Emmanuel Rodriguez

Universidad Tecnológica de Panamá, Facultad de Ingenieria Mecánica, Undergraduate

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Papers by Emmanuel Rodriguez

Semestral Sistemas II-EJRA,JMW,AR,BA

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Practica de estequiometria No.1 (masa masa y volumen)

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Optimisation Methods for Compression, Extension and Torsion Spring Design

ABSTRACT

Optimal design of conical springs

Engineering with Computers, 2008

Mechanical systems often use springs to store energy though their axial length must sometimes be ... more Mechanical systems often use springs to store energy though their axial length must sometimes be significantly reduced. This leads to the use of conical springs as they are able to telescope. Designers of mechanical systems can call on a large number of tools to assist them though most of these are merely validation tools requiring concomitant trial and error strategies.

Analytical Behavior Law for a Constant Pitch Conical Compression Spring

Journal of Mechanical Design, 2006

Cylindrical compression spring behavior has been described in the literature using an efficient a... more Cylindrical compression spring behavior has been described in the literature using an efficient analytical model. Conical compression spring behavior has a linear phase but can also have a nonlinear phase. The rate of the linear phase can easily be calculated but no analytical model exists to describe the nonlinear phase precisely. This nonlinear phase can only be determined by a discretizing algorithm. The present paper presents analytical continuous expressions of length as a function of load and load as a function of length for a constant pitch conical compression spring in the nonlinear phase. Whal’s basic cylindrical compression assumptions are adopted for these new models (Wahl, A. M., 1963, Mechanical Springs, Mc Graw-Hill, New York). The method leading to the analytical expression involves separating free and solid/ground coils, and integrating elementary deflections along the whole spring. The inverse process to obtain the spring load from its length is assimilated to solve...

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Industrial Equivalent Modelling of a Screw Assembly Subjected to a Thermal Load

This paper presents a study of a screw assembly subjected to a thermal load. The main objective i... more This paper presents a study of a screw assembly subjected to a thermal load. The main objective is to test the validity of current industrial practices regarding this kind of structure and loading. To do this, the study is divided into two parts. Firstly, experimental, detailed Finite Element Model (FEM) and analytical approaches are developed and confronted. Several thermo-elastic phenomena are studied. The study focuses on slips between the parts and under the screw heads, but also on loads in the parts and in the screw connections, and on the evolution of the preload in the screw connections. The detailed FEM and the analytical model take the microscopic behavior of the contacts into account by using a modified Coulomb model. The three approaches show rather good correlation. Secondly, industrial equivalent models of the assembly are developed and confronted with the previous work. These models are linear and the screw connections are represented in a very simplified way, by spri...

Stiffness and slip laws for threaded fasteners subjected to a transversal load

Lecture Notes in Mechanical Engineering, 2016

This article focuses on improving the design methods for simplified models of screwed connections... more This article focuses on improving the design methods for simplified models of screwed connections (spring, beam or bar elements), especially for the space sector. A detailed 3D model of a generic screwed connection has been developed using industrial finite elements (FE) software. An approach based on multiscale numerical designs of experiments (DOE) was used to obtain metamodels of stiffness and slip depending on geometric, material and contact parameters. In order to improve the integration of friction, an existing contact model was adapted and used to supply a modified Coulomb model. Metamodels from these numerical works were compared and correlated with experimental double shear tests on a specimen loaded by an imposed transverse displacement.

Vers une industrialisation du modèle de frottement dynamique de LuGre. Application à des essais de glissement en condition de frottement sec

Dans une démarche d'amélioration de la prédiction du comportement en glissement d'assembl... more Dans une démarche d'amélioration de la prédiction du comportement en glissement d'assemblages boulonnés, des essais de glissement en condition de frottement sec sous chargement statique ont été réalisés. Pour cela, une éprouvette en aluminium 2017 non revêtu a été boulonnée à précharge contrôlée avec une éprouvette en acier inoxydable 316L non revêtu. Un chargement transverse a alors été introduit dans l'assemblage à l'aide d'une machine de traction. Le glissement inter-éprouvette induit et l'évolution de l'effort normal dans l'assemblage ont été mesurés. Les résultats mettent notamment en évidence le phénomène d'instabilité dynamique dit de « stick-slip » (ou de « broutement »). Dans un premier temps, un état de l'art des modèles théoriques de frottements disponibles dans la littérature est présenté. Le modèle dynamique de LuGre a été sélectionné en vue d'une possible utilisation industrielle au sein des méthodes de pré-dimensionnement d&...

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