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ASME 1990 design Technical Conferences, DETC 1990

作者： Chuang, Li-Ping Kim, Sung-Soo Engineering Mechanics Research Corporation TroyMI United States Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa CityIA United States

ISBN: (纸本)9780791805213

Rotor dynamics are important for robots that are driven by motors and high gear ratio transmission systems. New generic recursive dynamic formulations of robotic systems with motor rotor effects are presented, where motors can be mounted on inboard or outboard bodies of the actuated joints. An organized form of the system dynamics equations is obtained through adoption of a state vector representation in equation derivation. The influence of rotors on the overall system dynamics are identified. Parallelism of the derived dynamics formulations is then exploited and a real-time parallel computational algorithm is proposed. A seven degree-of-freedom telerobot is used to illustrate rotor dynamics effects in the computational model. A computational speed that is faster than realtime simulation is demonstrated. © 1990 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Degrees of freedom (mechanics)

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Flexible-body dynamics modelling with a reduced-order model

Flexible-body dynamics modelling with a reduced-order model

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ASME 1990 design Technical Conferences, DETC 1990

作者： Yae, K. Harold Inman, Daniel J. Department of Mechanical Engineering Center for Simulation and Design Optimization The University of Iowa Iowa CityIA United States Department of Mechanical and Aerospace Engineering State University of New York at Buffalo BuffaloNY United States

ISBN: (纸本)9780791805213

In the dynamics modeling of a flexible body, finite element analysis employs Guyan's reduction that removes some of the "insignificant" physical coordinates, thus producing a dynamic model that has smaller mass and stiffness matrices. Despite such reduction, the resultant model is still too large for flexible-body dynamic analysis. That warrants further reduction as is frequently used in control design by approximating a large dynamical system with a fewer number of state variables. When the reduced model is being assembled with other bodies in a multi-body mechanism, a problem, however, arises because a model usually undergoes, before being reduced, some form of coordinate transformations that do not preserve the physical meanings of the states. To correct such a problem, we developed a method that expresses a reduced model in terms of a subset of the original states. The proposed method starts with a dynamic model that is originated and reduced in finite element analysis. Then the model is converted to the state space form, and reduced again by the internal balancing method. At this stage, being in the balanced coordinate system, the states in the reduced model have no apparent resemblance to those of the original model. Through another coordinate transformation that is developed in this paper, however, this reduced model is expressed by a subset of the original states. Then finally the model can be represented by the states assigned to the degrees of freedom of the selected nodal points. © 1990 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Dynamic models

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FLAMMABILITY AND TOXICITY OF COMPOSITE-MATERIALS FOR MARINE VEHICLES

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NAVAL ENGINEERS JOURNAL 1990年第5期102卷 45-54页

作者： SEVART, JL GRIFFIN, OH GURDAL, Z WARNER, GA Jeffrey L. Sevart:is a native of Kansas and a 1985 graduate of Kansas State University with a B.S. in mechanical engineering (magna cum laude). After working as a stress analysis engineer at Boeing Military Airplane Company in Wichita Kans. he attended Virginia Polytechnic Institute and State University and received an M.S. in engineering mechanics in February 1988. He currently resides in Akron Ohio working as a research engineer in tire composites research at The Goodyear Tire and Rubber Company. O. Hayden Griffin Jr.:received his B.S. and M.S. in mechanical engineering from Texas Tech University in 1970 and 1971 respectively. He received his Ph.D. in engineering mechanics from Virginia Polytechnic Institute and State University in 1980. Prior to joining the faculty of Virginia Polytechnic Institute and State University as associate professor of engineering science and mechanics in September 1985 he was employed at the U.S. Naval Surface Warfare Center (Dahlgren Virginia) BF Goodrich Tire Group (Akron Ohio) the Bendix Advanced Technology Center (Columbia Maryland) and the Johns Hopkins University Applied Physics Laboratory (Laurel Maryland). He is currently an associate director of the Virginia Institute for Material Systems. He is a registered professional engineer in Virginia and is a member of the American Society of Mechanical Engineers and the American Society for Composites. Zafer Gürdal:received his M.S. in mechanical and aerospace engineering from Illinois Institute of Technology in 1981 and his Ph.D. in aerospace engineering from Virginia Polytechnic Institute and State University in 1985. He worked as a research associate in the Aerospace and Ocean Engineering Department at Virginia Tech before joining the Engineering Science and Mechanics Department as an assistant professor in September 1985. Professor Gürdal's research interests include: composite structures failure mechanics of composites structural optimization and damage tolerant design. He is a member of the American Institute

Characteristics of both thermoplastic and thermoset composite materials as they pertain to marine vehicle applications are discussed. Comparison of various material selection factors such as strength, damage and moisture resistance, and flammability and toxicity as well as cost and availability of thermoset and thermoplastic composite materials are presented. Methods for testing and reducing the flammability and toxicity are discussed. Many commercially available composite systems are reported to provide favorable characteristics for marine applications. Although there seems to be a need for improved production technology for thermoplastics, they present potential advantages in physical properties over thermoset composites.

关键词： Composite Materials

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WORKSPACE ANALYSIS OF MULTIBODY mechanical systems USING CONTINUATION METHODS

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JOURNAL OF MECHANISMS TRANSMISSIONS AND AUTOMATION IN design-TRANSACTIONS OF THE ASME 1989年第4期111卷 581-589页

作者： JO, DY HAUG, EJ Center for Simulation and Design Optimization and Department of Mechanical Engineering College of Engineering The University of Iowa Iowa City Iowa 52242

A new approach to numerical analysis of workspaces of multibody mechanical systems is presented, based on manifold theory and computational continuation methods. Generalized coordinates that define the kinematics of a system are classified and interpreted from an input-output point of view. Boundaries of workspaces, which depend on the classification of generalized coordinates, are defined as sets of points for which Jacobian matrices of the kinematic equations are row rank deficient. This criterion generalizes the conventional determinant criteria for applications with square Jacobian matrices. Numerical methods for tracing families of one dimensional trajectories on a workspace boundary are outlined. Open and closed loop manipulator examples are analyzed, using a manifold mapping computer program.

关键词： Jacobian matrices Kinematics Manipulators Numerical analysis Computer software Equations of motion Manifolds

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TOPOLOGICAL ANALYSIS OF MULTIBODY systems FOR RECURSIVE DYNAMICS FORMULATIONS

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MECHANICS OF STRUCTURES AND MACHINES 1989年第2期17卷 239-258页

作者： HWANG, RS HAUG, EJ Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa City IOWA 52242 United States

Graph theory is used to characterize the topology of multibody systems for high speed parallel computer dynamic simulation. Decoupled loops are defined for use in the recursive dynamics formulations, wherein Langrange multipliers can be eliminated concurrently within each decoupled loop. A row-scanning process for the nondirected adjacency matrix of a graph is described, to generate an identification array that facilitates compact storage and defines system connectivities. A decision tree search algorithm is employed to generate all spanning trees associated with a closed loop graph. For each spanning tree generated from the decision tree search algorithm, a precedence array is defined. A path matrix for the spanning tree and an outdegree of junction nodes are defined to assist in parallel implementation of recursive dynamics algorithms and are then constructed from the precedence array. Finally, an optimal tree search algorithm that identifies a spanning tree that leads to best solution sequences for parallel implementation of recursive dynamics formulations is presented.

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Dual-rate integration of controlled multibody mechanical systems

Dual-rate integration of controlled multibody mechanical sys...

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IEEE Conference on Decision and Control

作者： W.-S. Lee T. Tak Department of Mechanical and Aerospace Engineering University of Missouri Kansas City MO USA Center of Simulation and Design Optimization College of Engineering University of Iowa Iowa IA USA

A dual-rate integration methodology for high-speed dynamic simulation of controlled multibody mechanical systems is proposed. Using a graphical representation of such systems, a variational approach is adopted to formulate the systems equations in state-space form, in terms of mechanical-subsystem-independent generalized coordinates and control-subsystem state variables. Different integration algorithms and step sizes that account for the different time scales of each subsystem are used to improve efficiency and stability. A coupling between the subsystems is accounted for by extrapolation.< >

关键词： Control systems mechanical systems mechanical variables control Differential equations Frequency Tree data structures Cities and towns Aerodynamics Control system synthesis State-space methods

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A recursive formulation for real-time dynamic simulation

A recursive formulation for real-time dynamic simulation

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ASME 1988 design Technology Conferences, DETC 1988

作者： Bae, D.-S. Hwang, R.S. Haug, E.J. Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa CityIA United States

ISBN: (纸本)9780791826584

A new recursive algorithm for real-time, interactive dynamic simulation, animated graphics, and design variation analysis is presented for mechanical systems with closed loops. State vector kinematic relations that represent translational and rotational motion are defined, to simplify the formulation and to relieve computational burden. Recursive equations of motion are first derived for a single loop multi-body system. Faster than real-time performance is demonstrated for a closed loop robot, using an Alliant FX/8 multiprocessor. The algorithm is extended to multi-loop, multibody systems for parallel processing real-time simulation in companion papers [1,2]. Performance of the algorithm on a shared memory multi-processor is compared with that achieved with other dynamic simulation algorithms. A vehicle example is used to demonstrate efficiency of the algorithm for real-time simulation and graphics rendering in a network environment, for use as an interactive design tool. © 1988 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Machine design

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A dynamic simulation approach to machine component life prediction

A dynamic simulation approach to machine component life pred...

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ASME 1988 design Technology Conferences, DETC 1988

作者： Liu, T.S. Haug, E.J. Dopker, B. Department of Mechanical Engineering National Chiao Tung University Hsinchu Taiwan Center for Simulation and Design Optimization and Department of Mechanical Engineering The University of Iowa Iowa CityIA United States

ISBN: (纸本)9780791826584

A system simulation approach is presented for dynamic stress analysis and life prediction of components of machines that undergo nonsteady gross motion and elastic deformation. The method employs finite element structural analysis, coupled gross motionelastic deformation dynamics, and computer-based fatigue analysis, A computer aided engineering methodology is developed for life prediction by linking together software from dynamics, structures, and fatigue life estimation;to compliment conventional fatigue experiments. Dynamic stress analysis is carried out using either an uncoupled gross motion-elastic deformation method or a more accurate approach that takes into account the coupling between large displacements and elastic deformation. With the aid of vehicle operational scenarios, stress/strain histories at critical regions in vehicle components during a projected service life are simulated. A local strain approach is used to calculate cumulative fatigue damage at notches, which is used in assessing fatigue life of components during the design phase;i.e., prior to availability of experimental data A vehicle example is presented, using a simplified dynamicstress analysis method. The more general and accurate fuUy coupled dynamic-stress analysis method will be illustrated in a subsequent paper. © 1988 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Forecasting

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A network implementation of real-time dynamic simulation with interactive animated graphics

A network implementation of real-time dynamic simulation wit...

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ASME 1988 design Technology Conferences, DETC 1988

作者： Dubetz, M.W. Kuhl, J.G. Haug, E.J. Department of Electrical and Computer Engineering The University of Iowa Iowa CityIA United States Center for Simulation and Design Optimization Department of Mechanical Engineering The University of Iowa Iowa CityIA United States

ISBN: (纸本)9780791826584

This paper presents a network based implementation of real-time dynamic simulation methods. An interactive animated graphics environment is presented that permits the engineer to view high quality animated graphics rendering of dynamic performance, to interact with the simulation, and to study the effects of design variations, while the simulation is being carried out. An iiidusuy standard network computing system is employed to interface the parallel processor that carries out the dynamic simulation and a high speed graphics processor that creates and displays animated graphics. Multi-windowing and graphics processing methods that are employed to provide visualization and operator control of the simulation are presented. A vehicle dynamics application is used to illustrate the methods developed and to analyze communication bandwidth requirements for implementation with a compute server that is remote from the graphics workstation. It is shown that, while massive data sets are generated on the parallel processor during realtime dynamic simulation and extensive graphics data are generated on the workstation during rendering and display, data communication requirements between the compute server and the workstation are well within the capability of existing networks. © 1988 American Society of mechanical Engineers (ASME). All rights reserved.

关键词： Parallel processing systems

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OPPORTUNITIES FOR PACIFIC FLEET FF-1052 CLASS SHIPS TO SAVE ENERGY

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NAVAL ENGINEERS JOURNAL 1985年第4期97卷 315-321页

作者： PEHLIVAN, H KENYON, CW Hasan Pehlivan:received his BS in marine engineering from the Merchant Marine Academy (Turkey) in 1971 and his MS degree from Old Dominion University (Norfolk) in 1975. He was employed by D.B. Cargo Line (Turkey) as an engineering officer on ocean-going cargo vessels from 1971 to 1973. After receiving his masters degree in power engineering in 1975 he was employed by J.J. Henry Co. Inc. in Washington DC where he was involved in supporting the DTNSRDC Shipboard Energy Conservation Program which included the development of the steam system simulation (STMSYS) heat balance computer program for FF-1052/1078 class frigates. In addition he was cognizant engineer for various fluid systems designs for PCG and CSGN. In 1978 he joined M. Rosenblatt & Sons Inc. where he was cognizant engineer for various fluid systems designs for CVV DDG-51 and ARS-50. He was also leading engineer in support of DTNSRDC for the development of innovative machinery options for the baseline DD-963. In 1980 he joined NKF Engineering Inc. where he directs and performs DTNSRDC ship energy conservation analyses for frigates cruisers destroyers and aircraft carriers. He has been assisting the NAVSEA energy office in directing and performing Ship Energy Conservation Assist Team (SECAT) surveys aboard Navy ships since 1982. Mr. Pehlivan is currently manager of ship auxiliary systems in charge of the design and development of fluid systems pollution abatement distilling plants etc. He is a member of ASNE. Clarence W. Kenyon:graduated from the State University of New York Maritime College in 1960 and sailed on a third assistant engineer's license with Isbrandtsen Steamship Company before accepting an engineering position with the Long Beach Naval Shipyard in 1961 where he worked in the Steam Propulsion and Auxiliaries Section and the Mechanical and Hydraulic Section. He also taught a course in engineering fundamentals to engineering technicians in the evenings. In 1963 he accepted a position with the Space Division of North American Avia

The shipboard energy conservation assist team (SECAT) program was introduced to the US Pacific Surface Fleet (SURFPAC) in 1983 following one year testing in the US Atlantic Surface Fleet (SURFLANT). Experiences aboard SURFLANT ships had provided the basis for improvements which could also be applied to SURFPAC ships. Chief among these improvements were simple fuel measurement, fuel curve development methods, an energy survey checklist, and an equipment status board which identifies economic machinery alignments. The first SURFPAC ship to receive a SECAT visit was a FF-1052 class ship. Fuel consumption was significantly higher on this ship than the six FF-1052/1078 class SURFLANT ships previously visited. SECAT immediately looked for reasons for this increase in fuel consumption. Three significant changes received by this ship and not received by the six SURFLANT ships were identified. They were a new design economizer, Navjet vice Wallsend burners, and removal of overload control valves on the forced draft blowers. Another SURFPAC frigate with the same three changes was visited to validate the results obtained from the first ship. This paper discusses recent improvements to the SECAT program. It also examines the differences in fuel consumption observed between SURFLANT and SURFPAC FF-1052/1078 class ships. The economics of potential solutions to the higher fuel consumption problem aboard SURFPAC ships is analyzed with special emphasis on alternative burner designs and forced draft blower changes. Recommendations are made to reduce fuel consumption both by equipment changes and expanded energy initiatives.

关键词： NAVAL VESSELS

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