COBEM99

S21 Vibrações e Análise Modal

Title:

DAMPING EVALUATION OF STRUCTURAL CARBON REINFORCED COMPOSITES

Summary :

ABSTRACT: CARBON FIBRE REINFORCED CARBON COMPOSITES ARE A CLASS OF ADVANCED MATERIALS THAT ARE BEING USED IN THE AEROSPACE INDUSTRY. THEY ARE INTENDED TO BE USED AS STRUCTURAL MATERIALS UNDER VARYING LOADING CONDITIONS. AS A RESULT THEIR DYNAMIC MECHANICAL PROPERTIES ARE FUNDAMENTAL CHARACTERISTICS BESIDES STRENGTH PARAMETERS. THE NON-DESTRUCTIVE CHARACTER OF THE DYNAMIC TEST MAKE IT THE IDEAL TOOL FOR MONITORING THE DEVELOPMENT OF MECHANICAL PROPERTIES DURING MATERIAL PROCESSING. THIS WORK REPORTS VIBRATION EXPERIMENTS CONDUCED ON DIFFERENT TYPES OF COMPOSITES MADE WITH CARBON FIBRE FABRICS. THE FIRST WAS A COMPOSITE MADE WITH A COMMERCIAL PLAIN WEAVE FABRIC, IN WHICH CARBON FIBRES WERE HEAT TREATED AT 1500OC. THE SECOND COMPOSITE WAS MADE WITH A TWILL WEAVE FABRIC, IN WHICH CARBON FIBRES WERE HEAT TREATED AT A TEMPERATURE BELOW 1000OC. THE FABRICS WERE MOULDED WITH PHENOLIC RESIN, AND CARBONISED. FREE VIBRATION TESTING WAS CONDUCED IN THE AS-MOULDED AND IN THE CARBONISED SAMPLES. A DECREASE IN STORAGE MODULUS WAS OBSERVED FOR BOTH PLAIN AND TWILL WEAVE FABRIC COMPOSITES DUE TO AN OVERALL INCREASE IN COMPOSITE POROSITY. A PRONOUNCED DECREASE IN LOSS MODULUS AND TAN  WAS OBSERVED FOR THE PLAIN WEAVE CARBONISED COMPOSITE IN RELATION TO THE AS-MOULDED COMPOSITE. THIS TREND WAS NOT FOLLOWED BY THE TWILL WEAVE CARBONISED COMPOSITE SINCE ADDITIONAL INTERNAL FRICTION SITES, DUE TO POOR FIBRE/MATRIX ADHESION, WERE CREATED. KEY-WORDS: COMPOSITES, CARBON REINFORCED CARBON COMPOSITES, VIBRATION DAMPING, CARBON FIBRES.

Author :

Dias, José Celio
Pardini, Luiz Claudio
Pina, Samanta Omena
Ribeiro, Marcelo 0

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