The brake system is critical for ensuring safe driving and has been the focus of development for many years. Pneumatic braking technology is commonly used in heavy vehicles,but it results in energy wastage and high service costs. Some countries mandate auxiliarybraking systems to assist in stopping the vehicle in addition to service brakes. One suchsystem is the regenerative braking system, which captures kinetic energy from braking andconverts it into electrical energy. Retarders are another commonly used auxiliary brakingsystem. These systems are essential due to heavy vehicle weight, which can weaken servicebrake performance.This thesis focuses on estimating net forces on the truck’s driven axle to understandhow auxiliary braking systems and vehicle traction affect the normal force on the drivenwheel axle. The expected result can assist in maintaining the slip ratio and increasing thelife span and performance of brakes.Scania uses a function to estimate forces on the driven axle and drive wheel slip. Theyneed to determine the normal force on the axle to improve performance of auxiliary brakingsystems, but tests showed that for the same specified slip ratio, the auxiliary braking forcerequired was smaller than that in an acceleration state. Scania believe that dynamic axleload transfer may be the cause, so a 6x2 electrified truck will be investigated in this thesis.The obtained results show the driven wheel axle’s behavior during different dynamicalscenarios.This research aimed to develop a model that can accurately simulate a truck’s movement and estimate the ground reaction force in response to variations in the scenario of thecontrol signal. By studying the quarter car model, bounce-pitch and half car model, theresearchers were able to obtain a model represented by 5 ODEs, which predicts the wheelaxle normal force. To verify the model, data from the CAN bus and measurements using ascale were collected and compared with the model’s output. The Mean Squared Error canbe used to evaluate and compare the model’s performance, and the results showed that themodel provides a reasonable estimate of the normal force on all axles. The study also analyzed the factors that contributed to the errors in the results. The behavior of the normalforce for each wheel axle during acceleration and braking was illustrated, explaining howthe normal force distribution becomes mirrored compared to the acceleration state duringbraking. The study’s discussions enhance the validity of the observed behavior and thereliability of the results.

Le rendement des compresseurs aéronautiques est amélioré en minimisant le jeu entre les aubes en rotation et le carter qui les entoure, réduisant ainsi les fuites aérodynamiques. Ce jeu réduit occasionne des contacts entre les aubes et le carter ; afin d’assurer leur intégrité mécanique, le carter est revêtu d’un matériau abradable sacrificiel, lequel accommode les incursions d’aube. Les interactions aube – revêtement abradable couplent des phénomènes tribologiques et vibratoires à haute vitesse et à haute température, dont l’étude expérimentale est requise pour le développement de modèles numériques prédictifs. L’objectif de cette thèse est d’identifier expérimentalement la force et les mécanismes d’interaction aube-abradable AlSi-Polyester dans une configuration d’essai représentative du fonctionnement des étages de compresseur basse-pression. Des méthodes couplées expérimentales - analytiques, prenant en compte la dynamique d’aube, ont été développées afin d’accéder à la force d’interaction et à l’incursion aube-abradable. L’influence de la température, de la nuance du matériau abradable et de la raideur d’aube a été étudiée. Les mécanismes d’usure et d’endommagement du revêtement abradable ont été investigués et corrélés aux conditions d’interaction. Ces travaux de thèse ont été réalisés dans le cadre d’une collaboration entre le Laboratoire de Mécanique de Lille, SNECMA Villaroche (groupe SAFRAN) et le centre ONERA de Lille. / Minimizing the clearance between turbofan blades and the surrounding casing is a key factor to re-ducing leakage flows and consequently improving efficiency. The tight clearance may lead to blade-casing interactions. An abradable coating is deposited on the casing to accommodate blade incursions and thus to protect the blades and the casing from severe damage. Blade/abradable-coating interactions involve tribological and vibratory phenomena at high velocity and temperature. Experimental knowledge of these interactions is paramount to the proper design of abradable materials and the prediction of their lifetimes through numerical simulations. The purpose of this thesis is to identify experimentally the force and the mechanisms occuring during interaction between a vibrating blade and an AlSi-Polyester abradable coating. To this end, experiments were conducted on a dedicated test rig, in conditions representative of low-pressure compressor situation. Specific methods involving dynamical measurements and analytical models have been developed in order to obtain the blade/abradable-coating interacting force as well as the blade tip incursion. The influence of temperature, coating nature and blade stiffness has been studied. The interaction mechanisms and wear of the abradable coating have been investigated and correlated with the interaction conditions. This work was achieved within the framework of cooperation between Laboratoire de Mécanique de Lille (France), SAFRAN-SNECMA (France) and ONERA, the French Aerospace Lab.

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