bluuebunny/crossref_metadata_2025 huggingface dataset:
Redundancy Allocation for Reliability Design of Engineering Systems With Failure Interactions
Authors: Wang Jing , Li Mian
Published: January 2015

In reliability design, allocating redundancy through various optimization methods is one of the important ways to improve the system reliability. Generally, in these redundancy allocation problems, it is assumed that failures of components are independent. However, under this assumption failure rates can be underestimated since failure interactions can significantly affect the performance of systems. This paper first proposed an analytical model describing the failure rates with failure interactions. Then a Modified Analytic Hierarchy Process (MAHP) is proposed to solve the redundancy allocation problems for systems with failure interactions. This method decomposes the system into several blocks and deals with those down-sized blocks before diving deep into the most appropriate component for redundancy allocation. Being simple and flexible, MAHP provides an intuitive way to design a complex system and complex explicit objective functions for the entire system is not required in the proposed approach. More importantly, with the help of the proposed analytical failure interaction model, MAHP can capture the effect of failure interactions. Results from case studies clearly demonstrate the applicability of the analytical model for failure interactions and MAHP for reliability design.
In-Situ Characterization of Nano-Structures Fabricated by Focused Ion Beam (FIB) and Nano Particle Deposition System (NPDS)
Authors: Lee Hyun-Taek , Kim Chung-Soo , Yoon Hae-Sung , Jang Ki-Hwan , Choi Jung-Oh , Ahn Sung-hoon
Published: January 2015

Nano particle deposition system (NPDS) had been developed for the creation of micro/nano structures with multimaterials in order to develop the micro/nano devices on the basis of specific localized surface on the multilayer. However, micro structures fabricated by NPDS show different mechanical properties when it compared to bulk material because of its porous and uneven deposition structure. To achieve reasonable mechanical properties of the structure fabricated by nanoscale 3D printing system, it requires in-situ mechanical property test method. Herein, a new approach for in-situ nanomechanical characterization system using microforce sensor and nanomanipulator installed in focused ion beam system. In this research, experimental setup for mechanical characterization was developed and mechanical property test was done in Focused Ion Beam (FIB) system. The specimen was fabricated by FIB milling process, then manipulation and compression processes are operated by this characterization system with real time imaging. The test was done for silver microstructures fabricated by NPDS and results show weaker hardness and smaller young’s modulus than bulk material.
Dynamic Response Analysis of Wind Turbine Planetary Gear System With Interval Stiffness Parameters
Authors: Wei Sha , Han Qinkai , Feng Zhipeng , Shen Yanhua , Chu Fulei
Published: January 2015

Planetary gear transmission system is one of the primary parts of the wind turbine drive train. Due to the assembly state, lubrication conditions and wear, the mesh stiffness of the planetary gear system is an uncertain parameter. In this paper, taking the uncertainty of mesh stiffness into account, the dynamic responses of a wind turbine gear system subjected to wind loads and transmission error excitations are studied. Firstly, a lumped-parameter model is extended to include both the planetary and parallel gears. Then the fluctuation ranges of dynamic mesh forces are predicted quantitatively and intuitively based on the combined Chebyshev interval inclusion function and numerical integration method. Finally, examples of gear trains with different interval mesh stiffnesses are simulated and the results show that tooth separations are becoming more obvious at the resonant speed by considering the fluctuating mesh stiffness of the second parallel gear stage. The nonlinear tooth separations are degenerated obviously as the fluctuation error of the mesh stiffness of the second parallel gear set is increased.
Improving Techniques in Statically Equivalent Serial Chain Modeling for Center of Mass Estimation
Authors: Li Bingjue , Murray Andrew P. , Myszka David H.
Published: January 2015

Any articulated system of rigid bodies defines a Statically Equivalent Serial Chain (SESC). The SESC is a virtual chain that terminates at the center of mass (CoM) of the original system of bodies. A SESC may be generated experimentally without knowing the mass, CoM, or length of each link in the system given that its joint angles and overall CoM may be measured. This paper presents three developments toward recognizing the SESC as a practical modeling technique. Two of the three developments improve utilizing the technique in practical applications where the arrangement of the joints impacts the derivation of the SESC. The final development provides insight into the number of poses needed to create a usable SESC in the presence of data collection errors. First, modifications to a matrix necessary in computing the SESC are proposed. Second, the problem of generating a SESC experimentally when the system of bodies includes a mass fixed in the ground frame are presented and a remedy is proposed for humanoid-like systems. Third, an investigation of the error of the experimental SESC versus the number of data readings collected in the presence of errors in joint readings and CoM data is conducted. By conducting the method on three different systems with various levels of data error, a general form of the function for estimating the error of the experimental SESC is proposed.
Incorporating Flexibility in the Design of Repairable Systems: Design of Microgrids
Authors: Pandey Vijitashwa , Skowronska Annette , Mourelatos Zissimos P. , Gorsich David , Castanier Matthew
Published: January 2015

The authors have recently proposed a ‘decision-based’ framework to design and maintain repairable systems. In their approach, a multiobjective optimization problem is solved to identify the best design using multiple short and long-term statistical performance metrics. The design solution considers the initial design, the system maintenance throughout the planning horizon, and the protocol to operate the system. Analysis and optimization of complex systems such as a microgrid is however, computationally intensive. The problem is exacerbated if we must incorporate flexibility in terms of allowing the microgrid architecture and its running protocol to change with time. To reduce the computational effort, this paper proposes an approach that “learns” the working characteristics of the microgrid and quantifies the stochastic processes of the total load and total supply using autoregressive time-series. This allows us to extrapolate the microgrid operation in time and eliminate therefore, the need to perform a full system simulation for the entire long-term planning horizon. The approach can be applied to any repairable system. We show that building in flexibility in the design of repairable systems is computationally feasible and leads to better designs.
A Novel Framework for Product/Service Systems Using Environment-Based Design Methodology
Authors: Deng Xiaoguang , Zeng Yong
Published: January 2015

The diversity of costumer’s needs requires manufacturers to provide a complex package of product and service. In contrast to traditional matured methods used for product design, Product/Service Systems (PSS) design still has a large room for development because of three following core research challenges: 1) development of a common shared structure to represent and understand PSS’s elements and their relations; 2) systematic modelling approaches to formulating design problems; and 3) holistic consideration of social, technological, economic and ecological elements.

This paper aims to propose a novel framework for PSS design by addressing three issues above. The proposed framework is derived step-by-step from a natural language description of PSS environment using Environment-Based Design (EBD) methodology. The proposed framework attempts to accommodate the recursive scenarios in PSS design along with PSS lifecycle. The PSS environment will be firstly analyzed through a question-asking strategy. Besides, a set of graphical tools will be presented to support the development of framework, such as product-environment system, performance network, and conflict map. A case study, concerning the service design of intellectual property protection in collaborative product development, will be presented to illustrate the proposed framework.
Spiral Tool Path Planning Using Eccentric Parameters
Authors: Guo Baosu , Peng Qingjin , Cheng Xiaosheng , Dai Ning
Published: January 2015

Free-form surfaces can be machined continuously with minimum tool retractions and at the high speed by following a spiral tool path. This paper presents an improved planning method of the spiral tool path using eccentric parameters for machining free-form surfaces. The relationship between a 3D machined surface and the 2D circular region is established through the conformal mapping. In order to generate an even path, eccentric parameters are used in 2D parametric circular regions to optimize the path interval. The proposed method produces planar spiral segments as a diagonal curve between every two adjacent parametric tool paths. A 2D spiral tool path is gained by linking spiral segments in sequence. Inverse mapping of the 2D spiral tool path onto the machined surface generates the 3D spiral tool path. The main processes of the proposed method include reducing dimensions of free-form surfaces, calculating the eccentric parametric tool path, and generating the planar diagonal spiral tool path. Some applications are used to verify the proposed methods. The proposed method allows the start point to be arbitrary and generates more even tool paths than the existing methods by introducing the mapping distortion.
A Fast Time-Stepping Strategy for the Newmark-Beta Method
Authors: Mirzendehdel Amir M. , Suresh Krishnan
Published: January 2015

In this paper, we develop a fast time-stepping strategy for the Newmark-beta method; the latter is used extensively in structural dynamics. In particular, we speed up the repeated inversion of the linear systems in the Newmark-beta method by implementing and merging four distinct but complementary concepts: (1) voxelization, (2) assembly-free finite element analysis, (3) deflated conjugate gradient, and (4) adaptive local refinement. The resulting assembly-free deflated conjugate gradient (AF-DCG) version of the Newmark-beta is well-suited for large-scale problems, and can be easily ported to multi-core architectures. Numerical experiments demonstrate the efficacy of the proposed method.
On the Issue of Redundancy in the Large Rotation Vector Formulation
Authors: Ding Jieyu , Wallin Michael , Wei Cheng , Recuero Antonio M. , Shabana Ahmed A.
Published: January 2015

In the large rotation vector formulations (LRVF), two independent interpolations are used in the nonlinear large displacement analysis of beams. This kinematic description leads to a fundamental redundancy problem. This paper examines this fundamental issue and demonstrates that the use of two geometrically independent meshes can lead to coordinate and geometric invariant redundancy that cannot be solved using constraints or forces. It is demonstrated in this paper that the two geometry meshes can define different space curves, which can differ by arbitrary rigid body displacements. The material points of the two meshes occupy different positions in the deformed configuration, and as a consequence, the geometries of the two meshes can differ significantly. Simple examples are presented in order to shed light on these fundamental issues.
Limited-Memory Deflated Conjugate Gradient for Solid Mechanics
Authors: Yadav Praveen , Suresh Krishnan
Published: January 2015

The primary computational bottle-neck in finite element based solid mechanics is the solution of the underlying linear systems of equations. Among the various numerical methods for solving such linear systems, the deflated conjugate gradient (DCG) is well-known for its efficiency and simplicity.

The first contribution of this paper is an extension of the “rigid-body agglomeration” concept used in DCG to a “curvature-sensitive agglomeration”. The latter exploits, classic Kirchoff-Love theory for plates and Euler-Bernoulli theory for beams. We demonstrate that curvature-sensitive agglomeration is much more efficient for highly ill-conditioned problems arising from thin structures.

The second contribution is a strategy for a limited-memory assembly-free DCG where neither the stiffness matrix nor the deflation matrix is assembled. The resulting implementation is particularly well suited for large-scale problems, and can be easily ported to multi-core architectures. For example, we show that one can solve a 50 million degree of freedom system on a single GPU card, equipped with 3 GB of memory.
Influence of Potential Function Asymmetries on the Performance of Nonlinear Energy Harvesters Under White Noise
Authors: He Qifan , Daqaq Mohammed F.
Published: January 2015

To improve the broadband transduction capabilities of vibratory energy harvesters (VEHs) under random and non-stationary excitations, many researchers have resorted to purposefully introducing nonlinearities into the restoring force of the harvester. While performing this task, it is often very challenging to maintain a perfectly symmetric restoring force which usually yields a VEH with an asymmetric potential energy function. This paper investigates the influence of potential function asymmetries on the performance of nonlinear VEHs under white noise inputs. To that end, a quadratic nonlinearity is introduced into the restoring force of the harvester and its influence on the mean power for both mono- and bi-stable potentials is investigated. It is shown that, for VEHs with a mono-stable potential function, the mean output power increases with the degree of potential function asymmetry. On the other hand, for energy harvesters with a bi-stable potential function, asymmetries in the restoring force appear to worsen performance especially for low to moderate noise intensities. When the noise intensity becomes sufficiently large, the influence of the potential function’s asymmetry on the mean power diminishes. Results also reveal that a VEH with a symmetric bi-stable potential function produces higher mean power levels than the one with the most asymmetric mono-stable potential. As such, it is concluded that a VEH with a bi-stable symmetric potential is most desirable to improve performance under white noise.
Determination of Acoustic Scattering From a Two-Dimensional Finite Phononic Crystal Using Bloch Wave Expansion
Authors: Kulpe Jason A. , Leamy Michael J. , Sabra Karim G.
Published: January 2015

In this study the acoustic scattering is determined from a finite phononic crystal through an implementation of the Helmholtz-Kirchhoff integral theorem. The approach employs the Bloch theorem applied to a semi-infinite phononic crystal (PC) half-space. The internal pressure field of the half-space, subject to an incident acoustic monochromatic plane wave, is formulated as an expansion of the Bloch wave modes. Modal coefficients of reflected (diffracted) plane waves are arrived at via boundary condition considerations on the PC interface. Next, the PC inter-facial pressure, as determined by the Bloch wave expansion (BWE), is employed along with the Helmholtz-Kirchhoff integral equation to compute the scattered pressure from a large finite PC. Under a short wavelength limit approximation (wavelength much smaller than finite PC dimensions), the integral approach is employed to calculate the scattered pressure field for a large PC subject to an incident wave with two distinct incident angles. In two dimensions we demonstrate good agreement of scattered pressure results of large finite PC when compared against detailed finite element calculations. The work here demonstrates an efficient and accurate uniform computational framework for modeling the scattered and internal pressure fields of a large finite phononic crystal.
Identification of Nonlinear Behavior in a Composite Structure With Core-Crushing Damage
Authors: Meyer Janette J. , Adams Douglas E. , Dittman Eric R.
Published: January 2015

Many damage detection methods that are applied to composite structures rely on nonlinear features in the dynamic response of the structure to identify the presence of defects. Presently, there is not a complete understanding of the physical mechanisms that cause the nonlinear behavior of a damaged composite structure. Correlating specific types of damage mechanisms to the resulting nonlinear response characteristics they cause would allow the detection methods to classify the type of damage that is present in the structure. In this work, a drop tower was used to impact an aluminum honeycomb sandwich panel in order to induce core-crushing. The response of the damaged panel to sinusoidal excitations of various amplitudes at resonant, super-, and sub-harmonic frequencies was then measured. The amplitudes of these measured responses and the corresponding restoring force curves were then compared to a predictive model to identify the type of theoretical nonlinearity (i.e. quadratic or cubic stiffness, quadratic or cubic damping, etc.) that was present. The predictive model is based on a nonlinear, single degree-of-freedom system. Nonlinear features in the response of the system were identified for different types of stiffness and damping nonlinearities. The experimentally measured response was analyzed to see which of these features were present. Based on this analysis, the response of the panel of damage due to core-crushing indicated a quadratic spring-type stiffness.
A Novel, Elastically-Based, Regenerative Brake and Launch Assist Mechanism
Authors: Nieman Joshua E. , Myszka David H. , Murray Andrew P.
Published: January 2015

This paper presents the development of a regenerative brake and launch assist (RBLA) mechanism that stores energy in an elastic medium. Automotive regenerative braking systems harness kinetic energy while a vehicle decelerates, and subsequently uses that stored energy to assist propulsion. Commercially available hybrid vehicles use generators, batteries, and motors to electrically implement regenerative braking and increase overall vehicle efficiency. With the intent to apply regenerative braking technology to conventional automobiles equipped with only an internal combustion engine, a spring-based mechanical device is proposed. This RBLA concept implements clutches, gears, a ratchet and a spring. The mechanism captures energy from, and releases energy to, an additional shaft allowing the axle to continually rotate. Governing equations were formulated and validated by a dynamic simulation. In creating the detailed design, an optimization determined ideal spring and mechanism dimensions. A physical prototype was designed and fabricated to demonstrate the concept. A model of the proposed spring-based RBLA shows an increase in the urban fuel efficiency for an average sedan.
An Improved Stochastic Upscaling Method for Multiscale Engineering Systems
Authors: Gorguluarslan Recep M. , Choi Seung-Kyum
Published: January 2015

A stochastic multiscale modeling technique is proposed to construct coarse scale representation of a fine scale model for use in engineering design problems. The complexity of the fine scale heterogeneity under uncertainty is replaced with the homogenized coarse scale parameters by seeking agreement between the responses at both scales. Generalized polynomial chaos expansion is implemented to reduce the dimensionality of propagating uncertainty through scales and the computational costs of the upscaling method. It is integrated into a hybrid optimization procedure with the genetic algorithm and sequential quadratic programming. Two structural engineering problems that involve uncertainties in elastic material properties and geometric properties at fine scales are presented to demonstrate the applicability and merit of the proposed technique.
Exploring Movements and Potential Actuation in Action Origami
Authors: Wilcox Eric W. , Magleby Spencer P. , Howell Larry L.
Published: January 2015

As interest in origami-inspired mechanisms continues to grow, there is an increasing need to better understand the fundamental types of motion possible in origami models and how to effectively actuate them. This paper addresses this need with an in-depth study of action origami models and their motion. Approximately 140 action origami models were folded and analyzed. Groupings of action origami models are proposed based on observed fundamental motions from this study. Eleven different motions are outlined and defined with the associated actuation forces that drive them. Considerations for effective placement of actuation forces and back-drivability of each defined motion are included in the discussion.
Novel Monitoring Method of Gear Meshing Using a High Response Infrared Thermography
Authors: Niwa Kodai , Pihet Raphael , Hirogaki Toshiki , Aoyama Eiichi
Published: January 2015

The hypoid gear used in automobile differential has a complex shape, and the estimation of the contact conditions is difficult. Therefore we devised a method of analysis of the tooth contact conditions using a high reply thermography as a non-contact analysis method by analyzing the temperature distribution during meshing between the pinion and the gear. We decided to perform a high-speed photography used by thermography and defined the extraction line in a shot thermal image to extract the temperature data from the thermal images. The temperature distribution provided by extraction line shows a different temperature rising shape and the position of the tooth surface obtained using the extraction line moves up and down during the cycle of each tooth. This cyclic nature is in good accordance with the whirling of the shaft caused by the geometry error of the shaft center which was thought to have an influence on the contact conditions. In addition, as the extraction line was defined on the thermal image, it does not follow the movement of the gear, but the movement of the temperature distribution obtained using the extraction line matches the displacement of the gear by the whirling.
Assessing the Greenhouse Gas Emissions and Cost of Thermoelectric Generators for Passenger Automobiles: A Life Cycle Perspective
Authors: Kishita Yusuke , Uwasu Michinori , Takeda Hiroyuki , Hara Keishiro , Ohishi Yuji , Kuroda Masashi
Published: January 2015

Toward realizing a low-carbon society, a thermoelectric generator (TEG) is promising for energy harvesting by generating electricity from thermal energy, especially waste heat. While there are various technologies available for energy recovery, one of the strengths of TEGs is to retrieve usable energy from waste heat whose temperature is as low as 200∼300 degrees Celsius. Yet, the conversion efficiency of the current thermoelectric materials remains low at 5∼10%, which makes it difficult to diffuse TEGs in our society. In order to clarify required performances of TEGs to diffuse them in the future, this paper aims to assess the life cycle CO2 emissions (LCCO2) and life cycle cost (LCC) of TEGs based on several product lifecycle scenarios, each of which assumes different future situations in, e.g., conversion efficiency of TEGs. In this paper, we focus on TEGs for passenger automobiles since a range of the temperatures of their exhaust gas is suitable for TEGs. Additionally, we focus on bismuth telluride (Bi-Te) materials to develop TEGs since they have already been available for commercial use. A case study of installing Bi-Te TEGs in passenger automobiles is carried out. The region of interest is Suita City, Osaka, Japan. By describing two scenarios that assume different conversion efficiency of thermoelectric materials, we compare assessment results from the viewpoints of LCCO2 and LCC. The results reveal that using TEGs has the potential to reduce CO2 emissions of the city by 0.07∼0.30%. It is also shown that the TEG cost needs to be drastically reduced to make the usage of TEGs profitable.
Leveraging Mechanical 3D CAD Systems Through Improved Model Quality Based on Best Practices and Rubrics
Authors: Company Pedro , Otey Jeffrey , Camba Jorge , Contero Manuel
Published: January 2015

CAD data quality may be leveraged by quality-oriented CAD instructional strategies, but current mechanical CAD practice fails in enforcing quality. The concept of CAD model quality is reviewed to discover how to convey different dimensions of quality through rubrics. The paper describes lessons learned from pilot studies designed to gain knowledge on introducing best practices throughout the training period of novice product designers. Best practices are conveyed by rubrics, so leading to increased quality in CAD models. Rubrics must adapt to the specific concept practiced at each stage of the training period. In this way, they become helpful in disclosing which currently available strategies and tools to enforce quality may be early comprehended and how they are better introduced. Lessons learned from pilot studies are proposed to be reformulated as strong hypothesis that should be validated or rejected in the future, by way of experiments with suitable statistical power.
Should Optimal Designers Worry About Consideration?
Authors: Long Minhua , Morrow W. Ross
Published: January 2015

Consideration set formation using non-compensatory screening rules is a vital component of real purchasing decisions with decades of experimental validation. Marketers have recently developed statistical methods that can estimate quantitative choice models that include consideration set formation via non-compensatory screening rules. But is capturing consideration within models of choice important for design? This paper reports on a simulation study of a vehicle portfolio design when households screen over vehicle body style built to explore the importance of capturing consideration rules for optimal designers. We generate synthetic market share data, fit a variety of discrete choice models to this data, and then optimize design decisions using the estimated models. Model predictive power, design “error”, and profitability relative to ideal profits are compared as the amount of market data available increases. We find that even when estimated compensatory models provide relatively good predictive accuracy, they can lead to sub-optimal design decisions when the population uses consideration behavior; convergence of compensatory models to non-compensatory behavior is likely to require unrealistic amounts of data; and modeling heterogeneity in non-compensatory screening is more valuable than heterogeneity in compensatory trade-offs. This supports the claim that designers should carefully identify consideration behaviors before optimizing product portfolios. We also find that higher model predictive power does not necessarily imply better design decisions; that is, different model forms can provide “descriptive” rather than “predictive” information that is useful for design.
Minimal Deviation Paths for Manipulators With Joint Clearances
Authors: Lai Ming-Cheng , Chan Kuei-Yuan
Published: January 2015

Manipulator joint clearance is a natural consequence of manufacturing processes. Although most studies in the literature have assumed zero joint clearance, its existence is unavoidable and thus its impact needs to be evaluated. With the miniaturizing trend in engineering products, errors due to joint clearance have become an increasingly important issue. This study investigates how manipulators deviate from the desired working sites due to joint clearance. Deviations from the target locations can be reduced by properly selecting the working path. The optimal path is obtained by first parameterizing the path based on the required target task locations. Corresponding controlling inputs, namely linear and angular velocities as well as their accelerations, are calculated using inverse kinematics. Joint clearances are then added to obtain the deviations a path will make. An optimization framework with path parameters as the design variables is then formulated to minimize the resulting deviations. The proposed framework is shown to improve accuracy without additional equipment cost or control effort. A five-bar parallel manipulator is used to demonstrate the proposed method.
A STEP-Based Approach Toward Cooperative Product Design for Sustainability
Authors: Li Yunpeng , Roy Utpal
Published: January 2015

Industries often employ heterogeneous computer aided tools (CAD/CAE/CAM) to carry out complex product designs and simulations resulting in a need for data sharing, data exchange, and computational activities. Nowadays the concept of “Design for Sustainability (DfS)” heightens this challenge, as most DfS approaches especially the Life Cycle Assessment (LCA) involve large amounts of data collection, sharing and computation tasks throughout the product life cycle. ISO 10303, also known as STEP (STandard for the Exchange of Product model data), has evolved for several decades and provides a set of standards for industrial automation systems and integration. In this paper, we propose a STEP-based collaborative framework to integrate heterogeneous CAD tools, LCA tools and other necessary computational tools to support cooperative product design for sustainability. The geometric information from CAD tools and the material/process information from material/process databases are formally represented in suitable STEP application protocols (APs). An agent is implemented to parse the geometric and non-geometric information encoded in STEP data format, and compose them into a complete product tree represented with a NIST CPM (Core Product Model) based information model. The information in the product tree is then evaluated by a LCA tool to obtain environmental impact score. The feasibility and benefits of the proposed methodology have been illustrated with a typical stapler product.
An Individual Wheel Inverse Dynamics-Based Control Algorithm of a UGV in Stochastic Terrain Conditions
Authors: Salama Mostafa , Vantsevich Vladimir V.
Published: January 2015

An All-Wheel Drive Unmanned Ground Vehicle (UGV) equipped with individual electric motors for each wheel offers tremendous potential to control indirectly the torque delivered to each individual wheel and thus control UGV energy efficiency and mobility. The objective of this study is to develop an analytical method for a single wheel angular velocity control that is based on inverse longitudinal dynamics of a quarter-of-vehicle. The method includes a stochastic terrain model and an inverse dynamics-based control algorithm of a UGV single pneumatic wheel to overcome stochastic terrain behavior.

A stochastic terrain mathematical model was developed and used as a disturbance load in the control algorithm to introduce the on-line (real time) influence of the terrain conditions on a single wheel of UGV. The control algorithm is based on a developed strategy that utilizes the inverse dynamics approach and the wheel torque control that provides a wheel with both the specified/required angular velocity and rolling radius.

Such an approach opens up new ways of optimization and control of both unmanned ground vehicle dynamics and vehicle performance by distributing power between the drive wheels.
Modeling and Experimental Validations of a Piezoelectric Energy Harvester Under Combined Galloping and Base Excitations
Authors: Bibo Amin , Abdelkefi Abdessattar , Daqaq Mohammed F.
Published: January 2015

This paper develops an experimentally validated model of a piezoelectric energy harvester under combined aeroelastic-galloping and base excitations. To that end, an energy harvester consisting of a thin piezoelectric cantilever beam subjected to vibratory base excitation is considered. To permit galloping excitation, a bluff body is rigidly attached at the free end such that a net aerodynamic lift is generated as the incoming airflow separates on both sides of the body giving rise to limit cycle oscillations when the flow velocity exceeds a critical value. A nonlinear electromechanical distributed-parameter model of the harvester under the combined excitation is derived using the energy approach and by adopting the nonlinear Euler-Bernoulli beam theory, linear constitutive relations for the piezoelectric transduction, and the quasi-steady assumption for the aerodynamic loading. The partial differential equations of the system are discretized and a reduced-order-model is obtained. The mathematical model is validated by conducting a series of experiments with different loading conditions represented by wind speed, base excitation amplitude, and excitation frequency around the primary resonance.
Modeling and Analysis of a Ball and Beam System Including Impacts and Dry Friction
Authors: Colón Diego , Bueno Átila Madureira , Diniz Ivando S. , Balthazar Jose M.
Published: January 2015

The Ball and Beam system is a common didactical plant that presents a complex nonlinear dynamics. This comes from the fact that the ball rolls over the beam, which rotates around its barycenter. In order to deduce the system’s equations, composition of movement must be applied, using a non-inertial reference frame attached to the beam. In the Literature, a common hypothesis is to suppose that the ball rolls without slipping. If a viscous friction is supposed to be present, a simpler situation is obtained, where Lagrangean mechanics can be applied, and no contact force is known. Even then, the dynamics is very nonlinear.

However, this model does not include all the relevant phenomena, such as ball’s slipping at higher beam’s inclination angles, dry friction between the ball and the beam, and impacts between: 1) the ball and the ends of the beam, and 2) the beam and the base (ground). These additions to the model impose the necessity to calculate, in a simulation setting, the contact forces, and the Newton’s approach to determine the system’s equations becomes more convenient. Also, discontinuities in the model are introduced, and the simpler mathematical object for model such systems are the differential inclusion systems.

In this work, we deduce the Ball and Beam differential inclusion system, including dry friction and the impact between the ball and beam. We also present simulation results for the corresponding differential inclusion system in a typical situation.
Synthesizing Soft Parallel Robots Comprised of Active Constraints
Authors: Rivera Jordan , Hopkins Jonathan B. , Kim Charles
Published: January 2015

In this paper, we introduce a new type of spatial parallel robot that is comprised of soft inflatable constraints called Tri-Chamber Actuators (TCAs). We extend the principles of the Freedom and Constraint Topologies (FACT) synthesis approach to enable the synthesis and analysis of this new type of soft robot. The concepts of passive and active freedom spaces are introduced and applied to the design of general parallel systems that consist of active constraints (i.e., constraint that can be actuated to impart various loads onto the system’s stage) that both drive desired motions and guide the system’s desired degrees of freedom (DOFs). We provide the fabrication details of the TCA constraints introduced in this paper and experimentally validate their FACT-predicted kinematics. Examples are provided as case studies.
A Design Method of Beads in Shell Structure Using Non-Parametric Shape Optimization Method
Authors: Shintani Kohei , Azegami Hideyuki
Published: January 2015

The present paper describes a method finding bead shapes in shell structure to increase the stiffness using a solution to shape optimization method. Variation of the shell structure in out-of-plane direction is chosen as a non-parametric design variable. To create beads, the out-of-plane variation is restricted by using the sigmoid function. Mean compliance is used as objective function. The main problem is defined as a linear elastic problem for shell structure. The Fréchet derivative with respect to the out-of-plane variation of the mean compliance is evaluated with the solutions of the main problem and an adjoint problem which is derived theoretically by the adjoint variable method. To solve the bead design problem, an iterative algorithm based on the H1 gradient method is used. Numerical results show the effectiveness of the method.
Investigating Ultrasound-Induced Acoustic Softening of Aluminum 6061
Authors: Mao Qing , Gibert James M. , Fadel Georges
Published: January 2015

Blaha and Langenecker are the first to document the phenomena known as “acoustic softening”: a significant reduction of static stress in tensile tests when applying longitudinal ultrasonic waves to various metals. Based on experimental observations, they hypothesized that acoustic heating due to internal friction and energy activation at dislocations was responsible for this temporary weakening of the material. Later research studies investigating the acoustic softening process used different experimental setups leading to alternative theories of the softening process such as superposition of static and dynamic stress. The variation in the design of the experiments leads to significant differences in observations, causing differing interpretations of the results and the formation of competing theories. We reviewed previous experimental studies and found that the optimum setup is similar to Blaha’s and Langenecker’s. Their setup minimizes noise factors such as friction at the oscillator specimen interface, which could contribute to heating and stress reduction. Therefore, we present our experimental setup composed of an MTS tensile test machine and a Branson ultrasonic welder to study the softening of aluminum 6061 and discuss our own results and how they compare with those in the literature. Additionally, we investigate the applicability of competing theories of softening based on our experimental data.
A Simultaneous Computing Framework for Metamodel-Based Design Optimization
Authors: Long Teng , Wang Lv , Wu Di , Guo Xiaosong , Liu Li
Published: January 2015

At the aim of reducing the computational time of engineering design optimization problems using metamodeling technologies, we developed a flexible distributed framework independent of any third-part parallel computing software to implement simultaneous sampling during metamodel-based design optimization procedures. In this paper, the idea and implementation of hardware configuration, software structure, the main functional modular and interfaces of this framework are represented in detail. The proposed framework is capable of integrating black-box functions and legacy software for analyzing and common MBDO methods for space exploring. In addition, a message-based communication infrastructure based on TCP/IP protocol is developed for distributed data exchange. The Client/Server architecture and computing budget allocation algorithm considering software dependency enable samples to be effectively allocated to the distributed computing nodes for simultaneous execution, which gives rise to decreasing the elapsed time and improving MBDO’s efficiency. Through testing on several numerical benchmark problems, the favorable results demonstrate that the proposal framework can evidently save the computational time, and is practical for engineering MBDO problems.
Optimum Solar HDH Desalination for Semi-Isolated Communities Using HGP and GA’s
Authors: Abd El-Aziz Khalid M. , Hamza Karim , El Morsi Mohamed , Nassef Ashraf O. , Metwalli Sayed M. , Saitou Kazuhiro
Published: January 2015

Modeling and unit-cost optimization of a water-heated humidification-dehumidification (HDH) desalination system were presented in previous work of the authors. The system controlled the saline water flow rate to prevent salts from precipitating at higher water temperatures. It was then realized that this scheme had a negative impact on condensation performance when the controlled flow rate was not sufficiently high. This work builds on the previous system by disconnecting the condenser from the saline water cycle and by introducing a solar air heater to further augment the humidification performance. In addition, improved models for the condenser and the humidifier were used to obtain more accurate productivity estimations. The Heuristic Gradient Projection (HGP) optimization procedure was also refactored to result in reduced number of function evaluations to reach the global optimum compared to Genetic Algorithms (GA’s). A case study which assumes a desalination plant on the Red Sea near the city of Hurghada is presented. The unit-cost of produced fresh water for the new optimum system is $0.5/m3 compared to $5.9/m3 for the HDH system from previous work and less than the reported minimum cost of reverse osmoses systems.
Design for Dimensional Accuracy in Bending Operations: Introducing the Concept of Flatness Limit Curves
Authors: Welo Torgeir
Published: January 2015

Eliciting knowledge about dimensional variability and influential parameters is crucial in competitive manufacturing. Moreover, this knowledge needs to be generalized and transferred into a practical tool box that design engineers can use as a decision basis in the early phases of product development processes when design flexibility is high and the ‘cost of learning’ is low. This paper introduces Flatness Limit Curves, a new Design For Manufacturing (DFM) tool, which is aimed at assessing cross-sectional distortions relative to dimensional tolerance requirements in bending operation. Analytical relationships are derived from the theoretical basis of continuum mechanics, applying the deformation theory of plasticity to plane stress sheet metal problems. The theoretical results are compared with experimental results obtained for hollow AA7xxx extrusions, which were formed in an industry-like rotary stretch bender in a controlled laboratory environment. The solutions are then structured and organized into a set of limit curves for assessing nominal flatness of the exterior of the cross section after bending. The associated variability may also be estimated by varying key input parameters to the tool (dimensional accuracy and material quality) within the capability ranges of the upstream process.
Explicit Dynamics Analysis for Harmonic Drives
Authors: Yu Zhiyuan , Ting Kwun-Lon
Published: January 2015

Harmonic drive can have a high nonlinear dynamic behavior. In order to find a way to simulate its operating process and evaluate its performance, this paper gave an introduction of different methods of tooth contact analysis (TCA) and found out that explicit dynamics as a newly used tool for TCA is the most suitable one. Because the harmonic drive’s high contact ratio and uncertainty of contact boundary match with explicit dynamics’ features of explicit algorithm, trajectory detection to deal with contact. A harmonic drive with a new tooth profile has been modeled in Ansys Workbench and solved by explicit dynamics solver. According to the results, the deformation of the simulation model has been compared with the theoretical calculation and experimental observation to make sure that the model reflects the harmonic drive’s elastic behavior correctly. And the nonlinear behavior of the harmonic drive including high contact ratio and output’s hysteresis effect can be predicted by explicit dynamics. So explicit dynamics can offer a new way to simulate harmonic drive’s working process. As a general case of gear drive, this method is possible to be widely adopted by gear industry in the future. Furthermore, the contact ratio and root fillet stress results show that the new tooth profile can significantly reduce the stress concentration to increase the fatigue life of the harmonic drive.
Quantifying Emotional States Based on Body Language Data Using Non Invasive Sensors
Authors: Behoora Ishan , Tucker Conrad S.
Published: January 2015

Determining participant engagement is an important issue across a large number of fields, ranging from entertainment to education. Traditionally, feedback from participants is taken after the activity has been completed. Alternately, continuous observation by trained humans is needed. Thus, there is a need for an automated real time solution. In this paper, the authors propose a data mining driven approach that models a participant’s engagement, based on body language data acquired in real time using non-invasive sensors. Skeletal position data, that approximates human body motions, is acquired from participants using off the shelf, non-invasive sensors. Thereafter, machine learning techniques are employed to detect body language patterns representing emotions such as delight, interest, boredom, frustration, and confusion. The methodology proposed in this paper enables researchers to predict the participants’ engagement levels in real time with high accuracy above 98%. A case study involving human participants enacting eight body language poses, is used to illustrate the effectiveness of the methodology. Finally, this methodology highlights the potential of a real time, automated engagement detection using non-invasive sensors which can ultimately have applications in a large variety of areas such as lectures, gaming and classroom learning.
Fabric Simulation Using Measurement Data for Dress Design
Authors: Hara Ayumi , Aoyama Hideki , Oya Tetsuo
Published: January 2015

The state of wrinkles and folds formed on our dress according to human postures and movements is an important design element. Fashion designers must envisage the fabric state as wrinkling and folding. However, this is not easy because the fabric state strongly depends on the mechanical properties of the fabric, and in this sense, fabric simulation can aid designers in envisaging the fabric state. In previous works on fabric simulation, fabric models are proposed and developed based on the simple mass spring model. Since none of the models proposed so far take into account the state of slipping at the contact point of the warp and weft, simulated results differ from real fabric states. This paper proposes a method to simulate real fabric state taking into consideration slipping. In order to obtain real simulation results, the mechanical properties of fabric obtained by KES: Kawabata Evaluation System [1], were used in the simulation. The effectiveness of the proposed model was confirmed by comparing simulated results obtained by the proposed method with simulated results obtained by a previous method. In addition, it was verified by comparing the simulated results obtained by the proposed method with real cloth states.
Design Project Planning Method With Task Option Model and Two-Level Multi-Objective Optimization
Authors: Dong Chunzhi , Horinouchi Takahiro , Nomaguchi Yutaka , Fujita Kikuo
Published: January 2015

This paper proposes a new optimization-based project planning method that aims at a Pareto-optimal of the potential product performance of designed product and a project failure risk. A task option model is introduced for risk assessment of option-based project management. As its planning includes a number of various design variables and various evaluation indices, in order to solve such a complicated problem with a reasonable computation cost, this research separates the optimization problem into two phases, i.e., (i) defining of process architecture and organization structure and (ii) scheduling of resource allocation into activities. This paper demonstrates its application to a student formula design project. A proposed optimization method facilitates a project manager to explore various process plans with assessing their risks.