Thermal cycling and ultraviolet radiation effects on fatigue performance of triaxial CFRP laminates for bridge applications

Abstract

Environmental processing such as thermal cycling and ultraviolet (UV) exposure contributes to degradation of polymer composites mechanical properties. This study focuses on assessing fatigue life of both unstressed and stressed triaxial carbon/epoxy composite laminates exposed to both thermal cycling and UV radiation. In this study, five test series were conducted to assess such effects on fatigue life of carbon fiber reinforced polymer laminates exposed to tensile-compressive (T-C) fatigue loading. This included the following: (i) Pre-exposure (baseline) test group tests; (ii) unstressed thermal cyclic aging; (iii) stressed (tensioned) thermal cyclic test group; (iv) stressed (compressed) thermal cyclic test group; and (v) UV radiation exposure test group. Fatigue life with 95%, 97.7%, and 99% guarantee rates is calculated based on stochastic analysis. In terms of different guarantee rates, the material parameters of S-N curves are fitted after transforming the data to a log–log space. Experimental results indicated that the difference of parameter [Formula: see text] is relatively small for different guarantee rates, and that the coefficient m decreased with increasing probabilistic guarantee rate. Furthermore, the ratio [Formula: see text] decreases with larger guarantee rates and increases as the stress range increases. Results of this study indicated that UV radiation exposure has the largest effect on fatigue life stress range less than 500.0 MPa. Also, fatigue life of pre-compressed specimens exposed to thermal cyclic is most affected when exposed to stress levels larger than 500.0 MPa. For stress ranges less than 500.0 MPa, the effects on fatigue life of unstressed and pre-compressed thermal cycled specimens are relatively large as compared to baseline group.

Polymer-Matrix Composites: Characterising the Impact of Environmental Factors on Their Lifetime

“…On the other hand, the energy associated with the wavelengths-290 to 400 nm-of the solar radiation incident on the surface of the earth is comparable to the breakdown energies of covalent bonds of epoxy and consequently can result in discolourations, chain scission-induced microscopic degradation and reduction in mechanical properties [61,91]. The exposure of tri-axial carbon/epoxy laminates 313-bulb UV for 750 h had major consequences on fatigue life for stress ranges smaller than 500.0 MPa with a major decrease from above 10 5 cycles to below 10 4 cycles [92]. Exposure to γ-rays corresponding to doses of 20, 100 and 200 kGy also detrimentally impacted the fatigue performance of glass/epoxy specimens, particularly at low-cycle fatigue (N < 10 4 ) where a gradual decrease in the maximum stress was identified with increasing irradiation doses.…”

Modelling of Environmental Ageing of Polymers and Polymer Composites—Durability Prediction Methods

“…These are comprehensively discussed and systematised in numerous review papers [ 121 , 126 , 129 , 130 , 131 , 132 , 133 , 134 ]. The traditional models are often used in conjunction with statistical data analysis [ 135 , 136 , 137 , 138 , 139 ]. The present section is not aimed to give an in-depth discussion of the fatigue models but point out the main differences in existing modelling approaches that are crucial for fatigue prediction under environmental impact.…”

“…The results are summarised in Table 2 regarding the environmental factors, material and testing parameters, and general concepts employed in modelling. Some alternative approaches for predicting fatigue lifetime under the influence of environmental factors are presented in [ 102 , 137 , 156 , 160 ].…”

Space radiation environment adaptability of the domestic 5056 high-performance aluminum honeycomb

“…In order to accurately and objectively evaluate the space radiation environment adaptability of spacecraft materials [7][8][9][10] , China Academy of Space Technology, Beihang University, Harbin Institute of Technology, and others have extensively conducted numerical simulation and space environment simulation experimental research in space environment models, environmental effect mechanisms, and spacecraft space environment damage modes [11][12][13][14] . It equipped complete and mature space environment simulators to evaluate the adaptability of spacecraft materials and structures to the space radiation environment.…”