bluuebunny/crossref_metadata_2025 huggingface dataset:
Preference Aggregation in Lifecycle Decision Making
Authors: Naranjo Sara , Patil Vidya , Pandey Vijitashwa
Published: December 2016

Rapid innovations in technology lead customers to frequently upgrade to new products. Their current products, now obsolete in terms of technology, aesthetic features and performance, leave behind an ecological footprint that is harmful to the environment. Product take-back systems and remanufacturing methods that promise to minimize the environmental impact are gaining attention among researchers and practitioners in the manufacturing field. A common objective is to find the best option for end of lifecycle (EOL) decisions on whether a product and the components comprising it should be reused, recycled, remanufactured, or disposed. These decisions must entail proper analysis while taking into account customer preferences, which can vary considerably from customer to customer. Mass customization, considered a plausible solution for this problem, is not viable model for many products. In this paper, therefore, we approach this problem from a preference aggregation perspective, particularly, the benevolent dictator model. Using this understanding of aggregated preferences, we address the take-back and possible remanufacturing of products. Once collected, it is questioned whether efficiency enhancing new technology or features should be added in take-back products to improve its performance or add any value. If that is the case, will these remanufactured products, with new technology or features, help in cost-effectively reducing the lifecycle environmental impact of the product, compared to a remanufactured product with original specifications? A home HVAC system was selected to exemplify the design and reuse problem, and show the benefit of favoring environmentally conscious customers in lifecycle decision making.
Motivating STEM Studies Through a Space Exploration Robotics Summer Camp
Authors: Du Sida , Ebert Tom , Bin Ishak Ismayuzri , Li Jihang , Mao Xiaoyang , Moffett Mark B. , Sundram Jugesh , Larochelle Pierre
Published: December 2016

In order to motivate the pursuit of and interest in a STEM curriculum for 12–17 year olds, an interactive space exploration robotics camp was developed by the Robotics and Spatial Systems Laboratory at the Florida Institute of Technology. The camp incorporated hands-on activities to explain robots and their practical uses. Problem solving with the versatile robot became the underlying theme of the camp under the guise of a space mission to Jupiter’s moon, Europa. Team building exercises were designed and executed during the camp to teach about engineering and problem solving. Through teamwork, discussions, patience, and dexterity the two teams of the camp successfully completed the simulated mission to save the fictitious base on Europa. The summer camp curriculum was original work developed by RASSL to provide young people with an introduction to robotics. This paper discusses the robot kit development, the activities created for the week, the group competitions, the insight learned by RASSL, and the participant feedback about the camp. This work may be used as a template for creating a small scale robotics camp hosted by a university or high school robotics lab or club.
A Passive Brace to Improve Activities of Daily Living Utilizing Compliant Parallel Mechanisms
Authors: Ring J. B. , Kim Charles
Published: December 2016

Idiopathic scoliosis is a deformity of the spine that affects 2–3% of adolescents. The treatment of scoliosis often requires the use of a rigid brace to align the spine and prevent progression of the deformation. The most common brace, referred to as the Boston brace, has a high success rate in preventing progression of the scoliotic curve. The common root failure is lack of patient compliance in wearing the brace for the prescribed time. This lack in compliance is due to patient discomfort, both physically and emotional, and the patients’ limited ability to perform activities of daily living (ADL) when wearing the brace. The likelihood of needing surgery increases dramatically when bracing is unsuccessful.

We seek to improve patients’ comfort by designing a brace that improves range of motion, while remaining stiff in the corrective direction. Primary ranges of motion were acquired using a motion capture system. A kinematic analysis was performed using homogeneous transformations and screw theory to determine primary screw axes of the motions. The required lateral stiffness for the brace was found in literature.

Compliant mechanisms are used because they can apply the corrective force, but also allow the patients some range of motion. The mechanism implementation was characterized using finite element analysis and compared to a physical model test.

Initial findings confirm that compliant mechanisms are suitable for the application of a scoliosis brace. We have found that the proposed brace can apply the necessary forces at reasonable displacements. The proposed brace will not allow the patient a full range of motion, but we believe that it will achieve an improved range of motion that will increase a patient’s ability to perform activities of daily living.
Simultaneous Topological and Dimensional Synthesis of Planar Morphing Mechanisms
Authors: Funke Lawrence , Schmiedeler James P.
Published: December 2016

This paper presents a general method to perform simultaneous topological and dimensional synthesis for planar rigid-body morphing mechanisms. The synthesis is framed as a multi-objective optimization problem for which the first objective is to minimize the error in matching the desired shapes. The second objective is typically to minimize the actuating force/moment required to move the mechanism, but different applications may require a different choice. The paper shows how all possible topologies can be enumerated for morphing mechanism designs with a specified number of degrees of freedom and how infeasible topologies can be removed from the search space. A multi-objective genetic algorithm is then used to perform the optimization since it can handle both the discrete nature of the topological optimization and the continuous nature of the dimensional optimization. In this way, candidate solutions from any of the feasible topologies enumerated can be evaluated and compared simultaneously. The method also allows for the straightforward incorporation of specific design constraints, such as size limitations and joint location bounds. Ultimately, it yields a sizable population of viable solutions, often of different topologies, so that the designer can manage engineering tradeoffs (beyond those associated with the two objectives) in selecting the best mechanism for the specified application. Two examples are presented to illustrate the strengths of this method. The first examines the advantages gained by considering and optimizing across all topologies simultaneously instead of individual topologies one at a time. The second demonstrates the versatility of the method by incorporating prismatic joints into the morphing chain to allow for morphing between shapes that have significant changes in both shape and arc length.
Multiple-Mode Dynamic Model for Piezoelectric Micro-Robot Walking
Authors: Qu Jinhong , Oldham Kenn R.
Published: December 2016

A multiple-mode dynamic model is developed for a piezoelectrically-actuated micro-robot with multiple legs. The motion of the micro robot results from dual direction motion of piezoelectric actuators in the legs, while the complexity of micro robot locomotion is increased by impact dynamics. The dynamic model is developed to describe and predict the micro robot motion, in the presence of asymmetrical behavior due to non-ideal fabrication and variable properties of the underlying terrain. The dynamic model considers each robot leg as a continuous structure moving in two directions derived from beam theory with specific boundary condition. Robot body motion is modeled in six degrees of freedom using a rigid body approximation. Individual modes of the resulting multimode robot are treated as second order linear systems. The dynamic model is tested with a meso-scale robot prototype having a similar actuation scheme as micro-robots. In accounting for the interaction between robot and ground, the dynamic model with first two modes of each leg shows good match with experimental results for the mesoscale prototype, in terms of both magnitude and the trends of robot locomotion with respect to actuation conditions.
The State of the Art of Origami-Inspired Products: A Review
Authors: Morris Elissa , McAdams Daniel A. , Malak Richard
Published: December 2016

Origami transforms a 2-dimensional sheet to a 3-dimensional structure through the act of folding paper. The principles of this ancient art form have inspired various products and emerging technologies engineered for applications far beyond art and aesthetic. Origami structures feature many useful characteristics pertinent to modern day design challenges such as reconfiguration, flexibility, compactness, and multifunctionality. In this paper, a survey of origami-inspired products is provided to identify and define the state-of-the-art in the evolving field of origami-based product design. Prior reviews of origami-inspired products have been published, but are limited to active structures and mechanical engineering applications only. This work aims to include as many products as possible, irrespective of function or application. Products are classified primarily by the depth of origami-inspiration utilized. Qualitative product comparisons are discussed based on depth of origami integration, scale, operation, and commercial viability. The objectives of this paper are to identify the wide range of product applications for origami principles, to provide a qualitative comparison of products that reveals interesting trends in origami-inspired design, and to determine areas for future work in this developing field.
On Multiphysics Discrete Element Modeling of Powder-Based Additive Manufacturing Processes
Authors: Steuben John C. , Iliopoulos Athanasios P. , Michopoulos John G.
Published: December 2016

Physically accurate modeling of powder-based additive manufacturing (AM) processes can play an enabling role for both the certification and qualification as well as the functional tailoring of materials produced by these processes. In an effort to address these needs in a computationally efficient and physically realistic manner, this paper presents the initial efforts towards the development of a methodology for simulating polydisperse particle-based AM processes by the use of the Multiphysics Discrete Element Method (MDEM). We discuss the formulation of a DEM framework for addressing the unique multiphysics behavior of AM materials and processes. In particular, we focus on coupled thermo-mechanical effects that result in residual strains and deformation. The MDEM approach is demonstrated on several test problems involving laser sintering of metal powders. The paper concludes with a discussion on how this approach may be generalized to broader classes of AM systems, and details are given regarding future work that must be accomplished in order to further develop the present methodology.
Simulating Geometric and Thermal Aspects of Powder-Jet Laser Additive Manufacturing
Authors: Birnbaum Andrew , Michopoulos John G. , Iliopoulos Athanasios P.
Published: December 2016

In order to predict the effects of energy and material deposition via laser and powder-jet based additive manufacturing methods, it is necessary to model a number of appropriate key process phenomena. In addition to solving the classical transient heat equation subject to a moving heat source, it is also critical that local, transient changes in domain geometry and properties also be addressed in order to approach as-build geometry and its associated functional behavior. Furthermore, the melting/solidification behavior of the deposited material may also need to be addressed due to its implications to local temperature-time histories. Finally, incorporating process parameters into a comprehensive simulation is also essential in providing accurate, high fidelity predictions. This work presents efforts at incorporating all of the above-mentioned phenomena via a finite element-based simulation framework to lay the groundwork for full-scale, fully coupled simulations of entire parts. A comparison of predictions including and omitting phase transformation effects along with mass conservation is also presented in the context of assessing the accuracy gained versus the requisite computational expense.
The Influence of Modal Geometrical Imperfections on the Nonlinear Vibrations of a Thin-Walled Circular Cylindrical Shell
Authors: Rodrigues Lara , Gonçalves Paulo B. , Silva Frederico M. A.
Published: December 2016

This work investigates the influence of several modal geometric imperfections on the nonlinear vibration of simply-supported transversally excited cylindrical shells. The Donnell nonlinear shallow shell theory is used to study the nonlinear vibrations of the shell. A general expression for the transversal displacement is obtained by a perturbation procedure which identifies all modes that couple with the linear modes through the quadratic and cubic nonlinearities. The imperfection shape is described by the same modal expansion. So, a particular solution is selected which ensures the convergence of the response up to very large deflections. Substituting the obtained modal expansions into the equations of motions and applying the standard Galerkin method, a discrete system in time domain is obtained. Several numerical strategies are used to study the nonlinear behavior of the imperfect shell. Special attention is given to the influence of the form of the initial geometric imperfections on the natural frequencies, frequency-amplitude relation, resonance curves and bifurcations of simply-supported transversally excited cylindrical shells.
Using an Anti-Relaxation Step to Improve the Accuracy of the Frictional Contact Solution in a DVI Framework for Rigid Body Dynamics
Authors: Melanz Daniel , Mazhar Hammad , Negrut Dan
Published: December 2016

Systems composed of rigid bodies interacting through frictional contact are manifest in several science and engineering problems. The number of contacts can be small, such as in robotics and geared machinery, or large, such as in terrame-chanics applications, additive manufacturing, farming, food industry, and pharmaceutical industry. Currently, there are two popular approaches for handling the frictional contact problem in dynamic systems. The penalty method calculates the frictional contact force based on the kinematics of the interaction, some representative parameters, and an empirical force law. Alternatively, the complementarity method, based on a differential variational inequality (DVI), enforces non-penetration of rigid bodies via a complementarity condition. This contribution concentrates on the latter approach and investigates the impact of an anti-relaxation step that improves the accuracy of the frictional contact solution. We show that the proposed anti-relaxation step incurs a relatively modest cost to improve the quality of a numerical solution strategy which poses the calculation of the frictional contact forces as a cone-complementarity problem.
Synthesis Design and Analysis of a Hybrid Controller for Robotic Arms
Authors: Zhang Dan , Wei Bin
Published: December 2016

In this paper, a hybrid controller for robotic arms is proposed and designed by combining a proportional-integral-derivative controller (PID) and a model reference adaptive controller (MRAC) in order to further improve the accuracy and joint convergence speed performance. The convergence performance of the PID controller, the model reference adaptive controller and the PID+MRAC hybrid controller for 1-DOF and 2-DOF manipulators are compared. The comparison results show that the convergence speed and its performance for the MRAC and the PID+MRAC controllers are better than that of the PID controller, and the convergence performance for the hybrid control is better than that of the MRAC control.
Estimation of Balance Stability States for Legged Robotic Systems
Authors: Mummolo Carlotta , Mangialardi Luigi , Kim Joo H.
Published: December 2016

A three-dimensional criterion is provided for the estimation of balance stability states of legged robotic systems subject to various constraints. A general framework is established to evaluate the balance stability boundary of a given system in the state space of Center of Mass (COM) Cartesian position and velocity. For each assigned COM initial position, an optimization-based iterative algorithm finds the minimum and maximum COM initial velocity that the system can handle along a given direction, such that it maintains the capability to reach a final static equilibrium. The resulting set of velocity extrema constitutes the system’s balance stability boundary, which represents the sufficient condition to estimate falling states versus balanced states, according to the definitions provided herein. The COM state space domain identified with this approach contains all possible balanced states for the given legged system, with respect to the necessary physical, balancing, and design constraints. The balance state estimation is demonstrated for 1- and 2-degrees of freedom planar legged systems in single support. The domain identified by the balance stability boundary can be used as a “map” for the given legged system in which the distance from a given state to the domain boundaries can provide a quantitative measure of balance stability/instability.
Finite Element Method-Based Analysis for Effect of Vibration on Healthy and Scoliotic Spines
Authors: Xu Ming , Yang James , Lieberman Isador H. , Haddas Ram
Published: December 2016

Whole body vibration (WBV) could increase the risk of spine disorders in human spine. Scoliosis is a disorder that results in abnormal three dimensional deformity of the human spine. Rigid fusion (RF) surgery is a common treatment for scoliosis subjects. Subjects with scoliosis have been proven to be more sensitive to WBV than healthy subjects. To date nobody has investigated the effect of WBV on post-surgical of scoliosis subjects although pre-surgical scoliosis subjects have been investigated. Finite element (FE) studies have provided important insights into the understanding of the functional biomechanics of the lumbar spine. The purpose of this study is to analyze the mechanical responses of the healthy, pre- and post-surgical scoliotic spines to vibration using FE methods. The FE models employed in this study were developed using extensively validated modeling methods. Vibration modal analysis was performed to obtain the first-order resonant frequencies in vertical direction in this study: 14.3 Hz in healthy subject, 3.9 Hz in pre-surgical scoliosis subject and 28 Hz in post-surgical scoliosis subject. A cyclic axial load of 40 N at 5 Hz was applied to all three FE models to represent the WBV in vehicle seats under normal driving condition. Intradiscal pressure (IDP) and disc bulge in the adjacent level (L1-L2) for the post-surgical scoliosis subject and healthy and pre-surgical scoliosis subjects were recorded. The IDP and disc bulge in post-surgical scoliosis model were larger than those in healthy and pre-surgical scoliosis subjects. To compare the effect of dynamic and static loads on the spine, static compressions of 360 N and 440 N were applied to the three models corresponding to the minimum and maximum magnitudes of dynamic loads. The differences in IDP and disc bulge under dynamic loads and corresponding static loads in the pre-surgical scoliosis subject was larger than those in both healthy and post-surgical scoliosis subjects. The pre-surgery scoliosis subject has the lowest resonant frequency which is lower than the resonant frequency of the healthy subject. RF surgery considerably increased the resonant frequency of scoliotic spine, which makes the resonance frequency higher in the post-surgery scoliosis subject than that for healthy subjects.
Parameter Design of a Pneumatic Dispensing 3D Printing System for Soft Scaffold Fabrication
Authors: Zhou Wenqi , Peng Qingjin
Published: December 2016

3D printing technologies have been widely used in Tissue Engineering. The pneumatic dispensing system is one of the promising dispensing technologies to fabricate scaffolds with controllable pore sizes and porosities. There are many factors to affect the printing quality in pneumatic systems. An effective method is required to help users to systematically select proper operational parameters to print strands with desired width. In this paper, the DoE method is introduced to evaluate operational parameters and their interactions. The solution is further verified using regression tests. Based on the proposed solution, a five steps parameters selection method is proposed and verified to select operational parameters for two targeted strand widths.
Design of Mechanisms to Trace Plane Curves
Authors: Liu Yang , McCarthy J. Michael
Published: December 2016

This paper describes a mechanism design methodology that assembles standard components to trace plane curves that have a Fourier series parameterization. This approach can be used to approximate complex plane curves to interpolate image boundaries constructed from points. We describe three ways to construct a mechanism that generates a curve from a Fourier series parameterization. One uses Scotch yoke linkages for each term of Fourier series which are added using a belt drive. The second approach uses a coupled serial chain for each coordinate Fourier parameterization. The third method uses one constrained coupled serial chain to trace a specified plane curve. This work can be viewed as a version of the Kempe Universality Theorem that states that a linkage exists that can trace any plane algebraic curve. In our case, we include belts and pulleys, and obtain linkages that trace curves that have Fourier parameterizations.
Promotion of Innovation and Entrepreneurship in Engineering Design by Synchronizing Engineering and Business School Courses
Authors: Lugo José E. , Zapata-Ramos Mari Luz , Perez-Vargas Manuel J.
Published: December 2016

There is a need to improve the innovation and entrepreneurship capacity of engineering design students before graduation, as innovation and entrepreneurship are drivers of economic growth. This paper presents the alignment of existing courses within a university system, mainly Design Thinking (Engineering) and Consumer Behavior (Marketing), with the purpose of developing technology-based entrepreneurship efforts that directly impact a society in need of economic development. Students from each course were presented with six current problems being faced by society, for them to work on in groups. The experience of having interdisciplinary teams working together to achieve a common goal is documented. Also, in order to measure the impact of the courses on the students, a survey of innovation self-efficacy was given to the students at the beginning and at the end of each semester. The results and implications for engineering design education are discussed.
Solution Region Synthesis Method for Six Positions Synthesis of 5-SS Spatial Linkage
Authors: Han Jianyou , Cui Guangzhen , Hu Junjie
Published: December 2016

This paper presents a systematic approach to perform the dimensional synthesis of spatial 5-SS (spherical-spherical) link-ages for six specified positions of the end-effector. The dimensional synthesis equations for a SS link are formulated and solved. We synthesize five SS links to connect the base and end-effector, and then obtain the one-degree-of-freedom spatial 5-SS linkage, which can move through six specified positions. We use the solution region method to build the planar solution region expressing the linkages, due to there are infinite linkages for six positions synthesis. It is convenient to select the linkages from the solution region for designers. The applicability of the proposed approach is illustrated by the example.
Analysis of a One-Dimensional Waveguide Incorporating a Clearance-Type Nonlinear Energy Sink and Attached Energy Harvester
Authors: Darabi Amir , Leamy Michael
Published: December 2016

This work proposes a clearance-type electromechanical nonlinear energy sink (NES) to increase the electrical energy harvested from non-stationary mechanical waves, such as those encountered during impact and intermittent events. The key idea is to trap energy in the NES such that it can be harvested over a time period longer than that afforded by the passing disturbance itself. This leads to an asymmetrical, piece-wise nonlinear device whose functionality and analysis lie at the intersection of several current research topics, including wave-based energy harvesting, non-reciprocal wave propagation, nonlinear energy sinks (NES’s), and hybrid dynamical systems. The nonlinear energy sink concept explored uses a clearance-type nonlinearity, and resulting impact, to pass the energy of the propagating wave from a primary subdomain to a secondary subdomain where a significant portion of it is subsequently trapped and harvested. Moreover, unlike traditionally-studied single-DOF NESs, both subdomains of the NES (i.e., on either side of the clearance) contain displaceable degrees of freedom, significantly increasing the complexity of analytical solution approaches as compared to systems where one side is constrained by a known (or zero) displacement. Computational and analytical techniques are employed to optimize the energy sink and explore qualitative behavior (to include bifurcations). The analysis includes insight from Poincaré sections and bifurcation diagrams, with and without harvesters. Bifurcation diagrams and trends therein provide insight into the number and state of impact events at the NES as excitation amplitude increases. However, analytic formulations are found which quantify the relationship between the impact amplitude and the energy produced, parameterized by system properties such as the harvester effective resistance, the clearance gap, and the domain mass and stiffness. Importantly, a linear relationship between the input energy amplitude and the number of NES impacts has been observed and captured by an approximate, closed-form Poincaré map. In addition to this linear relationship, a closed-form Poincaré map is derived which maps one NES impact location to the next, greatly simplifying the analysis while providing an important tool for follow-on bifurcation studies. The results may justify further exploration in which complex structures (e.g., plates and/or three-dimensional structures) incorporate one or more of the clearance-type NESs to enhance non-stationary electroacoustic wave energy harvesting.
Dimensional Synthesis of a Passive Eight-Bar Slider Exo-Limb for Grasping Tasks
Authors: Tan Guan Rong , Robson Nina , Soh Gim Song
Published: December 2016

This paper describes a dimensional synthesis method used in the design of a passively actuated finger exoskeleton that takes into account the user limb anthropometric dimensions and contact requirements for grasping objects. The paper is the first step in our current efforts on design of wearable devices that use a common slider at the hand to passively actuate each exo-finger. The finger exoskeleton is comprised of a 3R serial limb and is constrained to an eight-bar slider mechanism.

To design the exo-limb, the pose of the index finger was captured using an optical motion capture and its dimensions were determined using a constrained least square optimization of its center of rotation. To facilitate the data capture, a 3D printed wearable Infra-red (IR) marker system was designed and placed on the finger’s phalanx. To illustrate the approach, an example of the design of an index exo-finger is described.
Topology Optimization Software for Additive Manufacturing: A Review of Current Capabilities and a Real-World Example
Authors: Reddy K. Sai Nithin , Ferguson Ian , Frecker Mary , Simpson Timothy W. , Dickman Corey J.
Published: December 2016

Topology optimization is finding renewed interest thanks to additive manufacturing — a technology that is well-suited to fabricate the complex organic shapes and structures that often arise from topology optimization. This paper reviews the current state of topology optimization software through the redesign of a real aerospace mounting plate, focusing on manufacturing considerations that are important for additive manufacturing (AM). Twenty different commercial and educational software tools are investigated and categorized based on their capabilities. Two representative software tools are then demonstrated with well-known examples to compare user interfaces and outputs, and one is chosen to perform the mounting plate case study. We find that all of the commercially available topology optimization software packages offer similar capabilities and considerably more functionality than educational software, but only a few niche products can be tailored to specific applications and manufacturing processes. Current commercial software does not provide adequate manufacturing constraints to remove the need for manual interpretation of results for additive manufacture. A case study involving optimization of an industry-relevant component for AM is used to provide in-depth understanding of both topology optimization and manufacturing considerations in AM. Shortcomings in the existing software tools are presented, and future requirements to take advantage of the increasing AM capabilities, particularly in metals, are discussed.
Design of a Force Sensor Based on Flexure Beams With Piezoresistive and PVDF Elements
Authors: Wei Yuzhang , Xu Qingsong
Published: December 2016

Majority of existing methods of measuring micro-force are limited by the sensing elements, which are fixed on the manipulator and not well decoupled from other axes. In this paper, a unique 1-D force sensor with different sensing elements is first proposed as a micro-manipulator for 1-D force sensing applications in biological cell injection. The goal is to fabricate a compliant sensor using piezoresistive and PVDF (polyvinylidene fluoride) elements for cell injection with sufficient accuracy. The designed sensor is manufactured and calibrated with a commercial GSO gram sensor. Experimental results show a good linearity between the applied force and output voltage signals, which demonstrates the feasibility of the concept design of a force sensor acting as the cell holder. The performances of the force sensor employing piezoresistive and PVDF elements are compared by conducting experimental studies.
Vibration of High-Speed Compliant Gear Pairs
Authors: Cooley Christopher G. , Parker Robert G.
Published: December 2016

This study analytically investigates the vibration of high-speed, compliant gear pairs using a model consisting of coupled, spinning, elastic rings. The gears are elastically coupled by a space-fixed, discrete stiffness element that represents the contacting gear teeth. Hamilton’s principle is used to derive the nonlinear governing equations of motion and boundary conditions. These equations are linearized for small vibrations about the steady equilibrium due to rotation. The equations are cast in operator form, which exemplifies their gyroscopic system structure. The eigenvalue problem is discretized using Galerkin’s method. The natural frequencies and vibration modes for an example aerospace gear pair are numerically calculated for a wide-range of rotation speeds. The system coupling leads to multiple eigenvalue veering regions as the gear rotation speed varies. Highly coupled vibration modes that have meaningful deflection in the discrete mesh stiffness occur within a set frequency band. The vibration modes within this band have distinct nodal diameter components that evolve with rotation speed.
Static Stability Analysis of a Floating Rectangular Prism
Authors: Sequeira Dane , Mann Brian P.
Published: December 2016

This paper examines the static stability of a floating rectangular prism. A nonlinear model is developed to determine the stability of the upright and tilted equilibria positions as a function of the vertical location of the prism’s center of mass. These equilibria positions are defined by an angle of rotation and a vertical position where rotational motion is restricted to a two dimensional plane. Numerical investigations are conducted using path following continuation methods to determine equilibria solutions and evaluate stability. Bifurcation diagrams are generated that illustrate the stability of the equilibrium positions as a function of the vertical location of the center of mass. The bifurcation diagrams show complex stability behavior with many coexisting solutions.
Common Functionality Across Engineering Domains Through Transfer Functions and Bond Graphs
Authors: Lucero Briana M. , Adams Matthew J.
Published: December 2016

Functional Modeling allows a direct, and sometimes abstract, method for depicting a product. Through this method, product architecture, concept generation and physical modeling can be used to obtain repeatable and more meaningful results. The Functional Basis approach of engineering design, as taught to engineering design students, provides the vocabulary to produce a uniform approach to function structures with functions (verbs) and flows (nouns). This paper suggests that the flows, particularly the “signal” flows, can be correlated to additional domains domain through transfer functions common in controls engineering. Controls engineering employs transfer functions to mathematically represent the physical or digital functions of a system or product using block diagrams to show the individual steps. The research herein suggests the correlations between the mathematical representations of transfer functions and the functional basis of engineering design through the actions performed upon “signal” flows. Specifically, the methodologies employed by controls engineering can relate to engineering design by 1) Schematic similarities, 2) Quantifiable performance metric inputs/outputs, 3) Mathematical representations of the flows, and 4) isomorphic matching of the schematics. Controls systems use block diagrams to represent the sequential steps of the system, These block diagrams parallel the functions structures of engineering design. Performance metrics between the two domains can be complimentary when decomposed down to non-dimensional engineering units. Mathematical Functions of the actions in a controls systems can resemble the functional basis functions through the use if bond graphs by identifying characteristic behavior of the functions on the flows. Isomorphic matching using the schematic diagrams can be used to find analogies based upon similar functionality and target performance metrics. When these four similarities are performed, parallels between the engineering domain and the controls engineering can be establish. Examples of cross-domain matching via transfer functions and controls systems are provided as contextualization for the concepts proposed. Pathways forward for this preliminary research are additionally suggested.
Automated Mapping of Product Features Mined From Online Customer Reviews to Engineering Product Characteristics
Authors: Kang Sung woo , Tucker Conrad S.
Published: December 2016

Until now, translating product features expressed in the market into quantifiable engineering metrics has primarily been a manual process. This manual process establishes product features from large-scale customer feedback using a product’s components from large-scale design specifications. This process exacerbates the complexity and sheer amount of information that designers must handle during the early stages of new product development. The methodology proposed in this paper automatically identifies product features by mapping terms that describe product features from technical descriptions and customer reviews. In order to discover terms related to the features expressed in the market, the authors of this work employ WordNet and the PageRank algorithm, which search for semantically similar terms in products’ technical descriptions. A case study demonstrates the methodology’s viability for matching product features that are extracted from online customer reviews to the technical descriptions that address them.
Curved Crease Tube Structures as an Energy Absorbing Crash Box
Authors: Garrett Daniel , You Zhong , Gattas Joseph M.
Published: December 2016

Straight-crease origami crash boxes have previously been designed to possess a near optimum failure mode for a tubular energy-absorbing device. This failure mode, termed a ‘complete diamond mode’ (CDM), possesses a low peak force Pmax and high average force Pavg, caused by generation of travelling hinge lines that propagate laterally during crushing. The present study investigates the hypothesis that a curved crease structure could further improve failure characteristics by having a lower Pmax due to the initially curved corner lobes. An experimental and numerical investigation was conducted using aluminium curved crease origami tubes, with certain curved crease tubes exhibiting the desired CDM and good correspondence seen between experimental and numerical behaviours. A parametric numerical analysis on 45 steel curved crease origami tubes showed a maximum reduction in Pmax of 67% was observed, which is better than the straight-crease origami crash boxes in this respect. A maximum increase in Pavg of 65% was observed, which is worse than straight-crease origami crash boxes. A lower Pmax was thus achieved as hypothesised, however this improvement came at the expense of a reduction in average force. Curved crease crash boxes are therefore concluded to have minimal benefit over existing straight crease crash box designs.
Mechanism Design for Automated Handling and Multiaxial Draping of Reinforcing Textiles
Authors: Brinker Jan , Müller Mario , Paris Jascha , Hüsing Mathias , Corves Burkhard
Published: December 2016

In almost all industrial sectors handling processes are automated through the use of robotic systems. However, in the production of fiber-reinforced structures with complex geometries, the handling of dry, pre-impregnated semi-finished textiles is still performed mainly manually resulting in long processing times, low reproducibility and high manufacturing costs. The scope of the project AutoHD is to fully automate the draping and handling process of complex, three-dimensional fiber composite structures with high degrees of deformation and multiaxial curvature. Upcoming draping defects need to be detected early during the draping process in order to be able to take countermeasures and thus to meet strict requirements. Therefore, non-destructive inline inspection systems are integrated directly into the handling system. However, such integration does not allow the use of molding press tools but requires the use of mechanisms for draping the textile.

In this context, this contribution is concerned with the design of mechanisms as used with an end-effector for the automation task. Therefore, a demonstrator part was specified representing common challenges of draping including varying edges and curves of different radii. Analyses of the required draping movements provide information on the motion task and the resulting requirements. Based on that, the discoveries of systematic type syntheses of translational manipulators are employed to find feasible mechanisms. In order to reduce the solution field, selection criteria are developed and a detailed evaluation is carried out. A subsequent task-oriented dimensional synthesis is performed to analyze the remaining structures and to assess their suitability for their integration into the overall system design.
A Sparse Data-Driven Polynomial Chaos Expansion Method for Uncertainty Propagation
Authors: Wang F. , Xiong F. , Yang S. , Xiong Y.
Published: December 2016

The data-driven polynomial chaos expansion (DD-PCE) method is claimed to be a more general approach of uncertainty propagation (UP). However, as a common problem of all the full PCE approaches, the size of polynomial terms in the full DD-PCE model is significantly increased with the dimension of random inputs and the order of PCE model, which would greatly increase the computational cost especially for high-dimensional and highly non-linear problems. Therefore, a sparse DD-PCE is developed by employing the least angle regression technique and a stepwise regression strategy to adaptively remove some insignificant terms. Through comparative studies between sparse DD-PCE and the full DD-PCE on three mathematical examples with random input of raw data, common and nontrivial distributions, and a ten-bar structure problem for UP, it is observed that generally both methods yield comparably accurate results, while the computational cost is significantly reduced by sDD-PCE especially for high-dimensional problems, which demonstrates the effectiveness and advantage of the proposed method.
Flexoelectric Vibration Control of Plates by Line Electrodes
Authors: Zhang X. F. , Li H. Y. , Tzou H. S.
Published: December 2016

The electric polarization induced by the strain gradient is the direct flexoelectric effect; the mechanical stress/strain induced by the electric field gradient is the converse flexoelectric effect. Accordingly, flexoelectric sensors and actuators are respectively designed to monitor the structural dynamic behavior and to control the structural vibration. In this study, a line-electrode induced flexoelectric actuation is designed to control the plate vibrations. A flexoelectric layer laminated on the thin plate is used as a distributed actuator. The bottom surface of the flexoelectric actuator is a common electrode and the top surface is driven by a conductive line to generate an inhomogeneous electric field. Based on the converse flexoelectric effect, the electric filed gradient induces mechanical stresses in the flexoelectric layer resulting in induced bending moments to the plate structure. With the control moment imposed on the plate, flexoelectric vibration control of the plate is evaluated in this study. The objective of this study is to explore the modal control effects of the plate by the conductive line excitation. For a plate with two opposite sides simply supported and the other two are free (SS-F-SS-F), vibration control response of the plate is studied when the conductive line locates parallel to the y width direction. Then, independent modal control effects (i.e., the induced or controllable displacements by the flexoelectric actuator) are evaluated for the modes (1,1), (1,2), (1,3), (2,1) and (3,1) with different line actuation locations. Control effects of the conductive line location to various plate modes are explored and results show that the optimal conductive line location differs for different plate modes. When the FF width decreases to far less than the SS length, the SS-F-SS-F plate is degraded to a simply supported beam. Then, control effects for modes (1,1), (2,1) and (3,1) with different conductive line locations are discussed. The results are compared with the control effect derived directly by the simply supported beam theory. Thus, this study suggests that plate vibration can be controlled by the line-electrode induced converse flexoelectric effect. Conductive line locations are critical to control of various plate modes.
Probability-Based Power Dispatch in Wind-Integrated Electrical Grid for Energy Storage Capacity Determination
Authors: Hung Tzu-Chieh , Chan Kuei-Yuan
Published: December 2016

Implementing microgrids has become a current trend in the electric utility industry to either improve system reliability or energy access for energy sustainability. This study proposes a probability-based strategy for both long- and short-term power dispatch with wind and load uncertainty. The long-term power dispatch is used to determine a suitable capacity of energy storage, and the short-term power dispatch is used for real-time operation. For both short- and long-term power dispatch, the trends of wind energy and electricity demand are extracted using the wavelet packet analysis method and the moving average technique. The uncertainties from wind speed and power generation data are modeled with log-normal and extreme value distributions, respectively. From the obtained power dispatch and model forecasting, the capacity of energy storage is determined. To validate the proposed approach, a real-time operating simulation is used as a case study to observe the behavior of the wind-integrated electrical system. Results show that the proposed method can estimate the uncertainty variation range of wind energy and the state of charge of energy storage effectively.
Mass and Position Determination in MEMS Resonant Mass Sensors: Theoretical and Experimental Investigation
Authors: Bouchaala Adam , Nayfeh Ali H. , Jaber Nizar , Younis Mohammad I.
Published: December 2016

We present a method to determine accurately the position and mass of an entity attached to the surface of an electrostatically actuated clamped-clamped microbeam implemented as a mass sensor. In the theoretical investigation, the microbeam is modeled as a nonlinear Euler-Bernoulli beam and a perturbation technique is used to develop a closed-form expression for the frequency shift due to an added mass at a specific location on the microbeam surface. The experimental investigation was conducted on a microbeam made of Polyimide with a special lower electrode to excite both of the first and second modes of vibration. Using an ink-jet printer, we deposited droplets of polymers with a defined mass and position on the surface of the microbeam and we measured the shifts in its resonance frequencies. The theoretical predictions of the mass and position of the deposited droplets match well with the experimental measurements.
Static Power Properties of Robot Manipulators: General Formulation and Application Examples
Authors: Arikawa Keisuke
Published: December 2016

A method for analyzing the static power properties of robot manipulators is formulated. First, a formulation for nonredundant manipulators is discussed. A power transformation matrix (PTM) constructed from a Jacobian matrix plays important roles in the formulation. The special properties of the PTM are introduced. Next, the formulation is extended for manipulators with motion and actuation redundancy. In spite of the redundancy, the relationship between the power at the hand and joints is expressed in a similar form. Then, two types of criteria for evaluating the performances of robot manipulators are defined. The first is defined based on a consideration of the sign of the power at the joints (a mix of positive and negative joint power), the second is defined based on a consideration of the possible output power at the hand under a limited joint power constraint. Finally, application examples of the criteria for 2DOF non-redundant serial manipulator and 3DOF redundant manipulator (both motion and actuation redundancies are included) are demonstrated.