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RESUMEN: Inicialmente lleva a cabo un repaso del estado del arte para comprender adecuadamente la literatura sobre engranajes de plástico. A continuación, se propone introducir un modelo dinámico de 14 grados de libertad de un sistema tornillo sinfín – corona sobre el que se encuentran pocas referencias en la bibliografía a pesar de ser uno de los sistemas de engranajes más utilizados en aplicaciones de engranajes de plástico. El siguiente paso es modelar el comportamiento viscoelástico del plástico típicamente utilizado en los engranajes, para lo cual se utiliza un modelo reológico denominado modelo de Maxwell generalizado. Finalmente, se diseña y construye un banco de pruebas que se utiliza para validar el trabajo numérico. ABSTRACT: In the beginning of the PhD research work, a state of the art is made to properly understand the literature on plastic gears. Then, it is proposed to introduce a 14 degrees of freedom dynamic model of a worm drive. The latter is found to be one of the most widely used gearing systems in plastic gearing applications but with minimal mentions in the literature. The next step is to model the viscoelastic behaviour of the plastic typically used in gears. For this purpose, a rheological model called the generalized Maxwell model is used. In the end, a test bench is designed and built. It is therefore used to validate the numerical work.

Polymer-metal worm drives are common in automotives and mechatronic systems. Despite this, there is a lack of studies on this type of transmission, especially when it comes to their dynamic behaviour. With the modern orientation of Industry 4.0 towards advancing technology in predictive maintenance, it is of a great importance to consider the study of the dynamic behaviour of this mechanism. It is first proposed to introduce an appropriate dynamic model to correctly simulate, by numerical means, the behaviour of a non-defective polymer-metal worm drive. For this purpose, it is necessary to correctly model the Gear Mesh Stiffness (GMS) of the gearing system. The GMS depends on the nature of the worm and worm gear materials. It is assumed that no deformation occurs in the steel worm, in contrast to the polymer worm whose viscoelastic behaviour must be accurately modelled. Generalized Maxwell Model (GMM) is chosen to model this behaviour. Eventually, the vibration signals from the numerical model are compared with those determined by the experimental tests. To obtain more similarities between the numerical and experimental signals, it is proposed to perform an optimisation. The procedure consists in using the Nelder-Mead simplex method to obtain a minimum residual objective function. After optimisation, an accuracy of 94% between the experimental and numerical results is achieved. The authors gratefully acknowledge Project No. “19PEJC10-06” funded by the Tunisian Ministry of Higher Education and Scientific Research. The authors would like to also acknowledge projects PID2020-116213RB-I00 and PID2020-116572RA-I00 funded by the Spanish Ministry of Science and Innovation.