comparison with CFD data to assess the predictions accuracy. The choice of variables to describe the speedlines is also addressed by using both measured and predicted data. A discussion on velocity ratio versus corrected speed illustrates the advantages of the former parameter the adoption of which produces constant shape curves in a very wide range of operating conditions. The comparison between measurements and predictions suggests that CFD, in conjunction with performance correlations, is a viable tool to predict speedlines in a fairly wide range of conditions, provided that geometrical and operational details are carefully matched.
Simultaneously Eliminate Defects and Modify Surface for 3D Printed Components Using Femtosecond Laser
Authors: Li Shang , Yang Can , Yang Huan , Peng Fei , Yin Xiao-Hong
Published: January 2022

In this work, the femtosecond laser was used to process the surface of the 3D printed components. After femtosecond laser scanning, the scanning electron microscope (SEM) was utilized to observe the surface morphology of the samples. In addition, the laser confocal microscope (LCM) was adopted to measure the surface roughness, and the contact angle measuring instrument was employed to characterize the surface wettability. By adjusting two laser process parameters (i.e., the number of scan and scan pitch), the surface defects had been successfully eliminated and surface modification for certain application had been achieved. After laser processing, the surface roughness increases to a certain extent due to the generation of surface micro/nanostructures. Wettability experiments showed that compared with the superhydrophilicity of the original surface, the surface contact angle after laser processing increased to a certain extent, and the surface wettability had been changed. In summary, the feasibility of femtosecond laser processing for the surface of 3D printed specimens was preliminarily verified. In the future efforts, multi-parameter experiments and numerical simulation will be further carried out to achieve better post-processing effects for the 3D printed component surfaces.
Effects of Nozzle Diameter and Injection Volume of Drug on Performance of a Needle-Free Injector
Authors: Zhu Yang , Kang Can , Zhang Chunli , Li Haifei
Published: January 2022

Among the techniques of subcutaneous drug delivery, the needle-free injection is relatively new. Compared to the hypodermic syringe, the needle-free injection avoids accidental stabbing and cross-infection. Although the needle-free injection technique has been exercised, the knowledge about instantaneous behaviors of the drug during the injection process have not been clarified. The present study aims to reveal drug flow characteristics of the needle-free injection. The effects of major operating parameters were investigated. An experimental work incorporating the measurement of instantaneous stagnation pressure and the visualization of drug diffusion in gel was conducted. The results show that the needle-free injection process is characterized by time-varying stagnation pressure. The peak stagnation pressure at the initial stage of injection is an important indicator of the aggressivity of the drug. The peak stagnation pressure decreases linearly with the increase of the nozzle diameter or the volume of injection. It is evidenced that the increase in the volume of injection causes an enlargement of the diffusion area of the liquid in the gel, which implies that the drug absorption rate is improved accordingly. Furthermore, with large nozzle diameter, the amount of the power consumed is high. Therefore, the maximum penetration depth of the liquid in gel increases with the nozzle diameter. However, the attainable lateral distance of the liquid is nearly insensitive to the nozzle diameter.
Scaled Crash Testing Using Modeling, Similitude, and Experimentation
Authors: Melnyk Richard , Beattie Olivia , Waller Bogue
Published: January 2022

Due to the complexity and challenging nature of predicting the effects of impact on a vehicle, much of the crash-testing industry remains one which operates at full-scale. Automobiles and even aircraft are often crashed at full size, which is an expensive and time-consuming process. This paper details a novel approach to crash-testing that combines early use of simulation, scaling of the appropriate parameters using similitude, and limited testing. The method was used to predict the crashworthiness of a small, commercial unmanned aerial vehicle (UAV).

The authors were involved in an undergraduate design project to develop a system capable of safely decelerating the RQ-7 Shadow Unmanned Aerial System (UAS) from an operational flight without the use of a runway. For contingency reasons or tactical purposes, the use of a larger runway for the UAS was not feasible. The team developed an airbag-like system that used controlled release of air to decelerate the vehicle. However, due to testing constraints the team was unable to test the airbag system at full-scale with an actual RQ-7 vehicle. The system is already far in it’s life-cycle so there were no prototypes available and the team’s available facilities would not facilitate a large, high-speed test.

As a result, the team built a model of the existing vehicle, focusing on key components and materials. The team then conducted testing at both geometric and dynamic scale and used the results of those tests to determine if actual loading would potentially damage the vehicle. The paper demonstrates the utility of such an approach using the RQ-7 case study.

Key aspects of the approach were the use of a model of the vehicle to determine the likely loading conditions that would lead to material failure. An analysis of the important scaling characteristics was conducted and a novel, non-dimensional ratio was developed. Scaled testing was conducted using instrumentation to determine the unknown scaling parameters. The results were then compared to the actual vehicle through the use of the non-dimensional ratio. The ratio compared the size, the approach speed, and the mass of the model to the actual air vehicle with the ultimate goal of determining whether the decelerations experienced by the model when impacting the airbag, would result in damage to key components on the vehicle when decelerated at full-scale. Testing showed that the model airbag was capable of adequately decelerating the UAV, although improvements needed to be made for greater reliability.
A Deployable Tensegrity Microrobot for Minimally Invasive Interventions
Authors: Yuan Sichen , Jing Wuming , Jiang Hao
Published: January 2022

Micro-, and milli-scale robots have emerged as next generation of intelligent technology for minimally invasive diagnosis and treatment. Recent minimally invasive interventions call for robots that work as tiny “surgeons” or drug delivery “vehicles” to achieve inner body diagnostic, surgical, and therapeutic practices, without any trauma or discomfort. Most traditional medical robots are large, and lack effective locomotion design, which prevent them from entering small entrances and moving smoothly in small working areas, such as long and narrow passages. Presented in this paper is a design of an innovative milli-scale deployable tensegrity microrobot for minimally invasive interventions. The robot is made of a deployable tensegrity structure integrated by self-stress. A folded size of the robot is small for easily entering a desired working area with a small entrance. When deployed, the tensegrity body of the robot displays lightweight and high stiffness to sustain loads and prevent damages when burrowing through tightly packed tissues or high-pressure environments. Locomotion of the tensegrity microrobot is designed to mimic a crawling motion of an earthworm, which grants the robot an ability to move well through small working areas. The robot is also an untethered agent. Morphing for deployment and locomotion of the robot is actuated by magnetic forces generated by its active members that serve as electromagnetic coils.
Design and Prototype of an Electric Pollen Extractor
Authors: Alnouser Ali , Andergeri Turki , Duan Shawn
Published: January 2022

This paper presents design, analysis, manufacturing, and prototyping of an electric pollen extractor. The design project is based on a request from the Washington State Department of Natural Resources (DNR) to build a machine for extracting pollen from tree catkins. The machine designed at a low cost can shake off pollen from catkins cleaner and faster than other devices. The extractor can shake the pollen and clean the seeds faster by assembling a 6-volt DC gearbox motor, a drive wheel to stabilize the rotation of the extractor, and a vibrator to help shaking the pollen during the filtration process. The design idea is modeled in Autodesk Inventor and safety-factor-based design calculations are carried out, mechatronic circuits are designed and further CFD and FEA simulations are performed in Ansys to verify the validity of the design. The rotational speed of the extractor is selected based on the required motion for particles. After completion of the preliminary analysis, the design changes are passed through another round of testing. The first round of testing produced a positive change, eliminating some material, and lowering cost. Second round showed promising results with speeding up extraction time. Final design, prototype and successful testing results of the extractor is presented in the paper with concluding remarks and future work.
An Adaptive Control Framework for Unknown Input Estimation
Authors: Griffith Tristan D. , Balas Mark J.
Published: January 2022

Many dynamical systems experience inputs that are difficult to measure. Knowledge of these unknown inputs, from estimation techniques, may improve the performance of a system. However, there may be uncertainty in both the linear model of the plant and the unknown input. An architecture for the estimation of an unknown input simultaneously with the plant internal states is presented. The architecture allows for error in the realization of the dynamical model, which is corrected using an adaptive feedback term. This allows the estimator to recover the correct physical structure of the plant dynamics. Crucial to the approach is an internal model of the unknown input which is generated by an ordinary differential equation. Discussion on the advantages and disadvantages of the input generator follow, along with general considerations for the selection of basis functions for an unknown function space. Convergence proofs are presented along with illustrative examples to demonstrate the theoretical results. This novel scheme will allow for the reliable online estimates of an unknown input with known waveform while also recovering the physical structure of the internal dynamics.
Influence of Geometric Parameters on the Performance of Savonius Wind Turbine Using the Response Surface Methodology
Authors: Torres Sebastian , Marulanda Agustín , Montoya Miguel , Hernández Camilo
Published: January 2022

Rising concerns about climate change and the growth of energy consumption have led to the need to use technologies based on renewable sources. Wind energy is one of the most promising renewable technologies with an increasingly important role. Particularly Savonius Vertical Axis Wind Turbines (SVAWT) have several advantages for certain geographical conditions attracting designers to research them. The present study introduces the Response Surface Methodology (RSM) as a tool for evaluating multiple SVAWT configurations and estimating the influence of rotor geometric parameters on SVAWT performance. For this purpose, CFD simulations are developed for different SVAWT configurations modeled parametrically through the rotor geometric parameters. The numerical solutions obtained are used to generate a Response Surface (RS). The RS is evaluated by finding satisfactory quality metrics. The influence of the geometric parameters is estimated using the selected RS. As a result, an experimental space is proposed where it is more likely to find the values in the geometric parameters that maximize the SVAWT performance. This research provides tools for large-scale evaluation of SVAWTs. Therefore, influence analysis of the parameters is carried out with fewer experiments. RSM and proposed experimental space serve as a base for future studies that optimize the SVAWT configuration.
Fatigue Properties of 3D Printed Carbon Fiber
Authors: Schmitz Anne
Published: January 2022

Three-dimensional printing with carbon fiber has been used to create lower limb prosthetics. However, the fatigue resistance of carbon fiber is understudied. The goal of this work was to quantify the fatigue properties of three-dimensionally printed carbon fiber. Moore bending fatigue specimens were created using a commercially available printer (Markforged, Watertown, MA). Specimens were printed using (1) a chopped carbon fiber matrix or (2) chopped carbon fiber matrix with embedded continuous carbon fiber. Cycles to failure was measured for three bending stress levels: 11.8, 8.8, and 7.4 kpsi. Ultimately, adding continuous carbon fiber to the chopped matrix increased the short cycle fatigue life (i.e. 103) from 17 to 274 MPa and had no effect on the endurance limit. During a single stance phase of the gait cycle, the heel and toe portions of a prosthetic foot experience up to 262 MPa of von Mises stress. This means the carbon fiber produced from three-dimensional printing would last two gait cycles. Hence, lower limb prosthetics cannot yet be made completely from three-dimensionally printed carbon fiber.
Development of Algorithms for Improving Fiber-Optical Rail Circuit on Railway Spans
Authors: Mgebrishvili Nikoloz , Iavich Maksim , Tabidze Tengiz , Nodia Amiran
Published: January 2022

For the safety of train traffic, the most important step is the introduction of a new type of rail circuits — fiber-optic rail circuits.

The high sensitivity of the fiber optic cable to external influences (deformation, vibration) is an important property both for fixing mechanical damage to rails and for monitoring railway rolling stock.

The branches (fragments) of the optical fiber through mechanical amplifiers perform both the functions of the information perception element — the sensor and the conducting channel of the transmitted information.

Using reflectometer OTDR (Optical Time Domain Reflectometer), based on the analysis of the backscattered light signal, the form of the effect that caused the bending is determined. Knowing the exact distance between the OTDR and the sensors, when analyzing the received signals, it is possible to determine different parameters of the passing rolling stock.

The article shows the schematic diagram and the algorithm of the proposed system developed by the authors.
Nonlinear Wake-Induced Vibration of Downstream Cylinder in Staggered Arrangements
Authors: Soares Bruno , Srinil Narakorn
Published: January 2022

The fluid-structure interaction mechanism of flow past multiple structures in proximity is complex. Depending on the initial spacing between a pair of circular cylinders and the reduced flow velocity parameter, the downstream cylinder may undergo wake-induced vibration (WIV) and/or vortex-induced vibration (VIV). This study presents an advanced numerical time-domain simulation model to predict a two-degree-of-freedom WIV, combined with VIV response, of an elastically mounted rigid circular cylinder behind a stationary cylinder in staggered arrangements. The wake deficit flow is modelled based on the boundary layer theory, whereas the unsteady drag and lift hydrodynamic forces due to the vortex shedding of the downstream cylinder are modelled by using the nonlinear van der Pol wake oscillators. The proposed numerical prediction model is calibrated and compared versus experimental data in the literature. For the initial longitudinal centre-to-centre spacing of 4 diameters and the initial transverse spacing of less than 2 diameters, the downstream cylinder first behaves as an isolated cylinder undergoing VIV at a low deficit flow velocity. With increasing flow velocity and Reynolds number, the downstream cylinder exhibits WIV response with progressively increasing oscillation amplitudes in both cross-flow and in-line directions. For staggered cylinders, the time-varying feature of the mean lift force, directed towards the wake centreline and acting on the downstream cylinder, becomes locally asymmetric through the course of the cylinder motion trajectories. This feature modifies WIV response frequencies and leads to an asymmetric trajectory of the cylinder’s two-directional displacements.
Study of Carbody Structure Design Under Different Standards
Authors: Wang Jianran , Liu Xiaofang , Zhang Haifeng , Luo Qi , Jiang Shihong , Hong Haifeng
Published: January 2022

Under the background of economic globalization, more and more car-builders not only supply railway vehicles to domestic market, but also actively bidding international projects and deliver products all over the world. The railway vehicle design standards are significantly different throughout the world. Using carbody system as example, the popular standards include European standard system (EN), British standard GM/RT 2100, International Union of Railways (UIC) standard system, US standard system (AAR/APTA/ASME) and Japanese standard system (JIS). In addition, some country’s standard might have special requirement based on local conditions and culture. These various standards will inevitably present different carbody design requirements. Among the above standards, EN and US standards are applicable to Europe, China, and America, which are largest railway vehicle markets in the world. This paper will introduce the history and characteristics of the mainstream rail vehicle standards worldwide and analyze the relationship between standard and vehicle design. Light Rail Vehicle (LRV), subway and commuter rail vehicle (multi-level vehicle) are selected as typical examples for the interpretation and application of US standard and EN standard separately. The 3 major requirements of carbody design, including static strength, fatigue strength and crashworthiness, are compared between US and EN standards to specify the general difference as well as the influence on the carbody design, such as material distribution, structure development, which could provide valuable reference for researchers and engineers in the rail vehicle industry to define and design new products more efficiently across different country’s rail standards.
A New Approach to Design Geometric Dimensioning & Tolerancing
Authors: Sun Wangping , Gao Yanqing
Published: January 2022

Geometric Dimensioning and Tolerancing (GD&T) is an essential component in mechanical design, manufacturing, quality inspection and cost control. A datum-based GD&T model and a computer algorithm have been built to standardize and computerize the GD&T procedure. A VBA (Visual Basic Application) tool has also been developed to implement the algorithm and semi-automated the GD&T design. As part of the research, the model and its tool have been applied in GD&T design to verify their usefulness and capability. The result is promising. The quality of the GD&T designs by the junior engineering personnel has been much improved. The application of the model (and its software tool) has also formed a new design process. In this paper, the authors will introduce how the transition is made in the GD&T design by adopting the datum-based model and showcase some exemplary designs achieved through it. It will also disclose an important finding in the implementation of the new GD&T design process.
Characterization of Lateral Friction Surfaced AA6063 Coatings
Authors: Seidi Ebrahim , Miller Scott F.
Published: January 2022

Friction surfacing is a solid-state metal deposition technique suitable for a wide range of metallic materials. This technique results in coatings on surfaces for joining purposes or surface modification applications such as wear and corrosion performance improvements. In this study, a novel approach in friction surfacing is utilized in which the consumable tool deposits material from its side instead of the end of the tool, which has been employed in conventional friction surfacing. Frictional heat enables plastic deformation, which results in the depositing of the consumable material on the substrate surface. The process is carried out at temperatures below the melting point of the consumable material, resulting in a solid-state deposition process. In the current study, scanning electron microscopy and energy dispersive spectroscopy have been employed for the characterization of the interfaces and coatings. The results of this study exhibited that there is no elemental diffusion between the tool and substrate materials at the interface, showing that the process temperature was low enough to prevent plasticizing of the substrate surface.
Corrosion Mitigation for Mechanically-Fastened Fiber-Reinforced-Polymer Composites
Authors: Callahan Moira , Romsland Ruby , McDonald Kenneth J. , McCoy Brad C.
Published: January 2022

Mechanically-Fastened Fiber Reinforced Polymer Composites (MF-FRPs) are currently being used to extend the useful service life of deteriorated bridges. However, the A325 Steel fastener assemblies used to attach the MF-FRP system to the bridges are experiencing noticeable corrosion. Through electrochemical polarization measurements and Tafel analysis, the expected lifetime of the A325 fastener assembly was determined and compared to other similar materials, Military Specification Grade 5 Steel (MTD-STD) and PH 17-4 Stainless Steel (PH 17-4). ASTM B117 salt fog testing was performed on each material fastener assembly to simulate the corrosion that should be experienced by each material. The electrochemical analysis and the ASTM B117 salt fog test confirmed the MIL-STD assembly corroded at a much slower rate compared to either A325 or PH 17-4. It was determined that the useful life of the fastener assembly could be extended from 6.5 year using A325 to 372 years using MIL-STD. Implementation of this engineering materials solution will extend the useful life of the MF-FRP fastener assembly however, a cost benefit analysis determined that continuing to use A325 is still the best option given the desired useful life of the MF-FRP retrofit system is 3 to 5 years.
Biogas Upgrading System for the Generation of Electricity From Methane Combustion
Authors: Duan Lee , Newcomer Lawrence , Thompson Alice , Duan Shawn
Published: January 2022

The search for new and improved energy renewal systems has been widespread for years at a global level. One of the techniques that are increasingly being employed involves the utilization of biowaste, both human and animal, to generate electrical energy [1]. This is done through a process called upgrading, which separates CO2 and H2S from the biogas produced in the digestion of the organic matter. Under request of the Washington State Department of Transportation (WSDOT), the purpose of this project is to convert biogas from organic waste to usable energy at highway rest areas in Washington State, decreasing raw waste accumulation at sewage lagoons and providing means to electrical-grid independence for these sites. This project aims at creating a small-scale system that employs this principle, eventually providing rest areas on the highway with net-zero energy buildings. With the application of improvements and new features on a preexisting prototype, the team produced a suitable design to undergo a validation process. The system obtained from this process will therefore constitute a significant improvement both from an environmental and financial standpoint, eventually producing net zero energy buildings.
Laser Metal Deposition of Functionally Graded Ti-6Al-4V + Mo Samples and Characterization Studies
Authors: Kumpaty Subha , Coen Brietta , Coen Liam , Tlotleng Monnamme , Arthur Nana , Pityana Sisa
Published: January 2022

Ti-6Al-4V is a common alloy known for its use in aerospace and/or biomedical applications. In this study, Mo has been employed to increase the biocompatibility of Ti-6Al-4V. Two samples of Ti-6Al-4V with layers of differing percentages of Mo were produced using laser metal deposition at the National Laser Center of the Council of Scientific and Industrial Research, Pretoria, South Africa. One sample was manufactured with layers containing 15-10-5-0-5-10-15 wt% Mo at 1500W laser power and another sample was prepared with 0-5-10-15-10-5-0 wt% Mo at 1700W.

The microstructures of 0% Mo showed Widmanstätten alpha. Adding Mo, the layers indicated lamellar microstructure. The properties of lower and upper layers with the same concentration of Mo were found to vary due to thermal effects occurring in the process of printing and possible intermetallic bonding. This paper discusses underlying factors for the results obtained on graded samples at different laser powers (1500 and 1700 W) in detail. The findings infer that the higher percent of Mo (above 10%) is not advisable for biomedical applications due to cracking and other related issues. The results indicate need for further research to optimize the laser metal deposition process to yield consistent production of functionally graded material.
Lower Limb Joint Reaction Forces and Moments Calculations for a “Dabke Jump”: Application of 3D Inverse Dynamics Technique
Authors: Sammour Perla C. , Hage Ilige S. , Ghnatios Chady , Metni Najib , Hage Re-Mi S. , Hamade Ramsey F.
Published: January 2022

The study involves applying the inverse dynamics to calculate the 3-dimensional (3D) reaction forces and moments at the lower limbs namely: hip, knee, and ankle joints. The study is specific to performing the Lebanese folkloric dance known as the “Dabke jump”. The aim is to compare the impact forces generated at the three joints. Also envisioned is to contrast the forces generated for a male (63 Kg) and a female (50.4 kg) dancer (barefoot and while she wears 8.5 cm high heels).

The experimental part of the study consists of measuring position data of the right lower limb of the participant when performing the jump. All at once, the reaction forces generated at the impact are synchronously measured. The position data are obtained using the OptiTrack™ motion capture system. The ground reaction forces are measured using the AMTI force plate.

Using kinematics analysis in conjunction with inverse dynamics, the filtered and fitted experimental data are then imported into MATLAB® to obtain a table containing all the internal forces and moments at each joint (ankle, knee, and hip joints) as function of time. Next, the results are plotted and compared. Force and moment data are analyzed using R Project for statistical computing software. The boxplot technique is used to identify the presence of outliers. Using both MannWhitney and Krustkal Wallis tests, all joint reaction forces and moments in three dimensions are analyzed, at different time intervals to instantaneously identify the prominent effect on each joint.

It is found that the largest impact force is generated at the ankle joint for both subjects. For the male participant, the impact maximum vertical force measured at the ankle is about 2.2 of body weight (BW). For the female participant, a maximum vertical force of 1.84 BW is recorded both barefoot and with heals. The forces and moments obtained for this male individual are larger than those obtained for this female individual. Moreover, for the female participant the vertical forces obtained for all joints when wearing an 8.5 cm high heel are found to be lower than those obtained when she is barefoot. This is most notably recorded at the hip joint where a maximum decrease of 21.2% is observed. This finding suggests that when a dancer performs the “Dabke jump”, wearing an appropriate heel of suitable height will decrease the vertical impact forces on the lower limb joints and decrease the risk of injuries.
Examination of Resonant Frequencies Generated by Combustion Oscillation in a Combustor Fueled by a Hydrogen-Natural Gas Mixture and an Upstream Pipe
Authors: Uemichi Akane , Lyu Yifan , Kusaka Jin , Kaneko Shigehiko
Published: January 2022

A combustion oscillation experiment showed combustion oscillation frequencies of around 350 Hz when only natural gas was used as fuel and approximately 200 and 400 Hz when a hydrogen–natural gas mixture was used. To analyze the resonant frequency, two- and four-region models considering unburned and burned regions of the combustor were developed. The experimental frequencies of the 100% natural gas condition were successfully predicted. Conversely, the experimentally observed frequencies under the hydrogen–natural gas condition were not accurately predicted. A swirler-combustor model was then constructed to get closer to the actual configuration and shape of the experimental setup. However, the model could not reproduce the experimental value under the hydrogen–natural gas condition. A whole piping model was then developed by adding a casing and an air supply pipe to the combustor. The resonant frequencies under both the 100% natural gas and hydrogen–natural gas conditions were successfully calculated. The model reproduced the range and change tendency of the experimentally measured oscillation frequency.
Output-Only Structural System Identification Based on Symplectic Geometry Mode Decomposition
Authors: Pengming Zhan , Xianrong Qin , Qing Zhang , Yuantao Sun
Published: January 2022

In this paper, a novel output-only structural system identification method is proposed based on the decomposition of the response signal by applying newly developed symplectic geometry mode decomposition (SGMD). The SGMD can decompose the output signal into a limited of single component signals which are also called symplectic geometry components (SGCs) adaptively without determining too many parameters. Then the random decrement technique (RDT) is applied to extract the free decay responses from SGCs. Finally, the modal parameters such as modal frequency and damping ratio can be identified using the Hilbert transform (HT) method. To demonstrate the validity and effectiveness of the proposed method, a numerical example and a monitored quayside container crane structure are conducted. The modal parameters of those studies can be obtained accurately and effectively by using the proposed method.
Friction Element Riveting: Effects of Lower Element Geometry
Authors: Grimm Tyler J. , Deshpande Amit B. , Parvathy Gowtham V. , Mears Laine
Published: January 2022

Within manufacturing, resistance spot welding (RSW) has been the traditional method of choice when joining steel-steel sheets. However, within the transportation industry, the use of lighter weight materials such as aluminum has become necessary in order to improve fuel economy. This has required the creation of new technologies and adaptations of traditional ones in order to successfully join these materials.

One such adaptation, useful in joining aluminum-aluminum sheets, is friction element riveting (FER). This process is similar to the friction element welding process; however, two or more aluminum sheets are secured together between the element head and a relatively small steel sheet, which is termed lower element. Since this is a novel technology, the influence of different sized lower elements is unknown. A study is conducted which varies the diameter and thickness of the lower elements. A simulation was also created to estimate the thermal effects of these various geometries. Strength testing was used to determine the success of each parameter. It was discovered that the maximum joint strength occurs when using a lower element diameter of 25 mm and a thickness of 1.6 mm.
Nonlinear Dynamics Simulation of Contact Force in Cam-Follower System Using Lyapunov Exponent Parameter
Authors: Yousuf Louay S.
Published: January 2022

Nonlinear dynamics simulation of contact force is investigated for different cam angular speeds (N) and different internal dimensions of the follower guide (F.G.I.D.) using Lyapunov exponent conception. The follower is moved with three degrees of freedom. Power spectrum analysis is added to detect the non-periodic motion of the contact force using the amplitude of Fast Fourier Transform (FFT). SolidWorks software is used in the numerical simulation of the contact force. Four different values of internal dimensions of the follower guide such as (16, 17, 18, and 19 mm) are used in the simulation. The contact force is measured experimentally using OPTOTRACK/3020 by tracking the position of the follower through an infrared camera device. The cam is installed on the shaft of the motor which rotates at uniform angular velocity. The value of contact force has declined with the increasing of cam angular speeds (N) and internal dimension of the follower guide (F.G.I.D.).
Formation and Control of Defects on the Surface of Hollow Axles by Three-Roller Skew Rolling
Authors: Zhang Song , Shu Xuedao , Wang Jitai , Ye Caoqi
Published: January 2022

The surface of the three-roller skew rolled hollow axles is prone to spiral mark defects, which will cause the forming quality of the parts to deteriorate, or the size does not meet the requirements. In this work, the formation and deterioration mechanism of the spiral marks on the surface of the hollow axles by three-roller skew rolling are studied. Firstly, through the kinematics analysis of the three-roller skew rolling hollow axles, the forming mechanism of the spiral marks on the surface of the hollow axles is explained. Secondly, through simulation, the influence of process parameters on spiral marks is analyzed. And the conditions for preventing spiral marks are obtained. Finally, according to the theoretical analysis and simulation results, the optimal process parameters that minimize the depth of the spiral mark are obtained. The results show that the spiral pitch of the rolled piece is larger than the width of the finishing section of the roller, which is the main reason for the spiral marks on the surface of the hollow axles. The axial speed of the chuck and the rotation speed of the roller are the main process parameters that affect the depth of the spiral marks, and the forming quality is the best when they are 60rpm and 25mm/s, respectively.
An Atomic-Scale Investigation of the Temperature Influence on the Reactivity of Alkaline Water Electrolysis on an Optimized Nickel-Iron Catalyst Surface for the Hydrogen Generation
Authors: Oyinbo Sunday Temitope , Jen Tien-Chien , Imoisili Patrick Ehi , Oviroh Peter Ozaveshe
Published: January 2022

The temperature influence on the reactivity of alkaline potassium hydroxide (KOH) solution on a heterometallic NiFe surface was investigated with the aid of ReaxFF potential is performed using reactive molecular dynamics (RMD) simulations, with a particular focus on H2 generation. In this study, the hydrogen generation in the presence of Ni-doped with transition metals such as Fe in the temperature range 500–1500 K through steam water electrolysis was investigated. The composition of the surface was systematically altered by the integration of the second metal (Fe) into the monometallic (Ni) surfaces. A series of well-dispersed and uniform NiFe heterometallic nanocrystals with a 50 % surface ratio were successfully prepared by size control as model catalysts. Systematic electrochemical assessments found that the reactivity of the alkaline hydrogen evolution reaction was strongly dependent on the temperature increase to achieve optimum efficiency. Hydrogen molecules are also the most formed species at all temperature. The alloy catalyst efficiency in H2 generation rate increases with temperature. Hence, this study highlights the significance of temperature in the process of steam-water electrolysis, an important step towards successful H2 formation as a clean energy source.
Application of Data Processing and Machine Learning Techniques for In Situ Monitoring of Metal Additive Manufacturing Using Acoustic Emission Data
Authors: Hossain Md Shahjahan , Taheri Hossein
Published: January 2022

Additive manufacturing (AM) is one of the most expanding sectors in the current industrial world because of its adoption in different industries. Prototyping was one of AM’s main applications before, but now AM is also equally valuable for commercial components production in various industries such as aerospace, medical, consumer product, and others. Following its increased demand in the industry, the quality of the product is becoming a substantial concern for making sure of its safety and long-term usability. Several studies have been conducted on testing and quality inspection of the product by destructive and nondestructive testing (NDT) techniques. NDT can be used for testing without affecting the sample, which saves the material and production cost. Besides, in situ monitoring through different NDT techniques is also popular because it saves cost and time of production. Currently, in situ monitoring through acoustic emission (AE) is becoming one of the most popular techniques due to its provision of testing in the surface and subsurface of the material. In this study, the data acquired by AE is analyzes using data processing techniques, including wavelet transformation (WT). Because of the significant difference among process conditions in the graphical representation of the WT, the graphs of wavelet images are finally classified by a convolutional neural network (CNN). Proposed data and image processing techniques show that the acoustic data obtained from the AM processes can be efficiently classified for the purpose of process monitoring and quality control.