bluuebunny/crossref_metadata_2025 huggingface dataset:
Volumetric Error Control in Layered Manufacturing
Authors: Taufik Mohammad , Jain Prashant Kumar
Published: January 2015

This paper presents a novel method for adaptive slicing based on volumetric error considerations for Layered Manufacturing (LM). In the general LM process uses constant layer thickness throughout the part height which leads to poor surface finish at inclined surfaces. Therefore, adaptive slicing was proposed to control the surface roughness by adaptively selecting the layer thickness based on surface finish at a particular angle or slope of the surface. Most of the researchers used the cusp height concept for adaptive slicing. However, limitation of cusp height based adaptive slicing procedure is that, it does not have any direct control on volumetric error and it is quite possible that with a very little variation in cusp height a large variation in volumetric error may occur on steep slopes of surface. In the proposed work an algorithm is developed and implemented for adaptive slicing to control/select layer thickness based on user specified volumetric error/loss. A model is developed to calculate volumetric loss for the particular layer considering the geometry of the model.
Phenomena and Bifurcation Analysis of an Aeroelastic System With Impact Effects
Authors: Vasconcellos Rui M. G. , Abdelkefi Abdessattar
Published: January 2015

Impacts can happen in real aircraft movable surfaces, such as ailerons, flaps, rudder, elevators, trim tabs among others secondary control surfaces leading to complex, dangerous and unpredictable transitions. In a real mechanism, impacts can occur when the surface displacement increases and then regions of higher stiffness or impacts can take place. Abrupt transitions from LCO to chaos and secondary complex transitions are directly related with the discontinuous nature of impact systems, these abrupt transitions caused by impacts are different from the well-known routes to chaos. In this work, numerical simulations generate the data basis for the analysis of a two degrees of freedom aeroelastic wing with a nonlinearity in the pitch stiffness simulating an impact at higher angles. The objective is to characterize the behavior of this system with parametric variation and understand the mechanisms related to the observed bifurcations.
Dimensional Synthesis of a Novel 2T2R Parallel Manipulator for Medical Applications
Authors: Kumar Nitish , Piccin Olivier , Bayle Bernard
Published: January 2015

This paper deals with the dimensional synthesis of a novel parallel manipulator for medical applications. This parallel mechanism has a novel 2T2R mobility derived from the targeted application of needle manipulation. The kinematic design of this 2T2R manipulator and its novelty are illustrated in relation to the percutaneous procedures. Due to the demanding constraints on its size and compactness, achieving a large workspace especially in orientation, is a rather difficult task. The workspace size and kinematic constraint analysis are considered for the dimensional synthesis of this 2T2R parallel mechanism. A dimensional synthesis algorithm based on the screw theory and the geometric analysis of the singularities is described. This algorithm also helps to eliminate the existence of voids inside the workspace. The selection of the actuated joints is validated. Finally, the dimensions of the structural parameters of the mechanism are calculated for achieving the required workspace within the design constraints of size, compactness and a preliminary prototype without actuators is presented.
Energetic and Socioeconomic Justification for Solar-Powered Desalination Technology for Rural Indian Villages
Authors: Wright Natasha C. , Winter Amos G.
Published: January 2015

This paper provides justification for solar-powered electrodialysis desalination systems for rural Indian villages. It is estimated that 11% of India’s 800 million people living in rural areas do not have access to an improved water source. If the source’s quality in regards to biological, chemical, or physical contaminants is also considered, this percentage is even higher. User interviews conducted by the authors and in literature reveal that users judge the quality of their water source based on its aesthetic quality (taste, odor, and temperature). Seventy-three percent of Indian villages rely on groundwater as their primary drinking supply. However, saline groundwater underlies approximately 60% of the land area in India. Desalination is necessary in order to improve the aesthetics of this water (by reducing salinity below the taste threshold) and remove contaminants that cause health risks.

Both technical and socioeconomic factors were considered to identify the critical design requirements for inland water desalination in India. An off-grid power system is among those requirements due to the lack of grid access or intermittent supply, problems faced by half of Indian villages. The same regions in India that have high groundwater salinity also have the advantage of high solar potential, making solar a primary candidate. Within the salinity range of groundwater found in inland India, electrodialysis would substantially reduce the energy consumption to desalinate compared to reverse osmosis, which is the standard technology used for village-level systems. This energy savings leads to a smaller solar array required for electrodialysis systems, translating to reduced capital costs.
A Unified Algorithm for Analysis and Simulation of Planar Four-Bar Motions Defined With R- and P-Joints
Authors: Li Xiangyun , Ge Xin , Purwar Anurag , Ge Q. J.
Published: January 2015

This paper presents a single, unified and efficient algorithm for animating the motions of the coupler of all four-bar mechanisms formed with revolute (R) and prismatic (P) joints. This is achieved without having to formulate and solve the loop closure equation associated with each type of four-bar linkages separately. In our previous paper on four-bar linkage synthesis, we map the planar displacements from Cartesian to image space using planar quaternion. Given a set of image points that represent planar displacements, the problem of synthesizing a planar four-bar linkage is reduced to finding a pencil of Generalized- or G-manifolds that best fit the image points in the least squares sense. The three planar dyads associated with Generalized G-manifolds are RR, PR and RP which could construct six types of four-bar mechanisms. In this paper, we show that the same unified formulation for linkage synthesis leads to a unified algorithm for linkage analysis and simulation as well. Both the unified synthesis and analysis algorithms have been implemented on Apple’s iOS platform.
A Unified Algorithm for Geometric Design of Platform Linkages With Spherical and Plane Constraints
Authors: Li Xiangyun , Ge Q. J. , Gao Feng
Published: January 2015

This paper studies the constrained motion of a rigid body such that one or more of its points stays on a sphere or a plane. It extends Innocenti’s spatial Burmester problem from purely spherical constraints to include any combination of spherical and planar constraints for seven position synthesis of a spatial rigid body. The present paper provides a unified formulation using homogeneous coordinates and dual quaternions for simultaneous dimensional and type synthesis of spatial platform linkages and manipulators involving spherical and planar constraints. The algorithm is an extension of our previous work on unified solution for planar Burmester problem for geometric synthesis of planar dyads involving a combination of revolute and prismatic joints.
Serious Gaming for Design and Systems Engineering Research
Authors: Vermillion Sean D. , Malak Richard J. , Smallman Rachel , Fields Sherecce
Published: January 2015

In this paper, we investigate the use of serious gaming as a research tool for design and systems engineering research. Design and systems engineering research produces theories and methods aimed at bettering the engineering process and improving the quality of end products. However, the engineering process is largely human-driven and thus the way in which theories and methods are implemented and used depends greatly on the human element. Serious gaming provides a fully controllable environment in which to test and validate theories and methods against human behavior. To evaluate the viability of serious gaming as a research tool, we construct a game to study the sunk cost effect in the context of a manned Mars mission, and compare game results with results from a survey centered on the scenario. We observe a difference in results between the game and survey; those in the game fall victim to the sunk cost effect despite treatment whereas those in the survey do not fall for the sunk cost effect in a control treatment. We hypothesize that this may be caused by a preference for continued gameplay as opposed to the objectives in the narrative. Therefore, we conclude that gaming, at least in our case, induces behavior that may not be representative of real-world engineer behavior and must be mitigated.
An Efficient Application of Polynomial Chaos Expansion for the Dynamic Analysis of Multibody Systems With Uncertainty
Authors: Poursina Mohammad
Published: January 2015

In this paper the mathematical framework of an advanced algorithm is presented to efficiently form and solve the equations of motion of a multibody system involving uncertainty in the system parameters and/or the excitations. The uncertainty is introduced to the system through the application of the polynomial chaos expansion. In this scheme, states of the system, nondeterministic parameters, and the constraint loads are expanded using modal values as well as orthogonal basis functions. Computational complexity of the application of traditional methods to solve the stochastic equations of motion of a multibody system drastically grows as a cubic function of the number of the states of the system, uncertain parameters and the maximum degree of the polynomial chosen for the basis function. The presented method forms the equation of motion of the system without forming the entire mass and Jacobian matrices. In this strategy, the stochastic governing equations of motion of each individual body as well as the one associated with the kinematic constraint at the connecting joint are developed in terms of the basis functions and modal coordinates. Then sweeping the system in two passes assembly and disassembly, one can form and solve the stochastic equations of motion. In the assembly pass the non-deterministic equations of motion of the assemblies are obtained. In the disassembly process, these equations are then recursively solved for the modal values of the spatial accelerations and the constraints loads. In the serial and parallel implementations, computational complexity of the method increases as a linear and logarithmic functions of the number of the states of the system, uncertain variables, and the maximum degree of the basis functions used in the expansion.
Applying Robust Design Optimization to Large Systems
Authors: McIntire Matthew G. , Vasylkivska Veronika , Hoyle Christopher , Gibson Nathan
Published: January 2015

While Robust Optimization has been utilized for a variety of design problems, application of Robust Design to the control of large-scale systems presents unique challenges to assure rapid convergence of the solution. Specifically, the need to account for uncertainty in the optimization loop can lead to a prohibitively expensive optimization using existing methods when using robust optimization for control. In this work, a robust optimization framework suitable for operational control of large scale systems is presented. To enable this framework, robust optimization uses a utility function for the objective, dimension reduction in the uncertainty space, and a new algorithm for evaluating probabilistic constraints. The proposed solution accepts the basis in utility theory, where the goal is to maximize expected utility. This allows analytic gradient and Hessian calculations to be derived to reduce the number of iterations required. Dimension reduction reduces uncertain functions to low dimensional parametric uncertainty while the new algorithm for evaluating probabilistic constraints is specifically formulated to reuse information previously generated to estimate the robust objective. These processes reduce the computational expense to enable robust optimization to be used for operational control of a large-scale system. The framework is applied to a multiple-dam hydropower revenue optimization problem, then the solution is compared with the solution given by a non-probabilistic safety factor approach. The solution given by the framework is shown to dominate the other solution by improving upon the expected objective as well as the joint failure probability.
Design of Planar Multi-Degree-of-Freedom Morphing Mechanisms
Authors: Funke Lawrence , Schmiedeler James P. , Zhao Kai
Published: January 2015

This paper seeks to advance the design of planar shape-changing mechanisms used in a variety of applications, such as morphing extrusion dies and airfoils. The presence of defects is a limiting factor in finding suitable single-degree-of-freedom (DOF) mechanisms, particularly when the number of shapes to achieve is large and/or the changes among those shapes are significant. This paper presents a new method of designing multi-DOF mechanisms to aid in avoiding these defects. The primary method uses a building-block approach similar to the current one-DOF synthesis procedure and is compared to alternative strategies that seek to leverage the use of multiple single-DOF subchains. While more complex in terms of determining the actuation pattern, the primary method offers a larger design space in which to find solutions. In all cases a genetic algorithm is employed to search the design space. Two example problems involving four prescribed shapes demonstrate the benefits of using multi-DOF mechanisms in terms of shape matching and mechanical advantage.
Kinematics and Control of the TowPlow: A Steerable Articulated Vehicle System
Authors: Kang Jaeyoung , Velinsky Steven A.
Published: January 2015

The TowPlow is a novel type of snowplow that consists of a conventional snowplow vehicle and a steerable, plow-mounted trailer. The trailer is equipped with hydraulic-powered steerable axles so that it can be steered up to 30 degrees with respect to the tractor. The combination of the front plow of the towing snowplow and the trailer-equipped plow is able to clear a path up to approximately 24-ft wide, which is the width of two typical traffic lanes. In this paper, the kinematic characteristics of the TowPlow are derived using instantaneous centers of velocity. Based on the derived equations, the relation between the radius of curvature and the trailer wheel steering angle that allows the tractor-trailer to maintain its initial articulation angle is defined. Also, simulations of constant radius turning are performed with and without the trailer’s corrective steering, and the results are compared. Even though the kinematic analysis does not take forces and inertia into account, it is clearly demonstrated in the simulation results that appropriate steering of the trailer wheel is necessary to maintain the articulation angle of the TowPlow and to prevent the device from intruding into adjacent lanes.
Effect of Axial Load on the Response of Beams on Nonlinear Viscoelastic Unilateral Foundations
Authors: Bhattiprolu Udbhau , Bajaj Anil K. , Davies Patricia
Published: January 2015

Flexible polyurethane foams used for cushioning in the furniture and automotive industries serve as foundations and exhibit complex nonlinear viscoelastic behavior. To design systems that incorporate these materials, it is important to model their mechanical behavior and then to predict the dynamic response of such systems. The example of a pinned-pinned beam interacting with a nonlinear viscoelastic foundation is the focus of the present study. The foundation can either react in compression as well as tension (bilateral), or react only in compression (unilateral). In the latter case, the contact regions between the beam and the foundation are not known a priori, and thus the coefficients of the modal equations obtained in a Galerkin approximation solution approach, are functions of the solution as well. It is therefore computationally expensive to predict the dynamic and steady-state response of these structures to static and harmonic loads. For polynomial-type nonlinearities, it is possible to speed up the computation time by using a convolution method to evaluate integral terms in the model. Also, if only the steady-state response is of interest, direct-time integration can be replaced by incremental harmonic balance to make the frequency response predictions more efficient. The effect of axial load and the influence of various parameters e.g., loading configuration, excitation amplitude, linear and nonlinear stiffness, on the response of the beam on unilateral and bilateral foundations are studied.
A Novel Threshold for the Diagnostics of Rolling Element Bearing
Authors: Borghesani P. , Chatterton S. , Pennacchi P. , Vania A.
Published: January 2015

The identification of the damage type in rolling element bearings is usually performed by means of suitable vibration signal analysis tools such as the most used and simplest method, Envelope Analysis through the corresponding Square Envelope Spectrum. The diagnostics and the monitoring of the bearing health are often performed by means of other approaches based on the evaluation of a damage index as the root mean square, the Kurtosis of the filtered signal, or more efficient indexes as the so-called Ratio of Cyclic Content. At any rate, in the case of real-time diagnostics, the definition of a threshold for the assessment of the bearing health is mandatory due to the presence in the vibration signal of additional sources and noises. In the paper, a threshold for the band-Kurtosis index that depends only on the sampling frequency and the bandwidth of the filter used for the demodulation of the vibration signal has been introduced. The effectiveness of the threshold has been proven by the experimental data of a damaged bearing.
Reducing the Subjectivity in Creativity Assessment
Authors: Oman Sarah , Tumer Irem Y. , Stone Robert
Published: January 2015

Previous research presented a method, called the Comparative Creativity Assessment (CCA) that calculates the creativity of individual concepts in a set of designs. Several limitations regarding these metrics are addressed and mitigated within this paper with the creation of the Expanded Creativity Assessment Method (ECAM), namely how to reduce the subjectivity of the function weights and factor in combination effects between two or more functions. The subjectivity limitation is mitigated by the inclusion of the combination effects through a major expansion to the original metrics with data validation based on analyses of the original concept data (using the former method of setting the function weights) versus using the expanded method. Statistical analysis of the different methods to calculate creativity is discussed in the Results and Conclusions.
A Novel Method for Providing Global Assessments of Design Concepts Using Single-Word Adjectives and Semantic Similarity
Authors: Gosnell Christopher A. , Miller Scarlett R.
Published: January 2015

Engineering design idea-generation sessions often result in dozens, if not hundreds, of ideas. These ideas must be quickly evaluated and filtered in order to select a few candidate concepts to move forward in the design process. While creativity is often stressed in the conceptual phases of design, it receives little attention in these later phases — particularly during concept selection. This is largely because there are no methods for quickly rating or identifying worthwhile creative concepts during this process. Therefore, the purpose of this study was to develop and test a novel method for evaluating the creativity and feasibility of design concepts and compare this method to gold standards in our field. The SCAT method employed in this paper uses word selections and semantic similarity to quickly and effectively evaluate candidate concepts for their creativity and feasibility. This method requires little knowledge of the rating process by the evaluator. We tested this method with 10 engineering designers and three different design tasks. Our results revealed that SCAT ratings can be used as a proxy for measuring design concepts but there are modifications that could enhance its utility. This work contributes to our understanding of how to evaluate creativity after idea generation and provides a framework for further research in this field.
Application of a Biphasic Actuator in the Design of a Robot Gripper for Garment Handling
Authors: Le Loan , Zoppi Matteo , Jilich Michal , Bo Han , Zlatanov Dimiter , Molfino Rezia
Published: January 2015

The paper describes a novel robot gripper for garment handling. The device has been designed, developed, prototyped, and tested within the CloPeMa European Project creating a robot system for automated manipulation of clothing and other textile items. The gripper has two degrees of freedom and includes both rigid and flexible elements. A variable-stiffness actuator has been implemented to add controlled compliance in the gripper’s operation allowing the combining of various grasping and manipulation tasks. First, we analyze the specific application-determined task requirements, focusing on the need for adaptive flexibility and the role of compliant elements in the design. The chosen solution is a simple planar mechanism, equipped with one standard and one variable-stiffness actuator. The mechanical design of the gripper, including the hydraulic system used in the biphasic actuator, is outlined, and the control architecture, using sensor feedback, is described.
Development of a Lower Limb Orthosis to Form Neuromuscular Patterning
Authors: Camarillo–Gómez Karla A. , Pérez-Soto Gerardo I. , Torres-Rico Luis A.
Published: January 2015

In this paper, a lower limb orthosis is proposed to form the human gait neuromuscular patterns in patients with myelomeningocele. The orthosis has two lower limbs of 2–DOF each which reduces the motion of the hip and knee to the sagittal plane. The orthosis are assembled in a back support which also supports the patients weight. The control system for the orthosis allows to reproduce in a repetitive, controlled and autonomous way the human gait cycle at different velocities according to the patient requirements; so that, the neuromuscular patterning can be supervised by a therapist. The development of these orthosis seeks to improve the quality of life of those infants with myelomenigocele and to introduce a lower cost Mexican technology with Mexican anthropometric dimensions.
Novel Design of a Precision Planter for a Robotic Assistant Farmer
Authors: Aminzadeh Reza , Fotouhi Reza
Published: January 2015

Farming consumes considerable energy, natural resources and intensive human labor. Robotic assisted farmer can make farming activities more precise and more efficient; particularly it may remedy shortage of farmers in the future. A planter is a mechanism which performs precision seeding. Design of a planter in the optimum manner that needs minimum draft force when attached to a mobile robot, was the main objective of this work. A planter was developed, fabricated and tested in the course of a research project.

The main motivation for this research is the fact that a mobile robot, is an electric powered vehicle with limited power and pulling force. Thus, a customized planter with a customized connection mechanism should be designed that can be pulled by mobile robot. The developed planter should have the same efficiency as the existing planters in seeding.

To study the interaction between soil engagement tool (disc coulter) and soil, experiments were performed in the Linear Soil Bin. Different parameters of the disc coulter were changed and the draft force, vertical force and side force were measured. The results of the experiments were used to find the optimum parameters of the disc that caused minimum draft force. A novel planter was designed and fabricated; it was attached to a mobile robot, and field tested. Tests performed in outdoor and indoor settings showed satisfactory results. Draft force developed on the planter was close to analytical value and performance of the planter in other aspects was as expected.
Enabling Interoperability Between Serious Game and Virtual Engineering Ecosystems
Authors: Stanescu Ioana Andreea , Stanescu Aurelian Mihai , Moisescu Mihnea , Sacala Ioan Stefan , Stefan Antoniu , Hauge Jannicke Baalsrud
Published: January 2015

Interoperability and reusability stand out as key factors that nurture the cost-efficiency, quality and expansion of Serious Game Ecosystems (SGE). This paper builds upon the blooming development of SGE and explores the new horizons SGE have brought for the enhancement of virtual engineering technologies and applications. The authors consider the integration of SGE into the Virtual Engineering and Systems (VES) workflow. SGEs are becoming an important component in enterprise agility and sustainability. In this context, the authors propose an Interoperability SGE Framework to facilitate reusability and interconnection within Game-based VES. The framework focuses on data, information, services, processes and organization interoperability and proposes a technical, cyber-physical, functional and organizational view. The integration of Cyber-Physical Systems with SGEs enable the development of new paradigms and game models including sensor and actuator integration, context sensing, smart environments and sensing objects.
A Study of Correlation Between DMSMS Obsolescence and Counterfeit Electronics
Authors: Zheng Liyu , Orfi Nihal , Terpenny Janis
Published: January 2015

Diminishing Manufacturing Sources and Material Shortages (DMSMS) obsolescence of components and subsystems is a risk driver for long field -life defense systems such as aircraft, ships and avionics. Over their life in service, a substantial number of components required to produce and support such systems will become no longer available from the Original Component Manufacturers. There are different approaches to manage DMSMS obsolescence, some of which lead to the purchase of replacement parts from unreliable sources, hence, providing an opportunity for the infiltration of counterfeit parts. Counterfeits can contaminate the part supply source, further magnifying the obsolescence problem. Validating and understanding the correlation between obsolescence and counterfeits are important and necessary steps to improve decision-making and the management of both obsolescence and counterfeits. This paper describes an investigation of the correlation between DMSMS obsolescence and counterfeit electronics. A description of the study and the positive correlation results, as verified by statistical testing using the historical annual data of obsolescence and counterfeit reporting from the Government-Industry Data Exchange Program, are provided.
Analysis of Electromechanical Performance of Energy Harvesting Skin Based on the Kirchhoff Plate Theory
Authors: Yoon Heonjun , Youn Byeng D. , Kim Heung S.
Published: January 2015

As a compact and durable design concept, energy harvesting skin (EH skin), which consists of piezoelectric patches directly attached onto the surface of a vibrating structure as one embodiment, has been recently proposed. This study aims at developing an electromechanically-coupled analytical model of the EH skin so as to understand its electromechanical behavior and get physical insights about important design considerations. Based on the Kirchhoff plate theory, the Hamilton’s principle is used to derive the differential equations of motion. The Rayleigh-Ritz method is implemented to calculate the natural frequency and the corresponding mode shapes of the EH skin. The electrical circuit equation is derived by substituting the piezoelectric constitutive relation into Gauss’s law. Finally, the steady-state output voltage is obtained by solving the differential equations of motion and electrical circuit equation simultaneously. The results of the analytical model are verified by comparing those of the finite element analysis (FEA) in a hierarchical manner.
Point to-Point and Path Following Navigation of Mobile Robot in Farm Settings
Authors: Heidari F. , Fotouhi R.
Published: January 2015

A fully integrated navigation strategy of a wheeled mobile robot in farm settings and off-road terrains is described here. The proposed strategy is composed of four main actions which are: sensor data analysis, obstacle detection, obstacle avoidance, and goal seeking. Using these actions, the navigation approach is capable of autonomous row-detection, row-following and path planning motion in outdoor settings such as farms. In order to drive the robot in off-road terrain, it must detect holes or ground depressions (negative obstacles), that are inherent parts of these environments, in real-time at a safe distance from the robot. Key originalities of the proposed approach are its capability to accurately detect both positive (over ground) and negative obstacles, and accurately identify the end of the rows of trees/bushes in farm/orchard and enter the next row. Experimental evaluations were carried out using a differential wheeled mobile robot in different farm settings. The mobile robot, used for experiments, utilizes a tilting unit which carries a laser range finder to detect objects in the environment, and a RTK-DGPS unit for localization. The experiments demonstrate that the proposed technique is capable of successfully detecting and following rows (path following) as well as robust navigation of the robot for point-to-point motion.
Uncertainty Analysis of Energy Harvesting Systems
Authors: Madankan Reza , Karami M. Amin , Singla Puneet
Published: January 2015

This paper presents the relation between uncertainty in the excitation and parameters of vibrational energy harvesting systems and their power output. Nonlinear vibrational energy harvesters are very sensitive to the frequency of the base excitation. If the excitation frequency does not match with the resonance frequency of the energy harvester, the power output significantly deteriorates. The mismatch can be due to the inherent changes of the ambient oscillations. The fabrication errors or gradual changes of material properties also result in the mismatch. This paper quantitatively shows the probability density function for the power as a function of the probability densities of the excitation frequency, excitation amplitude, initial deflection of the energy harvester, and design parameters. Recently developed the conjugated unscented transformation methodology is used in conjunction with the principle of maximum entropy to compute the probability distribution for the base response and power. The computed nonlinear density functions are validated against Monte Carlo simulations.
A Simulation and Modeling Based Reliability Requirements Assessment Methodology
Authors: Honda Tomonori , Saund Eric , Matei Ion , Janssen Bill , Saha Bhaskar , Bobrow Daniel G. , de Kleer Johan , Kurtoglu Tolga , Lattmann Zsolt
Published: January 2015

To minimize the design cost of a complex system and maximize performance, a design team ideally must be able to quantify reliability and mitigate risk at the earliest phases of the design process, where 80% of the cost is committed. This paper demonstrates the capabilities of a new System Reliability Exploration Tool based on the improved simulation capabilities of a system called Fault-Augmented Modelica Extension (FAME). This novel tool combines concepts from FMEA, traditional Reliability Analysis, and Quality Engineering to identify, gain insight, and quantify the impact of component failure modes through time evolution of a system’s lifecycle. We illustrate how to use the FAME System Reliability Exploration Tool through a vehicle design case study.
Synthesis and Analysis of a Chebyschev’s Straight Line Four-Bar Linkage for Generating a Minimum Jerk Velocity Profile
Authors: Xydas Evagoras G.
Published: January 2015

The interaction between human and passive, constraint-based path generating mechanisms has been scarcely studied. When it comes to rehabilitation robots, output trajectories and/or forces are achieved mainly as a result of actuation on all joints, since they form an open kinematic chain. On the other end, there exists a wide range of mechanisms that can trace complex trajectories primarily due to mechanical constraints in their topology and structure. Probably the simplest example is the four bar linkage, a widely used 1-DOF mechanism. It consists of a driving link, a driven link, and a coupler which connects the two. As the input link rotates, each point on the coupler link traces a unique trajectory in space, called a coupler curve. Ideally, the linkage dimensions can be chosen so that a near-natural hand trajectory is generated for a specific task. As a first step, in this work a straight line generating four-bar mechanism, namely the Chebyshev’s linkage is considered for generating a natural bell-shaped velocity profile, as prescribed by the Minimum-Jerk-Model. Initially the mechanism is synthesized for producing a straight line trajectory of a desired length. Kinematic and kinetostatic analysis is performed in order to determine the required input torque necessary for achieving the desired spatio-temporal profile. The main objective is to determine whether this input torque can approximated by a series of linear torsional springs that can be installed on the pivoted side of the input link.
Parametric Instability in a Stationary String With a Periodically Varying Length
Authors: Wu K. , Zhu W. D.
Published: January 2015

Parametric instability in a stationary string with a periodically varying length is investigated. The free linear vibration of a stationary string with a constant tension, a fixed boundary, and a periodically moving boundary is studied first. The parametric instability in the string features a bounded displacement and an unbounded vibratory energy, and parametric instability regions in the parameter plane are classified as period-i (i ≥ 1) parametric instability regions. If the periodic boundary movement profile of the string satisfies certain condition, only period-1 parametric instability regions exist. However, parametric instability regions with higher period numbers can exist for a general periodic boundary movement profile. A corresponding nonlinear model that consider coupled transverse and longitudinal vibrations of the string are introduced next. Responses and vibratory energies of the linear and nonlinear models are calculated for both stable and unstable cases using the finite difference method. The mechanism of the parametric instability is explained in the linear model and through axial strains in the nonlinear model.
Synthesis of Useful Eight-Bar Linkages as Constrained 6R Loops
Authors: Sonawale Kaustubh H. , McCarthy J. Michael
Published: January 2015

This paper formulates a methodology for designing planar eight-bar linkages for five task positions, by adding two RR constraints to a user specified 6R loop. It is known that there are 32 ways in which these constraints can be added, to yield as many as 340 different linkages. The methodology uses a random search within the tolerance zones around the task specifications to increase the number of candidate linkages. These linkages are analyzed using the Dixon determinant approach, to find all possible linkage configurations over the range of motion. These configuration trajectories are sorted into branches. Linkages that have all the five task configurations on one branch, ensure their smooth movement through the five task positions. The result is an array of branch-free useful eight-bar linkage designs. An example is provided to illustrate the results.
A Stochastic Activity-Based Approach for Forecasting Occupant-Related Energy Consumption in Residential Buildings
Authors: Zaraket Toufic , Yannou Bernard , Leroy Yann , Minel Stephanie , Chapotot Emilie
Published: January 2015

Building occupants are considered as a major source of uncertainty in energy modeling nowadays. Yet, industrial energy simulation tools often account for occupant behavior through some predefined scenarios and fixed consumption profiles which yield to unrealistic and inaccurate predictions. In this paper, a stochastic activity-based approach for forecasting occupant-related energy consumption in residential buildings is proposed. First, the model is exposed together with its different variables. Second, a direct application of the model on the domestic activity “washing laundry” is performed. A number of simulations are performed and their results are presented and discussed. Finally, the model is validated by confronting simulation results to real measured data.
Stability Control for Tire Blowout Vehicle Based on Brake by Wire System Considering Driver Operation
Authors: Yu Liangyao , Wang Zhizhong , Pan Ning , Zhang Lei , Song Jian
Published: January 2015

Tire blowout is one of the most dangerous tire malfunctions which could result in severe property damage, personal injury, even loss of life. In the existing literatures, active tire blowout fail-safe control strategies based on rules or optimal control have been proposed. However, little attention has been put on driver behavior, which plays an important role in the stability performance control when tire blowout is experienced. Because of the uncertainties of failure mode and failure level, most of existing active control strategies are not easy to be implemented. This paper presents the research work on stability control for tire blowout vehicle, considering the driver behavior at the emergent scenario. The Electro Hydraulic Brake (EHB) based Brake by Wire (BBW) system is used as the brake system, which can regulate the wheel brake force individually and accurately. The simulation results show that stability and brake efficiency can be achieved in tire blowout fail-safe control by combining the driver operation model and BBW.
Pneumatic Micro-Hand Actuator for Future Space Manipulation and Robotics
Authors: Yuan Jianping , Cook Ellexis , Li Xin , Wu Ke , Suzuki Toshimune , Romaniello Charles , Shi Yong
Published: January 2015

Micro and nano technology has demonstrated the capability of creating miniaturized systems leading to significantly reduced mass, volume or power requirements, and therefore reduced cost but more advanced performances. Such micro systems are critical in the development of future space systems such as picosatellites, planetary probes, on-board instruments or nanorovers and swarm micro robotics. A pneumatically driven micro device has been proposed for manipulating and assembling space components or building-up a larger scale system based on individually launched micro robots. The device is a four fingered microhand actuator made of silicon rubber to grasp micro objects utilizing air pressure inside of its internal cavities. The grasp force and tip displacement of the fingers has been simulated using FEM. A prototype has been fabricated to validate its performance and the three-dimensional motion control using piezoelectric sensors to monitor the deflection in the fingers of the device.
Set-Based Thinking in the Engineering Design Community and Beyond
Authors: Ghosh Sourobh , Seering Warren
Published: January 2015

Since a series of academic case studies had revealed Toyota’s unique product development practices to the world, a flurry of research has been conducted into set-based design, also known as set-based concurrent engineering. In this paper, we review work related to set-based design across academic communities in efforts to find common themes and influences. After a review of this literature, we inductively arrive at two Principles of Set-Based Thinking: considering sets of distinct alternatives concurrently and delaying convergent decision making. These Principles allow us to articulate a working description of set-based design. We then examine these two Principles at work in a case example of a common theoretical construct in design.
Computation of Common Normal Between a Wheelset and Straight Rail at Singular Position
Authors: Fallahi Behrooz , Perla Arjun Kumar , Behnke Andrew
Published: January 2015

Computation of common normal between a pair of wheel and rail surface is an important sub problem in railroad simulations. In this study, it is shown that there are special position and orientation of every wheelset that makes the governing equation for computation of the common normal degenerate. This condition leads to divergence of the Newton’s iterate. To develop a procedure that can successfully compute the common normal between a straight rail and a wheelset, first parametric equation for the rail and wheel surface in track coordinate system is developed. Then four nonlinear equations whose solution is location of common normal are constructed. Three of the equations are used to eliminate three unknown in fourth equation. The resulting equation has only one unknown. A hybrid procedure based on Newton method and bisection method is used to solve the roots of the last equation. The utility of this approach is demonstrated by reporting the common normal for a pair of wheel and rail surface at singular position.
An Efficient Reduced-Order Model for the Nonlinear Dynamics of Carbon Nanotubes
Authors: Xu Tiantian , Younis Mohammad I.
Published: January 2015

Because of the inherent nonlinearities involving the behavior of CNTs when excited by electrostatic forces, modeling and simulating their behavior is challenging. The complicated form of the electrostatic force describing the interaction of their cylindrical shape, forming upper electrodes, to lower electrodes poises serious computational challenges. This presents an obstacle against applying and using several nonlinear dynamics tools that typically used to analyze the behavior of complicated nonlinear systems, such as shooting, continuation, and integrity analysis techniques. This works presents an attempt to resolve this issue. We present an investigation of the nonlinear dynamics of carbon nanotubes when actuated by large electrostatic forces. We study expanding the complicated form of the electrostatic force into enough number of terms of the Taylor series. We plot and compare the expanded form of the electrostatic force to the exact form and found that at least twenty terms are needed to capture accurately the strong nonlinear form of the force over the full range of motion. Then, we utilize this form along with an Euler–Bernoulli beam model to study the static and dynamic behavior of CNTs. The geometric nonlinearity and the nonlinear electrostatic force are considered. An efficient reduced-order model (ROM) based on the Galerkin method is developed and utilized to simulate the static and dynamic responses of the CNTs. We found that the use of the new expanded form of the electrostatic force enables avoiding the cumbersome evaluation of the spatial integrals involving the electrostatic force during the modal projection procedure in the Galerkin method, which needs to be done at every time step. Hence, the new method proves to be much more efficient computationally.
Exploring Equilibria in Stochastic Delay Differential Equations Using Persistent Homology
Authors: Khasawneh Firas A. , Munch Elizabeth
Published: January 2015

This paper explores the possibility of using techniques from topological data analysis for studying datasets generated from dynamical systems described by stochastic delay equations. The dataset is generated using Euler-Maryuama simulation for two first order systems with stochastic parameters drawn from a normal distribution. The first system contains additive noise whereas the second one contains parametric or multiplicative noise. Using Taken’s embedding, the dataset is converted into a point cloud in a high-dimensional space. Persistent homology is then employed to analyze the structure of the point cloud in order to study equilibria and periodic solutions of the underlying system. Our results show that the persistent homology successfully differentiates between different types of equilibria. Therefore, we believe this approach will prove useful for automatic data analysis of vibration measurements. For example, our approach can be used in machining processes for chatter detection and prevention.
Tire-Soil Modeling for Vehicle Rollover Over Sloped Compressible Terrains
Authors: Holtz Dale , Singh Amandeep , Megiveron Michael G.
Published: January 2015

Military vehicles have been experiencing high rollover rates over the last few years of deployment. There have been several hundred rollovers, of which approximately fifty percent are categorized as fall based. Fall based rollover occurs when the road gives way underneath the vehicle on one side as the soil is unable to support the vehicle load. To reduce fatalities, a real-time driving simulator can be used to simulate fall-based rollover for the driver training as well as for validating the effectiveness of advanced suspension technologies. The driver training can help prepare drivers with the varying degrees of terrain difficulties, by applying optimal steering and speed strategies in a simulated environment. The fall-based rollover occurs mainly due to combination of the tire sinkage and the lateral bulldozing. In the current research, equations for the tire-soil model are developed based on the Bekker’s equations and Mohr-Coulomb equations that compute the tire sinkage into the soil, the lateral and longitudinal forces from the soil deformation, rolling resistance due to the soil compaction, and the lateral plowing effects. The tire-soil model is incorporated into a commercial real-time multi-body code to simulate fall-based rollovers for various slopes and soil conditions. Results indicate rollover propensity changes depending the type of soil and the steering strategy used.
Generalized Jacobian Analysis of Parallel Manipulators With Multiple End-Effectors
Authors: Hoevenaars Antonius G. L. , Lambert Patrice , Herder Just L.
Published: January 2015

This paper presents a methodology for the Jacobian analysis of parallel manipulators with multiple end-effectors (PMxE). The end-effector velocity state of a PMxE is described by one twist of a principal end-effector with respect to the base and a set of relative twists of the remaining end-effectors with respect to the principal end-effector The twist of each terminal link with respect to the principal end-effector is then expressed as a linear function of the relative twists, which enables an extension of the generalized Jacobian analysis to PMxE. The presented methodology is detailed for parallel manipulators with two end-effectors, where a planar 6-RRR manipulator with a 2-RRR internal closed-loop is used as an example.
Vortex Dynamics of Ruptured and Unruptured Intracranial Aneurysms
Authors: Varble Nicole , Trylesinski Gabriel , Xiang Jianping , Meng Hui
Published: January 2015

Intracranial aneurysms are a potentially devastating pathological dilation of brain arteries that affect 1–5 % of the population. In this study we investigated the vortex structures of both unruptured and ruptured intracranial aneurysms as a discriminating property. We performed pulsatile computational fluid dynamic simulations on 204 patient-specific aneurysm models (57 ruptured and 147 unruptured) derived from patient angiographic imaging. Using Q-criterion we analyzed the coherent structures both throughout the aneurysm volume and at the wall. The relative surface area with positive Q values (indicating vortices at the wall) was able to differentiate ruptured and unruptured aneurysms. For the first time, in a large patient cohort, mechanistic fluid analysis is leading to insights into rupture pathways.