Fatigue behavior and modeling of thermoplastics including temperature and mean stress effects

Mellott, Stephen R.; Fatemi, Ali

doi:10.1002/pen.23591

Cited by 35 publications

(30 citation statements)

References 13 publications

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“…Data for the two mould flow directions for PP‐T at 23 °C are also included. To evaluate robustness of the model, PO and PP data at different test temperatures and stress ratios were also analysed using this model. β = 0.2 was obtained for all the materials, except for PPE/PS for which β was found to be 0.35.…”

Section: Correlation Of Fatigue Data With a General Modelmentioning

confidence: 88%

“…The Walker equation has been shown by Mortazavian and Fatemi and Mellott and Fatemi to better consider the effect of mean stress for thermoplastic composites. This model is expressed as:

S_{N f} = {(S_{a} + S_{m})}^{1 - γ} {(S_{a})}^{γ}

where γ is a mean stress sensitivity material parameter.…”

Section: Mean Stress Effect and Modellingmentioning

confidence: 91%

“…Several mean stress models which were reviewed in have been used in different studies to model the effect of mean stress on fatigue behaviour of talc‐filled and short glass fibre reinforced thermoplastics. Modified Goodman is the most common mean stress correction model, expressed as:

\frac{S_{a}}{S_{N f}} + \frac{S_{m}}{S_{u}} = 1

where S m is the mean stress, S u is the ultimate tensile strength and S Nf is the equivalent fatigue strength at cycle N f for fully reversed condition.…”

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

“…no mean stress sensitivity for these conditions evaluated). Comparison of γ values as a function of ultimate tensile strength for PP‐T, PP‐G and PA66 with those obtained for PA6 and PBT in the study of Mortazavian and Fatemi and neat PP and talc‐filled polyolefin (PO) in the study of Mellott and Fatemi are shown in Fig. .…”

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

“…Comparison of γ values in the Walker equation as a function of tensile strength for PP‐T, PP‐G and PA66 at 23, 85 and 125 °C with those reported for PBT and PA6 (○) in and PP (□) and PO (△) in …”

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

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

Eftekhari

Fatemi

2016

Fatigue Fract Eng Mat Struct

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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.

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Section: Correlation Of Fatigue Data With a General Modelmentioning

confidence: 88%

“…The Walker equation has been shown by Mortazavian and Fatemi and Mellott and Fatemi to better consider the effect of mean stress for thermoplastic composites. This model is expressed as:

S_{N f} = {(S_{a} + S_{m})}^{1 - γ} {(S_{a})}^{γ}

where γ is a mean stress sensitivity material parameter.…”

Section: Mean Stress Effect and Modellingmentioning

confidence: 91%

\frac{S_{a}}{S_{N f}} + \frac{S_{m}}{S_{u}} = 1

where S m is the mean stress, S u is the ultimate tensile strength and S Nf is the equivalent fatigue strength at cycle N f for fully reversed condition.…”

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

Section: Mean Stress Effect and Modellingmentioning

confidence: 99%

See 3 more Smart Citations

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

Eftekhari

Fatemi

2016

Fatigue Fract Eng Mat Struct

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Tensile and fatigue behaviors of polymers for automotive applications

Mortazavian

Fatemi

2015

Materialwissenschaft Werkst

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An experimental study was conducted on tensile and fatigue behaviors of two unreinforced polymers and two short glass fiber reinforced polymer composites. A number of effects including anisotropy, strain rate and temperature on tensile behavior was investigated. Fatigue behavior was evaluated with respect to effects of mold flow direction, temperature, mean stress, and stress concentration. Effect of mold flow direction on both tensile and fatigue behaviors of unreinforced materials was found to be negligible, while it was significant for reinforced materials. Tsai-Hill criterion commonly used for continuous fiber composites was used to predict the offaxis fatigue strengths of short fiber reinforced materials. Effect of strain rate on tensile properties was found to be significant for all materials. Test temperature also influenced tensile and fatigue behaviors of both unreinforced and reinforced materials. Mathematical equations were developed to represent variations of tensile properties with both temperature and strain rate. Walker equation with a mean stress correction parameter is proposed to correct for the effect of mean stress. Effect of stress concentration combined with mold flow direction and mean stress was also investigated and Neuber's rule resulted in accurate estimation of fatigue life. Keywords: Tensile behavior / fatigue behavior / polymer fatigue / thermoplastic / short fiber composite Schlüsselwörter: Zähigkeitsverhalten / Ermüdungsverhalten / Polymerermüdung / thermoplastisch / Kurzfaser-Verbundwerkstoff Corresponding author: A. Fatemi, The University of Toledo,

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Fatigue properties of vibration‐welded postindustrial waste nylon with glass fibers at room and elevated temperatures

Zhang

Lockwood

Bates

et al. 2014

Polymer Engineering & Sci

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The effect of temperature on the tensile and fatigue strength of vibration‐welded and unwelded postindustrial waste nylon 6 reinforced with 30 wt% glass fiber (PIWGF) was experimentally examined, and the results were compared to those obtained from a 30 wt% glass fiber reinforced prime nylon 6 compound (PAGF) from a previous study. Fatigue tests were performed under sinusoidal constant amplitude tension‐tension load at a stress ratio of R = 0.1 and within the frequency range of 2–10 Hz at temperatures from 24 to 120°C. Stress levels from just under the tensile strength down to the run‐out point at 5 million cycles were used. It was found that increasing temperature led to a significant decrease in both tensile strength and fatigue life. For PIWGF, there was ∼20% strength reduction under both static tensile and cyclic loading as compared to PAGF. For both welded and unwelded PIWGF, the endurance ratio; i.e., the ratio of fatigue strength to static tensile strength, was ∼45% regardless of the temperature. The fatigue notch factor (Kf) was between 1.4 and 1.8 for all test temperatures examined. POLYM. ENG. SCI., 55:799–806, 2015. © 2014 Society of Plastics Engineers

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Fatigue behavior and modeling of thermoplastics including temperature and mean stress effects

Cited by 35 publications

References 13 publications

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

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

Tensile and fatigue behaviors of polymers for automotive applications

Fatigue properties of vibration‐welded postindustrial waste nylon with glass fibers at room and elevated temperatures

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