Open Access
ARTICLE
Y.B. Shao1, S.P. Chiew2, Y. Chen1, S.T. Lie2
Structural Longevity, Vol.3, No.3, pp. 171-189, 2010, DOI:10.3970/sl.2010.003.171
Abstract For a square tubular T-joint under axial loading, failure occurs easily
along the weld toe because high stress concentration exists in this region. This
phenomenon can be used to explain why brittle fracture is dominant when the joint
is subjected to cyclic loading, such as faigue loading or earthquake loading. To
improve the seismic resistance of a square tubular joint, collar plate can be used
to reinforce the joint connection. However, the aseismic behaviour of the collarplate reinoforced tubular joint must be assessed because only the increase of the
load carrying capacity can not guarantee the capacity of energy dissipation… More >
Open Access
ARTICLE
N. Kawagoishi1, A. Ohkubo2, S. Yoshimi3, K. Yamane4, K. Morino5
Structural Longevity, Vol.3, No.3, pp. 191-199, 2010, DOI:10.3970/sl.2010.003.191
Abstract Rotating bending fatigue tests were carried out using a radical nitrided
nickel base superalloy, Alloy 718, at 500 ℃, to investigate the effect of radical
nitriding on the initiation and propagation behavior of a fatigue crack at elevated
temperature. The nitriding was conducted at 500 ℃ for 12h which was relatively
low temperature compared with other nitriding technologies. Compound layer was
formed on the specimen surface with the thickness of about 4µm. Hardness of the
base alloy was hardly affected by nitriding. When stress levels were high, a crack
initiated from the specimen surface in the aged alloy, and the… More >
Open Access
ARTICLE
T. Nagano1, M. Moriyama2,3, N. Kawagoishi4, Y. Kobayashi4
Structural Longevity, Vol.3, No.3, pp. 201-211, 2010, DOI:10.3970/sl.2010.003.201
Abstract In the present study, rotating bending fatigue tests up to 108
cycles
were carried out to investigate the effects of hardness of base steel and shot and
reverted austenite, γ, on the fatigue strength and the fracture mechanism in wide
range of fatigue life of shot peened 3.5GPa-grade maraging steel. By shot peening, hardening and compressive residual stress were yielded in the surface layer of
specimen, causing increase in fatigue strength in the wide region of fatigue life.
The S — N curves showed duplex S — N properties because of the transition of fracture origin from the specimen surface… More >
Open Access
ARTICLE
Younho Cho1, Weibin Li1, Bin Yang1
Structural Longevity, Vol.3, No.3, pp. 213-219, 2010, DOI:10.3970/sl.2010.003.213
Abstract This paper aims at an experimental method for detecting thermal-damages
in a tube-like structure using acoustic nonlinear parameter of ultrasonic guided
waves. The material nonlinearity of aluminum pipe specimens, which have been
subjected to different heat-loading cycles, is measured to characterize the microdamages. Flexible Polyvinylidene Fluoride (PVDF) comb transducers are used to
generate and receive the fundamental and second harmonic waves. The amplitude
of the second harmonic wave is extracted from the Fast Fourier Transform (FFT)
spectrum of a received signal. The measured relative nonlinear parameter increases
monotonically as a function of the propagation distance, and the relative nonlinear
parameter… More >
Open Access
ARTICLE
Hitesh Kapoor1, James L. Blackshire2, Som R. Soni3
Structural Longevity, Vol.3, No.3, pp. 221-238, 2010, DOI:10.3970/sl.2010.003.221
Abstract Damage detection in constrained geometry structures like z-pinned,
co-cured composite pi-joints is established using pitch-catch ultrasound and scanning laser vibrometry measurements. Ultrasonic pitch-catch measurements consisted of a network of PZT (Lead Zirconate Titanate) sensors placed on the specimen and sensing Lamb waves at each sensor location, where measurements were
taken at symmetric top and bottom sensor locations for healthy and damaged pijoint specimens. Results showed the presence of fatigue-induced bend damage
of the joint as a reduced peak-to-peak amplitude response across the joint. Scanning laser vibrometry measurements were used to study the propagation of Lamb
waves within the narrow, constrained… More >
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