Thermomechanical viscoelastic response of a unidirectional graphite/polyimide composite at elevated temperatures using a micromechanical approach

Abstract

In this work, the thermomechanical viscoelastic response of a high temperature polymer matrix composite system made up of T650-35 graphite fibers embedded in PMR-15 resin is studied through a micromechanical model based on the assumptions of simplified unit cell method within a temperature range of 250–300℃ corresponding to aerospace engine applications. The advantage of this particular micromechanical model lies in its ability to give closed-form expressions for the effective viscoelastic response of unidirectional composites as well as each of their constituents. Using the experimental data of the creep behavior of thermostable PMR-15 polyimide, the micromechanical model is first calibrated to account for the effect of temperature. The resulting elastic and viscoelastic responses are found to be in good agreement with the existing experimental data. The validated model is then used to predict the behavior of the composite material under different combinations of thermal and mechanical loadings. The results clearly demonstrate the importance of accounting for the viscoelastic effect of the matrix material as the temperature increases. Current works on modeling temperature-dependent viscoelastic behavior of polymer matrix composites are mainly based on the assumption of thermorheologically simple material. However, through the present approach where the matrix is modeled as a thermorheologically complex material, the effect of temperature on the elastic and viscoelastic response of the composite system can be individually investigated.

Evaluating unidirectional composite thermal conductivities through engineered interphase

“…Figure 1 shows the square RVE consisting of four sub-cells (three matrix sub-cells and one fibre sub-cell) with the fibres aligned in the X 1 -direction. The cross-section of the fibre-reinforced composites is usually idealised as a regular arrangement of fibres in a square array packing [43, 44, 48, 50, 51]. Also, the fibre cross-section has been assumed to be square [43, 44, 48, 50, 51].…”

“…[43] utilised the SUC micromechanical model to explore the effect of initiation and propagation of interface debonding on the elastoplastic behaviour of SiC fibre-reinforced Ti composites. Nonlinear viscoelastic behaviour of T650-35 graphite fibre-reinforced PMR-15 composites was evaluated using the SUC approach within a temperature range of 250–300°C corresponding to aerospace engine applications [44]. The comparisons between results of the SUC model in the case of mechanical and thermal expanding properties of various composite systems show very good agreement with the experiment [45-47].…”

Interphase influences on the mechanical behavior of carbon nanotube–shape memory polymer nanocomposites: A micromechanical approach

“…Another advantage of the SUC method is its ability to give closed-form solutions to evaluate the composite material response to shear and normal loadings (Falahatgar et al, 2009; Mahmoodi et al, 2010; Sayyidmousavi et al, 2015). Numerous research studies have revealed the validity of the model to predict the overall behavior of conventional composites (Falahatgar et al, 2009; Mahmoodi and Aghdam, 2011; Mahmoodi et al, 2010; Sayyidmousavi et al, 2015). The SUC micromechanical model was later extended by Ansari and Hassanzadeh-Aghdam (2016a, 2016b) to calculate the linear and non-linear viscoelastic properties of CNT-reinforced polymer nanocomposites.…”

Elastoplastic behavior of the metal matrix nanocomposites containing carbon nanotubes: A micromechanics-based analysis

“…Also, they investigated the creep behavior of the graphite/epoxy composites under off-axis loading for several stress levels. Sayyidmousavi et al 44 evaluated the thermomechanical viscoelastic response of graphitereinforced polyimide matrix composites within a temperature range of 250-300 C by the use of SUC model. Hassanzadeh-Aghdam et al 45 investigated the effect of interphase zone on the elastic and thermoelastic properties of fiber-reinforced composites using the SUC model.…”

“…Generally, prediction of the overall behavior of the composites reinforced with microfibers using the SUC micromechanical model demonstrate the close agreement with experimental and other micromechanical results available in the literature. [42][43][44][45] Recently, the SUC model has been employed to study the behavior of CNT-reinforced nanocomposites. This micromechanical model was used to evaluate the elastic properties 46 and thermal expansion behavior 47 of the CNT-reinforced polyimide nanocomposites.…”