Morphological study of fatigue-induced damage in isotactic polypropylene

Jones, Nathan; Lesser, Alan J.

doi:10.1002/(sici)1099-0488(19981115)36:15<2751::aid-polb9>3.0.co;2-6

Cited by 21 publications

(12 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Jones and Lesser [2] have studied fatigue damage of high molecular weight semicrystalline polymers subjected to uniaxial high cycle fatigue. Bar shaped specimens prepared by compressive molding were tested up to one million cycles at a frequency of 2 Hz.…”

Section: Fatigue Damage Of Polymeric Materialssupporting

confidence: 87%

Fatigue Fracture Resistance Analysis of Polymer Composites Based on the Energy Expended on Damage Formation

Aglan

Gan

Chu

et al. 2003

Journal of Reinforced Plastics and Composites

View full text Add to dashboard Cite

Analysis of the fatigue crack propagation behavior of filled polytetrafluoroethylene (PTFE) composites using the energy expended on damage formation was performed. A 25% chopped glass fiber filled PTFE with a commercial name of Rulon LR and a 25% polymer particle filled PTFE (Rulon J) were chosen as candidate materials for the study. Fatigue crack propagation (FCP) tests were performed using both unnotched and single edge notched (SEN) specimens under tension-tension load control condition. The notched specimens were prepared with the same notch length to sample width ratio (a/w) of 0.09. The applied frequency was 3 Hz. The maximum stress was 6 MPa, and the ratio of minimum stress to maximum stress was kept at 0.10. FCP data such as the crack length and the number of cycles were used to calculate the crack speed. The hysteresis energies for both notched and unnotched specimens during cyclic loading were obtained. The energy release rate was determined as the first derivative of the relationship between the potential energy and the crack length. The potential energy was calculated as the area above the unloading curve from the hysteresis loops at various crack lengths. The cyclic rate of energy dissipation on damage formation was calculated based on the hysteresis energies for both notched and unnotched specimens. It was found that the fatigue kinetics are related to the cyclic rate of energy dissipation into the active zone evolution. The specific energy of damage ( 0 ), a material parameter characteristic of the fatigue fracture resistance was evaluated using the Modified Crack Layer (MCL) theory. It was found that the value of 0 for the particle filled PTFE is 3200 kJ/m 3 , which is about three times higher than that for the fiber filled PTFE (750 kJ/m 3 ). This indicates that the particle filled PTFE has higher fracture resistance than the fiber filled PTFE. The fracture surface of the second region for both materials was examined using scanning electron microscopy (SEM). Interfacial debonding, drawn ligaments and large voids were associated with the fatigue fracture Downloaded from of the fiber filled PTFE. The particle filled PTFE displayed more fibrillation than that of the fiber filled PTFE, which indicates a higher energy consuming process related to the fatigue crack growth in the particle filled PTFE.KEY WORDS: particle and fiber filled PTFE composites, fatigue, energy on damage formation, modified crack layer (MCL) theory, specific energy of damage, fracture surface morphology.

show abstract

Section: Fatigue Damage Of Polymeric Materialssupporting

confidence: 87%

Fatigue Fracture Resistance Analysis of Polymer Composites Based on the Energy Expended on Damage Formation

Aglan

Gan

Chu

et al. 2003

Journal of Reinforced Plastics and Composites

View full text Add to dashboard Cite

show abstract

“…Though an investigation to the precise underlying (microstructural) mechanisms lies beyond the scope of this work, the results are in full agreement with observations that suggest fatigue induced (microstructural) changes in heterogeneous polymer systems. [41][42][43][44][45][46] B. Effect of Wave Form.…”

Section: Fatigue Failure: Validationmentioning

confidence: 99%

An Analytical Method To Predict Fatigue Life of Thermoplastics in Uniaxial Loading: Sensitivity to Wave Type, Frequency, and Stress Amplitude

2008

View full text Add to dashboard Cite

A method is presented that allows fatigue life predictions on the basis of creep life data. The approach is based on the assumption that the time-dependent failure of polymers is determined by the intrinsic strain softening that is initiated when a critical threshold value of the plastic strain is surpassed. To facilitate fatigue predictions, an acceleration factor is defined that indicates how much faster plastic strain is accumulated by a cyclic signal compared to its static mean stress. Analytical solutions of the acceleration factor are presented for triangular and square waves, which predict that only the stress amplitude of the cyclic signal and the material's stress dependency affect fatigue life, whereas frequency plays no role. Verification using several glassy and semicrystalline polymers demonstrates that this method yields accurate quantitative lifetime predictions not only for polymers that exhibit ductile failure but also for those that display brittle fracture, provided that fracture is preceded by (localized) plastic flow.

show abstract

“…For all testing conditions, the general effect of cycling was a decrease in the storage modulus. Similar results have been reported previously for polypropylene [46] and polyacetal [32,47,48]. It is proposed that the decrease in average stiffness is the result of local rearrangement processes in the chain network activated by the stress fluctuation leading to a relaxation of the stress field in regions of the network that were initially subjected to stresses higher than the average.…”

Section: Discussionmentioning

confidence: 99%

Bulk fatigue damage evolution in polyamide-6 and in a polyamide-6 nanocomposite

et al. 2005

View full text Add to dashboard Cite

The mechanical response of a polyamide‐6 montmorillonite clay nanocomposite and of a polyamide‐6 was monitored during axial fatigue tests performed at R‐ratios of 0.1 and −1. For both materials, two transitions were usually observed in the evolution of all the stress‐strain‐time parameters studied after similar numbers of loading cycles, suggesting interrelationships between the mechanisms of molecular reorganization. Fatigue test monitoring indicated an initial decrease in the storage modulus and a subsequent trend for this modulus to increase, especially in polyamide‐6. During all tests, a partially recoverable strain was accumulated because of viscoelastic deformation. Nanoparticles reduced this strain in the initial cyclic straining regime but not in the last regime, probably because such particles cannot inhibit viscoelastic events constrained in a volume larger than their interaction volume within the matrix. Based on the accumulated volume variation measured, the nucleation and growth of microvoids can be expected to occur in the last cyclic straining regime. POLYM. COMPOS., 26:636–646, 2005. © 2005 Society of Plastics Engineers

show abstract

Morphological study of fatigue-induced damage in isotactic polypropylene

Cited by 21 publications

References 10 publications

Fatigue Fracture Resistance Analysis of Polymer Composites Based on the Energy Expended on Damage Formation

Fatigue Fracture Resistance Analysis of Polymer Composites Based on the Energy Expended on Damage Formation

An Analytical Method To Predict Fatigue Life of Thermoplastics in Uniaxial Loading: Sensitivity to Wave Type, Frequency, and Stress Amplitude

Bulk fatigue damage evolution in polyamide-6 and in a polyamide-6 nanocomposite

Contact Info

Product

Resources

About