IJTC2007-44301 AN INVESTIGATION OF THREE DIMENSIONAL ELASTIC-PLASTIC HEMISPHERICAL SLIDING CONTACT, PART I: MODELING AND VALIDAITON

ABSTRACT This work presents a three dimensional (3D) finite element analysis (FEA) of an elastic-plastic hemispherical contact model for two hemispherical bodies sliding across each other with various preset vertical interferences. The boundary conditions, model simplifications, and the normalization scheme are presented. Sample results from this FEA investigation are compared to a semi-analytical solution to validate the methodology

DETC2005-85092 A HYBRID ROD-CATENARY MODEL TO SIMULATE NONLINEAR DYNAMICS OF CABLES WITH LOW AND HIGH TENSION ZONES

ABSTRACT Cables under very low tension may become highly contorted and form loops, tangles, knots and kinks. These nonlinear deformations, which are dominated by flexure and torsion, pose serious concerns for cable deployment. Simulation of the three-dimensional nonlinear dynamics of loop and tangle formation requires a 12 th order rod model and the computational effort increases rapidly with increasing cable length and integration time. However, marine cable applications which result in local zones of low-tension very frequently involve large zones of high-tension where the effects of flexure and torsion are insignificant. Simulation of the threedimensional dynamics of high-tension cables requires only a 6 th order catenary model which significantly reduces computational effort relative to a rod model. We propose herein a hybrid computational cable model that employs computationally efficient catenary elements in high-tension zones and rod elements in localized low-tension zones to capture flexure and torsion precisely where needed

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DIE LIFE PREDICTION IN RAPID PROTOTYPE DIES

ABSTRACT To meet the growing demand for rapid, low-cost die fabrication technology in the sheet metal forming industry, easy-to-machine, polyurethane-based, composite board stock is used widely as a rapid tooling material. In practice, it is desirable to terminate die life by wear rather than by catastrophic fatigue. However, the failure mechanisms of the rapid prototyped tools are not clearly understood, thus making the prediction of tool life difficult. This paper presents a method to estimate the fatigue life of a sheet metal forming die fabricated from ATH (aluminum trihydrate)-filled polyurethane. A finite element model of 90° V-die bending process was developed, and the effects of process parameters on stress distribution in the punch and die were investigated through simulation. Mechanical testing was performed to characterize the fatigue properties of the tooling material. The computer-simulated results were verified through experiments using instrumented, laboratory-scale punch and die sets. Keywords: Rapid Tooling, Die Life, Fatigue INTRODUCTION Rapid prototype (RP) technology has been drawing attention from the manufacturing industry for more than 10 years. Recent applications of RP technology include rapid tooling (RT), which is the technology that adopts RP techniques in die making. As today's ever-competitive business environment demands reductions in product development time and cost, the need for faster turn-around times and more efficient means of producing prototype and short-run tooling has increased. As a result, RT technology has made inroads into conventional die fabrication methods with the aim of reducing the lead time and investment costs of tooling development. Despite the fact that sheet metal forming is a widely practiced fabrication process in industry, its exposure to RP and RT technologies have been rather limited. This is due to th