bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanomolding of Nanostructured Biodegradable Tissue Engineering Scaffolds
Authors: Chung I-Cheng , Li Ching-Wen , Wang Gou-Jen
Published: February 2014

In replica molding or imprinting for industrial applications, robustness and durability of the replica mold are the main requirements. In this study, we demonstrate a replica mold fabrication method for nanohemisphere arrays nanomolding by nickel (Ni) electroforming using the highly ordered nanohemisphere array of the barrier-layer surface of an anodic aluminum oxide (AAO) membrane as the master mold. The feature size of the nanohemispheres can be controlled by using different etching solutions for anodic oxidation of aluminum (Al). Using the Ni replica mold, nanostructured tissue engineering scaffolds in poly(lactic-co-glycolic acid) (PLGA), polylactide (PLA), and chitosan are fabricated by casting. Hot embossing is also conducted to fabricate the nanostructured PC film for anti-fingerprint and anti-reflection. These results indicate that the proposed nanomolding method provides a feasible approach for repetitive production of biodegradable tissue engineering scaffolds with controllable nanostructure.
Non-Dimensional Kinetoelastostatic Maps for Compliant Mechanisms
Authors: Bhargav Santosh D. B. , Varma Harish I. , Ananthasuresh G. K.
Published: February 2014

How do we assess the capability of a compliant mechanism of given topology and shape? The kinetoelastostatic maps proposed in this paper help answer this question. These maps are drawn in 2D using two non-dimensional quantities, one capturing the nonlinear static response and the other the geometry, material, and applied forces. Geometrically nonlinear finite element analysis is used to create the maps for compliant mechanisms consisting of slender beams. In addition to the topology and shape, the overall proportions and the proportions of the cross-sections of the beam segments are kept fixed for a map. The finite region of the map is parameterized using a non-dimensional quantity defined as the slenderness ratio. The shape and size of the map and the parameterized curves inside it indicate the complete kinetoelastostatic capability of the corresponding compliant mechanism of given topology, shape, and fixed proportions.

Static responses considered in this paper include input/output displacement, geometric amplification, mechanical advantage, maximum stress, etc. The maps can be used to compare mechanisms, to choose a suitable mechanism for an application, or re-design as may be needed. The usefulness of the non-dimensional maps is presented with multiple applications of different variety. Non-dimensional portrayal of snap-through mechanisms is one such example. The effect of the shape of the cross-section of the beam segments and the role of different segments in the mechanism as well as extension to 3D compliant mechanisms, the cases of multiple inputs and outputs, and moment loads are also explained. The effects of disproportionate changes on the maps are also analyzed.
Composite and Multi-Scale Compliant Mechanisms for Manipulation and Mechanical Characterization
Authors: Bhargav Santosh D. B. , Singh Gaurav , Ananthasuresh G. K.
Published: February 2014

In this paper, we integrate two or more compliant mechanisms to get enhanced functionality for manipulating and mechanically characterizing the grasped objects of varied size (cm to sub-mm), stiffness (1e5 to 10 N/m), and materials (cement to biological cells). The concepts of spring-lever (SL) model, stiffness maps, and non-dimensional kinetoelastostatic maps are used to design composite and multi-scale compliant mechanisms. Composite compliant mechanisms comprise two or more different mechanisms within a single elastic continuum while multi-scale ones possess the additional feature of substantial difference in the sizes of the mechanisms that are combined into one. We present three applications: (i) a composite compliant device to measure the failure load of the cement samples; (ii) a composite multi-scale compliant gripper to measure the bulk stiffness of zebrafish embryos; and (iii) a compliant gripper combined with a negative-stiffness element to reduce the overall stiffness. The prototypes of all three devices are made and tested. The cement sample needed a breaking force of 22.5 N; the zebrafish embryo is found to have bulk stiffness of about 10 N/m; and the stiffness of a compliant gripper was reduced by 99.8 % to 0.2 N/m.
Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor
Authors: Schiffmann J.
Published: February 2014

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.
Large Amplitude Free Vibration Analysis of Nanotubes Using Variational and Homotopy Methods
Authors: Askari Hassan , Saadatnia Zia , Younesian Davood , Esmailzadeh Ebrahim
Published: February 2014

Linear theories are basically unable to model the dynamic behavior of nanotubes due to the large deflection/dimension ratios. In this paper the closed form expressions are obtained for the large-amplitude free vibration of nanotubes. The nonlinear governing differential-integral equation of motion is derived and solved using the Galerkin approach. The derived nonlinear differential equation is then solved using the Variational Approach (VA) and the Homotopy Analysis Method (HAM). The fundamental harmonic as well as higher-order harmonics are analytically obtained. The approximate solutions are compared with those of the numerical responses and accordingly a numerical analysis is carried out. A parametric sensitivity analysis is carried out and different effects of the physical parameters and initial conditions on the natural frequencies are examined. It is found that both the variational analysis and homotopy method are quite consistent and satisfactory techniques to analyze the vibration of nanotubes.
Broadband Wave Attenuation in Locally Resonant Periodic Flexural Beams With Force-Moment Resonators
Authors: Wang Michael Y. , Wang Xiaoming
Published: February 2014

We investigate flexural wave propagation in Euler-Bernoulli beams with periodically suspended 2-DOF force-moment resonators. We use the transfer matrix method for a unit cell in the beam in conjunction with Bloch’s theorem, to define the dispersion curves and frequency band structure. Our analysis shows that the uncoupled force-moment resonators generate rich attenuation properties that are not observed in the conventional locally resonant structures with suspended force-only (or moment-only) vibrators. As a prime focus, we identify a Bragg-like band gap below the resonance frequency of the resonator and its coupling with the resonance gap, giving rise to a potentially super-wide attenuation gap that can be tuned for any low frequency range. The analysis presented can be extended to other types of phononic meta-materials and structures of multi-degrees of freedom (and distributed) resonators, which may exhibit more practically significant wave attenuation characteristics.
Coupled Multibody-Fluid Dynamics Simulation of Flapping Wings
Authors: Alioli Mattia , Morandini Marco , Masarati Pierangelo
Published: February 2014

This paper deals with the coupled structural and fluid-dynamics analysis of flexible flapping wings using multibody dynamics. A general-purpose multidisciplinary multibody solver is coupled with a computational fluid dynamics code by means of a general-purpose, meshless boundary interfacing approach based on Moving Least Squares with Radial Basis Functions. The general-purpose, free software multibody solver MBDyn is used. A nonlinear 4-node shell element has been used for the structural model. The fluid dynamics code is based on a stabilized finite element approximation of the unsteady Navier-Stokes equations. The method (often referred to in the literature as G2 method) has been implemented within the programming environment provided by the free software project FEniCS, a collection of libraries specifically designed for the automated and efficient solution of differential equations. FEniCS provides extensive scripting capabilities, with a domain-specific language for the specification of variational formulations of Partial Differential Equations that is embedded within the programming language Python. This approach makes it possible to easily and quickly build complex simulation codes that are, at the same time, extremely efficient and easily adapted to run in parallel. The coupling of the multibody and Navier-Stokes codes is strictly enforced at each time step. The fluid dynamics discretization is automatically refined to keep the error on the overall lift and drag coefficients below a user-defined tolerance. The method is first tested by computing the drag force of a non-oscillating NACA 0012 airfoil traveling in air. Subsequently, the drag and lift forces on a rigid and flexible oscillating NACA 0012 wing are compared with experimental data. Encouraging results obtained from the modeling and analysis of the dynamics and aeroelasticity of flexible oscillating wing models confirm the ability of the structural and fluid dynamics models to capture the physics of the problem.
Design of Large-Range XY Compliant Parallel Manipulators Based on Parasitic Motion Compensation
Authors: Hao Guangbo , Meng Qiaoling , Li Yangmin
Published: February 2014

This paper presents a large-range decoupled XY compliant parallel manipulator (CPM) with good dynamics (no under-constrained/non-controllable mass). The present XY CPM is composed of novel parallelogram flexure modules (NPFMs) that are parallel four-bar mechanisms as prismatic (P) joints with four identical monolithic cross-spring flexural pivots, flexure revolute (R) joints. The parasitic translation of the NPFM is compensated via the rotational centre shift of the flexure R joint thereof based on the prior art. The optimization function and optimised geometrical parameters are investigated for the NPFM at first to achieve the largest translation. The design of a large-range XY CPM is then implemented according to the fully symmetrical 4-PP parallel kinematic mechanism (PKM) and through using the optimised NPFMs. Finally, the simplified analytical stiffness modelling and finite element analysis (FEA) are undertaken for the static and/or dynamic characteristics analysis of the 4-PP XY CPM. It is shown from FEA in the example case that the present 4-PP XY CPM has good performance characteristics such as large-range motion space (10 mm × 10 mm with the total dimension of 465 mm× 465 mm), no non-controllable mass, monolithic configuration, maximal kinematostatic decoupling (cross-axis coupling effect less than 1.2%), maximal actuator isolation (input coupling effect less than 0.13%) and well-constrained parasitic rotation (less than 0.4 urad). In addition, the stiffness-enhanced NPFM using over-constraint is proposed to produce a first/second modal frequency of about 100 Hz for the resulting XY CPM.
Enhancement of Mechatronic-System-Models
Authors: Sadlauer Alfred , Hehenberger Peter , Zeman Klaus
Published: February 2014

The Mechatronic System Model (MSM) [1] is an approach to fulfill the need to incorporate multiple disciplines and different hierarchical levels and views in the development of products. While the MSM already proved successful in some practical applications, certain aspects were worth improving, such as the handling of information and addressing the inevitable concurrency in larger projects. In this paper the goal is to enhance the MSM approach towards a general integrated design approach especially to overcome observed shortcomings e.g. through aspects from related work such as a “common repository” and “public and private work space”. For further clarification the development of a self-replicating printer is reconstructed with the MSM approach.
Multi-Flexible-Body Simulations Using Interpolating Splines in a Divide-and-Conquer Scheme
Authors: Khan Imad M. , Ahn Woojin , Anderson Kurt , De Suvranu
Published: February 2014

A new method for modeling multi-flexible-body systems is presented that incorporates interpolating splines in a divide-and-conquer scheme. This algorithm uses the floating frame of reference formulation and piece-wise interpolation spline functions to construct and solve the non-linear equations of motion of the multi-flexible-body systems undergoing large rotations and translations. We compare the new algorithm with the flexible divide-and-conquer algorithm (FDCA) that uses the assumed modes method and may resort to sub-structuring in many cases [1]. We demonstrate, through numerical examples, that in such cases the interpolating spline-based approach is comparable in accuracy and superior in efficiency to the FDCA. The algorithm retains the theoretical logarithmic complexity inherent to the divide-and-conquer algorithm when implemented in parallel.
Design of Agricultural Waste Charcoal Cooking Fuel for Developing Countries
Authors: Banzaert Amy , Winter Amos
Published: February 2014

Charcoal made from agricultural waste (AWC), intended for use in developing countries, has the potential to be a cooking fuel with health, economic, and environmental benefits. Investigations were undertaken to integrate the technical understanding of the fuel with the real-world context in which it may be produced and used. Multiple formulations of AWC were studied to understand the impact of raw material variation on charcoal briquette emissions. A key finding is the viability of manure as a binder, which should improve AWC production costs and proliferation. In Nicaragua, AWC emissions, end user interest, and producer economic viability was examined. Emissions of AWC appear to be similar to or less than wood and wood charcoal. End user interest seems moderate, a positive outcome given the lack of charcoal usage in the region studied. Based on the outcomes of pilot production, development of the manufacturing system must account for local preferences.
Advanced Robust Optimization Approach for Design Optimization With Interval Uncertainty Using Sequential Quadratic Programming
Authors: Zhou Jianhua , Li Mian
Published: February 2014

Uncertainty is inevitable in real world. It has to be taken into consideration, especially in engineering optimization; otherwise the obtained optimal solution may become infeasible. Robust optimization (RO) approaches have been proposed to deal with this issue. Most existing RO algorithms use double-looped structures in which a large amount of computational efforts have been spent in the inner loop optimization to determine the robustness of candidate solutions. In this paper, an advanced approach is presented where no optimization run is required to be performed for robustness evaluations in the inner loop. Instead, a concept of Utopian point is proposed and the corresponding maximum variable/parameter variation will be obtained by just solving a set of linear equations. The obtained robust optimal solution from the new approach may be conservative, but the deviation from the true robust optimal solution is very small given the significant improvement in the computational efficiency. Six numerical and engineering examples are tested to show the applicability and efficiency of the proposed approach, whose solutions and computational time are compared with those from a similar but double-looped approach, SQP-RO, proposed previously.
Using Morphing Techniques in Early Variation Analysis
Authors: Wagersten Ola , Lindau Björn , Lindkvist Lars , Söderberg Rikard
Published: February 2014

Today, in order to be competitive in a fierce global car market, higher demands are placed on the Perceived Quality (PQ) of the products. The end customer’s visual impression of fit and finish are one of several factors influencing the overall PQ. When assessing the PQ of split-lines, the assumed geometric variation of the ingoing parts is an important prerequisite for trustworthy visualization and for correct judgments. To facilitate early decision making in conceptual phases, new demands are set on virtual tools and methods to support the engineers.

In this study, a method for early evaluation of the impact of geometrical variation on PQ of split-lines is proposed. Starting from an exterior styling model, mesh morphing techniques have been used to distort the exterior model according to measurement data acquired in running production. Morphing techniques have also been used to adopt previous structural design solutions onto the new styling, in order to make an early assumption of the assembly stiffness.

The used method is described and adopted in an industrial case. The study shows that the presented technique can be used to create continuous and correlated datasets. Non-rigid part behavior can be included in early PQ evaluations, even if final CAD/FEA engineering design models do not yet exist.
Hybrid-Parallel Calculation of Jacobians in Multi-Body Dynamics
Authors: Clauberg Jan , Leistner Michael , Ulbrich Heinz
Published: February 2014

Implicit integration methods are often used for numerically stiff multi-body systems in order to reduce the timestep-size. But within most implicit integration methods, the jacobian of the right hand side must be calculated at every step. In case of multi-body dynamics, this is the vector of generalized forces and the calculation of its jacobian can be so expensive, that it often outweighs the advantage of a bigger step-size. For large systems, this task can take more than 99% of the whole simulation time, while it can be easily parallelized. In this paper, a hybrid-parallel implementation of calculating this jacobian is presented. With a combination of MPI and OpenMP, simulations on up to 512 cores are run. The experiments are carried out on a high-performance-computing cluster with an infiniband network. The performance of a pure MPI implementation is compared to several hybrid variants, using different numbers of OpenMP threads per process.
Optimal Stiffness Parameters of the Turbine Bladed Disk Computational Model
Authors: Polach Pavel
Published: February 2014

Motivation for introducing this paper is the topical application of the method using the rotational periodicity of the structure at calculating natural vibration characteristics of the steam turbine bladed disk with continuous binding, in this case in the form of integral shrouding and in the middle of the blade with the tie-boss connection. Part of the shroud and the part of the tie-boss are the integral parts of the blade. Blades are free at non-rotating bladed disk. Blades of the advanced design are continuously coupled in the zone of the shroud and in the tie-boss zone by the blades untwist caused by the centrifugal forces acting at turbine rotation. The method used for the calculation of natural frequencies and mode shapes of the bladed disk with the continuous binding does not enable to model the real contact properties. The contact must be modeled by the flexible connection. The stiffness of the connection in the zones of adjoining blades contact is “tuned” at turbine operational speed (i.e. at 3000 rpm) in such a way that the values of calculated natural frequencies may come as near as possible to the values of the measured natural frequencies.
Time-Dependent Reliability of Dynamic Systems Using Subset Simulation With Splitting Over a Series of Correlated Time Intervals
Authors: Wang Zhonglai , Mourelatos Zissimos P. , Li Jing , Singh Amandeep , Baseski Igor
Published: February 2014

Time-dependent reliability is the probability that a system will perform its intended function successfully for a specified time. Unless many and often unrealistic assumptions are made, the accuracy and efficiency of time-dependent reliability estimation are major issues which may limit its practicality. Monte Carlo simulation (MCS) is accurate and easy to use but it is computationally prohibitive for high dimensional, long duration, time-dependent (dynamic) systems with a low failure probability. This work addresses systems with random parameters excited by stochastic processes. Their response is calculated by time integrating a set of differential equations at discrete times. The limit state functions are therefore, explicit in time and depend on time-invariant random variables and time-dependent stochastic processes. We present an improved subset simulation with splitting approach by partitioning the original high dimensional random process into a series of correlated, short duration, low dimensional random processes. Subset simulation reduces the computational cost by introducing appropriate intermediate failure sub-domains to express the low failure probability as a product of larger conditional failure probabilities. Splitting is an efficient sampling method to estimate the conditional probabilities. The proposed subset simulation with splitting not only estimates the time-dependent probability of failure at a given time but also estimates the cumulative distribution function up to that time with approximately the same cost. A vibration example involving a vehicle on a stochastic road demonstrates the advantages of the proposed approach.
Design of Nonlinear Dynamic Systems Using Surrogate Models of Derivative Functions
Authors: Deshmukh Anand P. , Allison James T.
Published: February 2014

Optimization of nonlinear (or linear state-dependent) dynamic systems often requires system simulation. In many cases the associated state derivative evaluations are computationally expensive, resulting in simulations that are significantly slower than real-time. This makes the use of optimization techniques in the design of such systems impractical. Optimization of these systems is particularly challenging in cases where control and physical systems are designed simultaneously. In this article, an efficient two-loop method, based on surrogate modeling, is proposed for solving dynamic system design problems with computationally expensive derivative functions. A surrogate model is constructed for only the derivative function instead of the complete system analysis, as is the case in previous studies. This approach addresses the most expensive element of system analysis (i.e., the derivative function), while limiting surrogate model complexity. Simulation is performed based on the surrogate derivative functions, preserving the nature of the dynamic system, and improving estimation accuracy. The inner loop solves the system optimization problem for a given derivative function surrogate model, and the outer loop updates the surrogate model based on optimization results. This solution approach presents unique challenges. For example, the surrogate model approximates derivative functions that depend on both design and state variables. As a result, the method must not only ensure accuracy of the surrogate model near the optimal design point in the design space, but also the accuracy of the model in the state space near the state trajectory that corresponds to the optimal design. This method is demonstrated using two simple design examples, followed by a wind turbine design problem. In the last example, system dynamics are modeled using a linear state-dependent model where updating the system matrix based on state and design variable changes is computationally expensive.
Development of an Electric Vehicle Hardware-in-the-Loop Emulation Platform
Authors: Mohon Sara , Venkitakrishnan Arun , Ayalew Beshah , Pisu Pierluigi
Published: February 2014

Hardware-in-the-loop emulation allows for rapid testing of new control algorithms and hardware components without the need for a full vehicle prototype. This paper outlines an electric vehicle emulation platform consisting of hardware and simulation components carefully integrated together in order to emulate the operation of the vehicle’s powertrain. The main hardware components of the platform are two AC synchronous induction motors and their inverters/controllers, a rotary torque sensor, a battery pack, a programmable DC power supply, and a programmable DC load. The simulation components consist of a real-time data acquisition system with a control design and modeling interface. The control structure consists of speed and torque control mode selections for the two motors, vehicle and driver simulation models, as well as a feedforward component that improved the operation of the emulation platform during a typical EV drive cycle.
Evaluating the Performance of Constraint Formulations for Multibody Dynamics Simulation
Authors: Flickinger Daniel Montrallo , Williams Jedediyah , Trinkle Jeffrey C.
Published: February 2014

Contemporary software systems used in the dynamic simulation of rigid bodies suffer from problems in accuracy, performance, and robustness. Significant allowances for parameter tuning, coupled with the careful implementation of a broad phase collision detection scheme is required to make dynamic simulation useful for practical applications. A geometrically accurate constraint formulation, the Polyhedral Exact Geometry method, is presented. The Polyhedral Exact Geometry formulation is similar to the well-known Stewart-Trinkle formulation, but extended to produce unilateral constraints that are geometrically correct in cases where polyhedral bodies have a locally non-convex free space. The PEG method is less dependent on broad-phase collision detection or system tuning than similar methods, demonstrated by several examples.

Uncomplicated benchmark examples are presented to analyze and compare the new Polyhedral Exact Geometry formulation with the well-known Stewart-Trinkle and Anitescu-Potra methods. The behavior and performance for the methods are discussed. This includes specific cases where contemporary methods fail to match theorized and observed system states in simulation, and how they are ameliorated by PEG.
Creating a Domain Ontology to Support the Numerical Models Exchange Between Suppliers and Users in a Complex System Design
Authors: Sirin Göknur , Coatanéa Eric , Yannou Bernard , Landel Eric
Published: February 2014

Complex product development processes are evolving towards simulation driven design which leads to many heterogeneous computational models and design teams that interact with each other. However, this interaction creates a bottleneck for communication and models reuse throughout the design process because, very often, the model provider (i.e. analysts) and model users (i.e. designers) do not have the same level of understanding. In addition, the tools such as PDM (Product Data Management) or SDM (Simulation Data Management) consider the numerical models as black-box documents and they cannot access or link parameters and variables of models. The poverty of semantics in terms of simulation logics and design leads to a lack of interoperability between the contributing disciplinary simulation components, herein called numerical models. To reinforce this semantics, it is necessary to create a semantically-rich model characterization support to reduce knowledge gap between model provider and user, and to achieve a higher level of reuse. This work aims to introduce the first necessary step, herein, creation of domain ontology for formally characterizing reusable numerical model. Based on this common vocabulary, in automotive context, a Model Identity Card (MIC) is developed as an intermediate support which characterizes a model into five attributes; Physical Object, Interface, Methods, Means Usage, Validation and Verification. The MIC is illustrated with a Vehicle Thermic Comfort model example and a computer interface is developed to collect a series of representative MICs in a database.
The Uncertainty Elimination in Discrete Topology Optimization of Compliant Mechanisms
Authors: Zhou Hong , Kandala Satya Raviteja
Published: February 2014

Topology uncertainty leads to different topology solutions and makes topology optimization ambiguous. Point connection and grey cell might cause topology uncertainty. They are both eradicated when hybrid discretization model is used for discrete topology optimization. A common topology uncertainty in the current discrete topology optimization stems from mesh dependence. The topology solution of an optimized compliant mechanism might be uncertain when its design domain is discretized differently. To eliminate topology uncertainty from mesh dependence, the genus based topology optimization strategy is introduced in this paper. The topology of a compliant mechanism is defined by its genus which is the number of holes in the compliant mechanism. With this strategy, the genus of an optimized compliant mechanism is actively controlled during its topology optimization process. There is no topology uncertainty when this strategy is incorporated into discrete topology optimization. The introduced topology optimization strategy is demonstrated by examples with different degrees of genus.
Creative Exploration of Scaled Product Family 3D Models Using Gesture Based Conceptual Computer Aided Design (C-CAD) Tool
Authors: Jaiswal Prakhar , Bajad Anurag Baburao , Nanjundaswamy Vishwas Grama , Verma Anoop , Rai Rahul
Published: February 2014

The concepts of scale and platform based product family are being used by many companies to meet the customization needs of customers. Research in the area of product family design predominantly focuses on optimization frameworks. There is a lack of creative conceptual computer-aided 3D modeling tools for product family design exploration. In this paper, a gesture-based conceptual computer-aided design (C-CAD) exploration tool for scaled 3D product family models is presented. The proposed gesture-based C-CAD allows for easy, natural, and intuitive modification of 3D objects to create scaled 3D product family models. The input 3D model for conceptual design exploration purposes are obtained in two ways: (a) 3D model is generated by scanning an existing product using depth sensing (RGB-D) camera, and (b) 3D models available in large online repository such as Google Warehouse and TurboSquid are used as-is. Hand gestures recognized using the DepthSense® 311 (RGB-D) camera from SoftKinetic® are used in conjunction with Principal Component Analysis (PCA) based geometric algorithms to enable the interactive scaling of inputted 3D models. The efficacy of the proposed method is demonstrated through multiple example problems. The proposed method of 3D model exploration is most useful for product designs that are scaled variants.
The Effect of Collaborative Stimulation on Design Novelty
Authors: Sauder Jonathan , Lian Erin , Jin Yan
Published: February 2014

Many times when working together, designers feel they are inspired by each other. This effect can be explained by collaborative stimulation, occurring when the design entities or questions stimulate generative cognitive processes. To this point, four types of collaborative stimulation have been identified: prompting, seeding, clarifying and correcting, through observations in collaborative design settings by retrospective protocol analysis. Consistent relationships between collaborative stimulation and the cognitive processes they stimulate have also been identified. However, impact of collaborative stimulation on the “quality” of design entities, or the ideas produced, remains unknown. This paper identifies the novelty of design entities in the collaborative setting, and compares those which resulted directly from collaborative stimulation to those which were created by individuals working alone. It was found the collaborative stimulation types of seeding and correcting resulted in the greatest increases in novelty of design entities. This finding indicates that these types of collaborative stimulation tend to stimulate novelty. Interventions are suggested to encourage seeding and correcting in the design process.
An Energy-Based Design Approach for a Meso-Structure With High Shear Flexure
Authors: Shankar Prabhu , Fazelpour Mohammad , Summers Joshua D.
Published: February 2014

This paper presents a design approach for developing meso-structure for high shear flexure in considering distribution of strain energy for a unit cell. Currently, flexible components are often designed with elastomers to take advantage of their unique properties of low shear modulus and high elongation. However, elastomers exhibit high loss modulus at a high frequency when they are subjected to cyclic loading. As a design requirement to find an alternative material in one of the sub systems in the extraterrestrial rover, materials with high elongation but low energy loss is investigated using a meso-structure design approach. In this paper, an approach to design a meso-structure exhibiting shear flexure is developed by conducting comparative studies of shear flexure on three equivalent configurations: auxetic, honeycomb, and sinusoidal. Based on this comparative study, a new hypothesis is proposed that specific strain energy distribution pattern in these meso-structure has a direct impact on the high shear flexure performance. This proposition is verified by developing a new meso-structure, termed ‘S’-Type, which is compared with auxetic and sinusoidal auxetic meso-structures on their shear flexure ability. It is shown from this comparative analysis that the ‘S’-Type meso-structure exhibits higher shear flexure than the other two meso-structures at 5, 10, 20, and 40 MPa of effective shear moduli. Hence, based on this result, a four-step design approach is proposed to design future meso-structures with high shear flexure.
Correlating Problem/Process Exam Question Complexity to Anticipated Effort: A Modeling Protocol
Authors: Thoe Samantha , Summers Joshua D.
Published: February 2014

This paper presents the initial investigation of the use of complexity as a surrogate for problem difficulty in predicting the effort or point value of an exam problem. In previous research, complexity of graph-based models has been used to predict market value of products using function models and to predict assembly time from connectivity graphs. This research investigates the potential of applying graphical representations and complexity metrics for exam problem solutions using expert assigned values as an appropriate method to offer point values for new exam questions. The factors and sources of problem difficulty are examined and compared to the structural complexity of a graphical representation of the problem solution. Specifically, this paper presents a protocol for developing the graphical representation. Multiple participants used the protocol to create graphical models of three exam questions to test and validate the usability of the protocol. A secondary protocol was tested to improve the rater agreement for use of the protocol. This protocol will be used for transforming exam problems into graphical models that can be analyzed with the connectivity complexity metrics. These metrics will be used to create predictive models for point assignments based on historical data.
Local Fractional Fourier Series With Applications to Representations of Fractal Signals
Authors: Baleanu Dumitru , Yang Xiao-Jun
Published: February 2014

In this paper we discuss the local fractional Fourier series representations of fractal signals. Fractal signal processes are described within the local fractional integral operator. Four examples are presented in order to illustrate the developed technique.
Multi-Aspect Study of Mass Customization in the Context of Cyber-Physical Consumer Durables
Authors: Pourtalebi Shahab , Horváth Imre , Opiyo Eliab
Published: February 2014

A multi-faceted concept of customizing products and services, mass customization (MC), extends to multiple levels and to wide and diverse approaches and aspects. Although there are many related literature, the principles and technologies of mass customization of cyber-physical systems (CPSs), and in particular cyber-physical consumer durables (CPCDs), have not received enough attention. Unique characteristics of CPCDs make them difficult to be customized by using conventional MC approaches. This paper reports on the conduct and the results of a critical survey towards an in depth understanding of existing MC approaches. As a first step, a comprehensive reasoning model was created, which identified methodology, product life cycle, actors, artifact, and affordances as orthonormal domains of knowledge related to MC. Then, a different classification of MC approaches has been developed in order to provide a better resolution for product life cycle and more explicitly definite MC approaches. The outcome of our survey and analysis shows that although conventional MC approaches offer many applicable principles, none of these approaches, individually, is able to fulfill all the requirements for MC of CPCDs — therefore a novel approach is needed. Development of a novel approach would entail reformulation of applicable principles and generation of new ones. The survey revealed that more focused research is needed to come up with appropriate MC principles that focus on specific families of CPCDs.
A Simulation Based Approach to Automate Event Tree Generation for Early Complex System Designs
Authors: Papakonstantinou Nikolaos , Sierla Seppo , O’Halloran Bryan , Tumer Irem Y.
Published: February 2014

The Functional Failure Identification and Propagation (FFIP) risk assessment method has been proposed in past research for the evaluation of early system designs. Extensions of the method have been proposed in prior work to assess a set of system designs, in which there are several alternatives for component parameter values or for the configuration of components and software algorithms. A disadvantage of the method is that a single critical event scenario must be used at a time and that the simulation results must be processed manually. In this paper, an event tree-based methodology is proposed. An event tree is used to investigate the outcome of an initiating failure event when some or all of the system’s safety functions fail to activate; each branch of the tree corresponds to a specific sequence of safety functions which have failed. In this paper, a FFIP run is automatically generated for each branch of the event tree. The method determines the consequences on the system for each branch of the tree in terms of the functional failure output of the FFIP method. In addition, a software tool has been developed to support the methodology and to assist the user to investigate the consequences of each scenario that corresponds to a branch of the event tree. The methodology is illustrated with a case study from boiling water nuclear reactor design.
Robustness Against Large Variations in Multi-Objective Optimization Problems
Authors: Wang Weijun , Caro Stéphane , Bennis Fouad
Published: February 2014

In the presence of multiple optimal solutions in multi-modal optimization problems and in multi-objective optimization problems, the designer may be interested in the robustness of those solutions to make a decision. Here, the robustness is related to the sensitivity of the performance functions to uncertainties. The uncertainty sources include the uncertainties in the design variables, in the design environment parameters, in the model of objective functions and in the designer’s preference. There exist many robustness indices in the literature that deal with small variations in the design variables and design environment parameters, but few robustness indices consider large variations. In this paper, a new robustness index is introduced to deal with large variations in the design environment parameters. The proposed index is bounded between zero and one, and measures the probability of a solution to be optimal with respect to the values of the design environment parameters. The larger the robustness index, the more robust the solution with regard to large variations in the design environment parameters. Finally, two illustrative examples are given to highlight the contributions of this paper.
Design and Optimization of a Bend-and-Sweep Compliant Mechanism
Authors: Tummala Yashwanth , Frecker Mary , Wissa Aimy , Hubbard James E.
Published: February 2014

A novel contact aided compliant mechanism called a bend-and-sweep compliant mechanism is presented. This mechanism has tailorable nonlinear stiffness properties in two orthogonal directions. The fundamental element of this compliant mechanism is the Angled Compliant Joint (ACJ), and the geometric parameters determine the stiffness. This paper presents the design and optimization of such a compliant mechanism.

A multi-objective optimization problem was formulated for design optimization of the bend-and-sweep compliant mechanism. The objectives of the optimization problem were to maximize the bending and sweep displacements while minimizing the von Mises stress and mass of each mechanism. This optimization problem was solved using NSGA-II (a genetic algorithm). The results of this optimization for a single ACJ during upstroke and downstroke are presented. Results of two different loading conditions used during optimization of a single ACJ for upstroke are presented. Finally, optimization results comparing the performance of compliant mechanisms with one and two ACJs are also presented. It can be inferred from these results that the number of ACJs and the design of each ACJ determines the stiffness of the bend-and-sweep compliant mechanism. These mechanisms can be used in various applications.

Ornithopters or flapping wing unmanned aerial vehicles have unique potential to revolutionize both civil and military applications. The overall goal of this research is to improve the performance of such ornithopters by passively morphing their wings. Passive wing morphing of ornithopters can be achieved by inserting contact-aided compliant mechanisms in the leading edge wing spar. Previously the authors have shown that bending of ornithopter wings can be achieved by integrating a one degree of freedom contact aided compliant mechanism called a compliant spine. The spine was inserted into the leading edge spar and successful flight testing has shown that passive wing bending in ornithopters is feasible and results in significant improvements in lift and thrust. In order to achieve a bio-inspired wing gait called continuous vortex gait, the wings of the ornithopter need to bend, sweep, and twist simultaneously. This can be achieved by using the bend-and-sweep compliant presented in this paper.
Kinematic and Stiffness Analysis of an Origami-Type Carton
Authors: Qiu C. , Aminzadeh Vahid , Dai Jian S.
Published: February 2014

This paper investigates the stiffness characteristics of an origami-type carton, which can be modeled into an equivalent mechanism by considering creases as revolute joints and panels as links. Stiffness characteristics of a single crease is investigated regarding its relationships with folding angular velocity and crease length. Based on the kinematic analysis of carton folding, the aggregated stiffness is obtained by integrating the individual crease stiffness into the equivalent mechanism. Finally experiment results of carton folding manipulation are obtained, and comparisons between the mathematical model and experimental data show that the model predicts the carton’s behaviour well.
Stability Properties and Optimization of Multi-Cutter Turning Operations
Authors: Reith Marta J. , Bachrathy Daniel , Stepan Gabor
Published: February 2014

Multi-cutter turning systems offer huge potential to raise productivity in the manufacturing process of cylindrical parts. The application of a multi-cutter turning head increases cutting performance, material removal rate, since the advance rate is multiplied by the number of cutters involved. Another reason to apply the multi-cutter turning technology is to ensure high feasible accuracy, which is one of the most important quality measures of cutting operations. Furthermore, adverse chatter vibrations caused by the regenerative effect can also be eliminated through the application of optimized multi-cutters. The aim of this study is to investigate the stability properties of multi-cutter turning operations. It is shown that the application of dynamically uncoupled cutters with identical dynamic properties will not improve the stability properties of the system, however, the usage of cutters with different modal parameters — especially finding the optimal ratio of stiffness values of different cutters — will expand stable area in the stability charts, thus ensuring more flexibility and a wider range of stable operational parameters available for the machinist. This study proves that the stability properties of a multi-cutter turning system using dynamically uncoupled cutters are equal to the stability properties of a system using a single cutter with many degrees of freedom.
Accommodating Thickness in Origami-Based Deployable Arrays
Authors: Zirbel Shannon A. , Magleby Spencer P. , Howell Larry L. , Lang Robert J. , Thomson Mark W. , Sigel Deborah A. , Walkemeyer Phillip E. , Trease Brian P.
Published: February 2014

The purpose of this work is to create deployment systems with a large ratio of stowed-to-deployed diameter. Deployment from a compact form to a final flat state can be achieved through origami-inspired folding of panels. There are many models capable of this motion when folded in a material with negligible thickness; however, when the application requires the folding of thick, rigid panels, attention must be paid to the effect of material thickness not only on the final folded state, but also during the folding motion (i.e., the panels must not be required to flex to attain the final folded form). The objective is to develop new methods for deployment from a compact folded form to a large circular array (or other final form). This paper describes a mathematical model for modifying the pattern to accommodate material thickness in the context of the design, modeling, and testing of a deployable system inspired by an origami six-sided flasher model. The model is demonstrated in hardware as a 1/20th scale prototype of a deployable solar array for space applications. The resulting prototype has a ratio of stowed-to-deployed diameter of 9.2 (or 1.25 m deployed outer diameter to 0.136 m stowed outer diameter).