Time-temperature behavior of carbon/epoxy laminates under creep loading
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Time-temperature behavior of carbon/epoxy laminates under creep loading Heitor L. Ornaghi Jr.1 · José Humberto S. Almeida Jr.2 Roberta M. Neves3 · Maria Odila H. Cioffi1
· Francisco M. Monticeli1 ·
Received: 6 February 2020 / Accepted: 8 August 2020 © The Author(s) 2020
Abstract The time-temperature creep behavior of advanced composite laminates is herein determined through a comprehensive set of experiments and analytical modeling. A complete structure versus property relationship is determined through a wide range of temperature and applied stress levels at the three states of the composite: glassy, glass transition, and rubbery regions. Weibull, Eyring, Burger, and Findley models are employed to predict the experimental data and to better elucidate the material behavior. Experimental creep tests are carried out under ten min and two days aiming at calibrating fitting parameters, which are essential to validate short-term creep tests. The Weibull and Eyring models are more suitable for determining the time-temperature superposition (TTS) creep response in comparison to the Burger and Findley models. Keywords Advanced composites · Viscoelasticity · Creep · Time-temperature superposition
1 Introduction Creep in carbon fiber reinforced polymer (CFRP) composite materials may lead to unexpected stress redistribution over time, which can influence the durability and life service of composite structures (Gao et al. 2018; Mohammad et al. 2018; Wang et al. 2019). 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, 2018b; Ornaghi et al. 2020).
B J.H.S. Almeida Jr.
[email protected]; [email protected]
1
Department of Materials and Technology, Sao Paulo State University, 12516-410 Guaratinguetá, SP, Brazil
2
Department of Mechanical Engineering, Aalto University, 02150 Espoo, Finland
3
PPGE3M, Federal University of Rio Grande do Sul, Av. Bento Gonçalves 9500, Porto Alegre, RS, Brazil
Mech Time-Depend Mater
The long-term of such high-performance composites is important to be quantified, given the viscoelastic nature of polymeric matrices (Guedes 2006). A very few studies are found in the literature dealing with the long-term mechanical behavior relating thermoset matrix composites (Sullivan 1990; Sullivan et al. 1993; Hu and Sun 2000; Fancey 2001, 2005; Alrahlah et al. 2018). Fancey (2001, 2005) mentioned the importance of low-stress creep response for the tensile modulus prediction. A low-stress level analysis allows a fast and inexpensive way in relation to structure versus property relationship (Alrahlah et al. 2018; Fancey 2001, 2005). General failure mechanisms are present in two main scales, (i) microscopic and (ii) macroscale mechanisms that arise from microstructural changes (Khan et al. 2015). According to Alderliesten (2015), a merely phenomenological analysis could neglect important physical aspects at the
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