Benefits and limitations of parametric design implementation in helicopter gearbox design phase

International audiencehis paper describes a parametric design methodology implemented to reduce gearbox design phase. A helicopter gearbox is a complex mechanical system, in which parts are heavily loaded in order to save weight but that have to run for thousands of hours without failure. Such a system is strongly optimized therefore the smallest change in specifications or in geometrical environments can drastically jeopardize the scheduling. In order to speed up the gearbox design process and to strengthen its robustness regarding specifications variability, a parametric design methodology has been developed thanks to a close collaboration between the laboratories and Eurocopter

Analysis of Airless Tyre for Static Forces

In this work, models of air-less tire is constructs to simulate the loading condition. Air-less tire, air-tire are modelled by AUTODESK modelling software. Model imported from AUTODESK to ANSYS to simulate the static compressive loading condition. Both were analyzed through Non-Linear material model. A uniformly distributed center load acting at the center of tyre rim acting downwards. The tire is made by rubber of the hyper-elastic property. Both tires are analyzed by the FEA. Comparison is done between airless and air tyre for deflection and stress parameter

Modelação Paramétrica de Ferramentas

Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia MecânicaOs softwares de desenho assistido por computador representam uma ferramenta indispensável da engenharia moderna. Obter o máximo rendimento dos recursos ao seu dispor é prioridade de qualquer organização e, nesse sentido, foi desenvolvido, em parceria com a Optimal Structural Solutions, um modelo paramétrico generativo de um componente comummente utilizado no desenvolvimento de moldes de laminação de peças compósitas, com o objetivo de diminuir o tempo de modelação do mesmo. De modo a avaliar a qualidade e aplicabilidade do modelo, foram realizados pelos desenhadores afetos à Optimal Structural Solutions um conjunto de testes. As avaliações decorrentes dos testes realizados mostram que a implementação do modelo representa uma mais-valia para o processo de modelação e validam a possibilidade de aplicação desta metodologia a outros produtos, presentemente desenvolvidos pela Optimal Structural Solutions.Computer aided design software’s have become a fundamental tool of modern engineering. Taking maximum advantage of the available resources is a top priority of any organization and, with this purpose, a parametric generative model of a component commonly used in the design of lamination molds for composite parts has been developed, in partnership with Optimal Structural Solutions, with the objective of reducing the modelling time of this component. For evaluating the implementation advantages of the model, a series of tests were performed by the designers, connected to Optimal Structural Solutions. The results of these tests show that the model implementation represents an advantage for the design process, and give positive feedback concerning the implementation of this methodology to other products currently developed by Optimal Structural Solutions.N/

DeReFrame: a design-research framework to study game mechanics and game aesthetics in an engineering design process

The main aim of this research is to study gaming techniques and elements that may potentially be beneficial to the future development of CAD systems for engineering design, in particular to maintain cognitive engagement. A design-research framework, called DeReFrame, was employed to construct an experimental game-based CAD framework exploring this. This research is based on reviews from the literature and experimental studies and include quantitative and qualitative data analysis methods measuring engineers’ performance and emotional responses. The thesis presents the construction process of the framework (DeReframe) to study a set of game mechanics and game aesthetics in an engineering design process and compare this with the traditional CAD. The framework was used to design and implement a game-based CAD system, called ICAD which was embedded with the following game mechanics of Directional Goals, Progression, Performance-Feedback and Rewards-Achievement. The DeReFrame and ICAD evolved through the experimental studies. In each case, selected game mechanics were at the core of each interaction and iteration which gave rise to feelings of progress, competence and mastery. The final results from the DeReFrame framework and ICAD indicated that gamified approaches should be included in engineering design with CAD: in particular the game mechanics of performance feedback and rewards-achievements influence engineers’ behaviour by supporting them within the problem-solving process creating an engaging-challenging interaction. In conclusion, this research has shown that a framework, that includes both engineering requirements and gamified aspects into consideration, cam serve as a basis for implementing game-based CAD to facilitate performance by providing engaging experiences for engineers

Les traces de pneumatiques en sciences forensiques : de l'analyse chimique à l'évaluation de la force probante

This work is focused on the development of a methodology for the use of chemical characteristic of tire traces to help answer the following question: "Is the offending tire at the origin of the trace found on the crime scene?". This methodology goes from the trace sampling on the road to statistical analysis of its chemical characteristics. Knowledge about the composition and manufacture of tread tires as well as a review of instrumental techniques used for the analysis of polymeric materials were studied to select, as an ansi vi cal technique for this research, pyrolysis coupled to a gas Chromatograph with a mass spectrometry detector (Py-GC/MS). An analytical method was developed and optimized to obtain the lowest variability between replicates of the same sample. Within-variability of the tread was evaluated regarding width and circumference with several samples taken from twelve tires of different brands and/or models. The variability within each of the treads (within-variability) and between the treads (between-variability) could be quantified. Different statistical methods have shown that within-variability is lower than between-variability, which helped differentiate these tires. Ten tire traces were produced with tires of different brands and/or models by braking tests. These traces have been adequately sampled using sheets of gelatine. Particles of each trace were analysed using the same methodology as for the tires at their origin. The general chemical profile of a trace or of a tire has been characterized by eighty-six compounds. Based on a statistical comparison of the chemical profiles obtained, it has been shown that a tire trace is not differentiable from the tire at its origin but is generally differentiable from tires that are not at its origin. Thereafter, a sample containing sixty tires was analysed to assess the discrimination potential of the developed methodology. The statistical results showed that most of the tires of different brands and models are differentiable. However, tires of the same brand and model with identical characteristics, such as country of manufacture, size and DOT number, are not differentiable. A model, based on a likelihood ratio approach, was chosen to evaluate the results of the comparisons between the chemical profiles of the traces and tires. The methodology developed was finally blindly tested using three simulated scenarios. Each scenario involved a trace of an unknown tire as well as two tires possibly at its origin. The correct results for the three scenarios were used to validate the developed methodology. The different steps of this work were useful to collect the required information to test and validate the underlying assumption that it is possible to help determine if an offending tire » or is not at the origin of a trace, by means of a statistical comparison of their chemical profile. This aid was formalized by a measure of the probative value of the evidence, which is represented by the chemical profile of the trace of the tire. - Ce travail s'est proposé de développer une méthodologie pour l'exploitation des caractéristiques chimiques des traces de pneumatiques dans le but d'aider à répondre à la question suivante : «Est-ce que le pneumatique incriminé est ou n'est pas à l'origine de la trace relevée sur les lieux ? ». Cette méthodologie s'est intéressée du prélèvement de la trace de pneumatique sur la chaussée à l'exploitation statistique de ses caractéristiques chimiques. L'acquisition de connaissances sur la composition et la fabrication de la bande de roulement des pneumatiques ainsi que la revue de techniques instrumentales utilisées pour l'analyse de matériaux polymériques ont permis de choisir, comme technique analytique pour la présente recherche, la pyrolyse couplée à un chromatographe en phase gazeuse avec un détecteur de spectrométrie de masse (Py-GC/MS). Une méthode analytique a été développée et optimisée afin d'obtenir la plus faible variabilité entre les réplicas d'un même échantillon. L'évaluation de l'intravariabilité de la bande de roulement a été entreprise dans sa largeur et sa circonférence à l'aide de plusieurs prélèvements effectués sur douze pneumatiques de marques et/ou modèles différents. La variabilité au sein de chacune des bandes de roulement (intravariabilité) ainsi qu'entre les bandes de roulement considérées (intervariabilité) a pu être quantifiée. Les différentes méthodes statistiques appliquées ont montré que l'intravariabilité est plus faible que l'intervariabilité, ce qui a permis de différencier ces pneumatiques. Dix traces de pneumatiques ont été produites à l'aide de pneumatiques de marques et/ou modèles différents en effectuant des tests de freinage. Ces traces ont pu être adéquatement prélevées à l'aide de feuilles de gélatine. Des particules de chaque trace ont été analysées selon la même méthodologie que pour les pneumatiques à leur origine. Le profil chimique général d'une trace de pneumatique ou d'un pneumatique a été caractérisé à l'aide de huitante-six composés. Sur la base de la comparaison statistique des profils chimiques obtenus, il a pu être montré qu'une trace de pneumatique n'est pas différenciable du pneumatique à son origine mais est, généralement, différenciable des pneumatiques qui ne sont pas à son origine. Par la suite, un échantillonnage comprenant soixante pneumatiques a été analysé afin d'évaluer le potentiel de discrimination de la méthodologie développée. Les méthodes statistiques appliquées ont mis en évidence que des pneumatiques de marques et modèles différents sont, majoritairement, différenciables entre eux. La méthodologie développée présente ainsi un bon potentiel de discrimination. Toutefois, des pneumatiques de la même marque et du même modèle qui présentent des caractéristiques PTD (i.e. pays de fabrication, taille et numéro DOT) identiques ne sont pas différenciables. Un modèle d'évaluation, basé sur une approche dite du likelihood ratio, a été adopté pour apporter une signification au résultat des comparaisons entre les profils chimiques des traces et des pneumatiques. La méthodologie mise en place a finalement été testée à l'aveugle à l'aide de la simulation de trois scénarios. Chaque scénario impliquait une trace de pneumatique inconnue et deux pneumatiques suspectés d'être à l'origine de cette trace. Les résultats corrects obtenus pour les trois scénarios ont permis de valider la méthodologie développée. Les différentes étapes de ce travail ont permis d'acquérir les informations nécessaires au test et à la validation de l'hypothèse fondamentale selon laquelle il est possible d'aider à déterminer si un pneumatique incriminé est ou n'est pas à l'origine d'une trace, par le biais d'une comparaison statistique de leur profil chimique. Cette aide a été formalisée par une mesure de la force probante de l'indice, qui est représenté par le profil chimique de la trace de pneumatique