Accelerated aging of carbon fiber-reinforced polymeric materials
Topic(s) : Material and Structural Behavior - Simulation & Testing
Co-authors :
Piero DE FAZIO (ITALY), Tiziana CARDINALE (ITALY), Maria Bruna ALBA , Francesco CATUCCIAbstract :
The rapid increase in the application of carbon fiber-reinforced polymer composites in the fabrication and development of modern industrial products (within automotive, wind power and oil & gas sectors) is due, among other factors, to their lightweight nature, excellent mechanical properties and corrosion resistance. During their life service, these fiber composites are exposed to high temperatures and moist fibers. These composites were subjected to extreme environmental stresses to verify their response during ageing cyclic in terms of decay of mechanical performance and to better understand physico-chemical modification of fiber/matrix interface.
One of the stresses for which it is possible to formulate a significant theoretical trend of the life curve as a function of the stress is the thermal one. During its operational life the material is almost certainly subjected to thermal stress that varies over time; to determine a criterion capable of establishing the actual dure, causing water absorption, which leads to anisotropic expansion and yields residual stresses affecting its durability.
The main goal of this paper is to investigate the effect of environmental effects on the mechanical performance of fiber-reinforced polymers and to suggest future direction in this area. In addition to this, various damage prediction models in the hygrothermal environment will be discussed in detail, such as the evaluation of the recover capability of this material under discontinuous exposure (humid/dry cycle) to aggressive environmental conditions.
The materials tested are carbon fiber-reinforced polymeric (CFRP) materials, which differ from each other, generically, by percentage and length of the useduration of the lifetime, it is assumed that the material is subjected to N thermal cycles in which the temperature remains constant for certain time intervals in order to simulate the real operating conditions. To this aim, the CFRP manufactured has been aged in humid conditions (exposure to salt-fog at 35 °C) for 15-30-45-60 days and then stored under controlled dry conditions (50% R.H. and 23 °C).
Unaged and cyclic aged samples were characterized by tensile and flexural tests and by thermogravimetric analysis (TGA) to investigate the real impact of cyclic ageing on the thermal degradability and its durability issues. Moreover, water uptake and desorption measurements were carried out at different humid and dry phases in order to evaluate the mechanical stability over time and 3D optical microscope has been used to analyse the morphology of fractured samples thus correlating the properties evolution of the composite with its morphology.
The resulting framework has the potential to provide comparisons of long-term durability and degradation derived from any environmental condition to that gained from accelerated ageing tests, also providing a guideline to design new testing protocols tailored for specific climatic zones.
One of the stresses for which it is possible to formulate a significant theoretical trend of the life curve as a function of the stress is the thermal one. During its operational life the material is almost certainly subjected to thermal stress that varies over time; to determine a criterion capable of establishing the actual dure, causing water absorption, which leads to anisotropic expansion and yields residual stresses affecting its durability.
The main goal of this paper is to investigate the effect of environmental effects on the mechanical performance of fiber-reinforced polymers and to suggest future direction in this area. In addition to this, various damage prediction models in the hygrothermal environment will be discussed in detail, such as the evaluation of the recover capability of this material under discontinuous exposure (humid/dry cycle) to aggressive environmental conditions.
The materials tested are carbon fiber-reinforced polymeric (CFRP) materials, which differ from each other, generically, by percentage and length of the useduration of the lifetime, it is assumed that the material is subjected to N thermal cycles in which the temperature remains constant for certain time intervals in order to simulate the real operating conditions. To this aim, the CFRP manufactured has been aged in humid conditions (exposure to salt-fog at 35 °C) for 15-30-45-60 days and then stored under controlled dry conditions (50% R.H. and 23 °C).
Unaged and cyclic aged samples were characterized by tensile and flexural tests and by thermogravimetric analysis (TGA) to investigate the real impact of cyclic ageing on the thermal degradability and its durability issues. Moreover, water uptake and desorption measurements were carried out at different humid and dry phases in order to evaluate the mechanical stability over time and 3D optical microscope has been used to analyse the morphology of fractured samples thus correlating the properties evolution of the composite with its morphology.
The resulting framework has the potential to provide comparisons of long-term durability and degradation derived from any environmental condition to that gained from accelerated ageing tests, also providing a guideline to design new testing protocols tailored for specific climatic zones.