Creep and interfacial behavior of carbon fiber reinforced epoxy filament wound laminates

Abstract

This article focuses on the investigation of the interfacial and creep characteristics of carbon fiber‐reinforced epoxy laminates at different fiber orientations. Flat unidirectional 12‐layer laminates were manufactured by dry‐filament winding and cured under hot compression. The following winding sequences were studied: [0]12, [30]12, [45]12, [60]12, and [90]12. Short‐beam testing aided by microscopy and dynamic mechanical analysis were used to assess interfacial characteristics and creep behavior of the laminates. Short beam strength and creep behavior were strongly influenced by fiber orientation. Short beam strength decreased 270%, and only the laminates wound at 0° presented delamination purely at the mid‐plane. Fiber/matrix stress transfer is more efficient for laminates wound at 0°, providing better creep behavior. Dynamic mechanical analysis results indicated the storage modulus to be dependent on the ply angle. Findley's and Burger's fitting were used to analyze creep data from the DMA and correlate structure and property of the composites. The creep strain increases from longitudinal to transversal fiber orientation and by increasing the temperature. At higher temperatures, samples longitudinally oriented exhibited an elastic behavior, with good agreement with the Findley's model. POLYM. COMPOS., 39:E2199–E2206, 2018. © 2017 Society of Plastics Engineers

On the creep behavior of carbon/epoxy non-crimp fabric composites

“…Discrepancies presented on dynamic-mechanical results were associated to the matrix/ fiber interface, since resin, fiber volume and orientation were similar. In similar study, Almeida Jr. et al 11 analyzed the creep and interfacial behavior of carbon fiber reinforced epoxy filament wound laminates at five different winding sequences. The authors used two different analytical models for it (Findley and Burger's models).…”

“…The present study has as novelty a detailed structureproperty relationship study on viscoelastic properties of carbon NCF/epoxy composites molded by VARTM. The viscoelastic properties of the composite were evaluated by dynamic mechanical analysis and by Findley, Burgers and Weibull model parameters using creep testing based on literature [11][12][13][14] . Different conditions of temperature and static stress were selected aiming to evaluate the behavior along time on creep tests.…”

Time-temperature behavior of carbon/epoxy laminates under creep loading

“…This parameter is temperature-dependent because the bulk material tends to become softer with temperature, which decreases the instantaneous modulus (Fancey 2005;Xu et al 2010;Yang et al 2006aYang et al , 2006b). This parameter can be associated with the storage modulus in the glassy region, where higher temperatures decrease the modulus when compared to the same static stress applied (Almeida et al 2018a(Almeida et al , 2018b. These results suggest that it is difficult to have some viscous flow on the bulk material due to a higher elastic deformation at a short-time response.…”

“…Significant progress has been carried out in terms of the time-independent behavior of CFRP composites. However, in engineering applications, compliance and deformation properties are stress-and time-dependent (Almeida et al 2018a(Almeida et al , 2018bOrnaghi et al 2020).…”

Effect of Post-Cure on the Static and Viscoelastic Properties of a Polyester Resin

“…Regarding the creep behavior, the Findley power law model is one of the most widely used to describe this phenomenon in composite materials and has been recommended, inclusively, by the ASCE Structural Plastics Design Manual to analyze and design the long-term strength [ 50 ]. The Findley’s power law is given by Equation (5): where ε ( t ) is the creep displacement at time t , ε 0 is the instantaneous elastic displacement or time-independent, A is the amplitude of transient creep (time-dependent), and n is a constant independent of the stress and generally less than one [ 51 ]. Several studies can be found in the open literature, where the Findley’s power law was also applied to short-term creep data [ 27 , 28 , 51 , 52 , 53 ].…”