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Nawa, Kazuhiro*; Tanaka, Kimihito*; Kurita, Nubuyuki*; Sato, Taku*; Sugiyama, Haruki*; Uekusa, Hidehiro*; Kawamura, Seiko; Nakajima, Kenji; Tanaka, Hidekazu*
Nature Communications (Internet), 10, p.2096_1 - 2096_8, 2019/05
Times Cited Count：16 Percentile：74.55(Multidisciplinary Sciences)Search for topological materials has been actively promoted in the field of condensed matter physics for their potential application in energy-efficient information transmission and processing. Recent studies have revealed that topologically invariant states, such as edge states in topological insulators, can emerge not only in a fermionic electron system but also in a bosonic system, enabling nondissipative propagation of quasiparticles. Here we report the topologically nontrivial triplon bands measured by inelastic neutron scattering on the spin-1/2 two-dimensional dimerized antiferromagnet Ba
CuSiO
Cl. The excitation spectrum exhibits two triplon bands that are clearly separated by a band gap due to a small alternation in interdimer exchange interaction, consistent with a refined crystal structure. By analytically modeling the triplon dispersion, we show that BaCuSiOCl is the first bosonic realization of the coupled Su-Schrieffer-Heeger model, where the presence of topologically protected edge states is prompted by a bipartite nature of the lattice.
; Wakai, Takashi; ; ; ;
PNC TN9410 93-220, 112 Pages, 1993/09
This report describes elastic thermal stress analysis and creep-fatigue damage estimation results of Mod.9Cr-1Mo piping specimen which consists of three different thickness portions (20, 15, 10mm), and contains six circumferential weldments. Thermal fatigue failure test on the specimen has been conducted in the sodium test loop named SPTT to clarify fatigue crack initiation behavior under thermal bending stress conditions, which is caused by temperature gradient arisen in the wall thickness of the specimen. The thermal transient test is now underway, with the condition where sodium of 550
C and 300C sodium alternately flow into the specimen for 5 minutes in one cycle. The test is scheduled to complete after loading 9,000 cycles of thermal transients. Crack inspection by using penetration test tequnique is planned after the test. For an analytical study, heat transfer analysis using measured temperature data and elastic thermal stress analysis were carried out with the finite element method, and the analysis results were utilized to develop a candidate creep-fatigue damage evaluation method for Mod.9Cr-1Mo steels based on elastic analysis. Some analysis and damage estimation results of the specimen are presented here, and crack initiation after 9,000 cycles of thermal transients are predicted based on the calculated creep-fatigue damage.
; Wakai, Takashi; ; ; ;
PNC TN9410 93-209, 115 Pages, 1993/09
This report describes elastic thermal stress analysis and creep-fatiguedamage evaluation results of an SUS316FR piping specimen which contains circumferential weldment in the middle portion of it. Thermal creep-fatigue failure test on the specimen was conducted in a sodiumtest loop named STST to clarify creep-fatigue crack initiation behavior of SUS316FR base metal and weldment under thermal bending stress conditions, which is caused by temperature gradient arisen in the wall thickness or the specimen. Thermal transient test was conducted under the condition that 550C and 300C sodium alternately flow into the specimen for 5 hours and 1 hour, respectively in one cycle. The test had been completed after loading 1,600 cycles or thermal transients. After the test, crack inspection by PT was performed, and cracks were observed successfully in both the base metal and weldment. For an analytical study, heat transfer analysis using measured temperature data and elastic thermal stress analysis were carried out with the finite element method, and the analysis results were utilized to develop a candidate creep-fatigue damage evaluation method for SUS316FR steel based on elasticanalysis. Some analysis results and damage evaluation results of the specimen arepresented here, and crack initiation after 1,600 cycles of thermal transients is predicted based on the calculated creep-fatigue damage, which demonstrates a good agreements with the crack distribution on the specimen inner surface.
; ; ; ;
PNC TN9410 92-284, 229 Pages, 1992/05
This report describes the inelastic thermal stress analysis and creep-fatigue damage evaluation results of the three kinds of nozzle-like configuration models made of SUS304. Crack initiation test on the models has been conducted in Thermal Shock Test Sodium Loop to clarify crack initiation behavior in thermal bending stress conditions. The models have been loaded with two types of thermal bending stresses; one is caused by throughtout temperature distribution arisen in the nozzle-like configuration and the other is caused by temperature gradient arisen in the wall thickness of the models. Thermal transient test has been conducted under the condition that 550C and 300C sodium flow into the models for 5 hrs and 1 hr, respectively in one cycle, and finished after loading 1,700 cycles of thermal transient. After the test, crack inspection test by PT has been performed, and crack initiation at cross-sections interested have been observed successfully. For the analytical study, heat transfer analysis using the measured temperature data and inelastic thermal stress analysis were carried out by using cyclic stress-strain curves obtained from two kinds of strain rate conditions as the constitutive stress-strain relationships. Analysis results were utilized mainly for two objectives. One was to present the prospect of damage evaluation method based on inelastic analysis. And the other was to advance the present creep-fatigue damage evaluation method based on elastic analysis. Many analysis results and damage evaluation results of the test models are presented here, and discussed focusing on the application of inelastic analysis results to rational creep-fatigue failure predicting method.
