bluuebunny/crossref_metadata_2025 huggingface dataset:
Turn-Key Solutions: Virtual Reality
Authors: Webster Rustin , Clark Alex
Published: January 2016

A little over two decades ago the opportunity to purchase a turn-key virtual reality (VR) solution was scarce. High priced head-mounted displays (HMD) and projection based technologies dominated the first VR revolution, which experienced a peak of growth and excitement in the late 1990s before fading. However, many of the early adaptors, innovators, developers, and researchers would argue that the evolution of VR did not fade. They may say that VR was a medium that was just ahead its time and was waiting for individual pieces to mature and for society to demand and push the boundaries of technology. The question facing society today is, has the time finally come when a consumer can truly purchase a turn-key VR system, which does not cost hundreds of thousands of dollars or even thousands of dollars but under a thousand dollars?
Synthesis of Constant Torque Compliant Mechanisms
Authors: Zhou Hong , Prakashah Hari Nair
Published: January 2016

Constant torque compliant mechanisms produce an output torque that does not change in a large range of input rotation. They have wide applications in aerospace, automobile, timing, gardening, medical and healthcare devices. Unlike constant force compliant mechanisms, the synthesis of constant torque compliant mechanisms has not been extensively investigated yet. In this paper, a method is presented for synthesizing constant torque compliant mechanisms that have coaxial input rotation and output torque. The same shaft is employed for both input rotation and output torque. A synthesized constant torque compliant mechanism is modeled as a set of variable width spline curves within an annular design domain formed between a rotation shaft and a fixed ring. Interpolation circles are used to define variable width spline curves. The synthesis of constant torque compliant mechanisms is systematized as optimizing the control parameters of the interpolation circles of the variable width spline curves. The presented method is demonstrated by the synthesis of constant torque compliant mechanisms that have different number of variable width spline curves in the paper.
Parametric Study of the Effect of Hinged Connectors on the Behavior of Origami-Inspired Structures Comprised of Sandwich Panels
Authors: Ballard Zach C. , Thrall Ashley P. , Smith Brian J.
Published: January 2016

Origami can be a source of inspiration for rapidly deployable, rigid wall shelters. Folding panels comprised of sandwich panels will result in a lightweight, transportable design. The design of connections between panels is critical to the overall structural performance, but can pose a major design challenge. This paper investigates the implementation of hinges for connections between panels. A single panel, comprised of fiber-reinforced polymer faces and a foam core, is restrained by aluminum hinged connectors and subjected to a uniform load. An exhaustive parametric study is performed using a numerical model previously validated by experimental data. The numerical study will facilitate better understanding of the impact of the 1) number, 2) size, and 3) relative placement of connectors on panel behavior, with data comparisons focusing on the longitudinal surface strains and displacements of the panel. This investigation culminates in a set of guidelines for hinged connectors in origami-inspired structures.
Cost-Effective Architecture for Integrating Look-Ahead Information for Commercial Vehicle Powertrains
Authors: Song Xubin , Tang Zhijun , Verma Rajeev
Published: January 2016

Fuel saving technology can be pursued in many different forms, such as gearing mechanism improvement to powertrain system optimization. With the increasing maturity and availability of sensing technologies such as GPS, motion-detecting sensors, and wireless communications, the vehicle powertrain system design community is embracing these information sources by developing mobile platforms for efficiency improvement. In this paper, a self-contained system architecture is presented that integrates the digital map database, radar senor, V2x, and mobile traffic data from the wireless network for commercial vehicle driver assistance. Each data source utilizes a different communication protocol. As such, the system integration can be challenging and may involve significant investment including engineering development if a suitable system architecture is not defined. This paper introduces a single board computer (SBC) based architecture to integrate these sensors with the powertrain system as a cost-effective implementation. Finally, some field testing data will be presented to show the benefits of using look-ahead information for improving the freight efficiency.
A Novel Method for Modeling ANCF Based Finite Element Tire Assemblies
Authors: Patel Mohil , Orzechowski Grzegorz , Tian Qiang , Shabana Ahmed A.
Published: January 2016

This paper demonstrates a new method for modeling finite element tire assemblies. The tires are modeled using the large deformation and large rotation finite element method called the Absolute Nodal Coordinate Formulation (ANCF). The recently introduced concept of the ANCF reference node along with fully parameterized ANCF plate elements is used to create a tire-rim assembly. The rigid rim inertia is represented by the ANCF reference node whereas the tire structure is represented by ANCF plate elements. Six nonlinear constraint equations ensure the rigidity of the ANCF reference node during the dynamic simulation, whereas linear connectivity conditions that are eliminated at a preprocessing stage are imposed between the reference node and the ANCF plate elements in order to connect the rim to the tire structure. Additionally, a continuum-based air pressure model is used to describe the tire air pressure forces and a point based contact model is used describe the tire-ground interaction. The tire material is characterized by a composite material model that takes into account the composite nature of the tire structure. Finally, results from the dynamic simulation of a vehicle model that is described in a single ANCF mesh and makes use of the aforementioned concepts are shown.
Fabrication and Tribological Behavior of Ni-ZrO2 Nanocomposite Coatings Prepared by Electrodeposition in Ultrasonic Field
Authors: Xue Yu-Jun , Liu Chun-Yang , Li Ji-Shun , Ma Wei , Sui Xin , Yang Fang , Ma Xi-Qiang
Published: January 2016

Ni-ZrO2 nanocomposite coatings were fabricated by electrodeposition from a modified Watt’s type electrolyte containing ZrO2 nanoparticles, where an ultrasonic field was imposed during electrodeposition process. The weight percent of ZrO2 in coatings and the surface morphology of coatings were examined. The microhardness and tribological properties of Ni-ZrO2 nanocomposite coatings and pure Ni coating were investigated. The results show that ultrasonic agitation can greatly affect the microstructure and the tribological behavior of Ni-ZrO2 nanocomposite coatings. The Ni-ZrO2 nanocomposite coatings record variable ZrO2 contents and surface morphologies by modifying ZrO2 concentration in electrolyte and ultrasonic parameters. The Ni-ZrO2 nanocomposite coating fabricated with ultrasonic agitation exhibits finer grains and more compact structure compared to pure Ni coating and the Ni-ZrO2 nanocomposite coating fabricated without ultrasonic agitation. The dispersed ZrO2 nanoparticles in coatings and ultrasonic agitation during electrodeposition synthetically contribute to the grain refinement of the coatings. Therefore, the Ni-ZrO2 nanocomposite coating by ultrasonic electrodeposition exhibits high microhardness and excellent tribological behavior. In general, the improvement in friction and wear properties of Ni-ZrO2 nanocomposite coatings can be attributed to the homogeneously dispersed ZrO2 nanoparticles and the finer-grained structure.
Spiral Toolpaths for High-Speed Machining of 2D Pockets With or Without Islands
Authors: Abrahamsen Mikkel
Published: January 2016

We describe new methods for the construction of spiral toolpaths for high-speed machining. In the simplest case, our method takes a polygon as input and a number δ > 0 and returns a spiral starting at a central point in the polygon, going around towards the boundary while morphing to the shape of the polygon. The spiral consists of linear segments and circular arcs, it is G1 continuous, it has no self-intersections, and the distance from each point on the spiral to each of the neighboring revolutions is at most δ. Our method has the advantage over previously described methods that it is easily adjustable to the case where there is an island in the polygon to be avoided by the spiral. In that case, the spiral starts at the island and morphs the island to the outer boundary of the polygon. It is shown how to apply that method to make significantly shorter spirals in polygons with no islands than what is obtained by conventional spiral toolpaths. Finally, we show how to make a spiral in a polygon with multiple islands by connecting the islands into one island.
Graph Visualization Styles for Use in Configuration Management: A User Study
Authors: Phelan Keith , Wilson Crystal , Summers Joshua D. , Kurz Mary E.
Published: January 2016

The purpose of this research is to conduct a user study in order to determine the effect of numerous variables for data representation on the ability to answer questions about the system being represented. This research will be used in the development of a computer-based visualization tool to support configuration change management. The researchers hypothesized that the graph geometry and order of the questions being asked would not affect the results, while the color of the graph and the information being represented would affect the number of correct responses. The results showed an increase in the response accuracy for the answerable questions when the amount of information displayed in the data representation was minimized. On the other hand, none of the other factors showed to have a significant effect on the accuracy of the responses. The most significant limitation in this study was the possibility for different users putting different levels of effort into answering the questions.
Numerical Methods for the Design of Meso-Structures: A Comparative Review
Authors: Yoder Marcus , Satterfield Zachary , Fazelpour Mohammad , Summers Joshua D. , Fadel Georges
Published: January 2016

Over the past decade, there has been an increase in the intentional design of meso-structured materials that are optimized to target desired material properties. This paper reviews and critically compares common numerical methodologies and optimization techniques used to design these meso-structures by analyzing the methods themselves and published applications and results. Most of the reviewed research targets mechanical material properties, including effective stiffness and crushing energy absorption. The numerical methodologies reviewed include topology and size/shape optimization methods such as homogenization, Solid Isotropic Material with Penalization, and level sets. The optimization techniques reviewed include genetic algorithms (GAs), particle swarm optimization (PSO), gradient based, and exhaustive search methods. The research reviewed shows notable patterns. The literature reveals a push to apply topology optimization in an ever-growing number of 3-dimensional applications. Additionally, researchers are beginning to apply topology optimization and size/shape optimization to multiphysics problems. The research also shows notable gaps. Although PSOs are comparable evolutionary algorithms to GAs, the use of GAs dominates over PSOs. These patterns and gaps, along with others, are discussed in terms of possible future research in the design of meso-structured materials.
Ideation Variety in Mechanical Design: Examining the Effects of Cognitive Style and Design Heuristics
Authors: Jablokow Kathryn , Teerlink Wesley , Yilmaz Seda , Daly Shanna , Silk Eli , Wehr Christian
Published: January 2016

This paper examines ideation variety as a measure of the extent to which a design solution space has been explored. We investigated one cognitive factor (cognitive style) and one cognitive intervention (Design Heuristics cards) and their relationships with students’ ideation variety, both actual and perceived. Cognitive style was measured using the Kirton Adaption-Innovation inventory (KAI), while variety scores were computed using the metrics of Nelson et al. [18] and Shah et al. [20]; an adapted form of these metrics was also explored. A group of 132 sophomore mechanical engineering students generated ideas for two design problems (one with and one without Design Heuristics cards). They sketched and described their conceptual solutions in words and assessed the variety of their solutions after ideation. Linear statistical techniques were applied to explore the relationships among the variety scores, students’ self-assessments of variety, cognitive style, quantity of ideas, and the presence of the Design Heuristics intervention. Our results show statistically significant correlations between students’ perceived variety and their variety performance, and between cognitive style and both variety performance and student perceptions.
A Software Tool for Analyzing Motions and Loading in Spatial Tensegrity Structures
Authors: Nelson Carl A.
Published: January 2016

Tensegrity structures are a unique class of mechanisms since they are overconstrained but possess mobility due to member compliance. Visualization of these systems is an important step in their design. This paper presents a simulation tool developed in the MATLAB programming environment for simulation of spatial tensegrity structures. Particularly, it allows visualization of motion (animation) of tensegrity mechanisms, as well as determination of load distributions. A compatibility-based solution approach is used to handle the constraints of loading cables in tension only. The result is a design/analysis tool useful not only for tensegrity mechanisms, but general planar and spatial mechanisms as well. This is illustrated by examples.
Dynamic Response of Nonlinear Oscillators With Hysteresis
Authors: Carboni Biagio , Lacarbonara Walter
Published: January 2016

The nonlinear features of the steady-state periodic response of hysteretic oscillators are investigated. Frequency-response curves of base-excited single-degree-of-freedom (SDOF) systems possessing different hysteretic restoring forces are numerically obtained employing a continuation procedure based on the Jacobian of the Poincaré map. The memory-dependent restoring forces are expressed as a direct summation of linear and cubic elastic components and a hysteretic part described by a modified version of the Bouc-Wen law. The resulting force-displacement curves feature a pinching around the origin. Depending on the hysteresis material parameters (which regulate the shapes of the hysteresis loops), the oscillator exhibits hardening, softening and softening-hardening behaviors in which the switching from softening to hardening takes place above certain base excitation amplitudes. A comprehensive analysis in the parameters space is performed to identify the thresholds of these different behaviors. The restoring force features here considered have been experimentally obtained by means of an original rheological device comprising assemblies of steel and shape memory wire ropes. This study is carried out also with the aim of designing the restoring forces which give rise to dynamical behaviors useful for a variety of applications.
Human Facial Soft Tissue Thickness and Mechanical Properties: A Literature Review
Authors: Xu Ming , Yang James
Published: January 2016

The finite element method (FEM) has been used in human facial modeling both in clinical and engineering fields for decades. Applications of human head modeling include the interaction of personal protective equipment with the human head and modeling head impact. In human head modeling, it is critical to have a high fidelity model including accurate thicknesses of each layer and accurate material properties. Various experiments have been performed but do not report consistent results; therefore, it is difficult to find reliable parameter values to create an effective model of the human head. This paper attempts to review and summarize the state of the art of human facial studies including experimental measurements of different layer thicknesses and the mechanical properties of these layers.
Analysis of Tank Car Deformations Using Multibody Systems and Finite Element Algorithms
Authors: Wang Liang , Shi Huailong , Shabana Ahmed A.
Published: January 2016

This investigation demonstrates the effect of the tank flexibility and plate thickness on the wheel/rail contact and the nonlinear dynamic behavior of railroad vehicles. To this end, a flexible tank is modeled using the finite element (FE) floating frame of reference formulation (FFR). The tank car finite element model is integrated with a three-dimensional railroad vehicle using computational non-linear multibody system (MBS) framework in which the wheel/rail interaction is formulated using a three-dimensional elastic contact formulation that allows for the wheel/rail separation. A triangular shell element is used to build the tank car and describe its deformation, The effect of the coupling between different modes of displacements is demonstrated by comparing the results of the simulations of the flexible and rigid tank car models. It is shown that there is a strong dynamic coupling between different modes of displacements of the tank car, the plate thickness, and the wheel/rail contact parameters. The effect of the flexibility and plate thickness of the tank car on the vehicle critical speed and dynamic characteristics are also examined.
Analysis of Miura-Type Folded and Morphing Sandwich Beams
Authors: Cash Tamsin N. , Warren Hayden S. , Gattas Joseph M.
Published: January 2016

Folded-core sandwich structures have previously been proposed as lightweight, thin-plate building elements. Such structures typically use a Miura-type core pattern and have an efficient load transfer behaviour, however cannot be used for deployable structures as the attachment of face sheets suppresses any core kinematic behaviours. This limitation can be overcome with patterned face sheets that preserve rigid-foldability and form a layered meta-material, here termed a morphing sandwich structure. The relative performance of folded and morphing sandwich structures is unknown, with few studies on the structural behaviour of either configuration. The following paper uses a new digital fabrication methodology to manufacture folded and morphing beam prototypes from 0.9mm thick steel plate. These are subjected to experimental three point bending tests to assess force-displacement behaviour and failure modes. A numerical finite element analysis is conducted to simulate the failure behaviour of the experimental beams. It is seen that the morphing beam has a 44% reduction in strength compared with the folded beam, thought to be attributable to face plate eccentricity and flexibility introduced by the morphing beam hinge connection detail.
Risk Attitude Informed Route Planning in a Simulated Planetary Rover
Authors: Short Adam R. , Van Bossuyt Douglas L.
Published: January 2016

Algorithms used in rovers for route planning often focus on finding the shortest path between two points, but rarely take into account the risk to the physical roving system of taking a path. One issue presented by route planning optimized for risk is varying risk attitudes, which can lead to vastly different routes being chosen. A risk attitude is a preference concerning acceptable levels of risk to perform a specific action. The field of Prognostics and Health Management (PHM) aims to predict and prevent mechanical failure in electrical and mechanical systems, and can be used to inform route planning by assessing risk associated with taking an action. A method has been developed and is presented in this paper for Risk Attitude Informed Route-planning (RAIR) that takes into account the calculated risk, the benefit, and risk attitude and selects the optimal route. The risks to the rover will be calculated by using rover PHM data, terrain information, and Function Failure Identification Propagation (FFIP) to determine risk of specific routes. The route is navigated incrementally by selecting the best route across a small segment and then determining the best route from the new position until the rover has reached the final destination. Results of experiments utilizing a simulated planetary rover navigating between points using RAIR are presented in this paper and the effectiveness of the method is discussed. Improved route planning through RAIR enables more autonomous navigation of hazardous and remote environments that accurately reflects the desired risk attitude without direct human planning or interaction than is currently available, thus reducing cost and time for exploratory rover missions to accomplish mission objectives.
Kinematics and Singularity Analysis of a 2R2T Parallel Mechanism
Authors: Ye Wei , Fang Yuefa , Guo Sheng
Published: January 2016

In this paper, we focus our attention on a parallel mechanism with four identical limbs and two moving platforms that are connected by a prismatic joint. Firstly, the degrees of freedom analysis of the mechanism is conducted based on the displacement group theory. Both the two moving platforms have the ability to perform two rotational and two translational motions (2R2T). Secondly, forward and inverse kinematics of the proposed mechanism is analyzed, closed-from solutions are obtained for the forward kinematics. Finally, three types of singularity, i.e. limb singularity, actuation singularity and platform singularity of the 2R2T parallel mechanism are analyzed. No limb singularity and platform singularity is found and the actuation singularity can be avoided in the design stage. The proposed mechanism has the potential to be used in industry and medical applications.
Trade-Off Analysis of System Architecture Modularity Using Design Structure Matrix
Authors: Sanaei Roozbeh , Otto Kevin , Hölttä-Otto Katja , Luo Jianxi
Published: January 2016

Product modularity has been the subject of considerable research and debate in last decade. Various metrics have been proposed in design community to measure the level of modularity and various procedures have been developed to search for ideal modular architectures. These procedures are based on either manual heuristics or computer clustering algorithms. Both approaches are aimed at finding more ideal architectures by optimizing a definition of modularity. However, different desirable criteria are often in conflict with each other and improving one criteria is not feasible without a compromising effect on another. Here, we propose a procedure to find non-dominated optimal architectures where our criteria of interest are intra-cluster and extra-cluster costs. We demonstrate an approach where a designer can consider the architecture that minimizes total cost of interactions, but also allows visualization of the trade-off in increased and decreased costs when considering nearby architectures with more or less modules. An alternative approach has been to consider granularity and hierarchical clustering schemes. We also show through an example that cost optimal architectures for any choice of number of modules are not necessarily obtainable via dividing or aggregating modules, and restricting to hierarchical clustering algorithms produces non-optimal solutions at different numbers of modules.
Design Concepts and Prototypes of Vibration Isolators Using Bi-Stable Foldable Structures
Authors: Ishida Sachiko , Uchida Hiroshi , Shimosaka Haruo , Hagiwara Ichiro
Published: January 2016

In this paper, a new vibration isolator using origami-based foldable structures is proposed and the performance of the isolator is numerically evaluated to prevent structural vibration. Next, the prototype of the isolator is introduced.

It has been known that the origami-based foldable structures based on torsional buckling pattern provide the bistable folding motions under the given conditions. We propose to apply additional linear springs to this structure. It is numerically confirmed that the structure with additional linear springs can work as a vibration isolator around the region that the total spring stiffness of the whole structure reaches the relative minimum value that is close to zero. The prototype of the isolator consists of metallic components. The structure is adequately simplified from the above-mentioned conceptual foldable structure, still maintaining the bi-stability.
Compliant Mechanism Reconfiguration Based on Position Space Concept for Reducing Parasitic Motion
Authors: Li Haiyang , Hao Guangbo
Published: January 2016

This paper introduces a compliant mechanism reconfiguration approach that can be used to minimize the parasitic motions of a compliant mechanism. This reconfiguration approach is based on the position spaces, identified by the screw theory, of independent compliant modules in a compliant mechanism system. The parasitic motions (rotations) of a compliant mechanism are first modelled associated with the variables representing any positions of the compliant modules in the position spaces. The optimal positions of the compliant modules are then obtained where the parasitic motions are reduced to minimal values. A procedure of the compliant mechanism reconfiguration approach is summarized and demonstrated using a decoupled XYZ compliant parallel mechanism as an example. The analytical results show that the parasitic motions of the XYZ compliant parallel mechanism in the example can be dramatically reduced by the position/structure reconfiguration, which is also validated by finite element analysis. The position space of a compliant module contains a number of possible positions, thus a compliant mechanism can also be efficiently reconfigured to a variety of practical patterns such as the configuration with compact structure.
Topology Optimization of Large-Displacement Flexure Hinges
Authors: Liu Min , Zhang Xianmin , Fatikow Sergej
Published: January 2016

Research on topology optimization of compliant mechanisms is extensive but the design of flexure hinges using topology optimization method is comparatively rare. This paper deals with topology optimization of flexure hinges undergoing large-displacement. The basic optimization model is developed for topology optimization of the revolute hinge. The objective function for the synthesis of large-displacement flexure hinges are proposed together with constraints function. The geometrically nonlinear behaviour of flexure hinge is modelled using the total Lagrangian finite element formulation. The equilibrium is found by using a Newton-Raphson iterative scheme. The sensitivity analysis of the objective functions are calculated by the adjoint method and the optimization problem is solved using the method of moving asymptotes (MMA). Numerical examples are used to show the validity of the proposed method and the differences between the results obtained by linear and nonlinear modelling are large.
A Plant-Wide and Function-Specific Hierarchical Functional Fault Detection and Identification (HFFDI) System for Multiple Fault Scenarios on Complex Systems
Authors: Papakonstantinou Nikolaos , Proper Scott , O’Halloran Bryan , Tumer Irem Y.
Published: January 2016

The development of Fault Detection and Identification (FDI) systems for complex mechatronic systems is a challenging process. Many quantitative and qualitative fault detection methods have been proposed in past literature. Few methods address multiple faults, instead an emphasis is placed on accurately proving a single fault exists. The omission of multiple faults regulates the capability of most fault detection methods. The Functional Failure Identification and Propagation (FFIP) framework has been utilized in past research for various applications related to fault propagation in complex systems. In this paper a Hierarchical Functional Fault Detection and Identification (HFFDI) system is proposed. The development of the HFFDI system is based on machine learning techniques, commonly used as a basis for FDI systems, and the functional system decomposition of the FFIP framework. The HFFDI is composed of a plant-wide FDI system and function-specific FDI systems. The HFFDI aims at fault identification in multiple fault scenarios using single fault data sets, when faults happen in different system functions. The methodology is applied to a case study of a generic nuclear power plant with 17 system functions. Compared with a plant-wide FDI system, in multiple fault scenarios the HFFDI gave better results for identifying one fault and also was able to identify more than one faults. The case study results show that in two fault scenarios the HFFDI was able to identify one of the faults with 79% accuracy and both faults with 13% accuracy. In three fault scenarios the HFFDI was able to identify one of the faults with 69% accuracy, two faults with 22% accuracy and all three faults with 1% accuracy.
A Novel Method of Normal Estimation for 3D Surface Reconstruction
Authors: Yuan Xiaocui , Peng Qingjin , Wu Lushen , Chen Huawei
Published: January 2016

A 3D object can be recovered from scanned point data, which requires accurate estimating normal directions of the object surface from the cloud data. Many point cloud processing algorithms rely on the accurate normal as input to generate an accurate 3D surface model. The neighborhood of a data point in its smooth region can be well approximated by a plane. However, the neighborhood of a feature point employed for the normal estimation is isotropic which would enclose points belonging to different surface patches across the sharp feature. In this paper, isotropic neighborhoods are segmented to search anisotropic neighborhoods for the accurate normal estimation. Normals and candidate feature points are first estimated by the principal component analysis (PCA) method. Neighborhoods of the feature point are then mapped into a Gaussian image. A k-means clustering algorithm is then used for the Gaussian image to identify an anisotropic sub-neighborhood for the data point. The normal of the candidate feature point is finally estimated by the anisotropic neighborhood with the PCA method. The proposed method can accurately estimate normal directions while preserving sharp features of the object surface. Applications have demonstrated the effectiveness of the proposed method.
Investigating the Size-Dependent Static and Dynamic Behavior of Circular Micro-Plates Subjected to Capillary Force
Authors: Kahrobaiyan M. H. , Vardi I. , Ahmadian M. T. , Henein S.
Published: January 2016

The size-dependent static deflection, pull-in instability and resonant frequency of a circular microplate under capillary force have been studied using modified couple stress elasticity theory. Size-dependency is a phenomenon in which the normalized quantities that classical elasticity theory predicts to be independent of the structure size, such as normalized deflection or normalized frequency, vary significantly as the structure size changes. This phenomenon has been observed in micro-scale structures such as micro-electro-mechanical-systems (MEMS). Since classical elasticity theory is unable to predict the size-dependency, non-classical elasticity theories such as modified couple stress theory have been developed recently.

In this paper, modified couple stress theory is used for the first time to develop the governing equation and boundary conditions of circular microplates when subjected to capillary force. Consideration of capillary force is important since it is has a significant role in the mechanical behavior and stability of micro-scale structures in the presence of a liquid bridge. We investigated the static deflection and pull-in instability of microplates using the Galerkin method to assess the effect of size-dependency for static deflection. We observed that, as the ratio of the microplate thickness to length scale parameter (an additional material property suggested in modified couple stress theory to capture the size-dependency) decreases, the normalized deflection of the microplate also decreases. We further observed that the difference between the normalized deflection predicted by classical elasticity theory and the one evaluated using modified couple stress theory is significant when thickness of the microplate is small, but diminishes as thickness increases. Furthermore, we defined a dimensionless number called the dimensionless capillary tension (DCT) as a function of the mechanical, geometrical and size-dependent properties of the microplate as well as the characteristics of the liquid bridge such as the contact angle and the interfacial tension. We showed that for DCT values greater than a threshold evaluated in this paper, pull-in instability happens and the microplate collapses to the substrate. Moreover, we evaluated the size-dependent resonant frequency of the microplate under capillary force as a function of the DCT and obtained the result that the frequency decreases as DCT increases. In addition, our investigation of size-dependency revealed that as the ratio of the microplate thickness to length scale parameter increases, the frequency decreases in a way that for large values of the ratio, it asymptotically approaches the value predicted by classical elasticity theory.
Weighted Orthogonal Distance Regression for Tire Models Parameters Identification
Authors: Olazagoitia JoseLuis , López Alberto
Published: January 2016

Determining the parameters in existing tire models (e.g. Magic Formula (MF)) for calculating longitudinal and lateral forces depending on the tire slip is often based on standard least squares techniques. This type of optimization minimizes the vertical differences in the ordinate axis between the test data and the chosen tire model. Although the practice is to use this type of optimization in adjusting those model parameters, it should be noted that this approach disregards the errors that have been committed in the measurement of tire slips. These inaccuracies in the measured data affect the optimum parameters of the model, producing non optimum models. This paper presents a methodology to improve the fitting of mathematical tire models on available test data, taking into account the vertical errors together with errors in the independent variable.
FEA Tire Modeling and Validation Techniques
Authors: Marjani Mehrsa , El-Gindy Moustafa , Philipps David , Öijer Fredrik , Johansson Inge
Published: January 2016

Recent advances in power and efficiency of computerized modeling methods has made it easier to develop accurate tire models. These newer models are now created with such accuracy that it has become easy to predict the experimental tire’s behavior and characteristics. These models are helpful with determining tire, tire-road, and tire-soil interaction properties. By creating virtual models, the overall capital for research and development can be reduced as well as replacing unavailable experimental tires for research.

This research paper mainly focuses on the validation of computer generated FEA tire models which are then used for the prediction of the experimental tire’s rolling resistance, static and dynamic characteristics. Experimental data, such as rolling resistance and vertical acceleration are used in validation simulations in order to tune the virtual model to match the experimental tire’s behavior. The tire that was used for this research is a six-groove 445/50R22.5 FEA truck tire, which was constructed and validated over the course of this research.
Towards Inverse Estimation of Properties, Process Parameters and Residual Effects for Friction Stir Welding
Authors: Iliopoulos Athanasios , Michopoulos John G. , Lambrakos Samuel
Published: January 2016

Forward and inverse modeling of the friction stir welding (FSW) process is an important endeavor that can be used to optimize process parameters that play a significant role on achieving manufactured part specification requirements. One such requirement is the minimization of permanent deformation induced by the plastically deformed zone close and inside the stirred zone. However, at the same time modeling FSW requires the estimation of process parameters that are not directly measurable. In this work we present a computational framework for applying an inverse approach for the heat conduction equation with experimentally guided volume heat source term that can be used to identify such parameters and subsequently use them for solving the associated forward coupled thermo-plastic problem in a Lagrangian frame of reference. We demonstrate the versatility of our framework by determining the feasibility of determining plastic (and hence residual) deformation.
Elastic Wing Deployments in Beetles and Their Folding Mechanisms
Authors: Saito Kazuya , Okabe Yoji
Published: January 2016

Foldable hindwings in beetles are one of the ultimate deployable structures. They have sufficient strength and stiffness to tolerate 20–1000 beats per second in the flight position, although they can be folded and unfolded nearly instantly depending on the situation. This study focuses on a group of beetles that have unfolding-stable-type wings and aims to reveal their wing-folding/unfolding mechanisms. These beetles use their wing elasticity for deployment and can therefore quickly take off. First, on the basis of the reports of entomologists, the authors describe the factors related to the actuation of insect wing folding and unfolding. Then, the detailed motions involved in take-off and wing storing in ladybird beetles and rove beetles are observed by a high-speed camera. The analysis of these movies reveals the detailed processes of wing-unfolding and folding in these two species. Intrinsic elasticity plays a major role in wing development in both species. In the case of wing storing, a ladybird beetle folds its hindwings into a symmetric pattern using a simple up–down movement of the abdomen, whereas rove beetles also use their abdomens for wing-folding, but their movements are more complex, and the crease patterns are asymmetric. Finally, the characteristics of each wing-folding mechanism are summarized and the potential for engineering applications are discussed. Wing-folding/unfolding mechanisms in these insects have various unique capabilities which will provide new possibilities for designing deployable structures.
Robust Topology Design of Complex Infrastructure Systems
Authors: Piacenza Joseph R. , Proper Scott , Bozorgirad Mir Abbas , Tumer Irem Y. , Hoyle Christopher
Published: January 2016

Optimizing the topology of complex infrastructure systems can minimize the impact of cascading failures due to an initiating failure event. This paper presents a novel approach for the concept-stage design of complex infrastructure systems by integrating model-based design with network analysis to increase system robustness. This approach focuses on system performance after cascading has occurred, and examines design trade-offs of the resultant (or degraded) system state. In this research, robustness is defined as the invariability of system performance due to uncertain failure events. Where a robust network has the ability to meet minimum performance requirements despite the impact of cascading failures. This research is motivated by catastrophic complex infrastructure system failures such as the August 13th Blackout of 2003, highlighting the vulnerability of systems such as the North American Power Grid (NAPG). A mathematical model was developed using an adjacency matrix, where removing a network connection simulates uncertain failure events. Performance degradation is iteratively calculated as failures cascade throughout the system, and robustness is measured by the lack of performance variability over multiple cascading failure scenarios. Two case studies are provided: an extrapolated IEEE 14 test bus, and the Oregon State University campus power network. The overarching goal of this research is to understand key system design trade-offs between robustness, performance objectives, and cost. In addition, optimizing network topologies to mitigate performance loss during concept-stage design will enable system robustness.
An Analytical Formulation for the Lateral Support Stiffness of a Spatial Flexure Strip
Authors: Nijenhuis Marijn , Meijaard J. P. , Herder Just L. , Awtar Shorya , Brouwer Dannis M.
Published: January 2016

A flexure strip has constraint characteristics, such as stiffness properties and error motions, that limit its performance as a basic constituent of flexure mechanisms. This paper presents a framework for modeling the deformation and stiffness characteristics of general three-dimensional flexure strips that exhibit bending, shear and torsion deformation. The formulation is based on a finite strain discrete spatial beam element with refinements to account for plate-like behavior due to constrained cross-sectional warping. This framework is suited for analytical calculations thanks to the accuracy of the beam element, while its discrete nature allows for easy implementation in numeric software to serve as calculation aid. As case study, a closed-form parametric analytical expression is derived for the lateral support stiffness of a parallel flexure mechanism. This captures the deteriorating support stiffness when the mechanism moves in the intended degree of freedom. By incorporating relevant geometric nonlinearities and a warping constraint stiffening factor, an accurate load-displacement and stiffness expression for the lateral support direction is obtained. This result is verified by nonlinear finite element analysis.
Type Synthesis of a Family of 4-, 5- and 6-DOF Sea Lion Ball Mechanisms With Three Limbs
Authors: Lin Rongfu , Guo Weizhong , Gao Feng
Published: January 2016

In this paper, a family of novel mechanisms with three limbs is proposed. The novel family of mechanisms looks like a sea lion playing a ball therefore we called it the sea lion ball mechanism (SLBM). Its characteristics are described in detail below. The SLBM is composed of an upper part and a lower part connected together by three limbs in series. One of the most important advantages of SLBMs is that the translational and rotational motions are partially decoupled: the end-effector position is only determined by the inputs of the lower part, while the rotational angles are mainly determined by the inputs of the upper part. Then, the procedures for the type synthesis of SLBMs with three limbs are proposed based on the GF sets theory and the concept of virtual chain. Furthermore, according to the proposed procedure, 4-, 5- and 6-DOF SLBMs are investigated in terms of type synthesis based on a concept of upper-lower combination. The synthesis method of the upper limbs and lower limbs are presented. The PR and Pa joints are introduced to realize the functions of R and P joints to achieve more mechanisms. The six types kinematic limbs with 3T3R, 3T2R, 2T3R, 3T1R, 2T2R and 1T3R motion patterns of SLBMs are designed. Lastly, several novel 4-, 5- and 6-DOF SLBMs are proposed and sketched. The concept of the upper-lower combination may provide a new idea for type synthesis of decoupled parallel mechanism.
Motorcycle Tire Modeling
Authors: Ballo Federico , Gobbi Massimiliano , Mastinu Giampiero , Previati Giorgio , Zerboni Roberto
Published: January 2016

The knowledge of the actual distribution of the contact forces transmitted by the tire to the rim is of crucial importance for the lightweight design of motorcycles wheels.

In this paper, an analytical model of a motorcycle tire is developed and explicit formulae giving the distribution of the static radial and axial forces acting between the tyre and the rim for a given vertical load have been derived. The analytical model has been validated by means of a FE model of the tire and wheel and on the basis of indoor experimental tests.

The proposed analytical model is able to predict the radial static deflection of both a front and a rear tire for a racing motorbike with very good accuracy over a wide range of inflating pressures and vertical loads. The force distributions are in very good agreement with the results of the FE model.
Stability of Controlled Road Vehicles: A Preliminary Fundamental Study
Authors: della Rossa Fabio , Gobbi Massimiliano , Mastinu Giampiero , Piccardi Carlo , Previati Giorgio
Published: January 2016

A comparison of the lateral stability behaviour between an autonomous vehicle, a vehicle with driver and a vehicle without driver (fixed steering wheel) is made by introducing a simple mathematical model of a vehicle running on even road. The mechanical model of the vehicle has two degrees of freedom and the related equations of motion contain the nonlinear tyre characteristics. The driver is described by a well-known model proposed in the literature. The autonomous vehicle has a virtual driver (robot) that behaves substantially like a human, but with its proper reaction time and gain. The road vehicle model has been validated.

The study of vehicle stability has to be based on bifurcation analysis and a preliminary investigation is proposed here. The accurate computation of steady-state equilibria is crucial to study the stability of the three kinds of vehicles here compared. The stability of the bare vehicle without driver (fixed steering wheel) is studied in a rather complete way referring to a number of combinations of tyre characteristics. The (known) conclusion is that the understeering vehicle is stable at each lateral acceleration level and at each vehicle speed. The additional (partially unknown) conclusion is that the vehicle (model) with degradated tyres may exhibit a huge number of different bifurcations. The driver has many effects on the stability of the vehicle. One positive effect is to eliminate the many possible different equilibria of the bare vehicle and keep active one single equilibrium only. Another positive effect is to broaden the basin of attraction of stable equilibria (at least at relatively low speed). A negative effect is that, even for straight running, the driver seem introducing a subcritical Hopf bifurcation which limits the maximum forward speed of some understeering vehicles (that could run faster with fixed steering wheel). Both the mentioned positive and negative effects appear to be applicable to autonomous vehicles as well. Further studies could be useful to overcome the limitations on the stability of current autonomous vehicles that have been identified in the present research.
Knowledge Management With an Intelligent Tool for Additive Manufacturing
Authors: Eddy Douglas , Krishnamurty Sundar , Grosse Ian , Perham Maxwell , Wileden Jack , Ameri Farhad
Published: January 2016

Manufacturers face the challenge of deciding when additive manufacturing technology offers a suitable process to produce a given product. Information needed about process capabilities is constantly evolving and usually not organized well enough to support such decisions. This work introduces an ontological framework which identifies and semantically models the most applicable concepts of additive manufacturing relevant to process planning applications. Another salient feature includes the fit of this structural framework with both the new ASTM standard for additive manufacturing vocabulary and existing taxonomies for traditional manufacturing processes. Finally, within this framework we implemented description logic rules to identify the optimal set of processes for a product, the rationale for selecting this set of processes, and a logical link between a product’s features and its process plan. The reliability of the knowledge representation and its process planning capabilities are each tested and demonstrated by a case study example of the selection of the best processes to produce a steel spur gear.