bluuebunny/crossref_metadata_2025 huggingface dataset:
A Pillar of Mechanical Engineering Design Education in Australia: 25 Years of the Warman Design and Build Competition
Authors: Smith Warren F.
Published: February 2014

The “Warman Design and Build Competition”, running across Australasian Universities, is now in its 26th year in 2013. Presented in this paper is a brief history of the competition, documenting the objectives, yearly scenarios, key contributors and champion Universities since its beginning in 1988. Assuming the competition has reached the majority of mechanical and related discipline engineering students in that time, it is fair to say that this competition, as a vehicle of the National Committee on Engineering Design, has served to shape Australasian engineering education in an enduring way. The philosophy of the Warman Design and Build Competition and some of the challenges of running it are described in this perspective by its coordinator since 2003. In particular, the need is for the competition to work effectively across a wide range of student group ability. Not every group engaging with the competition will be competitive nationally, yet all should learn positively from the experience. Reported also in this paper is the collective feedback from the campus organizers in respect to their use of the competition as an educational experience in their classrooms. Each University participating uses the competition differently with respect to student assessment and the support students receive. However, all academic campus organizer responses suggest that the competition supports their own and their institutional learning objectives very well. While the project scenarios have varied widely over the years, the intent to challenge 2nd year university (predominantly mechanical) engineering students with an open-ended statement of requirements in a practical and experiential exercise has been a constant. Students are faced with understanding their opportunity and their client’s value system as expressed in a scoring algorithm. They are required to conceive, construct and demonstrate their device with limited prior knowledge and experience, and the learning outcomes clearly impact their appreciation for teamwork, leadership and product realization.
Visual HDMR Model Refinement Through Iterative Interaction
Authors: Cutbill Adam , Hajikolaei Kambiz Haji , Wang G. Gary
Published: February 2014

In engineering design, time-consuming simulations may be needed to find the input-output relationship of a system. High Dimensional Model Representation (HDMR) alleviates the need for intensive simulation by approximating the system’s design space with a surrogate model. Although HDMR can provide an overview, specific regions of interest to the designer may require higher accuracy. This paper presents a tool to visualize and interactively improve HDMR accuracy in specified regions of the design space. Regions of the HDMR are selected by iterative brushing in two-dimensional scatterplot planes. Once a region is chosen, designers may concentrate sampling within its bounds to improve the model locally. Regions can be also improved by modeling the error with a localized radial basis function (RBF) metamodel. The effect of local refinement was further evaluated with localized performance metrics. Testing of the tool shows that it can effectively display and improve HDMR models in regions of interest, if there are variables which have a dominating influence on the output.
Inverse Surfacelet Transform for Image Reconstruction With Prior Knowledge
Authors: Huang Wei , Wang Yan , Rosen David W.
Published: February 2014

Image reconstruction is the transformation process from some other data forms to image pixels. It can be utilized as a method to retrieve material composition information in materials characterization and design. In our previous work, a so-called surfacelet model was proposed to construct the geometric boundary and internal material distribution of heterogeneous materials at the same time. A surfacelet transform is able to efficiently represent boundary information in images of materials. In this paper, new constrained-conjugate-gradient-based image reconstruction methods are proposed as the inverse surfacelet transform. With geometric constraints on internal boundaries of materials, the proposed method is able to automatically identify the locations and orientations of the internal boundaries based on prior knowledge so as to reconstruct material composition with incomplete data.
Design for Micro-Enterprise: An Approach to Product Design for Emerging Markets
Authors: Austin-Breneman Jesse , Yang Maria
Published: February 2014

Product design for emerging markets in the developing world is a rapidly growing field due to a steadily increasing market and an interest in profitably transforming consumer quality of life for this population. Economic and cultural barriers as well as other constraints present a daunting challenge for designers working in this area. This study documents current best practices and proposes a framework for future designers with a focus on creating products that foster micro-enterprise. These guidelines are drawn from existing literature and interviews with practicing designers of products for emerging markets. Four case studies are presented ranging across several product categories.
The Influence of Timing in Exploratory Prototyping and Other Activities in Design Projects
Authors: Häggman Anders , Honda Tomonori , Yang Maria C.
Published: February 2014

The importance of prototyping in the design process has been widely recognized, but less research emphasis has been placed on the appropriate timing and detail of so-called “throwaway” prototyping during the preliminary design phase. Based on a study of mid-career professional graduate students, statistically significant correlations were found between the time such prototypes were created and design outcome. Building prototypes early on in the design process, or performing additional rounds of benchmarking and user interaction later on during the project (in addition to the typical early stage efforts), correlated with better design outcome, although the total time spent on these activities did not. The correlation between project presentations and reviewer scores are also touched upon. These findings suggest that the timing of design activities is more important than the time spent on them.
Analysis of Polymer Micro Fibers: A Smoothed Particle Hydrodynamics Approach
Authors: Cramer Nick , Teodorescu M.
Published: February 2014

The nanofibrillar array of a Gecko inspired Synthetic Adhesive (GSA) adheres to a surfaces when fibers undergo deformations of both the stems and the tip. The GSA’s show interesting changes in effectiveness dependent on use patterns, preloads, and material types, amongst other parameters. The polymers fibers also, display plastic creep even at relatively low strain rates and stresses below plastic yield. Therefore, a suitable numerical solution, which predicts the fiber geometry, must consider not only the initial shape of the fiber, but also the fiber progressive deformation (local and global) and the influence this has on the local mechanical properties (elastic, viscoelastic, strain hardening/softening and plastic flow). The localized mechanical properties are difficult to calculate using traditional methods because of the nonlinearities associated with viscoelastic effects, the large deformations, and the variable boundary conditions. However, the variable boundary conditions make a mesh free modeling method ideal. Smooth Particle Hydrodynamics (SPH) is one of the most prominent mesh free Lagrange method, which takes a set particle and uses particle kinematics, density gradients, and material properties to determine the interaction between particles.

As a first step towards modeling the behavior of a fibrillar adhesive surface, this paper focuses on the modeling of a single polymer fiber. The single micro fiber will be subjected to similar conditions to what it would see as part of an array. This will allow the SPH method of simulation to be critiqued for its further use in simulating polymer microfiber. While the localized mechanical properties of the polymer, which depend on viscoelastic effect and other nonlinear phenomena, are difficult to determine analytically. The modeling technique can be compared to standard analytical methods for global parameters. It was found that the SPH method was able to appropriately model the effect of various scenarios on the mechanical deformation and resonance of a polymer microfiber. Further more the friction force for the fiber on glass was calculated as were the localized fiber velocities and stresses.
Synthesis of a Stephenson II Function Generator for Eight Precision Positions
Authors: Plecnik Mark M. , McCarthy J. Michael
Published: February 2014

This paper presents a synthesis methodology for a Stephenson II six-bar function generator that provides eight accuracy points, that is it ensures the input and output angles of the linkage match at eight pairs of specified values. A complex number formulation of the two loop equations of the linkage and a normalization condition are used to form the synthesis equations, resulting in 22 equations in 22 unknowns. These equations are solved using the numerical homotopy continuation solver, Bertini. The approach is illustrated with an example.
The Difficulty of Modelling Damping in Linear Dynamic Systems
Authors: Goyder Hugh
Published: February 2014

The consequences of including damping in linear dynamic systems are investigated. One unexpected consequence is that, unlike an undamped system, modes cannot be found which uncouple the system and can be considered individually. In particular, most damped modes are a source of energy even though only passive damping is being considered. The methodology used is to investigate various sources of damping that have analytical models thus avoiding a dependence on measured data. It is suggested that all damping can be categorised into one of three types which have descriptions in terms of complex variables as i) off-axis pole pairs, ii) symmetry axis poles and iii) symmetry axis branch cuts. One physical example for each type of damping mechanism is identified and analysed. The types of damping covered include viscoelastic materials as well as combinations of dampers and springs in multi-degree of freedom configurations. An important physical model is that of the semi-infinite beam which takes energy off to infinity as well as adding stiffness or inertia to a structure.
Modeling Infinitely Long Flexible Railroad Tracks Using Moving Modes and Krylov Subspaces Techniques
Authors: Recuero Antonio M. , Escalona José L.
Published: February 2014

This paper presents a method to model the flexibility of railroad tracks for the dynamic analysis of vehicle-track interaction. In addition to being a complex structure, the flexible track is infinitely long and shows small areas of deformation whose position moves with time. Due to these properties, the efficient modeling of the track as a flexible body in a multibody system formalism is a challenging problem. In this work the model is developed using the moving modes method in combination with Krylov subspaces techniques. The moving modes method that was previously presented by the authors defines the deformation modes in a trajectory frame whose position changes with respect to the flexible track. In this paper the moving modes are selected from a detailed finite element model of the track and a model order reduction technique based on Krylov subspaces. These modes of deformation are adequate to be selected as moving modes since they affect a small area of the flexible body and they are obtained by assuming the load distribution that actually takes place during the dynamic interaction. However, the most interesting property of the Krylov subspace modes is that they can be selected such that the frequency response function of the reduced order model matches that of the full model with the desired degree of accuracy. In this paper a multibody formulation of railroad vehicles and flexible tracks based on the trajectory frame is presented and applied to the numerical simulation of a full railroad car on a track with geometric irregularities.
Estimating an Electric Vehicle’s “Distance to Empty” Using Both Past and Future Route Information
Authors: Rodgers Lennon , Frey Daniel , Wilhelm Erik
Published: February 2014

An electric vehicle’s Distance to Empty (DTE) is defined as the actual distance the vehicle can be driven before recharging is required. A real-time estimate is commonly displayed on the vehicle’s electronic instrument cluster and is used by the driver to plan their route. It is proved in this paper that the challenge for any DTE estimation algorithm is to accurately predict the future energy consumption of a vehicle. Future energy can be predicted reliably if either (i) future energy consumption is sufficiently similar to the past or (ii) applicable information about the future is known beforehand. A stochastic simulation was used to show that the average energy use (Wh/km) measured over the past ∼300 km often does an adequate job at predicting future energy use. A conventional DTE algorithm assumes this condition by “blending” both a long- and short-term average of past energy use. However, significant changes in driving conditions (e.g. traffic or auxiliary energy use) for sustained periods of time can cause large errors in DTE estimates. This paper showed that DTE error can be reduced if those future changes are detected beforehand by obtaining route information from the driver. For example, if the driver provides their destination(s) beforehand, a navigation system could obtain route, traffic and weather information via the internet and use this information to improve the DTE estimate. A multivariate linear regression model was derived that adjusts a historical average of energy consumption based on estimated changes in speeds, traffic and temperature. This method utilizes the measuring ability of the vehicle and thus does not require complex physics-based models. The algorithm could be implemented as a cloud-based mobile phone application since it is computationally light and the model is fitted using historical driving data. Finally, the algorithms were compared using a stochastic vehicle simulation and it was shown that incorporating future route information can significantly reduce DTE error.
A Method for Multiaxial Fatigue Reliability Analysis Based on Mixed Weibull Distribution
Authors: Ling Dan , Huang Hong-Zhong , Wang Song , Wu Chuan-hao , Zhu Shun-peng , Zhang Xiao-Ling
Published: February 2014

The fatigue life of mechanical element is a random variable in nature following some kind of statistical distribution.

In this paper, a method for reliability life prediction considering life randomness is proposed. Firstly, the Smith-Watson-Topper (SWT) model is used to describe the relationship of the maximum normal stress and strain range on the critical plane. Secondly, the maximum normal stress and strain range on the critical plane are calculated by finite element analysis. Thirdly, fatigue life samples are generated using Monte Carlo simulation method, and the mixed Weibull distribution is used to model the distribution of fatigue life of turbine discs. Finally, the proposed method is validated by comparing the prediction results from the proposed method, the observed cumulative failure probability based on median rank, and the standard two-parameter Weibull distribution.
Period-3 Motions and Bifurcation in a Softenning Duffing Oscillator
Authors: Luo Albert C. J. , Huang Jianzhe
Published: February 2014

In this paper, analytical solutions for period-3 motions in the periodically forced softening Duffing oscillator are developed by the harmonic balance method. From the Hopf bifurcation of period-3 motions, period-6 motions can be analytically determined. Numerical simulations for stable period-3 motions are completed and the corresponding harmonic amplitude spectrums are presented.
A Deterministic and Probabilistic Approach for Robust Optimal Design of a 6-DOF Haptic Device
Authors: Ahmad Aftab , Andersson Kjell , Sellgren Ulf
Published: February 2014

This work suggests a two-stage approach for robust optimal design of 6-DOF haptic devices based on a sequence of deterministic and probabilistic analyses with a multi-objective genetic algorithm and the Monte-Carlo method. The presented model-based design robust optimization approach consider simultaneously the kinematic, dynamic, and kinetostatic characteristics of the device in both a constant and a dexterous workspace in order to find a set of optimal design parameter values for structural configuration and dimensioning. Design evaluation is carried out based on local and global indices, like workspace volume, quasi-static torque requirements for the actuators, kinematic isotropy, dynamic isotropy, stiffness isotropy, and natural frequencies of the device. These indices were defined based on focused kinematic, dynamic, and stiffness models. A novel procedure to evaluate local indices at a singularity-free point in the dexterous workspace is presented. The deterministic optimization approach neglects the effects from variations of design variables, e.g. due to tolerances. A Monte-Carlo simulation was carried out to obtain the response variation of the design indices when independent design parameters are simultaneously regarded as uncertain variables. It has been observed that numerical evaluation of performance indices depends of the type of workspace used during optimization. To verify the effectiveness of the proposed procedure, the performance indices were evaluated and compared in constant orientation and in dexterous workspace.
Performance Analysis and Experimental Validation of the Direct Strain Imaging Method
Authors: Iliopoulos Athanasios , Michopoulos John G. , Hermanson John C.
Published: February 2014

Direct Strain Imaging accomplishes full field measurement of the strain tensor on the surface of a deforming body, by utilizing arbitrarily oriented engineering strain measurements originating from digital imaging. In this paper an evaluation of the method’s performance with respect to its operating parameter space is presented along with a preliminary validation based on actual experiments on composite material specimens under tension. It has been shown that the method exhibits excellent accuracy characteristics and outperforms methods based on displacement differentiation.
Novel Instant Vacuum Biopsy Needle System
Authors: Barnett Andrew , McLaughlin Patrick W. , Zheng Haojun , Moore Jason Z.
Published: February 2014

This paper explores the benefits of vacuum assistance to 18 gauge needle biopsy. Current biopsy methods are inefficient or have a high rate of failure, causing the need for further painful insertions. A novel needle insertion device was developed to create the vacuum in the needle. Using multiple pneumatic cylinders, a vacuum is created inside the end-cut needle by retracting the trocar while inserting the needle. Calculations were done to determine the force caused by the vacuum. Experiments inserting the needle into porcine kidney have shown that the vacuum assistance increases cutting efficiency.
Visual Inspection or Product Dissection? The Impact of Designer-Product Interactions on Engineering Design Creativity
Authors: Toh Christine A. , Miller Scarlett R.
Published: February 2014

Designers commonly interact with products in the early phases of design in order to understand the solution space and gain inspiration for new designs. Although designer-product interaction methods such as visual inspection and product dissection are recognized as a pivotal component of the engineering design process, little data is available on how these practices affect idea generation or when these activities are most useful for inspiring creative thought. Therefore, the current study was developed to understand the impact of these activities on creative idea generation. During our controlled study, fifty-nine undergraduate engineering students were instructed to either visually inspect or physically dissect an example milk frother and then generate ideas for a new, innovative design. These concepts were then evaluated for their novelty, variety, quality and quantity. Our analysis (ANOVA) revealed that participants who physically dissected the example frother produced ideas that were more novel but of lower quality than those that simply inspected the frother. Our results provide insights on the impact of designer-product interactions on creativity and we use these findings to develop recommendations for the use and alterations of these practices for improving creativity in engineering design.
Nondegenerate Continuation Problems for the Excitation Response of Nonlinear Beam Structures
Authors: Saghafi Mehdi , Dankowicz Harry
Published: February 2014

This paper investigates the dynamics of a slender beam subjected to transverse periodic excitation. Of particular interest is the formulation of nondegenerate continuation problems that may be analyzed numerically, in order to explore the parameter-dependence of the steady-state excitation response, while accounting for geometric nonlinearities. Several candidate formulations are presented, including finite-difference (FD) and finite-element (FE) discretizations of the governing scalar, integro-partial differential boundary-value problem (BVP), as well as of a corresponding first-order-in-space, mixed formulation. As an example, a periodic BVP — obtained from a Galerkin-type, FE discretization with continuously differentiable, piecewise-polynomial trial and test functions, and an elimination of Lagrange multipliers associated with spatial boundary conditions — is analyzed to determine the beam response via numerical continuation using a MATLAB-based software suite. In the case of an FE discretization of the mixed formulation with continuous, piecewise-polynomial trial and test functions, it is shown that the choice of spatial boundary conditions may render the resultant index-1, differential-algebraic BVP equivariant under a symmetry group of state-space translations. The paper demonstrates several methods for breaking the equivariance in order to obtain a nondegenerate continuation problem, including a projection onto a symmetry-reduced state space or the introduction of an artificial continuation parameter. As is further demonstrated, an orthogonal collocation discretization in time of the BVP gives rise to ghost solutions, corresponding to arbitrary drift in the algebraic variables. This singularity is resolved by using an asymmetric discretization in time.
Load Optimization of a Nonlinear Mono-Stable Duffing-Type Harvester Operating in a White Noise Environment
Authors: He Qifan , Daqaq Mohammed F.
Published: February 2014

This paper investigates electric load optimization of nonlinear mono-stable Duffing energy harvesters subjected to white Gaussian excitations. Both symmetric and asymmetric nonlinear restoring forces are considered. Statistical linearization is utilized to obtain an approximate analytical expression for the optimal load as function of the other systems parameters. It is shown that the optimal load is dependent on the nonlinearity unless the ratio between the harvesting circuit time constant and the period of the mechanical oscillator is very large. Under optimal loading conditions, a harvester with a symmetric nonlinear restoring force can never produce more power than an equivalent linear harvester regardless of the magnitude or nature of the nonlinearity. On the other hand, asymmetries in the restoring force are shown to provide performance enhancement over an equivalent linear harvester.
HSM Spindle Model Updating With Physical Phenomena Refinements
Authors: Noel David , Le Loch Sebastien , Ritou Mathieu , Furet Benoit
Published: February 2014

The modeling of High Speed Machining (HSM) spindles is a complex task due to the numerous physical phenomena involved in the dynamic behavior. Modeling is still rarely used in the industry, although sophisticated research work has been achieved. The boundary conditions of rotor models, which correspond to the ball bearings, are crucial and difficult to define. Indeed, they affect the dynamic behavior of the rotor in a non-linear and sometimes in an unpredictable way. The aim of the paper is to determine a relevant spindle model, i.e. the adequate level of complexity. To do so, a dynamic bearing model is introduced and the axial model of a spindle is established in relation to the preloaded bearing arrangement. Then, the operating stiffness of the spindle has been obtained experimentally with a new specific device that applies axial load and measures the resulting displacement, whatever the spindle speed. The model updating with the experimental data combined to sensibility analysis have led to the model refinement with additional physical phenomena, in order to account for non-linearities observed experimentally. The parameters of the model are also identified experimentally. As a result, a relevant spindle model is obtained and validated by the good agreement between simulations and experiments.
Regenerative Effect of Tire Carcass in Simple Shimmy Models
Authors: Takács Dénes , Stépan Gábor
Published: February 2014

A simple mechanical model of the towed elastic wheel is constructed and analyzed. The lateral deformation of the tire is described by the time delayed tire model, which considers the memory effect of the contact patch. The deformation outside the contact patch is also modeled with the help of the brush model in order to take into account the effect of the deformation waves that propagate along the circumference of the tire. The mathematical model for small oscillations is composed in the form of a functional differential equation of the neutral type. The linear stability of the towed wheel is analyzed via the construction of stability charts in the plane of the relevant engineering parameters. Simulations are also presented to illustrate the regenerative effect of the tire carcass.
An Experimental Investigation of Analogy Formation Using the Engineering-to-Biology Thesaurus
Authors: Glier Michael W. , McAdams Daniel A. , Linsey Julie S.
Published: February 2014

Identifying applicable biological systems for engineering design remains a persistent challenge for bioinspired design. Previous researchers have proposed an Engineering-to-Biology thesaurus that allows designers to identify biological keywords that are functionally similar to terms in the Functional Basis. This work presents an experimental examination of the effectiveness of the Engineering-to-Biology thesaurus. A group of 100 mechanical engineering students are presented with a simple design problem: to create a device to remove the husk and silk from ears of corn. The participants read passages drawn from a large biology corpus with keywords from the Engineering-to-Biology thesaurus and indicate which passages prompt some idea for solving the design problem. The analysis of student responses indicates that students’ level of design training is not a significant factor in the number of analogies they found in the passages and that some non-random criteria is used to identify passages as useful for idea generation. Passages that rarely offer participants ideas can be reasonably well classified as either being too technical for a lay-reader to understand or lacking information on a biological system. Passages that typically offer ideas cannot be so easily classified. Finally, keywords from the Engineering-to-Biology thesaurus are examined to find that keywords very specific to biology and those that are very common words with multiple meanings are rarely contained in sentences that offer strong design inspiration.
An Exploratory Study on the Effectiveness of an Inclusive Design Tool With a Metric to Evaluate Inclusivity of Conceptual Designs
Authors: Sangelkar Shraddha , McAdams Daniel A.
Published: February 2014

Inclusive design aims to provide equitable use of a product irrespective of the user’s ability. Currently, sufficient tools are not available for practicing inclusive design. Recent research efforts have developed a method for inclusive design during the conceptual phase; the method consists of applying an empirically derived set of inclusive design rules to the actionfunction diagram of a product. This exploratory study investigates the effectiveness of this inclusive design representation scheme in generating ideas for conceptual design. An experiment is conducted in which participants generate ideas for an inclusive product design with and without the inclusive design representation scheme. The participants are also trained to use the representation scheme before implementing it in the experimental condition. Presently, there is no pre-defined metric to measure the inclusiveness of a conceptual design. Consequently, this paper introduces a metric to evaluate the inclusiveness of an idea; inter-rater reliability is also established for the metric. The ideas generated in the control and experimental conditions are compared based on quality and inclusivity. The results indicate that the inclusive design representation scheme helps the designer perform inclusive product design to a limited extent. This representation scheme is a promising method and needs detailed exploration of its individual elements. Moreover, the inclusivity metric serves as a foundational block for benchmarking various methods for inclusive design.
A Novel Deployable Mechanism With Two Decoupled Degrees of Freedom
Authors: Lu Shengnan , Zlatanov Dimiter , Ding Xilun , Molfino Rezia , Zoppi Matteo
Published: February 2014

This paper presents a novel deployable mechanism. Unlike most deployable structures, which have one degree of freedom, the proposed device can be deployed and compacted independently in two directions. This widens the range of its potential applications, including flexible industrial fixtures and deployable tents. The mechanism’s basic deployable unit is assembled by combining a scissor linkage and a Sarrus linkage. The kinematic properties of the two component linkages and the combined unit are analyzed. The new deployable mechanism is obtained by linking the deployable units. The Mobility and kinematics are analyzed. The relationship between the degree of overconstraint and the number of deployable units is derived. The magnification ratio is calculated as a function of the geometry of the link and the number of deployable units. Finally, kinematic simulations are performed to validate the proposed design and analysis.
Extracting Consumer Preference From User-Generated Content Sources Using Classification
Authors: Stone Thomas , Choi Seung-Kyum
Published: February 2014

The use of online, user-generated content for consumer preference modeling has been a recent topic of interest among the engineering and marketing communities. With the rapid growth of many different types of user-generate content sources, the tasks of reliable opinion extraction and data interpretation are critical challenges. This research investigates one of the largest and most-active content sources, Twitter, and its viability as a content source for preference modeling. Support Vector Machine (SVM) is used for sentiment classification of the messages, and a Twitter query strategy is developed to categorize messages according to product attributes and attribute levels. Over 7,000 messages are collected for a smartphone design case study. The preference modeling results are compared with those from a typical product review study, including over 2,500 product reviews. Overall, the results demonstrate that consumers do express their product opinions through Twitter; thus, this content source could potentially facilitate product design and decision-making via preference modeling.
Resilient Design of Complex Engineered Systems
Authors: Mehrpouyan Hoda , Haley Brandon , Dong Andy , Tumer Irem Y. , Hoyle Chris
Published: February 2014

This paper presents a complex network and graph spectral approach to calculate the resiliency of complex engineered systems. Resiliency is a key driver in how systems are developed to operate in an unexpected operating environment, and how systems change and respond to the environments in which they operate. This paper deduces resiliency properties of complex engineered systems based on graph spectra calculated from their adjacency matrix representations, which describes the physical connections between components in a complex engineered systems. In conjunction with the adjacency matrix, the degree and Laplacian matrices also have eigenvalue and eigenspectrum properties that can be used to calculate the resiliency of the complex engineered system. One such property of the Laplacian matrix is the algebraic connectivity. The algebraic connectivity is defined as the second smallest eigenvalue of the Laplacian matrix and is proven to be directly related to the resiliency of a complex network. Our motivation in the present work is to calculate the algebraic connectivity and other graph spectra properties to predict the resiliency of the system under design.
Observations Regarding Numerical Results Obtained by the Floquet-Method
Authors: Kniffka Till J. , Ecker Horst
Published: February 2014

Stability studies of parametrically excited systems are frequently carried out by numerical methods. Especially for LTP-systems, several such methods are known and in practical use. This study investigates and compares two methods that are both based on Floquet’s theorem.

As an introductary benchmark problem a 1-dof system is employed, which is basically a mechanical representation of the damped Mathieu-equation. The second problem to be studied in this contribution is a time-periodic 2-dof vibrational system. The system equations are transformed into a modal representation to facilitate the application and interpretation of the results obtained by different methods.

Both numerical methods are similar in the sense that a monodromy matrix for the LTP-system is calculated numerically. However, one method uses the period of the parametric excitation as the interval for establishing that matrix. The other method is based on the period of the solution, which is not known exactly.

Numerical results are computed by both methods and compared in order to work out how they can be applied efficiently.
Optimization of the Shock Mitigation Layer in the Space Frame Joints of an Armored Vehicle
Authors: Thota Jagadeep , Trabia Mohamed , O’Toole Brendan , Lee Chang-Hyun , Park Hong-Lae , Koo Man-Hoi , Lee Kyoung-Hoon , Kim Ho-bum
Published: February 2014

Armored vehicles have to survive multiple threats such as projectile or land mines. The shocks induced by these threats can harm vehicle occupants or damage sensitive electronic components. Therefore, a goal of modern armored vehicle design is to reduce transmitted shocks to critical components. In this paper, finite element (FE) models of an armored vehicle prototype having the internal space frame structure with the aforementioned features are developed. One model comprises of only solid elements, while another model is created with purely beam elements. The beam elements model is used for optimization studies whose objective is to reduce the shocks within the vehicle, due to mine blast while maintaining its overall structural integrity. The thickness of the rubberized shock mitigation layer at the joints of the space frame is varied during the optimization process. The optimization problem is solved using the Successive Heuristic Quadratic Approximation (SHQA) algorithm, which combines successive quadratic approximation with an adaptive random search while varying the bounds of the search space. The entire optimization process is carried out within the MATLAB environment. The results show that a significant reduction in the shock can be achieved using this approach.
Non-Probabilistic Based Topology Optimization Under External Load Uncertainty With Eigenvalue-Superposition of Convex Models
Authors: Zhao Xike , Gea Hae Chang , Song Wei
Published: February 2014

In this paper the Eigenvalue-Superposition of Convex Models (ESCM) based topology optimization method for solving topology optimization problems under external load uncertainties is presented. The load uncertainties are formulated using the non-probabilistic based unknown-but-bounded convex model. The sensitivities are derived and the problem is solved using gradient based algorithm. The proposed ESCM based method yields the material distribution which would optimize the worst structure response under the uncertain loads. Comparing to the deterministic based topology optimization formulation the ESCM based method provided more reasonable solutions when load uncertainties were involved. The simplicity, efficiency and versatility of the proposed ESCM based topology optimization method can be considered as a supplement to the sophisticated reliability based topology optimization methods.
Massively Parallel Discrete Element Modeling of Legged Mobility on Granular Terrain
Authors: Mukherjee Rudranarayan , Kim Isaac
Published: February 2014

Legged mobility of robotic systems is an active area of research. Quantitatively understanding mobility of these systems on natural terrain is critical for design and operations of these systems. In this paper, we present results of computational simulations of legged mobility on granular terrain using massively parallel Discrete Element Method. We model the interactions of a leg from a micro ground vehicle with sandy terrain made of polydispersed granular media. In these simulations, we model the interactions between millions of granules and the leg to quantify ground reactions and associated qualitative behaviors. The simulations are run on parallel computers to overcome the severe computational complexity of simulating these large problems in physically feasible time-frames. We are using high fidelity first-principles approaches to model emergent complex behavior that cannot otherwise be modeled. We present results from a parametric sweep where different leg speeds and penetrations are used to understand differences in ground reaction.
Thermal Control of Continuous Resistance Welding of Fiberglass Laminates for Automated Manufacturing
Authors: Mantegh Iraj , Zammar Imad , Ahmadi Mojtaba , Yousefpour Ali
Published: February 2014

Resistance welding is an alternative process to mechanical fastening and adhesive bonding in joining thermoplastic composites. The resistance welding procedure involves the Joule heating of a heating element located between two adjoining thermoplastics. The application of heat causes the material in the interface between two surfaces to melt. The current stops then and the interfacing surfaces bound under a compaction pressure, while cooling. This results in a fusion bond between the two components. A fuzzy logic controller is designed and implemented in real-time using the temperature estimate as the feedback signal. The result is a controller capable of maintaining the weld temperature within 10% of the reference temperature.
Tools for Sustainable Product Design: Review and Expectation
Authors: Peng Qingjin , Hosseinpour Arash , Gu Peihua , Fan Zhun
Published: February 2014

Sustainable product design plans the entire life cycle of a product from its raw material selection, conceptual and structural formation, manufacturing processing, and usage to its end-of-life, reuse, and recycle. The product design needs the sustainable knowledge and proper tools. Current computer-aided design systems are insufficient to represent complex relationships of product functions, structures and life cycle options. It is required for design tools to support product life cycle planning with multi-objective optimal solutions. In this paper, our experience in design of a wheelchair is used as an example to discuss the need of design tools. The aim is to define ideal tools for design of sustainable products.
Understanding Brainstorming Through Text Visualization
Authors: Chandrasegaran Senthil , Kisselburgh Lorraine , Ramani Karthik
Published: February 2014

Automated content analysis software tools have significantly aided in the study of design processes in the recent past. However, they suffer from the lack of domain knowledge and insight that a human expert can provide. In this paper, we adopt the use of text visualization techniques that help in gaining insights and identifying relevant patterns from the results obtained through a content analysis software. We motivate our approach with the observation that examining overall patterns in data aids us significantly in identifying interesting and relevant details concerning specific contexts in the data. We use the proposed approach to study the effect of adopting Laseau’s “design funnel” of alternating divergent and convergent design processes among student teams in a toy design course, and compare it to student teams that follow a free brainstorming process. We demonstrate the application of lexical dispersion plots and text concordances as a means to further examine the output of a conventional content analysis tool, and use these techniques to separate patterns from anomalies. We identify cases of concept consistency across teams using the dispersion plots, and identify cases of multiple word senses through text concordances. Finally, we present insights that were obtained through these visualizations and propose contexts for further studies of the data.
On the Parameter Identification of LuGre Tire Friction Model
Authors: Matsutani Yusuke , Sugiyama Hiroyuki
Published: February 2014

In this investigation, use of the LuGre tire friction model for the transient brake force analysis is discussed. In particular, a numerical procedure for estimating parameters for the LuGre tire force model is developed. The parameters of the distributed LuGre model are identified such that the error function of tire forces obtained using the model and experiment can be minimized. Friction parameters used in the LuGre tire force model are estimated using the characteristics curve of the friction coefficient as a function of the slip velocity first, and then the adhesion parameter is estimated using the slope around the zero slip ratio using the least square fitting. Iterative solution procedures are then employed to identify the overall model parameters using the initial estimates provided. It is demonstrated that use of the proposed numerical procedure leads to accurate prediction of the LuGre model parameters for various loading and speed conditions. Furthermore, it is demonstrated that the decrease in the peak of the brake force as the increase in the running speed can be well predicted using the transient distributed LuGre tire force model with model parameters predicated using the proposed procedure.
Structure Design, Kinematics and Grasp Constraint of a Metamorphic Robotic Hand for Meat Deboning Operation
Authors: Wei Guowu , Aminzadeh Vahid , Emmanouil Evangelos , Dai Jian S.
Published: February 2014

A four-fingered metamorphic robotic hand with a reconfigurable palm is presented in this paper with the application in deboning operation of meat industry. This robotic hand has a reconfigurable palm that generates changeable topology and augments dexterity and versatility for the hand. Mechanical structure and design of the robotic hand are presented and based on mechanism decomposition, kinematics of the metamorphic hand is investigated with closed-form solutions leading to the workspace characterization of the robotic hand. Based on the kinematics of the four-fingered metamorphic hand, utilizing product-of-exponentials formula, grasp map and grasp constraint of the hand are then formulated revealing the grasp robustness and manipulability performed by the metamorphic hand. A prototype of the four-fingered metamorphic hand is consequently fabricated and integrated with low level control and sensor systems leading to a scenario of applying the hand in the field of meat industry for deboning operation.
Interesting Eigenvalue Behavior in High-Speed Planetary Gears With Gyroscopic Effects
Authors: Cooley Christopher G. , Parker Robert G.
Published: February 2014

This study demonstrates interesting and unusual gyroscopic system eigenvalue behavior observed in a lumped-parameter planetary gear model. The focus of this work is on the eigenvalue phenomena that occur at especially high speeds rather than practical planetary gear behavior. The behaviors include calculation of exact trajectories across critical speeds, uncommon stability features near degenerate critical speeds, and unique stability transitions. These eigenvalue behaviors differ from those of other gyroscopic systems such as spinning disks, shafts, and rings, and axially-moving media.
A Nonlinear Volumetric Contact Model for Planetary Rover Wheel/Soil Interaction
Authors: Petersen Willem , McPhee John
Published: February 2014

A novel nonlinear planetary rover wheel/soil interaction model based on the properties of the penetration volume is proposed. This approach allows for fast multibody dynamic simulation of planetary rover operations by providing a closed-form solution for the contact forces. For the derivation of this contact model, the normal stress distribution under the planetary rover wheel is assumed to be a nonlinear function of the soil compression. The soil foundation with which the wheels of a robotic vehicle may interfere is represented by a continuum of hyperelastic springs. A linear version of this representation of the contact interface as a mattress of springs has been derived previously [1] and validated for the simulation of the interaction between two relatively inflexible objects [2]. However, for contacts involving large deformations, the nonlinear material properties have to be considered. In this paper, a brief summary of the elastic foundation model is given and the extension of the model to a hyperelastic foundation is provided so that it can be used for the intended purpose of modelling rover wheels in contact with soft terrain. A solution for the integral of the normal stress distribution of the rover wheels is proposed and verified in a number of numerical experiments by comparing the results against Bekker’s analytical approach. Although the focus of this work is on wheel/soil interaction, the general form of the volumetric contact modelling approach can be applied to any hyperelastic contact problem.
Information-Theoretic Characterization of Bifurcations in Nonlinear Dynamical Systems With Noise
Authors: Patil Navendu S. , Cusumano Joseph P.
Published: February 2014

Detecting bifurcations in noisy and/or high-dimensional physical systems is an important problem in nonlinear dynamics. Near bifurcations, the dynamics of even a high dimensional system is typically dominated by its behavior on a low dimensional manifold. Since the system is sensitive to perturbations near bifurcations, they can be detected by looking at the apparent deterministic structure generated by the interaction between the noise and low-dimensional dynamics. We use minimal hidden Markov models built from the noisy time series to quantify this deterministic structure at the period-doubling bifurcations in the two-well forced Duffing oscillator perturbed by noise. The apparent randomness in the system is characterized using the entropy rate of the discrete stochastic process generated by partitioning time series data. We show that as the bifurcation parameter is varied, sharp changes in the statistical complexity and the entropy rate can be used to locate incipient bifurcations.