Plastics Part Design: Low Cycle Fatigue Strength of Glass-fiber-reinforced Polyethylene Terephthalate (PET)

Abstract

This paper summarizes our extensive investigation on the low cycle (up to Nf1/4 5 10 4, where Nf is the number of cycles to failure) fatigue behavior of short glass-fiber-reinforced poly(ethylene terephthalate), or PET, thermoplastic [PET - Thermo plastic polyester for injection molding]. The modes of fatigue test include tension-tension, compression-compression, four-point bending (flexural) - all at frequency f 1/4 1-3 Hz, and flexural fatigue at f 1/4 30 Hz (ASTM D-671). All tests were stress-controlled with stress ratio R 1/4 Smin/Smax1/4 0.1, except for flexural fatigue at f 1/4 30 Hz where stress ratio R 1/4 1. The fracture surfaces of tested specimens were analyzed using scanning electronic microscopy (SEM). The results from this investigation provide comprehensive, up-to-date information and recommendations concerning methods for fatigue testing of injection-molded specimens and models, prediction and optimization of low cycle fatigue properties that play a key role in determining a highly stressed plastic parts life and end-use performance, preselection of PET-based plastic for various industrial applications.

Comparative Studies on the Mechanical, Degradation and Interfacial Properties between Jute and E-Glass Fiber-Reinforced PET Composites

“…PET is a low cost and high performance thermoplastic [6][7][8][9] . It is widely used as packaging materials, fiber and sheet due to good rigidity, hardness, abrasion resistance, solvent resistance, and electric insulation properties.…”

Fabrication of Cellulose Based Reinforced Linear Low Density Polyethylene with Polyethylene Terephthalate Composite: Effect of <i> Acacia catechu </i> as Coupling Agent

“…Polyethylene terephthalate (PET) and Linear Low Density Polyethylene (LLDPE) were used as a matrix material in this study because they have some excellent characters for composite fabrication. PET a low cost and high performance thermoplastic is widely used as packaging materials, fiber and sheet due to good rigidity, hardness, abrasion resistance, solvent resistance and electric insulation [8] [9]. The majority of the world's PET production is for synthetic fibers (60%) with bottle production accounting for 30% of demand.…”

Multiaxial fatigue criterion for a high‐density polyethylene thermoplastic

“…Compression – compression loadings have been also reported to be detrimental to the fatigue crack resistance. Only a few studies have been performed in a biaxial 35 or flexural 18,20,36 loading mode.…”

“…10,11 Characterizing the damage mechanisms ahead of the crack tip is still under consideration. [12][13][14] Among other semi-crystalline polymers like polyamides (PA), 8,15,16 polyvinylidene fluoride (PVDF), 8 polyoxymethylene (POM), 17 poly-ether-ether-ketone (PEEK), 18 polyethylene-terephtalate (PET), [19][20][21] polyethylene (PE) 22 and polytetrafluoroethylene (PTFE), 23 a lot of attention has been paid on ultrahigh molecular weight polyethylene (UHMWPE) widely involved in the orthopedics field (see reference 24 for a review). Excepted for a few works, 25 a great majority of studies have been centred on the characterization of fatigue crack propagation in association with the influence of some microstructure parameters such as the crystallinity ratio, 26,27 the molecular mass, 28 the entanglement density, 29 or the tie molecule concentration.…”

“…34 Compression -compression loadings have been also reported to be detrimental to the fatigue crack resistance. Only a few studies have been performed in a biaxial 35 or flexural 18,20,36 loading mode. So far, there are only a few studies on the multiaxial endurance fatigue behaviour of semi-crystalline thermoplastics.…”