Effect of Thermal Ageing on the Impact and Flexural Damage Behaviour of Carbon Fibre-Reinforced Epoxy Laminates

Abstract

Most of the composite materials that are used in aerospace structures have been manufactured using a thermostable matrix, as epoxy resin. The region of stability of these polymers is defined by the glass transition temperature (Tg). However, operating temperatures close and above the Tg can cause a variation in the properties of the polymer and consequently, modify the mechanical properties of the composite material. Therefore, it is necessary to understand the failure mechanisms that occur in the material in order to ensure stability and durability. The effect of temperature and time of exposure on the impact and flexural mechanical responses of carbon/epoxy composites are studied in this work. For that purpose, ageing treatments at temperatures below and above the Tg have been considered and then, impact and flexural tests have been performed. It was observed that thermal ageing cause two different effects: at temperatures below the Tg, there is an increase of the maximum strength because of a post-curing effect; however, the mechanical properties decrease at higher temperatures of thermal ageing due to the thermo-oxidation of the epoxy resin and the loss of adhesion in the matrix/fibre interface.

Thermal Aging Rheological Behavior of Magnetorheological Elastomers Based on Silicone Rubber

“…The obtained result was due to the changes of the molecular configuration accompanied by a hydro-thermal deterioration, which led to the development of microcracks of the matrix and the filler/matrix interface. However, a contradictory effect has been demonstrated in some studies [5,6], where the rubber composites exhibited a higher modulus of up to 215% in aged samples as compared to an unaged sample. Moreover, the maximum flexural stress was also increased by up to 15% and tended to decrease to almost 275% in comparison to the unaged sample.…”

“…The condition of exposure to these applications such as surrounding temperature, humidity, heat, and chemical attack will result in degradation with regard to time as well as aging issues. In general, the aging of the rubber composite is caused by chemical [5,6] and oxidative-destructive processes [7][8][9], thermal [10,11], heat, moisture, radiation [12,13], and also dynamical and mechanical strains. Among them, the two crucial factors negatively influencing the degradation or aging stability of rubber composites are temperature or heat, and the presence of an oxygen, which received from ambient condition or it is generated by their mechanical or dynamic strain test.…”

“…Moreover, numerous studies by other researchers [5,6,10,19] have concluded that, with the increased of temperature and aging time, the mechanical properties such as hardness, tear strength, and tensile strength would decrease as high as 72%. The obtained result was due to the changes of the molecular configuration accompanied by a hydro-thermal deterioration, which led to the development of microcracks of the matrix and the filler/matrix interface.…”

Effect of Thermal Ageing on the Impact Damage Resistance and Tolerance of Carbon-Fibre-Reinforced Epoxy Laminates

“…In this study, the characterization and the assessment of the effect of thermal ageing on the damage response of CFRP laminates subjected to low velocity impact loading is evaluated. Temperatures below and above the glass-transition temperature of the epoxy resin (195 °C) [43] and different periods of time were considered for the thermal ageing treatments. Drop-weight impact tests at low velocity energy were performed to cause barely visible impact damage (BVID) and to determine the impact response of CFRP laminates.…”

Comparison of Self-Etching Ceramic Primer and Conventional Silanization to Bond Strength in Cementation of Fiber Reinforced Composite Post

“…When comparing the push-out strength difference and the fracture patterns according to the post position, the result of the volumetric change by artificial aging mentioned above should also be considered. Meanwhile, previous studies regarding the thermal aging of reinforced thermoset matrix composites frequently revealed a physicochemical degradation of the resin matrix and the loss of adhesion in the matrix /fiber interface [46,47]. These changes could have resulted in lower bond strength and a higher frequency of the cohesive and mixed failure of the luting material in all groups, unlike previous studies without artificial aging [26,40].…”