[en] Thermoplastic polyurethane elastomers (TPU) are a class of elastomer that can be processed by heat without being destroyed. In addition to the unique mechanical performance properties of elastomers (soft, high deformation elastically, the ability to dissipate energy…), TPUs exhibit high abrasion and bending fatigue resistances. Therefore, they are used as cover rope in the lift industry. These elastomeric cover ropes allow downsizing sheaves and homogenizing contact pressures over sheaves. Therefore, in order to understand the behaviour of TPU coatings when they pass over sheaves, the contact behaviour must be analyzed. In the present work, the contact between an ether-based TPU processed by extrusion and a hard material (gray iron) has been investigated using theoretical, experimental and numerical analysis. The contact behaviour has been studied dividing into normal and tangential contacts. Therefore it has been necessary to obtain a model of the TPU mechanical behaviour at moderate strains (under 100%) and a friction model between the TPU and the gray iron. As result of this work, an analytic visco-hyperelastic model with the deformation history, which has been implemented into numeric calculus using an iterative FEA based technique, has been proposed. Moreover an analytic friction model, which has been locally implemented into numeric calculus using finite element method, has been also proposed. Finally, these both models have been validated using simulations of normal contact (indentation) between the TPU and the gray iron as well as tangential (sliding) contact.

[eu] Poliuretanozko termoplastiko elastomeroak (TPU) beroarekin suntsitu gabe prozesa daitezkeen materiala elastomeroak dira. TPU material hauek elastomeroen ohiko konportamentu mekanikoez gain (elastikoki deformazio handiak onartzea, zailtasun handia, bigun izatea, eta abar) urradura eta flexio bidezko nekearekiko erresistentzia handia aurrezten dute. Hori dela eta igogailuen industrian erabilitako kable metalikoen estaldura gisa komenigarriak dira. Mota honetako estaldurek poleen tamaina murriztu eta haienganako presioak homogeneizatzea ahalbidetzen dute. Horregatik TPU estaldurek poleekiko duten portaera mekanikoa ulertu ahal izateko, beren kontaktu portaera ikertu behar da. Lan honetan estrusio bidez prozesatutako eter motako TPU-aren jarrera askoz gogorragoa den material batekin kontaktuan dagoenean (galdaketa grisa) ikertu da analisi teoriko, esperimentala eta zenbakizko erabiliz. Horretarako ikerketa lana deformazio txikiko TPU-aren portaera mekanikoa eta TPU eta galdaketaren arteko marruskaduraren modelo baten garapenean oinarritu egin da. Hauekin bi zatian normala eta tangentziala banatu izan den kontaktuzko portaeraren ikerketa da. Modu honetan TPU-ak jasandako deformazio historia kontuan hartzen duen modelo bisco-hiperelastiko analitiko bat garatu egin da. Material modelo hori zenbakizko kalkuluan inplementatua izan da elementu finituetan oinarritutako teknika iteratibo baten bitartez. Horrez gain kontaktu bidezko presio eta irristatze abiaduran oinarritutako marruskadura modelo analitikoa bat proposatu da, zein elementu finituen bitartez zenbakizko kalkuluan inplementatua izan da. Azkenik bi modelo hauek TPU eta galdaketaren arteko kontaktu normal (indentazio) eta tangentzialen simulazioen bitartez balioztatuak izan dira.