Banca de QUALIFICAÇÃO: Thiago Pandim Barbosa Machado

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Thiago Pandim Barbosa Machado
DATE: 23/08/2023
TIME: 08:00
LOCAL: Plataforma Microsoft Teams
TITLE:

Experimental analysis of PC/ABS blends: an investigation of mechanical behavior under indentation, creep and fretting wear

KEY WORDS:

PC; ABS; Indentation; Creep; Fretting wear

PAGES: 68
BIG AREA: Engenharias
AREA: Engenharia Mecânica
SUMMARY:

PC/ABS is a polymer blend widely used due to its nearly additive combination of the best properties of its components. However, there is almost no literature available regarding its failure behavior while under compression loading. Therefore, this work aims to investigate the behavior of this material under complex loads. Four PC/ABS weight ratio compositions: 100:0, 80:20, 65:35 and 0:100 were used to manufacture prismatic flat samples that are tested in various scenarios to assess their response to: i) indentation; ii) compressive creep; iii) torsional fretting wear; and iv) variable normal load. A hemispherical pad made of R3 offshore steel is employed as a counterpart tool. Therefore, the contact configuration used in this study is sphere-to-flat. The goal is to try and isolate the effects of each load type, as well as the influence of adding ABS to a PC matrix on its damage resistance.

So far, tests have been conducted to address the first three phenomena. Specimens were tested for indentation, creep and axial-torsional fretting wear at severe loads (1.0 and 2.0 kN). Moreover, the contribution of each one of these three failure phenomena was determined and discussed. Creep had a major effect in most materials, while fretting wear is particularly critical to the 100:0 and 80:20 compositions. The 65:35 blend exhibited the best results in all test conditions, making it a good candidate for various industrial applications.

The next step, already initiated, is to evaluate the uncertainties involved in the tests conducted, with respect to the application of the normal load and the measurements taken on the laser confocal microscope used. Preliminary results indicate that the measurements made on pure PC after indentation of 1.0 kN have a very high overall uncertainty, mainly due to the fact that the scars left on the samples have a few micrometers in depth, which are dimensions very close to the possible resolution of the method used on the microscope.

Finally, the last problem to be addressed in this research is the effects of introducing a variable normal load to the already complex loading scheme employed, keeping a mean value of probably 1.5 kN and applying a range of 0.5 kN, while keeping the torsional motion. No literature whatsoever has been found on that topic, making it a very inovative attempt. Two possible outcomes are expected in this case: radial fretting wear and/or fatigue wear.

Therefore, a detailed description of PC/ABS's response to different compressive damage phenomena is expected, highly contributing to the body of knowledge concerning this extremely important engineering material.

Keywords: PC; ABS; Indentation; Creep; Fretting wear

COMMITTEE MEMBERS:
Interno - 1646090 - FABIO COMES DE CASTRO
Interno - 1345908 - JOSE ALEXANDER ARAUJO
Interna - 1720225 - SANDRA MARIA DA LUZ
Externo à Instituição - SANDRO CAMPOS AMICO - UFRGS
Presidente - 2143651 - THIAGO DE CARVALHO RODRIGUES DOCA