Abstract
Abstract In this article, mode II fracture toughness ( G IIc {G}_{\text{IIc}} ) of unidirectional E-glass/vinyl ester composites subjected to sulfuric acid aging is studied at two different temperatures (25 and 90°C). Specimens were manufactured using the hand lay-up method with the [ 0 ] 20 {{[}0]}_{20} stacking sequence. To study the effects of environmental conditions, samples were exposed to 30 wt% sulfuric acid at room temperature (25°C) for 0, 1, 2, 4, and 8 weeks. Some samples were also placed in the same solution but at 90°C and for 3, 6, 9, and 12 days to determine the interlaminar fracture toughness at different aging conditions. Fracture tests were conducted using end notched flexure (ENF) specimens according to ASTM D7905. The results obtained at 25°C showed that mode II fracture toughness increases for the first 2 weeks of aging and then it decreases for the last 8 weeks. It was also found that the flexural modulus changes with the same trend. Based on the results of the specimens aged at 90°C, a sharp drop in fracture toughness and flexural modulus with a significant decrease in maximum load have been observed due to the aging. Finite element simulations were performed using the cohesive zone model (CZM) to predict the global response of the tested beams.
Highlights
Nowadays, polymeric matrix composites are widely used in a variety of industrial sectors especially in aerospaceThis work is licensed under the Creative Commons AttributionMode II fracture toughness of unidirectional E-glass/vinyl ester composites 383 and automotive industries due to their advantages such as corrosion reduction
4.2 Fracture toughness decrease in this parameter is more intense compared to the trend observed for samples exposed at 25°C, which indicates the importance of temperature of the environmental conditions in this test that accelerate the aging process
The improvement in fracture toughness at the beginning of the environmental conditions can be due to the filling of the cavities by molecules of the acidic solution, which leads to better integrity of the specimens [29]
Summary
Polymeric matrix composites are widely used in a variety of industrial sectors especially in aerospaceThis work is licensed under the Creative Commons AttributionMode II fracture toughness of unidirectional E-glass/vinyl ester composites 383 and automotive industries due to their advantages such as corrosion reduction. The results of mode I for the hygrothermal condition showed that delamination energy experiences a lower loss over the aging time for the 8-Harness Satin fabric instead of the 2/2 Twill fabric. Experimental mode I fracture characterization of samples that were exposed to hygro–thermo–mechanical aging conditions showed that the samples reinforced by carbon fiber and glass fiber have a slight decrease in resistance. The results showed that for mode I DCB tests, long-term seawater exposure caused a significant decrease (25%) in fracture toughness for the samples immersed at 80°C. The materials studied in their research were two composites composed of glass fiber reinforcement (twill and satin weave) with two types of epoxy resin matrixes (120°C class called R1 and a 180°C class called R2). The results showed that the R1 epoxy matrix was very absorbent, and the fibers did not protect the laminated composites, which affects the final mechanical properties of Mazaher Salamt-Talab et al
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