Optimization of materials for a user-formed mouthguard
A mouthguard that can be custom formed by the user at the time of need to achieve optimum fit and protection is required for sports and clinical applications. This study has evaluated two silicone-based polymer systems found sufficiently workable to be molded to the user's mouth. Compositions were optimized for setting time and mechanical properties by varying the proportions of catalyst, cross-linking agent, and filler. Mechanical tests showed the optimized silicones to have lower tensile and tear strengths and higher penetration and rebound than most present mouthguard materials. Detailed measurements of compressive stress-strain, coupled with a stress analysis of conditions in actual mouthguard use, indicate that the optimized silicone polymers possess more than adequate strength and durability for a user-formed mouthguard.
Étude du comportement à l'impact des protections intra-buccales
Les Protections Intra-Buccales (PIB) sont presentees dans la litterature comme un dispositif efficace de prevention des traumatismes oro-faciaux. Le niveau de protection d'une PIB ne peut etre evalue qu'a partir de tests validant ses proprietes mecaniques. Les tests proposes comprennent des essais de compression, de resistance a la traction, d'absorption d'eau, d'absorption de l'energie d'impact et de retention. L'absorption de l'energie d'impact est une notion indispensable dans les capacites de prevention des traumatismes oro-faciaux des PIB. De nombreuses etudes ont ete menees afin d'evaluer l'absorption de l'energie d'impact de differents materiaux et de differentes protections. Cependant, les protocoles proposes peuvent varier : etudes sur les materiaux (plaque ou eprouvette), etudes sur des protections testees sur des modeles d'arcades differents (en acier, en plâtre, en resine ou en ceramique) ou sur crânes (synthetiques et naturels). Les criteres d'evaluation varient egalement (nombre de dents cassees, le rebond de la bille, energie absorbee mesuree par un capteur...). L'objectif de ce travail est de proposer un protocole d'essai normalise permettant l'etude comparative du comportement a l'impact des PIB et d'utiliser ce protocole d'essai pour tester diverses PIB. Dans un premier temps, nous avons propose une classification des PIB permettant d'englober tous les dispositifs et de definir le champ d'application de ce protocole d'essai. Puis, une revue de la litterature nous a permis de conclure que, pour repondre a notre objectif, les tests doivent etre effectues directement sur la PIB positionnee sur un modele en acier et l'absorption de l'energie doit etre quantifiee en utilisant un capteur positionne sur l'impacteur. Ce protocole d'essai nous a ainsi permis d'effectuer une etude comparative du comportement a l'impact de plusieurs PIB presentant des caracteristiques differentes.
Computer-Aided System of Virtual Testing of Gas Turbine Engines
The article describes the concept of a virtual lab that includes subsystem of gas turbine engine simulation, subsystem of experiment planning, subsystem of measurement errors simulation, subsystem of simulator identification and others. The basis for virtual lab development is the computer-aided system of thermogasdynamic research and analysis “ASTRA”. The features of gas turbine engine transient modes simulator are described. The principal difference between the simulators of transient and stationary modes of gas turbine engines is that the energy balance of the compressor and turbine becomes not applicable. The computer-aided system of virtual gas turbine engine testing was created using the developed transient modes simulator. This system solves the tasks of operational (throttling, speed, climatic, altitude) characteristics calculation, analysis of transient dynamics and selection of optimal control laws. Besides, the system of virtual gas turbine engine testing is a clear demonstration of gas turbine engine working process and the regularities of engine elements collaboration. The interface of the system of virtual gas turbine engine testing is described in the article and some screenshots of the interface elements are provided. The developed system of virtual gas turbine engine testing provides means for reducing the laboriousness of gas turbine engines testing. Besides, the implementation of this system in the learning process allows the diversification of lab works and therefore improve the quality of training.