Fatigue behaviour and modelling of talc‐filled and short glass fibre reinforced thermoplastics, including temperature and mean stress effects

Abstract

Effects of temperature and mean stress on fatigue behaviour of talc‐filled polypropylene (PP‐T) and short glass fibre reinforced polypropylene (PP‐G), polyamide‐66 (PA66), and a blend of polyphenylene ether and polystyrene (PPE/PS) were investigated. Load‐controlled fatigue tests were conducted under positive stress ratios (R = 0.1 and 0.3) and at several temperatures (T = 23, 85 and 120 °C). Larson–Miller parameter was used and a shift factor of Arrhenius type was developed to correlate fatigue data at various temperatures. Effect of mean stress on fatigue life was significant for some of the studied materials; however, for the PPE/PS blend no effect of mean stress was observed. Modified Goodman and Walker mean stress equations were evaluated for their ability to correlate mean stress data. A general fatigue life prediction model was also used to account for the effects of mean stress, temperature, anisotropy and frequency.

Modelling the effect of temperature on the probabilistic stress–life fatigue diagram of glass fibre–polymer composites loaded in tension along the fibre direction

“…However, at higher frequency, fatigue becomes cycle dominated. This behaviour was corroborated by results from Eftekhari and Fatemi [16,22]. The accumulation of fatigue induced creep strains was also reported by Kujawski and Eyllin [23] for [±45] 5s glass-epoxy composites at room temperature.…”

“…This behaviour was corroborated by results from Eftekhari and Fatemi. 16,22 The accumulation of fatigue induced creep strains was also reported by Kujawski and Eyllin 23 for ½AE45 5s glass-epoxy composites at room temperature. Evidence of viscoelastic behaviour was also reported in Cormier et al 4 for ½AE45 2s glass-epoxy at À40 C.…”

“…Thus, although a transition temperature such as T g seems like a natural candidate for Â, it is not a requirement of the model. Finally, Eftekhari and Fatemi 16,22 have used the model by Epaarachchi and Clausen 13 -which is also the basis of the current work -in order to predict the effects of frequency and temperature on several neat, talc filled or short glass fibres reinforced thermoplastics. In these papers, they found that Epaarachchi and Clausen's model provides a good fit on experimental results and used a Larson-Miller type relationship to account for viscoelastic effects that were present at higher temperatures or lower load rates.…”

“…An alternative model based on the work of Reifsnider's [12] strength evolution integral concept is also shown to provide better life predictions when accounting for viscoelastic effects at low stresses (long fatigue life). Also, Eftekhari and Fatemi [16,22] used Epaarachchi and Clausen's [13] fatigue model in conjunction with a Larson-Miller type relationship to adequately model the effects of high temperature and high frequencies on neat, talc filled and short glass fibres reinforced thermoplastics.…”

A Fatigue Damage Model for Life Prediction of Injection-Molded Short Glass Fiber-Reinforced Thermoplastic Composites

“…In Figure 4 a,c, uniaxial fatigue data for PP-30GF from and PA66-30GF from [ 15 ] are shown as the normal stress amplitude versus fatigue life in transverse (perpendicular to injection) direction at 23 °C, 85 °C, and 125 °C. As can be seen from Figure 4 a,c, mean stress (i.e., at different R ratios) has a significant effect on fatigue life at each temperature.…”