bluuebunny/crossref_metadata_2025 huggingface dataset:
Topology Optimization and Dynamic Performance of a Bike Frame With Dampers
Authors: Huang Yuan Mao , Pan Jiung-Cheng
Published: June 2008

This study utilizes the topology optimization with the finite element method and the simulated annealing algorithms to optimize the structure and the dynamic performance of a bike frame with dampers. Design domains, loadings and boundary conditions of bike frames are defined. Joint locations of a damper with the front and the rear frames and the joint location of the front and the rear frames are considered as design variables. The transient response and the acceleration of a bike on a sinusoid curved road surface are analyzed. Effects of the joint locations and the stiffness of frames on the dynamic performance are studied. The structural topology of frames and joint locations of a bike are recommended to improve the dynamic performance.
Structural Topology Optimization Using Function-Oriented Elements Based on the Concept of First Order Analysis
Authors: Takezawa Akihiro , Nishiwaki Shinji , Izui Kazuhiro , Yoshimura Masataka
Published: June 2008

Computer Aided Engineering (CAE) has been successfully utilized in mechanical industries, but few mechanical design engineers use CAE tools that include structural optimization, since the development of such tools has been based on continuum mechanics that limit the provision of useful design suggestions at the initial design phase. In order to mitigate this problem, a new type of CAE based on classical structural mechanics, First Order Analysis (FOA), has been proposed. This paper presents the outcome of research concerning the development of a structural topology optimization methodology within FOA. This optimization method is constructed based on discrete and function-oriented elements such as beam and panel elements, and sequential convex programming. In addition, examples are provided to show the utility of the methodology presented here for mechanical design engineers.
Parameterization Strategy for Optimization of Shape Morphing Compliant Mechanisms Using Load Path Representation
Authors: Lu Kerr-Jia , Kota Sridhar
Published: June 2008

The distributed compliance and smooth deformation field of compliant mechanisms provide a viable means to achieve shape morphing in many systems, such as flexible antenna reflectors and morphing aircraft wings. We previously developed a systematic synthesis approach to design shape morphing compliant mechanisms using Genetic Algorithm (GA). However, the design variable definition, in fact, allows the generation of invalid designs (disconnected structures) within the GA. In this research, we developed a load path representation to include the structure connectivity information into the design variables, thus improving the GA efficiency. The number of design variables is also independent of the number of elements in the finite element model that is used to solve for the structural deformation. The shape morphing synthesis approach, incorporating this path representation, is demonstrated through two examples, followed by discussions on further refinements.
Design Process Error-Proofing: Development of Automated Error-Proofing Information Systems
Authors: Chao Lawrence P. , Ishii Kosuke
Published: June 2008

This paper presents a framework for representing and deploying error-proofs (poka-yoke) in the product development process. Information technology (IT) already plays a key role in product development through tools such as numerical computation, CAD, simulations, and process planning. Information management for error-proofing in manufacturing is also quite common in many industries. However, experts agree that many field failures and quality problems stem back to errors in engineering design. While there are many case studies on design process error-proofing, one must deploy them through leveraging engineering information systems for them to be effective. Towards this goal, this paper proposes the use of quality function deployment (QFD) to characterize potential design errors, evaluate the risks, identify effective error proofing elements, and prioritize their implementation.
Design Methodology for the Thermal Packaging of Hybrid Electronic-Mechanical Products: A Case Study on the Berkeley Emulation Engine (BEE)
Authors: Lee Roderick K. W. , Montero Michael G. , Wright Paul K.
Published: June 2008

This paper presents a design methodology for the thermal design and packaging of hybrid electronic-mechanical products. In this work, tight integration between ECAD and MCAD was achieved through the use of a web-based tool used in managing the concurrent designs, called the Domain Unified CAD Environment (DUCADE). This work also reduced the amount of time required for thermal simulation by using a web-based Design of Experiment Testbed (DOET) to systematically determine effects of varying system parameters before full-scale computational fluid dynamics (CFD) thermal modeling was performed. The design process began by proper selection of material, manufacturing process and cooling methods, based on electrical and integrated circuit design. DUCADE was then set up to monitor couplings between the various domains. This was followed by computer-aided-design and computer-aided-engineering of the mechanical package. In computer-aided-engineering, DOET was first used to determine variables that had significant effect on the thermal system response. Detailed CFD thermal simulations were then carried out in FLOTHERM only focusing on variables that the DOET determined to have strong effect. Rapid prototypes were fabricated to refine the design before final production. Each step of the cycle was tested and demonstrated through a case study on the design of the Berkeley Emulation Engine (BEE) which involved multi-disciplinary electrical, mechanical, and thermal design.
Constraint Dominance Methods Applied to the Design of a Linear Motor
Authors: Deshpande Ashish D. , Rinderle James R.
Published: June 2008

Reasoning about relationships among design constraints can facilitate objective and effective decision making at various stages of engineering design. Exploiting dominance among constraints is one particularly strong approach to simplifying design problems and to focusing designers’ attention on critical design issues. Three distinct approaches to constraint dominance identification have been reported in the literature. We lay down the basic principles of these approaches with simple examples and we apply these methods to a practical linear electric actuator design problem. The identification of dominance along with the use of Interval Propagation and Monotonicity Analysis leads to an optimal solution for a particular design configuration of the linear actuator. Identification of dominance also provides insight into the design of linear actuators, which may lead to effective decisions at the conceptual stage of the design.
Optimization of Helicopter Air Intake Scoop Design
Authors: Wang Dapeng , Wang G. Gary , Naterer Greg F.
Published: June 2008

In this paper, a global optimization technique based on the Adaptive Response Surface Method (ARSM) is integrated with a Control Volume Finite Element Method (CVFEM) for thermofluid optimization. The objective of the optimization is to improve the thermal effectiveness of an aircraft de-icing strategy by re-designing the cooling bay surface shape. By optimizing objective function in terms of the de-icing strategy and shape of the intake scoop, the best performance of the helicopter engine is achieved. This design problem is implemented on two different physical models. One model involves a heat conduction finite element analysis (FEA) process and the other combines the heat conduction and potential fluid flow FEA processes. Based on the comparison between the ARSM predicted results and the plotted objective function, it is observed that the integrated technique provides an effective method for thermofluid optimization. It also shows that the ARSM has a good flexibility to work with the computationally intensive process, e.g. CVFEM, and, potentially, could be developed and applied to the multidisciplinary design optimization (MDO) due to its open structure.
A Study on Immune Algorithms Considering Interaction of Design With Environment Properties
Authors: Miyashita Tomoyuki , Yamakawa Hiroshi
Published: June 2008

In design problems, designers have to decide many properties of products to satisfy requirements from users or market. The designers also have to consider the environment under the use of the products and the environment is often unpredictable or difficult to be determined in detail. The optimization techniques are useful to support the designers to decide the properties of the product. However, it is required before the application of the optimization techniques to formulate mathematical models and it is difficult to formulate the all properties of products, for examples preferences of the customer. In this situation, it seems to be useful to derive several solutions that equip the variety or diversity about the value of design variables or objective functions. In this paper, the new method to derive several solutions using immune algorithms is described. The proposed method equips the interaction mechanism between the design parameter and the environment parameters. Through some numerical examples of the structural design problems and job-shop scheduling problems, the effectiveness is confirmed.
On Honeycomb Parameterization for Topology Optimization of Compliant Mechanisms
Authors: Saxena Rajat , Saxena Anupam
Published: June 2008

Discrete parameterization using full or partial ground structures of truss/frame elements is not appropriate for domain representation as they do not map all points in the continuum and can lead to dangling or overlapping elements in the optimal topology. Existing continuum parameterization using units cells with holes, ranked microstructures or penalized Young’s modulus (SIMP model) mainly have problems like the appearance of checkerboard patterns and stiffness singularity regions. This is probably due to point-contact between diagonally placed cells and such regions can be avoided by using higher order elements, perimeter constraints or filtering schemes which result in additional computational load on the optimization procedures. An edge connectivity throughout is ensured when using a honeycomb representation with staggered regular hexagonal cells. In this paper, such a parameterization is employed for topology synthesis of compliant mechanisms with flexibility-stiffness and flexibility-strength multi-criteria formulations. The material connectivity is well-defined, and checkerboard and zero-stiffness singularities are not seen in numerous examples solved with honeycomb parameterization.
Suggesting Joint Limitations and Physical Parameters for Motion Generating 3 DOF Planar Chains
Authors: Perry Lauren S. , Murray Andrew P.
Published: June 2008

Synthesizing a motion generating 3-jointed planar chain, under no additional constraints, is trivial. Given a set of desired planar rigid body positions, one can select via straightforward geometric considerations the locations of the revolute (R) joints and prismatic (P) joints of a chain that will reach the positions. On the other hand, specifying constraints on joint limitations or physical parameters may result in no chains that reach the desired positions. In this paper, we study a rigid body in a set of positions in order to determine the point on the body that lies nearest a point, circle or line. Note that the point, circle or line is unknown and is determined as part of the process. The set of points formed by the rigid body point in all of its positions defines a workspace for the outermost moving pivot of the chain. By fitting a generic RPR, PRR or RRR chain’s workspace to these points, we can suggest nearly minimal joint constraints and physical parameters.
Kinetic Analysis of Planar Frictionless Mechanisms Made Simple
Authors: Abhary Kazem
Published: June 2008

A purely analytical method has been developed for the kinetic (force or kinetostatic) analysis of frictionless planar mechanisms. It employs polar notation of vectors, the principle of conservation of energy and the force equilibrium of the links. Unlike many other methods which lead to a system of several simultaneous equations, it leads to only one algebraic or one vectorial equation at a time and, interestingly, it is less time consuming that the conventional graphical methods. The method is general, comprehensive and systematic such that it could also serve as a suitable teaching technique for manual approach to the problem. It easily lends itself to automation too.
Analysis of Multiple Equilibrium Positions in Magnetostatic Field
Authors: Limaye Advait A. , King Carey W. , Campbell Matthew I.
Published: June 2008

This work is a part of a larger research project to understand the challenges in creating MultiStable Equilibrium (MSE) devices. MSE devices are those that have more than one stable position or configuration which can be maintained with no power input. The study of potential energy minima in magnetic systems can be used to create novel and efficient MSE mechanisms. This research focuses on using the magnetic energy in space as the main criteria for analysis of MSE devices. Permanent magnets are used to create a 2D magnetostatic field. The magnetic energy density in air is then plotted along a path through the field. For a piece of iron following a specified path, the stable equilibrium positions correspond to the locations of maximum air energy density. Furthermore, the stiffness at each of the equilibrium positions can be correlated to a pseudo-stiffness of the energy density. This information can help one design systems for multiple stable positions with minimal computational time and effort without simplifying the problem geometry.
Forward Kinematics of 3-GPR Planar Parallel Manipulators With Circular Rolling Contact Joints
Authors: Collins Curtis L.
Published: June 2008

In this work, we investigate the geometry and position kinematics of planar parallel manipulators composed of three GPR serial sub-chains, where G denotes a rolling contact, or geared joint, P denotes a prismatic joint, and R denotes a revolute joint. The rolling contact joints provide a passive one degree-of-freedom relative motion between the base and the prismatic links. It is shown, both theoretically and numerically, that when all the G-joints have equal circular contact profiles, there are at most 48 real forward kinematic solutions when the P joints are actuated. The solution procedure is general and can be used to predict and solve for the kinematics solutions of 3-GPR manipulators with any combination of rational contact ratios.
Design of a Self-Actuating, Traction Drive System for High-Speed Ratios
Authors: Harper Michael J. , Flugrad Donald R. , Qamhiyah Abir Z.
Published: June 2008

Traction drive systems offer unique advantages over geared systems. They will typically run quieter and they can be designed to eliminate all backlash. Furthermore, rolling elements are easy to manufacture and the rolling motion will produce very efficient power transmission. In this paper the authors describe a two-stage, self-actuating, traction drive system that has been fabricated to produce a speed ratio of 50:1. Given specific values for coefficients of friction, the geometry of each stage of the device must be designed to ensure self-actuation. In addition, dimensions of the drive rollers and output rings for the two stages must be selected to ensure that one stage does not cause the other stage to overrun.
Applying Design for Production Methods for Improved Product Development
Authors: Chincholkar Mandar M. , Hermann Jeffrey W. , Wei Yu-Feng
Published: June 2008

Design for production (DFP) refers to methods that evaluate manufacturing system performance as a function of product design variables. DFP can lead a product development team to consider changing the product design to avoid problems or improve profitability. In addition, DFP can provoke suggestions to improve the manufacturing system. This paper reviews studies that have successfully applied DFP techniques in a variety of product domains. In addition, the paper discusses how product development teams can create new DFP techniques that will help them create more profitable products. The presentation of these examples and guidelines should encourage the use of DFP and improve product development.
A Novel Web-Based Approach to Quality Function Deployment
Authors: Wang Hong-jun , Chen Xin , Zhang Ping , Zheng De-tao , Sun Jian
Published: June 2008

Quality Function Deployment (QFD), as an effective tool for customer-driven product development, has been widely adopted in manufacturing companies for many years. The main difficulties in using QFD lie in capturing the actual needs of customers, and in the conflicting conclusions provided by different experts while establishing the relationship matrix between customer requirements and engineering characteristics. This paper describes a novel approach to applying QFD. Firstly, the customer requirements are captured through Web-based technology. Secondly, the relationship matrix between customer requirements and engineering characteristics is established by handling coordinately fuzzy knowledge. Thirdly, the translation of a customer’s importance ratings into engineering weightings is carried out by fuzzy mapping technology. In order to reduce the complexity of HOQ, the less important customer requirements and engineering characteristics are identified and eliminated from the model by using α-cuts. Finally, an example using a refrigerator illustrates that the proposed approach is both available and practicable.
Internet Collaboration of 3D-CAD Design and Manufacturing for Product Development
Authors: Sakamoto Haruo , Tsuneishi Takuya , Sakamoto Masaoki
Published: June 2008

This paper describes internet collaboration of 3D-CAD design and manufacturing for product development. The product example is a small-sized wind power generator, which was actually produced. From the viewpoint of research interest, wind power generators using rare-earth material permanent magnets were studied. Through internet multi-stations collaboration, which will be realized in the very near future in industries, 3D-CAD and manufacture of a small-sized wind power generator was conducted with cooperation of the Kochi University of Technology and Sakamoto Giken Co. In order to realize the internet collaboration, a file compression software and a tool for collaboration is required. The commercially available file compression and collaboration software were tried for the product development of the small-sized wind power generator. This paper reports the example of the product development using the internet collaboration technique.
A Systematic Method for Designing Profitable Product Families
Authors: Nidamarthi Srinivas , Mechler Gu¨nther , Karandikar Harsh
Published: June 2008

Every company has the business objectives of maximizing customer choice as well as its profitability. Typically, companies address maximum customer choice through a large spectrum of variants in their products to satisfy varying customer needs. For example, a camera manufacturer may wish to offer various choices such as fixed focus, auto-focus, variable zoom, different zoom ranges, SLR, APS, and digital cameras, and in different combinations, to satisfy customers with different demands (including the price that they wish to pay). The business goal, therefore, is to design a product family that meets a wide range of customer choices but at a minimum cost so as to maximize the profit margin. These two objectives, choice and profit margin, are not as contradictory as they seem. In this paper, we show that by using a set of systematic methods a company can identify the essential design elements of a profitable product family. We have successfully applied this method in a number of product families ranging from airhandling fans to robot controllers, and from mass-produced products to project based customized products.
Remanufacturing: Impacts of Sacrificial Cylinder Liners
Authors: Krill Malte , Thurston Deborah
Published: June 2008

Remanufacturing presents tremendous potential for recovering the economic value of manufactured components, and improving the environment. Some design features make remanufacturing less expensive, and/or increase the proportion of components that can be remanufactured. For example, sacrificial components can be used to protect key parts from wear. However, tradeoffs are sometimes involved, and product designers need tools to support design for remanufacturing. This paper presents models for estimating the costs and environmental impacts of employing sacrificial components (cylinder liners) in engine blocks. These models are incorporated into a spreadsheet-based design decision tool. Three illustrative examples demonstrate that 1) remanufacturing lowers overall costs when two lifecycles are considered, 2) sacrificial cylinder liners should be employed for small (2 liter) engines, and their superiority increases with multiple remanufacturing cycles, and 3) for large engines (5.3 liter) using cylinder liners is equally preferred to not using them, with respect to both overall cost and environmental impacts.
Design Process Error-Proofing: Failure Modes and Effects Analysis of the Design Process
Authors: Chao Lawrence P. , Ishii Kosuke
Published: June 2008

This paper presents a new application of Failure Modes and Effects Analysis (FMEA) on product development processes. Our research develops error-proofing methods for product development processes to prevent serious design errors that compromise project features, time, or cost. Design process FMEA categorizes design errors in six areas: knowledge, analysis, communication, execution, change, and organization errors. The paper explains the method, illustrates it with an example, and discusses its effectiveness. The paper concludes with the proposed work to address the existing lack of a systematic approach to design process error-proofing.
Information Requirements for Cost Estimating in the Automotive Industry
Authors: Roy Rajkumar , Souchoroukov Petros , Koponen Harri S.
Published: June 2008

The automotive companies operate in a very competitive market. Competitiveness requires controlling product costs, and cost estimation is an important activity for this. Cost estimation requires quality information but the conducted research found several issues that hinder this activity, namely a lack of resources and information acquiring and validation difficulties. Data and Information requirements are a major issue in cost estimating. Research in cost estimating mainly focus on improving techniques and methodologies. There is a need to investigate the data and information requirements and corresponding sources of information for cost estimating. These issues have led to the extensive use of expert judgement. Experienced cost estimators use a variety of information resources and cost elements to create a cost estimate, and this causes communication issues. Better information is needed for both creating sound cost estimates and increasing understanding of these created cost estimates. This paper proposes a novel idea, an information infrastructure for automotive cost estimation to address the issue. The constructed Infrastructure provides relevant cost information needed to develop sound and robust cost estimates using a webportal design. It defines in depth the necessary cost information, explains why it is used and gives details where to find it and how to validate it. The research increases understanding of the cost estimation information requirements for the automotive industry.
Rapid Prototyping Using CNC Machining
Authors: Frank Matthew C. , Wysk Richard A. , Joshi Sanjay B.
Published: June 2008

Although current rapid prototyping methods have had a significant impact on product and process design, they are often limited in both accuracy and choice of suitable materials. Also, the current methods share little similarity to typical manufacturing processes. In this paper, a method for using CNC machining as a Rapid Prototyping process is described in order to exploit the creation of functional prototypes in a wide array of materials. The method uses a plurality of simple 2 1/2-D toolpaths from various orientations about an axis of rotation, in order to machine the entire surface of a part without refixturing. It is our goal to automatically create these tool paths for machining, and eliminate the complex planning traditionally associated with CNC machining. The current approach to process planning involves calculating all the necessary data from the slice information of an STL model. An overview of the CNC-RP process and the process planning methodology is presented.
Visibility Analysis for Assembly Fixture Calibration Using Screen Space Transformation
Authors: Kong Zhenyu , Huang Wenzhen , Ceglarek Dariusz
Published: June 2008

In a number of manufacturing processes, tooling installation, calibration and maintenance guarantee the precision of fixtures and play important roles towards the overall quality of products. Recently a new type of measurement equipment called “laser tracker” was developed and utilized for assembly fixture calibration to shorten calibration time and improve the accuracy of the currently used theodolite systems. Though, the calibration of assembly fixture is critical for product quality, the calibration time creates significant burden for productivity of multi-station assembly processes. In order to shorten the calibration lead time, the number of necessary calibration setups which is determined by visibility analysis needs to be minimized. This paper presents a screen space transformation based visibility analysis that allows minimizing the number of setups. The screen space transformation is applied to transform the visibility problem from 3D to 2D space, consequently the visibility problem can be solved efficiently. A case study illustrates the procedure and verifies the validity of the proposed methodology.
Base Part Identification in Mechanical Assemblies Using Interaction Graphs for Redesign Toward a Star Architecture
Authors: Steiner Mark W.
Published: June 2008

This paper explores base part identification in mechanical assemblies using interaction graphs. It presents a methodology for analyzing and migrating toward a star architecture during product redesign, where the base part is the central element in the design upon which assembly variations can be configured, thus making it possible to migrate toward modular design architecture. This paper reviews past work related to architectural orientations, part interfaces, and part connectivity. A methodology for architecture analysis during product redesign is then presented using a computer mouse example.
Effect of Tapered Guide Shape on Spaghetti Problems
Authors: Kobayashi Nobuyuki , Komaki Yoshimasa , Irie Takamune , Watanabe Masahiro
Published: June 2008

The dynamic behavior of a flexible beam that is pulled into an opening in an elastic wall with a constant velocity is studied using a mechanical model and experiments. We focus particularly on the effects of the tapered guide that is provided in front of the inlet of the wall gap on the beam behavior. We developed a finite-segment-based model for flexibility of the beam, and the nonlinear spring and damper are introduced for representing the stiffness of the inlet of the elastic wall gap and the tapered guide. Experimental investigations are conducted with FRP thin beam as the Spaghetti, and compared their results with numerical simulation results. As the results of simulation and experiment, the effects of the tapered guide angle guide length and the pulling velocity on oscillation mechanism of the Spaghetti are discussed.
Extracting Signatures for Rigid Body Motion and Modes of Coupled Vibration in Elastic Multi-Rod Mechanisms by POD Processing of the Finite Element Dynamics
Authors: Georgiou Ioannis T. , Bani-Khaled Mohammad A.
Published: June 2008

The method of Proper Orthogonal Decomposition for coupled dynamic fields is applied to systematically analyze the free dynamics, approximated by the method of finite elements, of a set of moving flexible rods and a two-rod flexible mechanism. The POD analysis identifies unique optimum degrees-of-freedom, Proper Orthogonal (PO) modes, for these systems. For moving stiff rods, the single dominant PO mode involves weak coupling of rigid body motion to deformation motion. The shapes of the PO modes for rigid body motion and vibration have invariant characteristic signatures for rigid body motion coupled to deformation motion. These signatures remain almost the same when two stiff rods are connected to form a slider-crank mechanism. The two dominant POMs of the mechanism represent rigid body mode of motion, which are coupled weakly to higher order PO modes. The weak coupling is due to the high rigidity of the rods in the mechanism.
Parallel Computing Procedure Based on DAE for Multibody Dynamics
Authors: Takahashi Yoshitaka , Shimizu Nobuyuki
Published: June 2008

Establishing a methodology of parallel computing which considers collaborative computation with other computer codes and/or softwares which may be installed in different computers is important for collaborative parallel computing with other softowares of multibody system which are developed under separate developing environments. In this paper, a fundamental parallel computing procedure is proposed by means of DAE approach in multibody dynamics. Then constraint errors in DAE are analyzed and a stabilization procedure of constrained errors is derived to be introduced into the proposed parallel computing procedure. By modifying standard DAE of multibody system, each subsystem is obtained by decomposing a total system into several subsystems so that parallel computation can be proceeded. The proposed method is effective for combining multibody subsystems which are developed in different developing environments. This paper describes a proposed procedure, and presents numerical simulation of a fundamental example to show the effectiveness of the proposed method.
A Gluing Algorithm for Distributed Simulation of Multibody Systems
Authors: Wang Jinzhong , Ma Zheng-Dong , Hulbert Gregory M.
Published: June 2008

A new gluing algorithm is presented that can be used to couple subsystem models for dynamics simulation of mechanical systems. The gluing algorithm developed relies only on information available at the subsystem interfaces. This strategy not only improves the efficiency of the algorithm, but also engenders model security by limiting model access only to the exposed interface information. These features make the algorithm suitable for a real and practical distributed simulation environment.
Methods of Recursive Coordinate Reduction
Authors: Anderson Kurt S. , Critchley James H.
Published: June 2008

The method of Recursive Coordinate Reduction (RCR) offers solutions to the forward problem of multibody dynamics in a number of operations linear in both the number of generalized coordinates, n, and the number of independent algebraic constraints, m (e.g. O(n + m)). However, the RCR is presently restricted in applicability (although broad) and susceptible to formulation singularities. This paper develops two methods for avoiding formulation singularities as well as a recursive general coupled loop solution which extends the RCR to the complete set of multibody systems. The existing RCR coupled with these developments constitute a Generalized Recursive Coordinate Reduction method which should be used in place of the traditional “O(n)” constraint technique (truly O(n + nm2 + m3)) for superior O(n + m) computational performance.
On Parallel Methods of Multibody Dynamics
Authors: Critchley James H. , Anderson Kurt S.
Published: June 2008

Optimal time efficient parallel computation methods for large multibody system dynamics are defined and investigated in detail. Comparative observations are made which demonstrate significant deficiencies in operating regions of practical importance and a new parallel algorithm is generated to address them. The new method of Recursive Coordinate Reduction Parallelism (RCRP) outperforms or directly reduces to the fastest general multibody algorithms available for small parallel resources and obtains “O(logk(n))” time complexity in the presence of larger parallel arrays. Performance of this method relative to the Divide and Conquer Algorithm is illustrated with an operations count for the worst case of a multibody chain system.
Torsional Buckling and Writhing Dynamics of Elastic Cables and DNA
Authors: Goyal S. , Perkins N. C. , Lee Christopher L.
Published: June 2008

Marine cables under low tension and torsion on the sea floor can undergo a dynamic buckling process during which torsional strain energy is converted to bending strain energy. The resulting threedimensional cable geometries can be highly contorted and include loops and tangles. Similar geometries are known to exist for supercoiled DNA (deoxyribonucleic acid) and these also arise from the conversion of torsional strain energy to bending strain energy or, kinematically, a conversion of twist to writhe. A dynamic form of Kirchhoff rod theory is presented herein that captures these nonlinear dynamic processes. The resulting theory is discretized using the generalized-α method for finite differencing in both space and time. The important kinematics of cross-section rotation are described using an incremental rotation “vector” as opposed to traditional Euler angles or Euler parameters. Numerical solutions are presented for an example system of a cable subjected to increasing twist at one end. The solutions show the dynamic evolution of the cable from an initially straight element, through a buckled element in the approximate form of a helix, and through the dynamic collapse of this helix through a looped form.
Describing Rigid-Flexible Multibody Systems Using Natural and Absolute Nodal Coordinates
Authors: Garci´a-Vallejo D. , Escalona J. L. , Mayo J. , Domi´nguez J. , A´lvarez A.
Published: June 2008

This paper deals with the dynamic description of interconnected rigid and flexible bodies. The absolute nodal coordinate formulation is used to describe the motion of flexible bodies and natural coordinates are used to describe the motion of the rigid bodies. The absolute nodal coordinate formulation is a non-incremental finite element procedure specially suitable for the dynamic analysis of flexible bodies exhibiting rigid body motion and large deformations. Nodal coordinates, that include global position vectors and global slopes, are all defined in a global inertial coordinate system. The advantages of using the absolute nodal coordinate formulation include constancy in the mass matrix, and the need for only a minimal set of non-linear constraint equations when connecting different flexible bodies with kinematic joints. When bodies within the system can be considered rigid, the above-mentioned advantages of the equations of motion can be preserved provided natural coordinates are used. In the natural coordinates method, the coordinates used to describe rigid bodies include global position vectors of basic points and global unit vectors. As in the absolute nodal coordinate formulation, rotational coordinates are avoided and the mass matrix is also constant. This paper provides computer implementation of this formulation that only uses absolute coordinates for general two-dimensional multibody systems. The constraint equations needed to define kinematic joints between different bodies can be linear or non-linear. The linear constraint equations, that include those needed to define rigid connections and revolute joints, are used to define constant connectivity matrices that reduce the size of the system coordinates. These constant connectivity matrices are also used to obtain the system mass matrix and the system generalized forces. However, the non-linear constraint equations that account for sliding joints, require the use of the Lagrange multipliers technique. Numerical examples are provided and compared to the results of other existing formulations.
A Self-Stabilized Algorithm for Enforcing Constraints in Multibody Systems
Authors: Bauchau Olivier A.
Published: June 2008

A new algorithm is developed for the enforcement of constraints within the framework of nonlinear, flexible multibody system modeled with the finite element approach. The proposed algorithm exactly satisfies the constraints at the displacement and velocity levels, and furthermore, it achieves nonlinear unconditional stability by imposing the vanishing of the work done by the constraint forces when combined with specific discretizations of the inertial and elastic forces. Identical convergence rates are observed for the displacements, velocities, and Lagrange multipliers. The proposed algorithm is closely related to the stabilized index-2 or GGL method, although no additional multipliers are introduced in the present approach. These desirable characteristics are obtained without resorting to numerically dissipative algorithms. If high frequencies are present in the system, i.e. the system +is physically stiff, dissipative schemes become necessary; the proposed algorithm is extended to deal with this situation.
A Method to Investigate Vibrations in Tendon Driven Mechanisms
Authors: Londi F. , Valentini P. P. , Vita L.
Published: June 2008

In this paper the authors develop a mechanical model to analyze the vibrational behavior of tendon driven mechanisms. The description of kinematics makes use of the correspondence between graphs and mechanisms, based on the works of L.W. Tsai and J.J. Lee [1–4], and on Denavithartenberg approach to study serial manipulators [5,6]. The equations of dynamics for a generic n-link manipulator have been deduced by Londi [8] by means of a Lagrangian approach in case of rigid belts. These equations have been modified to take into account belt elasticity, according to the Hooke’s law. The correct value of belt tension is computed using the λ-corrector algorithm developed by the authors [9]. A numerical example concerning a three degree-of-freedom manipulator is also presented.
Experimental Approach for Finding the Response Time of MR Dampers for Vehicle Applications
Authors: Goncalves Fernando D. , Koo Jeong-Hoi , Ahmadian Mehdi
Published: June 2008

This paper offers a method and an experimental example of determining the response time of Magneto-Rheological (MR) dampers. The response time of MR dampers for automotive suspension applications is valuable information because it is one of the key factors that determine the practical effectiveness of the use of MR dampers in vehicles. However, a detailed description of the response time of MR dampers is seldom given in the literature. Furthermore, the methods of computing the response time are not discussed in detail. Therefore, this study intends to develop a method for experimental determination of the response time of MR dampers for automotive suspensions. A triangle wave that maintains a constant velocity across the damper is proposed as the input to use in experiments. This triangle wave ensures a constant velocity across the damper in order to accurately evaluate the response time of the MR damper. The response time was defined as the time required to make the transition from the initial state to 63.2% of the final state, or one time constant. The time constant is a measure of how long it takes a system to respond to a given input. In other words, the response time is the time necessary for the damper to achieve the desired force upon activation. To demonstrate the method, the response time was found for an MR damper particularly designed and fabricated for vehicle applications. Two cases were considered: activation response time of the damper and deactivation response time of the damper. Both cases were studied during the rebound stroke of the damper. It was found that the response time of the MR damper under activation and deactivation was 15.4 ms and 13.9 ms respectively. The results are comparable to those found in the literature.
Reconstruction of the Dynamic Rail-Wheel Contact Forces
Authors: Kirchenkamp Svenja , So¨ffker Dirk
Published: June 2008

This contribution introduces a virtual measurement device for the reconstruction of the in practice unmeasureable railwheel contact forces. For this aim the Proportional-Integral (PI)-Observer is used. Then, the concept of a measurement sleeve at the axle bearing is shown. With the displacement measurements resulting from the sleeve using the PI-Observer, an estimation of the tangential contact force and the dynamic normal force is possible. Using the simulation of the rail-wheel contact, the feasibility of the estimation of the contact force behavior is shown. As an outlook for further applications of the PI-Observer in the context of rail-wheel contact force estimation, the reconstruction of contact forces by using acceleration measurements is demonstrated by an example of an elastic beam for the first time.
A Technique for Validating a Multibody Wheel/Rail Contact Algorithm
Authors: Escalona Jose´ L. , Gonza´lez Manuel , Zaazaa Khaled E. , Shabana Ahmed A.
Published: June 2008

In this paper, a specialized steady state formulation is developed in order to validate the results obtained using multibody wheel/rail two-point contact algorithms developed at the University of Illinois at Chicago. In the specialized formulation, the wheel set is assumed to have three points of contact with the rail. The steady state curving behavior of the wheel set is examined using this specialized formulation. The balanced steady state curving behavior in which the centrifugal force is equal to the lateral component of the gravity force can be obtained as a special case of the specialized steady state formulation developed in this investigation. No derailment analysis or scenarios are considered in this paper in order to validate the results of both the constraint and elastic contact formulations. The results of the simple specialized formulation are compared with the results of the multibody inverse and forward dynamics approaches. In the inverse dynamics, approach it is assumed that the wheel set will maintain three points of contact with the rail. The inverse dynamics formulation model is conceptually different from the specialized steady state formulation since in the inverse dynamics all the degrees of freedom are specified. In the multibody forward dynamics method, no assumptions are made with regard to the existence of the flange contact.
A Nonlinear Finite Element Model for Leaf Springs
Authors: Omar Mohamed A. , Sugiyama Hiroyuki , Shabana Ahmed A. , Loh Wei-Yi , Basch Rena
Published: June 2008

This paper presents a nonlinear finite element model for the leaf spring that can be used in multibody applications and vehicle dynamic simulations. The floating frame of reference formulation is used in this investigation to model leaf spring nonlinear dynamics. This formulation accounts for the coupling between different modes of deformation as well as the nonlinear coupling between the rigid body motion and the elastic deformation. By employing component mode synthesis techniques, a reduced order model is obtained for the leaf spring while maintaining a good degree of accuracy. The inertia shape integrals can be calculated once in advance using a preprocessor and then stored to be used to automatically generate the nonlinear equations of motion of the leaf spring. The use of a preprocessor to evaluate the inertia shape integrals before the dynamic simulation leads to considerable saving in CPU time and allows the utilization of existing finite element computer codes to obtain the data required for the flexible body simulation. This reduced order model is implemented in a general multibody algorithm in order to examine the effectiveness and robustness of the proposed techniques. As an application, the wind-up deformation of the front suspension system of a typical sport utility vehicle under severe braking condition is investigated.
Extremal Properties of Some Resonant Motions of Natural Celestial Bodies
Authors: Beletskii Vladimir V. , Khentov Anatoli A.
Published: June 2008

The modern results of the theory of semistationary resonant solutions and their applications for the explanations of some remarkable phenomena in the motions of celestial bodies are discussed.
On the Bending of a Cantilever Flexible Beam With an Embedded Ribbon of Shape Memory Alloy
Authors: Chiroiu Veturia , Munteanu Ligia , Chiroiu Calin
Published: June 2008

The paper analyses the thermomechanical coupling between a cantilever aluminium beam and an embedded SMA ribbon. The SMA is selected to be Nickel-Titanium (NiTi) because of the high strength and large strains associated with this material. The actuation of the beam is achieved by applying a current across the SMA ribbon in order to heat the beam above the transition temperature. We show that the actuated beam exhibit the essential functions of an active system, i. e. the deflected beam may return to the initial configuration.
Study on Air Spring’s Finite Element Model
Authors: Wu Shanyue , Huang Yingyun , Zhu Shijian
Published: June 2008

In order to analyze air spring’s characteristic numerically, multi-step method is presented to establish its finite element model. In the model, air spring’s rubber bladder is described with approximation method, and the inside volume is calculated by means of discrete summation. The actual analysis results show that the model is practical.
Six Degree of Freedom Active Isolation in Flexible Supporting Structures: Numerical Simulation and Experiment
Authors: Cheng Yuan , Zhou Qian , Ren Ge-Xue , Zhang Hui
Published: June 2008

This paper studies the six degree-of-freedom active isolation of flexible supporting structures using Gough-Stewart platform. The problem arises from a large radio telescope in which the astronomical equipment is mounted on a platform to be stabilized, while the base platform of the mechanism itself is carried by a cable car moving along flexible cables. In this paper, the stabilization problem is equivalent to a dynamics and control problem of multi-body system. A control law of the prediction of the base platform and PD feedback is proposed for the six actuators of the Gough-Stewart platform. Based on numerical results, a model experimental setup has been built up. The control effects are measured with LTD 500 Laser Tracker.
On Fractional Order Disturbance Observer
Authors: Chen YangQuan , Vinagre Blas M. , Podlubny Igor
Published: June 2008

In this paper, for the first time, the fractional order disturbance observer (FO-DOB) is proposed for vibration suppression applications such as hard disk drive servo control. It has been discovered in a recently published US patent application (US20010036026) (Chen et al., 2001) that there is a tradeoff between the the phase margin loss and the strength of the low frequency vibration suppression. Given the required cutoff frequency of the low pass filter, also known as the Q-filter, it turns out that the relative degree of the Q-filter is the major tuning knob for this tradeoff. As a motivation for the fractional order Q-filter, a solution based on integer order Q-filter with a variable relative degree is introduced which is the key contribution of US20010036026. Then, a fractional order disturbance observer based on the fractional order Q-filter is proposed. The implementation issue is also discussed. The nice point of this paper is that the traditional DOB is extended to fractional order DOB with the advantage that the FO-DOB design is now no longer conservative or aggressive, i.e., given the cutoff frequency and the desired phase margin, we can uniquely determine the fractional order of the low pass filter.
Modal Placement Control Method for Fractional Systems: Application to a Testing Bench
Authors: Sabatier Jocelyn , Cois Olivier , Oustaloup Alain
Published: June 2008

This paper is dedicated to modal placement control for fractional systems. The influence of the complex plane eigenvalue locations on their time response is discussed for two elementary fractional systems. A dynamic output feedback modal placement control method is proposed. It is applied to the temperature control of a thermal system whose dynamic model is obtained through system identification.