PhD defence of Laura Montalban

Laura Montalban conducted her PhD work in PSF team under the supervision of Pierre Montmitonnet and Imène Lahouij. She defends her PhD in "Computational Mechanics and Materials" on October 2022 (subject to the agreement of the reviewers) in front of the following jury:

 

– DELBÉ Karl, Ecole Nationale d'Ingénieurs de Tarbes, Reviewer

 

– LE HOUÉROU Vincent, Université de Strasbourg – IUT Robert Schuman Illkirch, Reviewer

 

– CHATEAUMINOIS Antoine, ESPCI

 

– JRIDI Nidhal, Hutchinson, guest

 

– MONTMITONNET Pierre, Mines Paris – PSL, CEMEF

 

– LAHOUIJ Imène, Mines Paris – PSL, CEMEF

 

 

Abstract: 

 

Poly-V Belts are multilayered flexible elements that enable power transmission between rotational shafts of automotive engine drives. Wear of the external coating of the belts is inevitable because friction at the interface between the pulley and the belt is required for the transmission of torque. The aim of this PhD thesis is to understand the tribological behavior of the TPV elastomer coating of the Poly-V belts in order to improve the wear resistance and increase their lifetime. First, the wear behavior of the Poly-V belts was studied by means of two industrial test rigs: electric and diesel test benches.  Experiments were performed at different operating conditions such as: applied contact pressure, sliding velocity and slip (%). The abraded surface of the belts was also observed in order to identify the dominant wear mechanisms and determine their evolution with the aforementioned input parameters. Then, a high temperature tribometer was developed in order to perform wear tests of the material of the TPV coating at a laboratory scale. The main purpose was to reproduce the kinematical configuration found on industrial test rigs and to control the main input parameters. Due to the nature of the thermoplastic constituent of the TPV coating, an analytical model for predicting the contact temperature at the interface was also proposed. A good agreement between the contact temperature measured with the infrared camera and the numerical simulations was observed. Results suggests that an increase in contact pressure and sliding velocity affects the wear kinetics of the TPV coating. In this context, the contact temperature rise generated by frictional heating is detrimental for the wear resistance of the TPV coating. The presence of a non-woven layer of fibers decreases friction at the interface, however, it also seems to increase the wear rate of the TPV coating. The incorporation of a substrate with an elastic modulus E’ affects the wear performance of the TPV coating. The previous findings indicate that the mechanical properties (e.g rupture and fatigue) of the TPV coating and the substrate play a major role in the wear behavior of the Poly- V belts. Moreover, SEM images of the worn surface showed two main types of wear features characteristic of abrasive wear (fiber pull out – detachment of thermoplastic constituent of the non-woven layer and abrasion patterns). Lastly, wear trends and wear mechanisms obtained with the high temperature tribometer are similar to the ones reported on industrial test benches. The approach presented in this work provides a basis for the development of future material formulations that could enhance the wear performance of the coating of the Poly-V belts. 

 

 

Keywords: Thermoplastic elastomer, high temperature tribometer, contact temperature, sliding wear, friction