TY - THES

T1 - InSitu tribological and fracture mechanical investigation of Thermoplastic Polyurethanes

AU - Stiller, Tanja

N1 - embargoed until 17-09-2023

PY - 2018

Y1 - 2018

N2 - A much-debated topic is saving energy and resources by developing new technologies as well as better materials. This is also an issue in tribological applications for example for seals. An application optimized material will last longer and therefore elongates the maintenance intervals. A crucial factor for seal is wear which leads in almost all cases after some time to failure. It is important to understand the wear initiation process to prevent the failure of seals. To understand the different influences on tribological values as coefficient of friction and wear rate a variation of test parameters as time, load, roughness, types of movement and lubrication were investigated for two Thermoplastic Polyurethanes (TPU) on different tribometers. To receive information about the wear initiation process tests were conducted on a reciprocating InSitu-tribometer. This setup allows to observe the processes taking place in the contact area and how wear particles interact with each other. The observation enables to build up a wear-initiation model with crack-initiated wear particles. For understanding the crack growth behaviour, dynamic fatigue tests were conducted with “Faint-Waist-Pure-Shear” specimen. This special geometry ensures a horizontal crack growth, which facilitates the observation of the growing crack. The last part covers a mathematical comparison to find a correlation between tribological and fracture mechanical values. Basis for this is a proportionality of the tribological wear rates and the fracture mechanical fatigue-cycle-number. Due to the given accordance, the experimentally received values from the fatigue tests can be used to calculate a wear rate based only on fracture mechanical values. The trend of those calculated wear values can be found in some parameter variations of the tribological tests

AB - A much-debated topic is saving energy and resources by developing new technologies as well as better materials. This is also an issue in tribological applications for example for seals. An application optimized material will last longer and therefore elongates the maintenance intervals. A crucial factor for seal is wear which leads in almost all cases after some time to failure. It is important to understand the wear initiation process to prevent the failure of seals. To understand the different influences on tribological values as coefficient of friction and wear rate a variation of test parameters as time, load, roughness, types of movement and lubrication were investigated for two Thermoplastic Polyurethanes (TPU) on different tribometers. To receive information about the wear initiation process tests were conducted on a reciprocating InSitu-tribometer. This setup allows to observe the processes taking place in the contact area and how wear particles interact with each other. The observation enables to build up a wear-initiation model with crack-initiated wear particles. For understanding the crack growth behaviour, dynamic fatigue tests were conducted with “Faint-Waist-Pure-Shear” specimen. This special geometry ensures a horizontal crack growth, which facilitates the observation of the growing crack. The last part covers a mathematical comparison to find a correlation between tribological and fracture mechanical values. Basis for this is a proportionality of the tribological wear rates and the fracture mechanical fatigue-cycle-number. Due to the given accordance, the experimentally received values from the fatigue tests can be used to calculate a wear rate based only on fracture mechanical values. The trend of those calculated wear values can be found in some parameter variations of the tribological tests

KW - InSitu

KW - Tribologie

KW - Bruchmechanik

KW - TPU

KW - Korrelation

KW - InSitu

KW - tribology

KW - fracture mechanic

KW - TPU

KW - correlation

M3 - Master's Thesis

ER -