bluuebunny/crossref_metadata_2025 huggingface dataset:
The Design of the Crowd: Organizing Mass Collaboration Efforts
Authors: Ball Zachary , Lewis Kemper
Published: November 2017

The potential for mass collaboration and concurrent engineering among individuals working on a design project allows for increased innovation in idea generation while also supporting the parallelization of project development. The former of these two benefits is highlighted by recent corporate initiatives to incorporate crowdsourcing in their design process. This is done in an effort to garner new and unique perspectives while also driving designs that carry greater acceptance from the community and/or intended market. The latter benefit is emphasized by the pronounced success of concurrent engineering projects which tend to reduce production costs, all while enhancing overall product performance. This work aims to exploit these two concepts in a structured and methodical crowd centered design framework. A simulated pool of individuals, representing the crowd, are used to form design groups using game-theoretic principles. The outcome of each sub-game aims to increase the overall improvement to the designed system by maximizing what each individual can potentially add to the project. The optimization of resource allocation is then performed where time spent on individual or collaborative efforts is determined. The proposed framework is applied to simplified design projects at their initial conception, before detailed mathematical design models are determined.
Design of an Integrated Cotton Picking System for Small-Scale Indian Agriculture
Authors: Bautista Brittany N. , Diaz Lankenau Guillermo F. , Guitron Steven P. , Jennings Brandon D. , Nechlani Rahul , Tang Astera S. , Tucker Matthew R. , Winter Amos G.
Published: November 2017

India, the world’s largest producer of cotton, contains more than 4 million cotton farms that are less than 5 acres. These farms are incapable of large-scale mechanization due to small farm size and irregular farm shape. A previous team developed a handheld, roller-based picking device that demonstrated increased performance over similar products. However, a significant improvement in productivity requires increasing picking speed through mechanization as well as increasing worker cotton carrying capacity. We present a system that utilizes the roller-based picking device in tandem with a compressive storage bag and an efficient carrier. Through modeling and initial testing, the system demonstrates a two times (2X) improvement in worker productivity over current methods. This paper characterizes the cotton picking process, details the modules of the integrated system, and suggests further procedural improvements for greater increases in worker productivity.
Fabrication of Experimental Setup for Investigation of Drill String Fatigue Failure
Authors: Abdo Jamil , Hassan Edris , Al-Shabibi Abdullah
Published: November 2017

Drill string and downhole tool failure usually results from failing to control one or more of the vibration mechanisms. The solution starts with the ability to measure different modes and hence identify the different vibration mechanisms. An in house experimental setup was developed to imitate the downhole axial, lateral and torsional vibration modes and mechanisms. Single and coupled vibration modes and mechanisms were created. This paper mainly focused the design and fabrication of the experimental setup. Capability of the setup for creating different vibration modes were examined. Experiments were performed to investigate the effects of rotational speeds and lateral vibration mode on the fatigue life of drill strings. Fatigue life is measured from the number of cycles associated with the amplitude of the stress cycles created due to lateral vibration Results showed that drill string size and lateral vibration stress cycles have significant effects on the fatigue life of the drill string. Investigations also showed that operating on a rotation speed higher than 90% of the drill string critical speed leads to yielding of the drill string. Such setup is essential for oil/gas industries as it can be utilized to investigate and provide solutions for very common problems such as drill string fatigue failure.
A Non-Iterative Carrier Phase Differential GNSS Kinematic Localization Method
Authors: Tabatabaee Mohammad Hadi , Ravani Bahram
Published: November 2017

Reliable and accurate kinematic localization is becoming more important in autonomous vehicles and advanced driver assistance systems (ADAS) which need to precisely locate vehicles on roadways. Code-base undifferenced GNSS receivers provide rough position estimates with errors too large to be practical for such applications. Carrier-phase observations are able to provide sub-meter accuracies and have been receiving much attention in recent years. Iterative methods are commonly used for solving the double-difference equations and find the receiver co-ordinates. This paper presents a non-iterative method for solving double-differenced carrier phase observation equations and evaluates its effectiveness for kinematic localization for vehicle positioning.
Parallel Time-Integration of Flexible Multibody Dynamics Based on Newton-Waveform Method
Authors: Han Shilei , Bauchau Olivier A.
Published: November 2017

Traditionally, the time integration algorithms for multibody dynamics are in sequential. The predictions of previous time steps are necessary to get the solutions at current time step. This time-marching character impedes the application of parallel processor implementation. In this paper, the idea of computing a number of time steps concurrently is applied to flexible multi-body dynamics, which makes parallel time-integration possible. In the present method, the solution at the current time step is computed before accurate values at previous time step are available. This method is suitable for small-scale parallel analysis of flexible multibody systems.
Comparing the Sustainability Performance of Metal-Based Additive Manufacturing Processes
Authors: Chan Rothanak , Manoharan Sriram , Haapala Karl R.
Published: November 2017

While there have been many advancements in additive manufacturing (AM) technologies for metal products, there has not been a great deal of attention paid toward developing an understanding of the relative sustainability performance of various AM processes for production of aerospace components, such as wire feed and powder bed fusion processes. This research presents a method to calculate and compare quantitative metrics for evaluating metal AM process on a basis of sustainability performance. The process-level evaluation method encompasses a triple bottom line analysis for low volume part production. A representative aerospace titanium alloy (Ti-6Al-4V) component is considered for the study and the production of the part is modeled using direct energy deposition (DED) as the representative wire feed AM process and selective laser melting (SLM) as the representative powder bed AM process. The results indicate that DED has a superior sustainability performance to SLM, mainly due to the relatively slower deposition rate and higher cost of material for SLM than DED. This research provides decision makers an approach method and a demonstrated case study in comparing DED and SLM AM processes. This understanding reveals advantages between the two options and offers avenues of future investigation for these technologies for further development and larger scale use.
Does Designing for Additive Manufacturing Help Us Be More Creative? An Exploration in Engineering Design Education
Authors: Sinha Swapnil , Chen Hong-En , Meisel Nicholas A. , Miller Scarlett R.
Published: November 2017

Designing for manufacturing encourages designers to tailor products for manufacturing constraints, assembly requirements, and limited resources. The additive manufacturing (AM) process challenges traditional manufacturing constraints by building material layer-by-layer, providing opportunities for increased complexity, mass customization, multifunctional embedding, and multi-material production, which were previously difficult with traditional manufacturing (TM) processes. With its application as an effective prototyping and manufacturing tool, AM is prevailing in the educational and industrial engineering design process. For proper utilization of the potential it offers, AM has created a need for an effective Designing for AM (DfAM) curriculum. This exploratory study examines how current formal education on DfAM considerations influence creative concept generation as compared to designing for TM (DfTM). A design study was conducted in two different classrooms, one with and one without formal training in DfAM. It was found that the ideas generated for AM on average were significantly more elegant than the ideas generated for TM. On the other hand, ideas generated for TM scored higher than AM in feasibility. These results indicate that AM significantly aids in generating aesthetically appealing ideas, but not necessarily in the generation of feasible ideas, compared to TM. We use these findings to provide recommendations for design education.
Design for Marketing Mix: The Past, Present, and Future of Market-Driven Product Design
Authors: Donndelinger Joseph , Ferguson Scott M.
Published: November 2017

The four Ps of the Marketing Mix are defined as Product, Price, Place and Promotion. The last forty years of engineering design research has seen an increased incorporation of preference into the design process in response to meeting the demands of each ‘P’. This incorporation began with surrogates of preference in Design for Product problem formulations where an objective (such as minimizing weight, for example) represented a firm’s desire to reduce cost and maximize profit. As our community progressed toward Design for Price problem formulations, we began to represent preferences both of the designer — using decision theory techniques — and of the customer — often in the form of random utility models that then informed models of demand. The Design for Market System special session was created in response to our transition to Design for Place, though much work remains to be done. The objective of this paper is to highlight the advancements of the community through the first two P’s (Product and Price) while also highlighting the need, and exciting research opportunities, that exist as we transition to Design for Place and Design for Promotion.
Modeling an Impact Vibration Harvester With Triboelectric Transduction
Authors: Ibrahim Alwathiqbellah , Ramini Abdallah , Towfighian Shahrzad
Published: November 2017

We demonstrate numerically an efficient vibrational energy harvester based on a triboelectric mechanism. The energy harvester consists of a clamped-clamped beam with center mass to enable the impact between the triboelectric layers subjected to external vibrations. The lower electrode is aluminum covered with a polydimethylsiloxane (PDMS) layer and the top electrode is an aluminum foil. Upon contact, electric charges are generated and alternative current flows between the upper and lower electrodes. We report the frequency bandwidth gets wider with a hardening behavior introduced by the impact nonlinearity in the structure. We then investigate the effect of the surface charge density on the output voltage, current, and power. The output voltage and power are as large as 1.73 V, 3 μW, respectively with 0.4 g vibrational amplitude and 30 μC/m2 surface charge density. The frequency bandwidth ranged between 5–18 Hz.
Scalable Microstructure Reconstruction With Multi-Scale Pattern Preservation
Authors: Cang Ruijin , Vipradas Aditya , Ren Yi
Published: November 2017

A key challenge in computational material design is to optimize for particular material properties by searching in an often high-dimensional design space of microstructures. A tractable approach to this optimization task is to identify an encoder that maps from microstructures, which are 2D or 3D images, to a lower-dimensional feature space, and a decoder that generates new microstructures based on samples from the feature space. This two-way mapping has been achieved through feature learning, as common features often exist in microstructures from the same material system. Yet existing approaches limit the size of the generated images to that of the training samples, making it less applicable to designing microstructures at an arbitrary scale. This paper proposes a hybrid model that learns both common features and the spatial distributions of them. We show through various material systems that unlike existing reconstruction methods, our method can generate new microstructure samples of arbitrary sizes that are both visually and statistically close to the training samples while preserving local microstructure patterns.
Slip Prediction of Skid-Steer Mobile Robots in Manufacturing Environments
Authors: Zuccaro Stephen G. , Canfield Stephen L. , Hill Tristan W.
Published: November 2017

Skid steer mobile robots (SSMR) are platforms with simplistic mechanical drives readily adapted for a variety of applications. Skid Steer robots require slipping when navigating general paths. This slipping behavior is a function of surface conditions (friction) as well as robot motion and forces (system dynamics). Slipping affects motion along the path as well as drive torques and power consumption and is therefore an important consideration in robot design. Slipping can be characterized through the instant centers of rotation of the contact patches of the left and right tracks, and it has been shown that these are functions of the system dynamics. Therefore, prediction of system dynamics is needed to better evaluate robot slipping behavior during run time. In this paper, these instant center locations are called the slip parameters. In particular, the paper looked at two alternative models for the slip parameters, one a kinematic estimate assuming constant slip behavior for a class of tasks and the other a dynamic estimate which predicts slip parameters to lie on continuous, closed curves that vary in size relative to payload conditions. Each of these models for slip parameters have been presented in the previous literature, but this paper experimentally tests the slipping for track-based SSMR’s and compares these results to the kinematic and dynamic estimates. This paper will evaluate the validity of each model through real-time tracking and will improve understanding of slip behavior during typical manufacturing tasks. The paper will then present guidelines for the design of SSMR systems based on knowledge of ICR behavior.
Understanding the Effects of Soil Characteristics on Mobility
Authors: Jayakumar Paramsothy , Mechergui Dave , Wasfy Tamer M.
Published: November 2017

The Army’s mission is to develop, integrate, and sustain the right technology solutions for all manned and unmanned ground vehicles, and mobility is a key requirement for all ground vehicles. Mobility focuses on ground vehicles’ capabilities that enable them to be deployable worldwide, operationally mobile in all environments, and protected from symmetrical and asymmetrical threats. In order for military ground vehicles to operate in any combat zone, mobility on off-road terrains should be extensively investigated. Mobility on off-road terrains is poorly understood because of the empirical and semi-empirical methods used in predicting the mobility map. These methods do not capture the soil deformation as well as its non-linear behavior. The discrete element method (DEM) was identified as a high-fidelity method that can capture the deformation of the soil and its non-linear behavior. The DEM method allows to simulate the vehicle on any off-road terrain and to generate an accurate mobility map.

In this paper, a simulation study was undertaken to understand the influence of soil characteristics on mobility parameters such as wheel sinkage, wheel slip, vehicle speed, and tractive force. The interaction of the vehicle wheels with soft soil is poorly understood, this study helps understand this interaction. A nominal wheeled vehicle model was built in the DIS/IVRESS software and simulated over different cohesive and non-cohesive soils modeled using DEM. Some characteristics of these soils were varied namely, the soil inter-particle cohesion, the soil inter-particle friction, the soil particle size, and the soil density. The mobility parameters were measured and correlated to the soil characteristics. This study showed that the vehicle speed increased with cohesion, friction, soil density, and particle size, while wheel sinkage and wheel slip decreased with those parameters. The influence of these characteristics combined is more complex; extensive studies of other soil characteristics need to be carried out in the future to understand their effect on vehicle mobility.
Planar Tooth Profile Synthesis for Relative Curvature
Authors: Yu Zhiyuan , Ting Kwun-Lon
Published: November 2017

This paper is the first that uses the new conjugation curvature theory [1] to directly synthesize conjugate tooth profiles with the given relative curvature that determines the Hertzian contact stress. Conjugation curvature theory offers a systematic methodology to synthesize the relative curvature for a tooth pair. For any given relative curvature between the contact tooth profiles, a generating point can be located on an auxiliary body. Under the rolling motion among the pinion pitch, the gear pitch and the pitch on the auxiliary body, the generating point will trace fully conjugate profiles on the pinion and gear bodies with the given relative curvature at the instant of the contact. Full conjugation throughout the contact of the profiles is guaranteed with the three instant centers remaining coincident [1]. The methodology is demonstrated with a planar tooth profile synthesis with given relative curvature. One may find that the Wildhaber-Novikov tooth profile, which is known to have low relative curvature and Hertzian contact stress, and its variations become special cases under such methodology.
Fractional Chebyshev Collocation Method for Solving Linear Fractional-Order Delay-Differential Equations
Authors: Dabiri Arman , Butcher Eric A.
Published: November 2017

An efficient numerical method, the fractional Chebyshev collocation method, is proposed for obtaining the solution of a system of linear fractional order delay-differential equations (FDDEs). It is shown that the proposed method overcomes several limitations of current numerical methods for solving linear FDDEs. For instance, the proposed method can be used for linear incommensurate order fractional differential equations and FDDEs, has spectral convergence (unlike finite differences), and does not require a canonical form. To accomplish this, a fractional differentiation matrix is derived at the Chebyshev-Gauss-Lobatto collocation points by using the discrete orthogonal relationship of the Chebyshev polynomials. Then, using two proposed discretization operators for matrix functions results in an explicit form of solution for a system of linear FDDEs with discrete delays. The advantages of using the fractional Chebyshev collocation method are demonstrated in two numerical examples in which the proposed method is compared with the Adams-Bashforth-Moulton method.
An Experimental Study of Feedback and Risk in Engineering Decision-Making
Authors: Arezoomand Mojtaba , Austin-Breneman Jesse
Published: November 2017

Effectively managing risk is crucial to successful engineering design. Formal methods offer strategies for making decisions under uncertainty and mitigating risk. However, insights from other fields such as cognitive science and behavioral economics suggest that decision-makers may exhibit behaviors in response to feedback which can undermine these strategies. This study presents results from an experiment in which participants were tasked with selecting a design factor of safety for four design prompts under objective risk conditions. Participants were randomly assigned to receive only negative or positive feedback after each decision. Results suggest that the type of feedback influenced the choice of factor of safety even though subjects were provided with the exact benefits and probabilities of all possible outcomes. This experiment suggests further study of the mechanisms by which engineering decision-makers incorporate feedback is necessary.
Nonlinear Modal Analysis of a One-Dimensional Bar Undergoing Unilateral Contact via the Time-Domain Boundary Element Method
Authors: Venkatesh Jayantheeswar , Thorin Anders , Legrand Mathias
Published: November 2017

Finite elements in space with time-stepping numerical schemes, even though versatile, face theoretical and numerical difficulties when dealing with unilateral contact conditions. In most cases, an impact law has to be introduced to ensure the uniqueness of the solution: total energy is either not preserved or spurious high-frequency oscillations arise. In this work, the Time Domain Boundary Element Method (TD-BEM) is shown to overcome these issues on a one-dimensional system undergoing a unilateral Signorini contact condition. Unilateral contact is implemented by switching between free boundary conditions (open gap) and fixed boundary conditions (closed gap). The solution method does not numerically dissipate energy unlike the Finite Element Method and properly captures wave fronts, allowing for the search of periodic solutions. Indeed, TD-BEM relies on fundamental solutions which are travelling Heaviside functions in the considered one-dimensional setting. The proposed formulation is capable of capturing main, subharmonic as well as internal resonance backbone curves useful to the vibration analyst. For the system of interest, the nonlinear modeshapes are piecewise-linear unseparated functions of space and time, as opposed to the linear modeshapes that are separated half sine waves in space and full sine waves in time.
Geometric Analysis of Adaptive Origami Channels for Heat Transfer Applications
Authors: Price Nathan , Gillman Andrew , Fuchi Kazuko , Alyanak Edward J. , Buskohl Philip R.
Published: November 2017

Thermal management is a ubiquitous and critical engineering challenge for a broad range of applications, including combustion engines, high power electronics and chemical processing. However, conventional heat exchanger solutions are often static with limited ability to adaptively modulate heat transfer. Folding concepts from the ancient art form of origami could potentially address these challenges by providing large conducting surfaces that can also spatially reconfigure to regulate the flow and temperature field interactions with the heat transferring medium. In this study, trigonometric and nonlinear mechanical analysis techniques are applied to origami channel designs based on the “waterbomb” and Miura-ori unit cell to characterize the geometric properties of the structures as a function of folding. Both channels demonstrate a large range of flow control, with potentially enhanced mixing in the “waterbomb” channel, due to an axially varying cross-section. The results show promise for the use of origami-based heat exchanger designs for both improved passive and active control of heat transfer.
An Experimental Investigation of Churning Power Losses of a Gearbox
Authors: Polly J. , Talbot David , Kahraman Ahmet , Singh Avinash , Xu Hai
Published: November 2017

In this study, load-independent (spin) power losses of a gearbox operating under dip-lubrication conditions are investigated experimentally using a final-drive helical gear pair from an automotive transmission as the example system. A dedicated gearbox is developed to operate a single gear or a gear pair under given speed and temperature conditions. A test matrix that consists of sets of tests with (i) single gears (spur, helical, or representative disks with no teeth), and (ii) helical gear pairs is executed at various temperatures, immersion depths and pinion positions relative to its mating gear. Power losses from single gears and gear pairs at identical operating conditions are compared to quantify the components of the total spin loss in the form of losses due to gear drag, gear mesh pocketing, and bearings and seals.
Analysis of Maximum Possible Sampling Period for a Real-Time Vision-Based Control System
Authors: Shang Bo , Wu Chengdong , Zhang Yunzhou , Chen YangQuan
Published: November 2017

Drone control systems are experiencing more and more challenges when integrating with more sensors. For example, the drone visual servoing systems often have a large sampling period due to limited on-board computing capability. Therefore, controllers that can tolerate a large sampling period are needed. Our previous work showed that a fractional order proportional-derivative controller (FOPD controller) can tolerate a larger sampling period than an integer order proportional-integralderivative controller (IOPID controller). In this paper, we verified this conclusion using control system stability criteria to estimate the largest sampling periods and time-domain simulation.
An Origami-Inspired Design of a Thermal Mixing Element Within a Concentrated Solar Power System
Authors: Hamer Tyler T. , Zhou Lei , Trumper David L. , Slocum Alexander H. , Calvet Nicolas
Published: November 2017

A Concentrated Solar Power on Demand (CSPonD) system heats a tank of molten salt with sunlight, storing the sun’s energy thermally and generating electricity when needed using a heat exchanger. To prevent the heated salt from forming thermal gradients (reducing the heat exchanger’s efficiency) or overheating (and becoming corrosive), a thermal mixing element mixes the heated salt both axially and radially. Since the mixing element can only move axially within the tank, it contains internal, radial channels to induce radial flow of the salt. These channels are constructed from tabbed wall-components, whose tabs seat into and extend past slots in the top- and bottom-plates of the mixing element. The top- and bottom-plates are constructed from multiple panels with overlapping slots, allowing the panels to form the plates when the tabs are inserted. This interlocking design allows majority of the mixing element to be rapidly manufactured at a low cost from sheet metal and simplifies transportation. In situ, the assembled components fasten together by bending the over-extending tabs, minimizing the number of fasteners needed.
Designing for Power Transfer Across Fold-Lines in Mechanisms With Origami-Like Movement Using Surrogate Folds
Authors: Allen Jason T. , DeFigueiredo Bryce P. , Magleby Spencer P.
Published: November 2017

As mechanisms with origami-like movement increase in popularity, there is a need for conducting electrical power across folds. This need could potentially be filled by the use of surrogate folds. Surrogate folds are a localized reduction in stiffness in a given direction allowing the material to function like a fold. Current methods for conducting across folds are reviewed along with current opportunities. A framework for designing conductive surrogate folds that can be adapted to fit specific applications is presented. Equations for calculating the resistance in single surrogate folds as well as arrays are given. Prototypes of several conductive joints are presented and discussed. The framework is then followed in the designing and manufacturing of a conductive origami-inspired mechanism.
Moving in the Rain: Should We Run or Should We Walk?
Authors: Kwarta Michał , Pazouki Arman , Negrut Dan
Published: November 2017

We use simulation to gauge how various strategies for purposefully moving in the rain control the degree to which an individual is soaked while getting from point A to point B. The study is only concerned with the number of rain droplet hits. We use this as a proxy for “degree of soaking” without any regard to the clothing that the individual wears. The motion of the individual is assumed not to influence the rain intensity and direction. The two-way coupling emerging at high speeds will be addressed in a different study.
Demographic Factors and Their Influence on Designer Creativity and Empathy Evoked Through User Extreme Conditions
Authors: Raviselvam Sujithra , Sanaei Roozbeh , Blessing Lucienne , Hölttä-Otto Katja , Wood Kristin L.
Published: November 2017

Past work has demonstrated that simulating an extraordinary user scenario could have an impact on increasing designer empathy and creativity. It is likely, however, that an individual’s background could make a difference on how such simulated scenarios influence designers and how well the design method works. In this paper, we study the impact of demography and personal connection of the participants to any given simulated scenario versus their response to different empathic simulation workshops. With a variety of design tools and techniques available, understanding such influencing factors could help designers decide on the appropriate design tool for effective ideation. In this study, we investigated the effect of 81 (49 female and 32 male) users from three different workshops that simulated three different extraordinary user scenarios. Results of the study show that personal connection to a population being simulated significantly affects the impact a simulated scenario has on evoking creativity and empathy. And, for the given set of participants, gender did not show significant impact on the participants’ response.
Optimal Metamodeling to Interpret Activity-Based Health Sensor Data
Authors: Chowdhury Souma , Mehmani Ali
Published: November 2017

Wearable sensors are revolutionizing the health monitoring and medical diagnostics arena. Algorithms and software platforms that can convert the sensor data streams into useful/actionable knowledge are central to this emerging domain, with machine learning and signal processing tools dominating this space. While serving important ends, these tools are not designed to provide functional relationships between vital signs and measures of physical activity. This paper investigates the application of the metamodeling paradigm to health data to unearth important relationships between vital signs and physical activity. To this end, we leverage neural networks and a recently developed metamodeling framework that automatically selects and trains the metamodel that best represents the data set. A publicly available data set is used that provides the ECG data and the IMU data from three sensors (ankle/arm/chest) for ten volunteers, each performing various activities over one-minute time periods. We consider three activities, namely running, climbing stairs, and the baseline resting activity. For the following three extracted ECG features — heart rate, QRS time, and QR ratio in each heartbeat period — models with median error of <25% are obtained. Fourier amplitude sensitivity testing, facilitated by the metamodels, provides further important insights into the impact of the different physical activity parameters on the ECG features, and the variation across the ten volunteers.
An Investigation Into the Driving Factors of Creativity in Design for Additive Manufacturing
Authors: Barclift Michael , Simpson Timothy W. , Alessandra Nusiner Maria , Miller Scarlett
Published: November 2017

Additive manufacturing (AM) provides engineers with nearly unlimited design freedom, but how much do they take advantage of that freedom? The objective is to understand what factors influence a designer’s creativity and performance in Design for Additive Manufacturing (DFAM). Inspired by the popular Marshmallow Challenge, this exploratory study proposes a framework in which participants apply their DFAM skills in sketching, CAD modeling, 3D-Printing, and a part testing task. Risk attitudes are assessed through the Engineering Domain-Specific Risk-Taking (E-DOSPERT) scale, and prior experiences are captured by a self-report skills survey. Multiple regression analysis found that the average novelty of the participant’s ideas, engineering degree program, and risk seeking preference were statistically significant when predicting the performance of their ideas in AM. This study provides a common framework for AM educators to assess students’ understanding and creativity in DFAM, while also identifying student risk attitudes when conducting an engineering design task.
Conceptual Regenerative Nozzle Cooling Design for a Hydroxyl-Terminated Polybutadiene and Oxygen Hybrid Rocket Engine
Authors: Robles Luis R. , Ho Johnny , Nguyen Bao , Wagner Geoffrey , Surmi Jeremy , Faruqui Khulood , Carter Ashley , Hinz Tom , Kakish Fady , Zousel Zachariah , Matthys Kory , Piacenza Joseph
Published: November 2017

Regenerative rocket nozzle cooling technology is well developed for liquid fueled rocket engines, but the technology has yet to be widely applied to hybrid rockets. Liquid engines use fuel as coolant, and while the oxidizers typically used in hybrids are not as efficient at conducting heat, the increased renewability of a rocket using regenerative cycle should still make the technology attractive. Due to the high temperatures that permeate throughout a rocket nozzle, most nozzles are predisposed to ablation, supporting the need to implement a nozzle cooling system. This paper presents a proof-of-concept regenerative cooling system for a hybrid engine which uses hydroxyl-terminated polybutadiene (HTPB) as its solid fuel and gaseous oxygen (O2) as its oxidizer, whereby a portion of gaseous oxygen is injected directly into the combustion chamber and another portion is routed up through grooves on the exterior of a copper-chromium nozzle and, afterwards, injected into the combustion chamber. Using O2 as a coolant will significantly lower the temperature of the nozzle which will prevent ablation due to the high temperatures produced by the exhaust. Additional advantages are an increase in combustion efficiency due to the heated O2 being used for combustion and an increased overall efficiency from the regenerative cycle. A computational model is presented, and several experiments are performed using computational fluid dynamics (CFD).
Design of a Multi-DOF Motion System for X-Ray Split and Delay
Authors: Shi Hongliang , Zhu Diling , Schafer Donald W. , Barada Andrew H. , Sun Yanwen , Zhang Lin , Gumerlock Karl L. , James Justin H. , Osier Ted O. , Whitney Randy A. , Smith Brian E. , Robert Aymeric
Published: November 2017

The ability to split femtosecond free electron laser pulses and recombine them with an adjustable delay has numerous scientific applications. In this work, we present a symmetrical multi-DOF motion system placed on a granite table for a wavefront-splitting based hard X-ray split-delay system at the Linac Coherent Light Source [1,2]. In order to achieve ultra-precision multi-DOF motion, a planar air bearing based linear stage is embedded into the system. It features setting the granite table as the reference plane and using flexure mechanisms to decouple the parasitic motion errors. In this application, it is located in the delay line for improving stability and accuracy during the delay adjustments in order to maintain spatial overlap between the two branches. Stiffness matrix derivation and analysis are also presented.
How It Is Made Matters: Distinguishing Traits of Designs Created by Sketches, Prototypes, and CAD
Authors: Tsai Geoff , Yang Maria C.
Published: November 2017

In the early stages of design, designers may use a variety of tools to represent their ideas, including sketches, physical prototypes, and digital models. Prior research suggests that the choice of tool and design representation can influence user opinions of the concept. In this paper, we explore how aware designers and users are of the ways different design tools can influence a design. Specifically, we investigate the question “How is a design influenced by the tool used to create it?” Designs that had originally been created as either a sketch, foam prototype, or CAD model were sketched into a consistent visual style. Designers experienced with these tools exhibited a better-than-random likelihood of identifying the original tool used to create the design, despite viewing only the re-sketch. This suggests artifacts of a design tool persist in a design representation despite the design being translated from one medium to another.
Uncertainty Modeling Using Mixture Distributions in Engineering Systems
Authors: Pandey Vijitashwa , Mourelatos Zissimos P. , Estes Judson
Published: November 2017

Uncertainty is an engineering reality. Attempts to model and reconcile with this uncertainty are generally thwarted by the dearth of available data. In this paper, we use the concept of mixture distributions to address uncertainty modeling under limited information. Mixtures allow for flexibility in modeling of the distributions in question, especially when multimodality exists, is expected to exist, or the data does not come from any of the well-known distributions types. This is expected and observed in domains such as manufacturing, where data intrinsically comes from various sources — e.g. a part provided by multiple suppliers. The proposed approach uses a maximum likelihood based optimization algorithm (EM algorithm) to model limited data as a mixture of multivariate normal distributions. The application problem we choose is that of alignment of vehicles during manufacture. For the application problem, our approach is able to accurately predict repair frequency and outperforms the use of a single multivariate distribution. Our results indicate that the use of mixture distributions warrants further investigations particularly for efficient calculation of expectations of metrics of interest in engineering design.
Analysis of a Simplified Blade Design to Facilitate Wind Energy Penetration in the Developing World
Authors: Khakpour Nejadkhaki Hamid , Hu Yi-Meng Sylvia , Dürrnagel Michelle , Lippert Moritz , Ngo Thanh Danh Anthony , Hall John
Published: November 2017

Wind turbines can provide energy in developing countries. However, there are limitations to the skilled labor and manufacturing equipment required to manufacture these systems in these regions. Accordingly, the manufacturing process needs to be adapted to the potential of the developing world. In this work, a simplified wind turbine blade design is investigated. The turbine efficiency is analyzed by the blade element momentum (BEM) theory. Two different scenarios are considered to simplify the design of the wind turbine blade. The shape of the blade is simulated by a rectangular root connected to several trapezoidal segments. This results in a simple chord length distribution. The design of the twist angle is also considered. The area under the power curve is used to compare the performance of the simplified blades with that of the original design. Results show that the twist angle can be completely omitted as a tradeoff between efficiency and manufacturability. Depending on the number of simplified design segments, the area under the power curve is reduced between 13% and 25 % with respect to the original blade. The model also demonstrates how the loss in efficiency increases as the simplicity of blade design increases. Still, the design simplification enables a manufacturing process which may facilitate the use of wind energy in the developing world.
Study the Effects From Gear Rim Thickness on the Gear Pair Time-Varying Mesh Stiffness and Dynamic Behaviors
Authors: Wang Zi , Zhu Caichao , Song Chaosheng
Published: November 2017

This work will introduce two methods for calculating the gear mesh stiffness which includes the potential energy method and Finite Element/ Contact Mechanics method. The elastic theory of Muskhelishvili will be used to calculate the elastic deformation from the gear body during one mesh cycle for the gear pair in the potential energy method. Also the involute curve, the geometric and kinematics properties of the gear mesh pair will be taken into account of these two methods. The quasi-static time-varying mesh stiffness considering the deflection of gear rim body is learned in detail. Results from both two methods will show the importance of gear rim body elasticity on the gear pair mesh stiffness and the comparison of the results will reveal the validity and efficiency of the methods. Then lumped-parameter model is presented for studying the whole system dynamic behaviors. The effect from the body elastic deformation from component itself on the macro rigid body motion of the system is investigated. The conclusion from the results shows that the elasticity from gear rim body will take prominent effects on the gear pair dynamic behaviors, which should be regarded as an important factor during the design process.
Stress Analysis of a Fixed-Free Compliant Segment Using the Pseudo-Rigid-Body Model (PRBM) Concept
Authors: Crews Joshua , Midha Ashok , Dharani Lokeswarappa R.
Published: November 2017

A method is presented to analyze stress in ambient-temperature, fixed-free compliant segments subjected to end load or displacement boundary conditions. The analysis method outlined herein relies on key outputs from the pseudo-rigid-body models (PRBMs). Simplified equations for stress are presented for both homogeneous and metallic-reinforced segments. Stresses in both the polymer compliant segment and the metallic reinforcing element are addressed to enable a comprehensive stress analysis method. The stress analysis method is exemplified by using two design cases: one, a homogeneous compliant segment, and two, a compliant segment reinforced with a spring steel element. The results showed that introducing a metallic reinforcement increases the flexural rigidity, but does not reduce the bending stress in the casing unless the cross-sectional thickness is reduced. This vein of research is undertaken using metallic reinforcement (inserts) toward the development of a new class of compliant mechanisms with significantly greater performance, particularly insofar as the problems of fatigue and creep are concerned.
Stress Analysis of a Metallic-Reinforced, Small-Length Flexural Pivot Compliant Segment Using the Pseudo-Rigid-Body Model (PRBM)
Authors: Crews Joshua , Midha Ashok , Dharani Lokeswarappa R.
Published: November 2017

A method based on the pseudo-rigid-body model (PRBM) is presented for the analysis of stress in metallic-reinforced, small-length flexural pivot (SLFP) compliant segments, subjected to end loads or displacement boundary conditions. The analysis method provides the designer with a tool to ensure that stress levels are maintained that are appropriate for the intended application and materials of construction. Simplified equations for stress are presented for both homogeneous polymer and metallic-reinforced composite segments, where the reinforcement shares a neutral axis with a polymer casing. The method is exemplified with two case studies, one, a homogeneous compliant segment, and, two, the segment reinforced with spring steel. The introduction of metallic reinforcement increases the flexural rigidity, but does not reduce the bending stress in the casing of a small-length flexural pivot unless the cross-sectional thickness is reduced. This vein of research is undertaken using metallic reinforcement (inserts) toward the development of a new class of compliant mechanisms with significantly greater performance, particularly insofar as the problems of fatigue and creep are concerned.
Investigating Problem Similarity Through Study of Between-Subject and Within-Subject Experiments
Authors: Levy Bryan , Hilton Ethan , Tomko Megan , Linsey Julie
Published: November 2017

Design problems are used to evaluate students’ abilities, the impact of various teaching approaches and of design methods. Design problems greatly vary in style and subject area in order to accommodate for a wide distribution of disciplines, cultures, and expertise. While design problems are occasionally reused between studies, new design problems are continuously created in order to account for the fact that a design problem cannot be used multiple times on an individual in order to effectively measure one’s abilities to perform design. More specifically, in repeated measures testing, students cannot receive the same design problem multiple times, for this would cause bias; therefore, multiple design problems are needed to allow for repeated measures testing. The nature and structure of these multiple design problems need to be similar or “equivalent” in order to accurately measure students’ abilities to perform in design. In this study, we examine four design problems: peanut shelling, corn husking, coconut harvesting, and a personal alarm clock. We determine whether these problems could be deemed equivalent for the purposes of evaluating student design performance through repeated measures testing. We implemented idea generation sessions using both between-subject and within-subjects approaches. Solutions were evaluated on quantity, quality, novelty, variety, and completeness metrics. The data implies that the Peanut and Corn problems are similar in nature and the Alarm and Coconut problems are also similar in nature; as such, these problem pairings may be used to test differences based on group means.
Analysis of the Periodic Damping Coefficient Equation Based on Floquet Theory
Authors: Afzali Fatemeh , Acar Gizem D. , Feeny Brian F.
Published: November 2017

In this paper, we study the response of a linear differential equation, for which the damping coefficient varies periodically in time. We use Floquet theory combined with the harmonic balance method to find the approximate solution and capture the stability criteria. Based on Floquet theory the approximate solution includes the exponential part having an unknown exponent, and a periodic part, which is expressed using a truncated series of harmonics. After substituting the assumed response in the equation, the harmonic balance method is applied. We use the characteristic equation of the truncated harmonic series to obtain the Floquet exponents. The free response and stability characteristics of the damped system for a set of parameters are shown.
Design of a Spherical Robot With Cable-Actuated Driving Mechanism
Authors: Karadoğan Ernur , DeJong Brian P.
Published: November 2017

This paper presents the kinematics and dynamics of a spherical robot with a mechanical driving system that consists of four cable-actuated moving masses. Four cable-pulley systems control four tetrahedrally-located movable masses and the robot functions by shifting its center of mass to create rolling torque. The cable actuation decreases overall mass and, therefore, allow for less energy expenditure, as compared to other moving mass mechanisms that translate the masses by powered-screws. Additionally, the design allows the center of mass for the static (spherical shell, electronics, motors etc.) and dynamic mass (moving masses) to be at the geometric center at any given time, therefore has potential for tumbleweeding when needed. The derived equations of motion are verified by means of simulations.