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Estudo do Comportamento à Fadiga de Provetes Produzidos por Impressão 3D de PEEK
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O PEEK (poli-éter-éter-cetona) é um polímero orgânico termoplástico de densidade
baixa, estabilidade térmica e resistência química elevadas, biocompatível e com excelentes
propriedades mecânicas. Dado a sua biocompatibilidade, capacidade de ser produzido por
Manufatura Aditiva (ou impressão 3D) e propriedades mecânicas comparáveis às do osso hu-
mano, o PEEK torna-se de elevada relevância para a área da medicina, uma vez que é possível
a sua implementação cirúrgica no corpo humano, na forma de próteses internas.
No entanto, o estudo deste material à fadiga, está longe do desejável. O objetivo da
presente dissertação, é, assim, a caracterização do comportamento à fadiga de provetes de
PEEK produzidos por impressão 3D.
Para tal, foram impressos provetes de PEEK normalizados, tendo em conta os parâmetros
de impressão do processo FFF considerados otimizados para os ensaios de tração uniaxial. Os
provetes foram sujeitos a ensaios à fadiga com amplitude de tensão constante, com uma razão
de tensões (R) de 0,2 e uma frequência (f) de 7 Hz. Ao todo, foram ensaiados 8 provetes, para
3 carregamentos distintos, correspondentes a 95 %, 85 % e 75 % da tensão de rotura obtida
para os provetes.
Com os resultados obtidos, determinou-se a curva S-N e os parâmetros da equação do
Modelo de Basquin para descrever o comportamento do PEEK à fadiga a elevado número de
ciclos,
high cycle fatigue (HCF), e obteve-se também a sua resistência à fadiga para 1 000 000
(um milhão) de ciclos. Por último, as superfícies de fratura dos provetes foram analisadas no
Microscópio Eletrónico de Varrimento (MEV).
PEEK (polyether-ether-ketone) is a thermoplastic organic polymer with low density, high thermal stability and chemical resistance, biocompatible and with excellent mechanical prop- erties. Due to its biocompatibility, capacity of being produced by Additive Manufacturing (or 3D printing) and mechanical properties comparable to those of human bone, PEEK becomes extremely relevant in the medicine field, since its surgical implementation in the human body, on the form of implants or prosthetics, is possible. However, the study of this material fatigue behavior is far from desirable. The objective of this dissertation is thus the characterization of the fatigue behavior of PEEK specimens pro- duced by 3D printing. To this end, standardized PEEK specimens were printed, considering the printing param- eters of the FFF process obtained from uniaxial tensile tests. The specimens were subjected to fatigue tests with constant stress amplitude, with a stress ratio (R) of 0.2 and a frequency (f) of 7 Hz. In total, 8 specimens were tested, in 3 distinct loads, corresponding to 95 %, 85 % and 75 % of the ultimate tensile strength of the tensile specimens. With the results obtained, the S-N curve and the parameters of the Basquin Model equa- tion - which describes the high cycle fatigue (HCF) behaviour of PEEK - were determined, and its fatigue resistance at 1 000 000 (one million) cycles was also obtained. Finally, the specimens fracture surfaces were analysed using a Scanning Electronic Microscope (SEM).
PEEK (polyether-ether-ketone) is a thermoplastic organic polymer with low density, high thermal stability and chemical resistance, biocompatible and with excellent mechanical prop- erties. Due to its biocompatibility, capacity of being produced by Additive Manufacturing (or 3D printing) and mechanical properties comparable to those of human bone, PEEK becomes extremely relevant in the medicine field, since its surgical implementation in the human body, on the form of implants or prosthetics, is possible. However, the study of this material fatigue behavior is far from desirable. The objective of this dissertation is thus the characterization of the fatigue behavior of PEEK specimens pro- duced by 3D printing. To this end, standardized PEEK specimens were printed, considering the printing param- eters of the FFF process obtained from uniaxial tensile tests. The specimens were subjected to fatigue tests with constant stress amplitude, with a stress ratio (R) of 0.2 and a frequency (f) of 7 Hz. In total, 8 specimens were tested, in 3 distinct loads, corresponding to 95 %, 85 % and 75 % of the ultimate tensile strength of the tensile specimens. With the results obtained, the S-N curve and the parameters of the Basquin Model equa- tion - which describes the high cycle fatigue (HCF) behaviour of PEEK - were determined, and its fatigue resistance at 1 000 000 (one million) cycles was also obtained. Finally, the specimens fracture surfaces were analysed using a Scanning Electronic Microscope (SEM).
Descrição
Palavras-chave
PEEK Manufatura Aditiva Fadiga a elevado número de ciclos Curva S-N Análise MEV