Fatigue crack propagation in short-fiber reinforced plastics

Abstract

The influence of fiber orientation on the crack propagation behavior was studied with single edgenotched specimens which were cut from an injection-molded plate of short-fiber reinforced plastics of polyphenylenesulphide (PPS) reinforced with 30wt% carbon fibers. Specimens were cut at five fiber angles relative to the molding direction, i.e. ??= 0° (MD), 22.5°, 45°, 67.5°, 90° (TD). Fracture mechanics parameters derived based on anisotropic elasticity were used as a crack driving force. Macroscopic crack propagation path was nearly perpendicular to the loading axis for the cases of MD and TD. For the other fiber angles, the crack path was inclined because the crack tended to propagate along inclined fibers. For mode I crack propagation in MD and TD, the resistance to crack propagation is improved by fiber reinforcement, when the rate is correlated to the range of stress intensity factor. The crack propagation rate, da/dN, was slowest for MD and fastest for TD. For each material, the crack propagation rate is higher for larger R ratio. The effect of R ratio on da/dN diminished in the relation between da/dN and the range of energy release rate, ?GI. Difference among MD, TD and matrix resin becomes small when da/dN correlated to a parameter corresponding the crack-tip radius, H?GI, where H is compliance parameter. Fatigue cracks propagated under mixed loading of mode I and II for the fiber angles other than 0° and 90°. The data of the crack propagation rate correlated to the range of total energy release rate, ?Gtotal, lie between the relations obtained for MD and TD. All data of crack propagation tend to merge a single relation when the rate is correlated to the range of total energy release rate divided by Young’s modulus.

A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey

“…All-sky HVC maps are a useful tool for a wide range of scientific applications, including, among others, the study of the HVC population itself (Wakker 1991;Wakker & van Woerden 1991), comparison of the H I emission with optical and ultra-violet absorption lines of ionised gas in the Galactic halo (Fox et al 2006;Lehner et al 2012), cross-correlation of the H I emission with X-ray emission (Kerp et al 1996(Kerp et al , 1999Shelton et al 2012) and Hα emission (Tufte et al 1998;Barger et al 2012), and comparison of the H I gas with molecular gas Lenz et al 2016) in the quest for evidence of star formation in HVC complexes such as the Magellanic Stream (Tanaka & Hamajima 1982;Brück & Hawkins 1983) and Leading Arm (Casetti-Dinescu et al 2014).…”

Effects of different stress ratios on fatigue crack growth of rice husk fibre-reinforced composite

“…Composite materials are inhomogeneous and anisotropic (Mortazavian and Fatemi 2015;Tanaka et al 2015), whereby their behaviour is more intricate than that of homogeneous and isotropic materials, such as metals. The main reasons for this are that the varied types of damages that can occur, such as fibre fracture, matrix cracking, matrix crazing, fibre buckling, fibre-matrix interface failure, and delamination (Jollivet et al 2013), which strongly affect their varying growth rates.…”

Transiting from Adipic Acid to Bioadipic Acid. 1, Petroleum-Based Processes

“…Since the one-step conversion of cyclohexane to adipic acid (in ∼50% yield) was described by Loder in 1940, a plethora of references (both patents and reports in the scientific literature) have involved the direct synthesis of adipic acid, i.e., without the intermediate extraction of olone, via the oxidation of not-very-reactive cyclohexane. Until recently, the relevant patent positions have been consolidated, ,− but less actively so after 2000, ,, when interest shifted to biochemical methods for preparing adipic acid from carbohydrate sources …”

“…WO 01/87,815 A2 (to Lonza), Fumagalli et al disclosed a high conversion of III (97.5%) to AA with high selectivity (93.4%) at 40 °C in 1 atm O 2 , using Mn­(NO 3 ) 2 /Co­(NO 3 ) 2 /HNO 3 (in 1:1:3 mol ratio) in acetic acid for 5 h . Also, Asahi has repeatedly expressed interest in the development of a prospective industrial route for adipic acid production from III based on O 2 oxidation without the generation of N 2 O. , Using Mn­(OAc) 2 /Co­(OAc) 2 in air containing <10 vol % O 2 at 12.2 atm (in order to avoid explosion hazards) and acetic acid solvent oxidation at 70 °C leads to 78% selectivity in adipic acid (along with 16% glutaric and succinic acids) for 99.3% conversion of cyclohexanone. Figure shows the relationship between the reaction conditions and the selectivity of carboxylic acids in detail.…”

“…More recently, Japanese Patent No. JP 2001/253845 A (to Asahi Chemical Corp.) has disclosed a method for the production of adipic acid with high selectivity by oxidizing III with O 2 in a more environmentally friendly aqueous solvent using a (Fe,V)-based catalyst …”