Development of realistic simulation techniques to predict cure-induced microcracking in 3D woven composites

Considering aeronautics requirements, academies and industries are developing matrixes and reinforcements with higher mechanical performance. The same occurs with the process where new studies focus on obtaining composites with suitable matrix/reinforcement interface. The use of epoxy resin and carbon fiber with high mechanical performance does not guarantee a composite with high mechanical properties, considering imperfections and void formation along the laminate in case of inappropriate processing parameters. The aim of this article was to analyze and quantify the mechanical behavior of polymer composite reinforced with continuous fibers using finite element methodology and postprocessing software simulation. In addition, the classical laminate theory and finite elements were used to simulate flexural and tensile tests of composite specimens. Simulation results were compared with experimental test results using a carbon fiber noncrimp fabric quadriaxial/epoxy resin composite processed by resin transfer molding. Although void volume fraction for structural materials presenting results under aeronautics requirements regarding of 2%, imperfections like lack of resin and impregnation discontinuity showed an influence in tensile and flexural experimental results. Experimental mechanical behavior decreased 10% of strength, in comparison with simulation results due to imperfection on impregnation measured by C-Scan map. Improvement in processing procedures could able to provide greater impregnation continuity, reducing defect formation and ensuring better matrix/reinforcement interface. As a final conclusion, the process plays a role as important as the characteristics of reinforcement and matrix and, consequently, the mechanical properties.

show abstract

“…The epoxy resin and NCF data, presented in Table 1, were important to use in the laminate theory calculation. 32…”

Section: Methodsmentioning

confidence: 99%

Mechanical behavior simulation: NCF/epoxy composite processed by RTM

Monticeli

Daou

Dinulović

et al. 2018

Polymers and Polymer Composites

View full text Add to dashboard Cite

show abstract

Curing cycle modification for RTM6 to reduce hydrostatic residual tensile stress in 3D woven composites

Gross

Jafari

Tsukrov

et al. 2016

J of Applied Polymer Sci

Self Cite

View full text Add to dashboard Cite

Triaxial residual tensile stresses resulting after cooling a 3D woven composite from the curing temperature cause cracking in the resin pockets for weave architectures that have high through‐the‐thickness constraint. We show how curing cycle modifications can reduce the hydrostatic tensile stress generated by thermal mismatch during cooling of Hexcel RTM6 epoxy resin constrained in a quartz tube which simulates extreme constraint in a composite. The modified curing schedule consists of a high temperature cure to just before the glass transition, a lower temperature hold that takes the resin through the glass transition thereby freezing in the zero stress state, followed by high temperature cure to bring the resin to full conversion. We show that this process is sensitive to heating rates and can reduce the zero stress state of non‐toughened RTM6 resin to a temperature similar to a commercial rubber‐toughened resin, Cycom PR520. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43373.

show abstract

Development of realistic simulation techniques to predict cure-induced microcracking in 3D woven composites

Cited by 2 publications

References 13 publications

Mechanical behavior simulation: NCF/epoxy composite processed by RTM

Mechanical behavior simulation: NCF/epoxy composite processed by RTM

Curing cycle modification for RTM6 to reduce hydrostatic residual tensile stress in 3D woven composites

Contact Info

Product

Resources

About