Ronald L. Huston

Dynamics of constrained multibody systems

Etude des equations de mouvement de systemes a n corps soumis a des contraintes soit geometriques (boucles fermees), soit cinematiques (mouvement specifique)

On the dynamics of a human body model

Abstract Equations of motion for a model of the human body are developed. Basically, the model consists of an elliptical cylinder representing the torso, together with a system of frustrums of elliptical cones representing the limbs. They are connected to the main body and each other by hinges and ball and socket joints. Vector, tensor, and matrix methods provide a systematic organization of the geometry. The equations of motion are developed from the principles of classical mechanics. The solution of these equations then provide the displacement and rotation of the main body when the external forces and relative limb motions are specified. Three simple example motions are studied to illustrate the method. The first is an analysis and comparison of simple lifting on the earth and the moon. The second is an elementary approach to underwater swimming, including both viscous and inertia effects. The third is an analysis of kicking motion and its effect upon a vertically suspended man such as a parachutist.

Modeling of Variable Length Towed and Tethered Cable Systems

An algorithm is presented for modeling the dynamics of towed and tethered cable systems with e xed and varying lengths (specie cally, tethers, towing, reel-in/pay-out cone gurations ). The systems may have one or many open branches, but they must be towed or tethered from a single point. The modeling uses e nite-segment (rigidlink/lumped-parameter ) elements. Cable length changes (reel-in/pay-out ) are modeled by having a link near the towing (or anchoring )vessel change length. Thephysical properties of the cable may change from link to link. The towed bodies may have control surfaces. Effects of e uid drag, lift, and buoyancy are included. Added mass forces and moments are included for the towed bodies but not for the cable itself. An illustrative application is presented for a system with three different pay-out rates. Nomenclature aJ;aK = acceleration of J; K eijk = permutation symbol,

Cable dynamics—a finite segment approach

Abstract The paper presents and discusses a nonlinear, three-dimensional, finite-segment, dynamic model of a cable or chain. The model consists of a series of links connected to each other by ball-and-socket joints. The size, shape, and mass of the links is arbitrary. Furthermore, these parameters may be distinct for each link. Also, the number of links is arbitrary. The model allows an arbitrary force system to be applied to each link. The model is used to develop a computer code which consists primarily of subroutines containing algorithms to develop the kinematics, force systems, and governing dynamical equations. Although the integration of the equations is performed with a Runge-Kutta algorithm, the code is developed so that any other suitable integration technique or algorithm may be substituted. The input for the code requires the following: the number of links; the mass, centroidal inertia matrix, mass-center position, connection point, and external forces on each link; and the time history of the specified variables. The output consists of the time history of each variable, the position, velocity, and the acceleration of the mass-center of each link, and the unknown forces and moments. An example problem is presented which describes the motion of a sphere drug through water by a partially submerged cable suspended from a rotating surface crane. Viscous forces of the water are included. Although the example simulates a typical nautical rig. its inclusion in the paper is introduced primarily to illustrate the capability of the model.

The need for worker training in advanced manufacturing technology (AMT) environments: A white paper

The international globalization of the World markets for manufactured goods, particularly consumer goods, has placed an emphasis on nations to improve manufacturing productivity. This need to improve productivity is further prompted by a potential loss of competitive edge in the global marketplace. The market competitiveness and e

Multibody Dynamics Modeling of Variable Length Cable Systems

ciency of any nation is primarily dependent upon the economy, reliability, quality, quickness, and ease of its manufacturing processes and the resulting quality of outcomes (products). To a major extent, the skills of the workforce determine the e!ectiveness and the e

The dynamics of flexible multibody systems: A finite segment approach—I. Theoretical aspects

ciency of the process of manufacturing and the quality of goods produced. And yet, there is a severe lack of standardized and consistent worker training programs for skills needed by workers in modern manufacturing organizations. This review paper shows that there is a dire need to train workers in manufacturing organizations and thereby improve the overall e!ectiveness and e

A comprehensive lifting model: beyond the NIOSH lifting equation

ciency of such organizations. Relevance to industry As technology changes, so do the skills workers need. In order to compete successfully in the global market, manufacturing organizations must aim at training workers in skills necessary to produce quality goods. ( 1999 Elsevier Science B.V. All rights reserved.

On Dynamic Stiffening of Flexible Bodies Having High Angular Velocity

This paper presents a procedure for studying the dynamics ofvariable length cable systems. Such systems commonly occur in deploymentand retrieval (pay-out and reel-in) in cable towing systems such as inship and marine applications.The cable is modeled as a chainand treated as a multibody system. The chain links in turn are modeledas lumped masses. The pay-out/reel-in process is modeled with variablelength links near the towing point.Application in marine systems are presented and discussed.

Validation of finite segment cable models

Abstract Modelling the dynamics of flexible multibody systems is a difficult problem. There has been much discussion about how to approach this problem. This paper presents a method in which the flexibility may be included in the dynamical analysis. The method has distinct advantages over other proposed methods. The dynamical formulation is based on Kanes equations. The flexibility is modelled by using springs and dampers at the joints of the system. The stiffness and damping coefficients of these are found using the physical properties of the members. These are then incorporated into the equations of motion. Part I of this paper discusses the theoretical aspects of this type of analysis, while part II shows two example problems.