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In order to provide a sufficient theoretical basis for the fatigue‐resistant design of the aircraft wheels, strain‐controlled low‐cycle fatigue (LCF) tests were carried out on specimens machined in the extrusion direction (ED) and transverse direction (TD) of die‐forged 2014 aluminum alloy wheels. Although the TD specimens have lower tensile strength and yield strength, the fatigue test results show that the TD specimens have superior fatigue life compared with the ED specimens at total strain amplitudes of 0.5–0.8%. This is predominantly caused by the coarse Al12(MnSi)2(FeCu) intermetallic particles close to the surface layer, which results in a relatively short crack initiation stage for the ED specimens. In contrast, TD specimens with finer and more uniform recrystallized grains exhibit more excellent resistance to fatigue crack initiation (FCI) and propagation (FCP). Moreover, the fatigue life of alloys could be accurately predicted via a Manson–Coffin–Basquin (MCB) model based on total strain. Highlights: A new die forging method was used to fabricate the aircraft wheel.Fatigue characteristics and fracture behavior of aircraft wheels were explored.The accuracy of different fatigue life prediction models was evaluated.Coarse Al12(MnSi)2(FeCu) intermetallic particles affected fatigue crack initiation. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of diet type (normal or low Ca and P diets) and 25(OH)D3 supplementation (with or with not 2000 IU/kg 25(OH)D3) during late gestation on the serum biochemistry and reproductive performance of aged sows and newborn piglets. A total of 40 sows, which are at their 7th parity, were divided into four groups: control group (standard diet), low Ca group, 25(OH)D3 group and low Ca plus 25(OH)D3 group respectively (10 in each group). The blood of sows on day 100 and 114 of gestation and newborn piglets was collected for serum biochemical analyses. Results showed that the reproductive performance of sows was not influenced by diet type or 25(OH)D3 supplementation (p > 0.05). And the addition of 25(OH)D3 to diet low Ca group caused that the content of serum TG in sows on day 100 of gestation was not different from that of the control group (p > 0.05). The addition of 25(OH)D3 significantly decreases the content of serum TG in sows on day 114 of gestation (p < 0.05). The addition of 25(OH)D3 significantly increased the content of serum UREA and CREA in newborn piglets (p < 0.05). Overall, feeding 2000 IU/kg 25(OH)D3 to aged sows at late gestation had no effects on reproductive performance, but partly contributed to keeping serum TG balance in sows and may indicate increased pressure on kidneys in newborn piglets. [ABSTRACT FROM AUTHOR]

The microstructure in different regions of 2A14 aluminum alloy wheel and their effects on both mechanical properties and corrosion properties were studied by electron backscatter diffraction (EBSD), field emission scanning electron microscope ( SEM), transmission electron microscope ( TEM), room temperature tensile test, immersion test and electrochemical polarization. The results show that the grains size of the center and 1/4 layer of the 2A14 aluminum alloy wheel are 113 and 54 µm respectively, and the recrystallization fractions are 16% and 36%. The intermetallics and the aging precipitates in the 1/4 layer are larger than those of the center and the number density of the two aging precipitates (ϑ' and Q phase) is about twice that of the center. The lower quenching cooling rate of the center of the 2A14 aluminum alloy wheel reduces the number of precipitates and the dislocation resistance. Therefore it is mechanical properties are worse than 1/4 layer. The number of intergranular corrosion sites and the depth of intergranular corrosion in the center are smaller than those in the 1/4 layer due to the lower intermetallics content [ABSTRACT FROM AUTHOR]