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An effective method for improving the fatigue life of Duralumin plates with fastener holes, such as those used in the construction of aircraft, is to introduce a compressive residual stress around the fastener holes. Cavitation peening is a novel peening method that uses the cavitation impact produced when a high-speed water jet is injected into a water-filled chamber. In this paper, Duralumin plate specimens with holes were treated by cavitation peening under various conditions, and the fatigue strength of the specimens was determined using a plate bending fatigue test. It was revealed that a compressive residual stress was introduced not only on surfaces perpendicular to the axis of the cavitating jet but also on the walls of holes which were parallel to this. It was found that a 51% improvement in fatigue strength could be achieved by cavitation peening. Note that this is first report demonstrating an improvement in the fatigue life of Duralumin plates with fastener holes by cavitation peening.
Using the langasite
crystal microbalance (LCM), the trends in film thickness produced by means of
the chemical vapor deposition using trichlorosilane gas, monomethylsilane gas
and their mixed gas were observed at 600?C and evaluated by comparison with the information
from a transmission electron microscope (TEM). The crystalline silicon film
thickness from trichlorosilane gas was comparable to that of an amorphous
silicon carbide film from monomethylsilane gas. The film obtained from the gas
mixture was amorphous and was the thinnest in this study. Because the thickness
trend obtained by the LCM agreed with that by the TEM, the LCM is shown to be a
convenient evaluation tool for the behavior of various film deposition.
In order to optimize the conditions for residual stress measurement using a two-dimensional X-ray
diffraction (2D-XRD) in terms of both efficiency and accuracy. The
measurements have been conducted on three stainless steel specimens in this
study. The three specimens were processed by annealing, a cavitating jet in air
and a disc grinder, with each method introducing different residual stresses at
the surface. The specimens were oscillated in the ω-direction, representing a right-hand rotation of the specimen
about the incident X-ray beam. The range of the oscillation, Δω, was varied
and optimum Δω was determined.
Moreover, combinations of the tilt angle between the specimen surface normal
and the diffraction vector, ψ, with
the rotation angle about its surface normal, f, have been studied with a view to find the most optimum condition.
The results show that the use of ω oscillations is an effective method for improving analysis accuracy,
especially for large grain metals. The standard error rapidly decreased with
increasing range of the ω oscillation, especially for the annealed specimen which generated strong
diffraction spots due to its large grain size.
of this study was to examine the psychometric properties of the Postpartum
Bonding Questionnaire (PBQ) in Japanese mothers. Additionally, we investigated
the association between postpartum bonding and postnatal depression. The participants
of this study were 1786 Japanese mothers, recruited during their infants’ 3
months check-ups at a public health center. The mothers completed the PBQ and
the Edinburgh Postnatal Depression Scale (EPDS). We examined the factor
structure of the PBQ. However, we were unable to confirm the original 4
factors. A 1-factor solution was extracted by omitting 9 items that did not
have significant loadings onto the single factor. According to the cut-off
values of the original PBQ, the positive rate was 7.7%. The PBQ score was
moderately correlated with the EPDS score. The abridged 16-item Japanese
version of the PBQ can be used as a reliable screening tool during check-ups
for Japanese mothers. Health practitioners should pay attention to mothers who
have bonding disturbances at postpartum.