bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metamaterial Design for Targeted Limb-Socket Interface Pressure Offloading in Transtibial Amputees
Authors: Brown Nathan , Owen Meredith K. , DesJardins John D. , Garland Anthony , Fadel Georges M. 
Published: November 2020

Abstract
While using a prosthesis, transtibial amputees can experience pain and discomfort brought on by large pressure gradients, at the interface between the residual limb and prosthetic socket. Current prosthetic interface solutions attempt to alleviate these pressure gradients by using soft homogenous liners to reduce and distribute pressures. This research investigates an additively manufactured metamaterial inlay with adjustable mechanical response in order to reduce peak pressure gradients around the limb. The inlay uses a hyperelastic behaving metamaterial (US10244818) comprised of triangular pattern unit cells which can be 3D printed with walls of various thicknesses controlled by draft angles. The hyperelastic material properties are modeled using a third order representation based on Yeoh 3rd order coefficients. The 3rd order coefficients can be adjusted and optimized to represent a change in the unit cell wall thickness to create an inlay that can meet the unique offloading needs of an amputee. Finite element analyses evaluated the pressure gradient reduction from: 1) A common homogenous silicone liner, 2) A prosthetist’s inlay prescription that utilizes three variations of the metamaterial, and 3) A metamaterial solution with optimized Yeoh 3rd order coefficients. When compared to a traditional homogenous silicone liner for two unique limb loading scenarios, the prosthetist prescribed inlay and optimized material inlay can achieve equal or greater pressure gradient reduction capabilities. These results show the potential feasibility of implementing this metamaterial as a method of personalized medicine for transtibial amputees by creating customizable interface solution to the meet unique performance needs of an individual patient.
Eight-Cable Robocrane Extension for NASA JSC ARGOS
Authors: Williams Robert L. , Graf Eric 
Published: November 2020

Abstract
This paper presents extension of the triangular 6-cable NIST RoboCrane to a rectangular 8-cable-suspended robot, motivated by an application in the ARGOS (Active Response Gravity Offload System) Laboratory at NASA Johnson Space Center. Six candidate cable/platform design arrangements are considered and evaluated in MATLAB simulation, based on all-eight-cable-positive tensions workspace, singularities, magnitude and slope of cable tensions during trajectories, translational/rotational stiffness, and cable interference. As ever in engineering design, there are tradeoffs, and recommendations are made as to the most suitable design out of the six candidates.
Comparison of Exams and Design Practica for Assessment in First Year Engineering Design Courses
Authors: Nolte Hannah , Berdanier Catherine , Menold Jessica , McComb Christopher 
Published: November 2020

Abstract
In response to calls for engineering programs to better prepare students for future careers, many institutions offer courses with a design component to first-year engineering students. This work proposes that traditional exam-based assessments of design concepts are inadequate, and alternative forms of assessment are needed to assess student learning in design courses. This paper investigates the self-efficacy differences between a traditional exam and a two-part practicum as a mid-semester assessment for introductory engineering students enrolled in a first-year design course. Increased self-efficacy has been linked to various positive student outcomes and increased retention of underrepresented students. The practicum consisted of an in-class team design task and an out-of-class individual reflection, while the exam was a traditional, individual written exam. All students completed a pre-assessment survey and a post-assessment survey, both of which included measures of design self-efficacy. Analysis showed that the practicum increased the design self-efficacy of students more effectively than the exam. Students who identified as women had greater gains in design self-efficacy during the practicum as compared to men. Identifying as a minority subgroup student was also trending towards being a significant predictor of change in self-efficacy for the practicum. Findings suggest that a mid-semester practicum is a successful assessment of design competencies that contributes to increased first-year engineering student self-efficacy.
Design of a Flexure Based Low Frequency Foucault Pendulum
Authors: Fluckiger Patrick , Vardi Ilan , Henein Simon 
Published: November 2020

Abstract
The Foucault pendulum is a well-known mechanism used to demonstrate the rotation of the Earth. It consists in a pendulum launched on linear orbits and, following Mach’s Principle, this line of oscillation will remain fixed with respect to absolute space but appear to slowly precess for a terrestrial observer due to the turning of the Earth. The theoretical proof of this phenomenon uses the fact that, to first approximation, the Foucault pendulum is a harmonic isotropic two degree of freedom (2-DOF) oscillator. Our interest in this mechanism follows from our research on flexure-based implementations of 2-DOF oscillators for their application as time bases for mechanical timekeeping.
The concept of the Foucault pendulum therefore applies directly to 2-DOF flexure based harmonic oscillators. In the Foucault pendulum experiment, the rotation of the Earth is not the only source of precession. The unavoidable defects in the isotropy of the pendulum along with its well-known intrinsic isochronism defect induce additional precession which can easily mask the precession due to Earth rotation. These effects become more prominent as the frequency increases, that is, when the length of the pendulum decreases. For this reason, short Foucault pendulums are difficult to implement, museum Foucault pendulum are typically at least 7 meters long. These effects are also present in our flexure based oscillators and reducing these parasitic effects, requires decreasing their frequency.
This paper discusses the design and dimensioning of a new flexure based 2-DOF oscillator which can reach low frequencies of the order of 0.1[Hz]. The motion of this oscillator is approximately planar, like the classical Foucault pendulum, and will have the same Foucault precession rate. The construction of a low frequency demonstrator is underway and will be followed by quantitative measurements which will examine both the Foucault effect as well as parasitic precession.
Anechoic Stubs As a Means for Damping Frame Vibrations: Analysis Using an Exact Wave-Based Approach
Authors: Lv Hangyuan , Leamy Michael J. 
Published: November 2020

Abstract
This paper explores the addition of small stubs with anechoic terminations (termed herein ‘anechoic stubs’) as means for damping and/or removing vibration modes from planar frame structures. Due to the difficulties associated with representing anechoic boundary conditions in more traditional analysis approaches (e.g., analytical, finite element, finite difference, finite volume, etc.), the paper employs an exact wave-based approach, incorporating Timoshenko beams, in which an anechoic boundary is simply represented by a zero reflection matrix. Several numerically-evaluated examples are presented documenting novel effects anechoic stubs have on the vibration modes of a two-story frame, such as eliminated, inserted and exchanged mode shapes. Modal damping ratios are also computed as a function of the location and number of anechoic stubs, illustrating optimal locations as a function of mode number. Forced vibration studies are then carried-out, demonstrating reduced, eliminated, and inserted resonance response.
Individual Differences in Describing Levels of Automation
Authors: Wentzky Chase , Summers Joshua D. 
Published: November 2020

Abstract
Level of automation (LoA) is increasingly recognized as an important principle in improving manufacturing strategies. However, many automation decisions are made without formally assessing LoA and can be made based on a host of organizational factors, like varied mental models used by managers in decision-making. In this study, respondents (N = 186) were asked to watch five different assembly tasks being completed in an automotive manufacturing environment, and then identify “how automated” or “how manual” they perceived the task to be. Responses were given using a visual analogue scale (VAS) and sliding scale, where possible responses ranged from 0 (totally manual) to 100 (totally automated). The activity explored how and when individuals recognized the automated technologies being employed in each task. The tasks of the videos varied primarily by whether the human played active or passive role in the process. Focus group comments collected as a part of the study show how rating patterns revealed functional systems-level thinking and a focus on cognitive automation in manufacturing. While the video ratings generally followed the LoA framework discussed, slight departures in the rating of each video were found.
Topology Optimization for Stiffened Panels: A Ground Structure Method
Authors: Gamache Jean-François , Vadean Aurelian , Dodane Nicolas , Achiche Sofiane 
Published: November 2020

Abstract
Reducing the weight of structures remains a major challenge in the aviation industry in order to reduce fuel consumption. The stiffened panel is the main assembly method for primary structures in aircraft, e.g. fuselage or wing.
Density-based topology optimization has been used in research and in industry as a tool to help create new stiffening patterns for aircraft components, such as ribs, spars, bulkheads or even floor design.
One critical aspect of stiffened panel design for wing structures is the buckling resistance. However, most work found in the literature does not include buckling analysis during optimization which leads to sub-optimal results when the stiffening layout is validated for buckling.
Including buckling as a constraint for the density-based topology optimization has proven to be a complex task, mainly caused by the fact that the buckling of the stiffeners is not captured accurately. As such, this work presents an optimization method for stiffened panels based on the ground structure approach usually used for truss topology optimization. The main novelty of the method is the use of a stiffener activation variable (SAV) to activate only one variable at a time, either the height or density variable associated with each stiffeners of the ground structure.
This work shows that while ground structure topology optimization requires more setup time and limiting the degrees of freedom of the optimization, it finds the best stiffening layout efficiently when compared to the density method.
The Value of Prototyping: An Investigation of the Relationship Between the Costs of Prototyping, Perceived Value, and Design Outcome
Authors: Nelson Jacob , Menold Jessica 
Published: November 2020

Abstract
Prototyping is an important part of the design process and has repeatedly been identified in prior work as an important tool for designers to test assumptions, communicate ideas, and develop design knowledge. Researchers, however, currently have a limited understanding of how the resources invested in a prototype influence designers’ decision-making and their perceptions of a prototype’s value. Prior work has shown that significant investment of time or money in a prototype can lead to undesirable effects such as design fixation, but the full impact of these factors on designers’ perceived value of the prototypes remains unclear. Likewise, it is unclear how prototype usage impacts the evolution of designer knowledge. To explore these relationships, a study was performed in a 16 week-long design project involving 32 teams of mechanical engineering students. Results suggest that effective prototyping uncovered new design knowledge and limited uncertainty early in the design process, allowing teams to spend more time testing and iterating later in the design process. High-performing teams also reported final prototypes as less valuable for gathering new knowledge than their peers. Importantly, the study did not find any significant relationships between the cost of a prototype in terms of money and time, and the perceived value of that prototype. Nor were any significant relationships found between costs and final design outcomes. This work underscores the need for better methods to evaluate the value of prototyping efforts.
Influence of Conceptual Sketches on Variety, Typology, and Novelty of Elicited Requirements
Authors: Spivey Nick , Davenport Brian , Patel Akash , Ortiz Joshua , Summers Joshua D. 
Published: November 2020

Abstract
The generally accepted engineering design process involves generating requirements prior to developing concepts. Despite this, educators often observe that student engineers tend to have ideas for the eventual solution even before fully defining the problem. Thus, a method of exploiting this natural proclivity may result in a better overall product or process. Coevolutionary design, in which a problem and its solution are developed interdependently, may provide a theoretical construct for such a method. It may be that allowing for the creation of sketches as a first step may improve the resulting requirements, which in turn would enhance the result. To test this, an experiment was developed to observe the effects of rearranging the design sequence to use an early conceptual sketch in the elicitation of constraints and criteria. Requirements were generated by third- and fourth-year mechanical engineering students and were subsequently analyzed based on their variety, typology, and novelty. It was found that the use of a preliminary conceptual sketch had a significant (positive) effect on the typology and novelty of the resulting requirements (α = 0.05), though no change in their variety was observed. Also, an additional intermediate step of identifying key features in the sketch further influenced requirement characteristics. The findings of this study support the coevolutionary model of design and suggest that the sketching of ideas and the identification of features in advance of listing requirements may be a valid design practice in the future. By creating an initial concept sketch and then distinguishing the important aspects of that sketch, engineers would be able to extract applicable requirements which they find inherent in their initial ideas. Finally, this method can align more naturally with the approach that many students employ in design. Rather than modifying behaviors, this method can exploit student behaviors to positive effect.
Three-Dimensional Symmetric Maximum Weight Lifting Prediction
Authors: Zaman Rahid , Xiang Yujiang , Cruz Jazmin , Yang James 
Published: November 2020

Abstract
Lifting heavy weight is one of the main reasons for manual material handling related injuries which can be mitigated by determining the limiting lifting weight of a person. In this study, a 40 degrees of freedom (DOFs) spatial skeletal model was employed to predict the symmetric maximum weight lifting motion. The lifting problem was formulated as a multi-objective optimization (MOO) problem to minimize the dynamic effort and maximize the box weight. An inverse-dynamics-based optimization approach was used to determine the optimal lifting motion and the maximum lifting weight considering dynamic joint strength. The predicted lifting motion, ground reaction forces (GRFs), and maximum box weight were shown to match well with the experimental results. It was found that for the three-dimensional (3D) symmetric lifting the left and right GRFs were not same.
A Test Rig for the Accurate Measurement of Bicycle Tyres Characteristics
Authors: Ballo Federico , Gobbi Massimiliano , Mastinu Giampiero , Previati Giorgio 
Published: November 2020

Abstract
In this paper, a new test rig for measuring the characteristics of bicycle tyres is presented. The test rig is designed to measure the parameters of a wide range of bicycle tyres, including race bicycles, mountain-bikes and city-bikes. The test rig consists of a frame that allows a single wheel to be cambered and steered. Electric motors can be added to produce longitudinal slip. The test rig is conceived to be employed either on a drum or on a flat surface. The friction on the drum or on the flat surface can be varied in a relatively easy way.
The test rig can measure the vertical force, the lateral force, the self aligning torque, the moment around the longitudinal axis, and, after proper arrangement, the longitudinal force. The steering and camber axles of the test rig intersect at the centre of the contact patch. In this way, the vertical vibrations of the wheel cause a pure vertical motion of the centre of the contact patch i.e. without longitudinal velocity. The lateral force is measured by a Watt’s linkage. The steering motion is allowed by pneumatic bearings, which guarantee a vanishing friction moment and thus an accurate measurement of the self-aligning moment. Some measured tyre characteristics are provided.
Modal Reduction Procedures for Flexible Multibody System Applications
Authors: Scapolan Matteo , Shan Minghe , Bauchau Olivier A. 
Published: November 2020

Abstract
The comprehensive simulation of flexible multibody systems calls for the ability to model various types of structural components such as rigid bodies, beams, plates, and kinematic joints. Modal components test offer additional modeling versatility by enabling the treatment of complex, three-dimensional structures via modal reduction procedures based on the small deformation assumption. In this paper, the problem is formulated within the framework of the motion formalism. The kinematic description involves simple, straightforward frame transformations and leads to deformation measures that are both objective and tensorial. Derivatives are expressed in the material frame, which results in the remarkable property that the tangent matrices are independent of the configuration of the modal component with respect to an inertial frame. This implies a reduced level of geometric nonlinearity as compared to standard description. In particular, geometrically nonlinear problems can be solved with the constant tangent matrices of the reference configuration, without re-evaluation and re-factorization.
Temporal Fault Injection Considerations in Resilience Quantification
Authors: Hulse Daniel , Hoyle Christopher , Tumer Irem Y. , Goebel Kai , Kulkarni Chetan 
Published: November 2020

Abstract
Resilience models assess a system’s ability to withstand disruption by quantifying the value of metrics (e.g. expected cost or loss) over time. When such a metric is the result of injecting faults in a dynamic model over an interval of time, it is important that it represent the statistical expectation of fault responses rather than a single response. Since fault responses vary over fault injection times, representing the statistical expectation of responses requires sampling a number of points. However, fault models are often built around computationally expensive dynamic simulations, and it is desirable to be able to iterate over designs as quickly as possible to improve system resilience. With this in mind, this paper explores approaches to sample fault injection times to minimize computational cost while accurately representing the expectation of fault resilience metrics over the set possible occurrence times. Two general approaches are presented: an a priori approach that attempts to minimize error without knowing the underlying cost function, and an a posteriori approach that minimizes error when the cost function is known. Among a priori methods, numerical integration minimizes error and computational time compared to Monte Carlo sampling, however both are prone to error when the metric’s fault response curve is discontinuous. While a posteriori approaches can locate and correct for these discontinuities, the resulting error reduction is not robust to design changes that shift the underlying location of discontinuities. The ultimate decision to use an a priori or a posteriori approach to quantify resilience is thus dependent on a number of considerations, including computational cost, the robustness of the approximation to design changes, and the underlying form of the resilience function.
Analysis and Study of Variable Stiffness Joints Based on Bi-Material Nested Elastomers
Authors: Sun Wei , Yu Jingjun , Cai Yueri 
Published: November 2020

Abstract
Variable stiffness joints are a kind of compliant mechanisms which can improve the safety of physical human-robot interaction which has attracted much attention in recent years. Elastic elements are used in the internal kinematic structures of variable stiffness joints. In this paper, Elastomers with magneto-rheological fluids (MRFs) properties have great potential application for variable stiffness joints (VSJs) and implantable bioelectronics devices by allowing actuators to rapidly and reversibly changed from a “fluid” to a “solid-like” state and precisely controlled within a very short time and over a wide range under a magnetic field. A new adjustable stiffness composites (ASCs) that combine an outside liner (PDMS) with a chamber (MRFs) is introduced. When improving the magnetic field intensity, the MRFs hardens and the stiffness increases by as much as 4–5 orders of magnitude. In order to solve the bi-material nested cantilever beam subjected to a concentrated tangential force at the free end of the beam, a theoretical approach is proposed by means of the Airy stress function method together with the stress function test solution. By comparing the results obtained from the theoretical and experimental measurements, a very good agreement is found, showing the accuracy and feasibility of the theoretical results. This solution will be useful in analyzing cantilever beam with arbitrary variations of bi-material nested and it can serve as a basis for establishing stiffness and stress theories. Due to the highly deformable of the ASCs, it has great potentially for our future soft robot design and manufacture work.
Uncertainty-Based Multidisciplinary Design Optimization for Feedback-Coupled Systems Under Both Parametric and Metamodeling Uncertainties
Authors: Liu Zhao , Song Zhouzhou , Zhu Ping , Xu Can 
Published: November 2020

Abstract
Uncertainty-based multidisciplinary design optimization (UMDO) is an effective methodology to deal with uncertainties in the engineering system design. In order to shorten the design cycle and improve the design efficiency, the time-consuming computer simulation models are often replaced by metamodels, which consequently introduces metamodeling uncertainty into the UMDO procedure. The optimal solutions may deviate from the true results or even become infeasible if the metamodeling uncertainty is neglected. However, it is difficult to quantify and propagate the metamodeling uncertainty, especially in the UMDO process with feedback-coupled systems since the interdisciplinary consistency needs to be satisfied. In this paper, a new approach is proposed to solve the UMDO problem for the feedback-coupled systems under both parametric and metamodeling uncertainties. This approach adopts the decoupled formulation and it applies the Kriging technique to quantify the metamodeling uncertainty. The polynomial chaos expansion (PCE) technique is applied to propagate the two types of uncertainties and represent the interdisciplinary consistency constraints. In the optimization approach, the proposed method uses the iterative construction of PCE models for response means and variances to satisfy the multidisciplinary consistency at the optimal solution. The proposed approach is verified by a mathematical example and applied to the fire satellite design. The results demonstrate the proposed approach can solve the UMDO problem for coupled systems accurately and efficiently.