Authors: Jie Liu, Xiang Bo Li, Jia Wang
Abstract: In natural seawater environment, temperature and chlorine ion are important factors for organic coating degradation. The alternating pressure of seawater can also affect the lifetime in deep-sea environment and probably is conducive to synergistic effects with other ageing factors. The present work is to investigate the effect of alternating pressure of seawater on protective properties of epoxy organic coating on 907A steel substrate, and evaluates the organic coating degradation process after pressure tests at atmospheric pressure. EIS was used to study the degradation process of the organic coating in natural seawater. The results demonstrated that the impedance of coating under alternating pressure of seawater conditions decreased faster than that at atmospheric pressure. With the increase of alternating pressure cycles, the entire degradation process of organic coating was accelerated. It is concluded that alternating pressure of seawater has to be considered as an aggressive factor like temperature or chlorine ion.
985
Authors: Hisaaki Tobushi, K. Kitamura, Yukiharu Yoshimi, K. Miyamoto, K. Mitsui
Abstract: In order to develop a brain spatula or a brain retractor made of a shape memory alloy (SMA), the bending characteristics of the brain spatula of TiNi SMA made by the precision casting were discussed based on the tensile deformation properties of the existing copper and the TiNi rolled-SMA. The fatigue properties of both materials were also investigated by the plane-bending fatigue test. The results obtained can be summarized as follows. (1) The modulus of elasticity and the yield stress for the cast and rolled SMAs are lower than those for the copper. Therefore, the conventional rolled-SMA spatula and the new cast-SMA spatula can be bent easily compared to the existing copper-brain spatula. (2) With respect to the alternating- and pulsating-plane bending fatigue, the fatigue life of both the copper and the SMAs in the region of low-cycle fatigue is expressed by a power function of the maximum bending strain. The fatigue life of the conventional rolled SMA and the new cast SMA is longer than that of the existing copper. The fatigue life of the new cast and rolled SMAs in the pulsating-plane bending is longer than that in the alternating-plane bending. (3) The fatigue life of the rolled-SMA and the cast SMA for alternating- and pulsating-plane bendings can be expressed by the unified relationship with a power function of the dissipated work.
213
Authors: Yi Hua Dou, Xing Wang, Yang Yu, Xiang Tong Yang
Abstract: In order to know the sealing ability under axial alternating tension load, a 88.9mm×6.45mm P110 premium tubing connection is established with multiple linear elastic plastic finite element model, stress and contact pressure on sealing surface and torque shoulder are analyzed under axial alternating tension load and 80 MPa inner pressure. The results show that tubing connection slide by the axial tension, while the maximum contact pressure on seal surface reduced. With the increasing of alternating cycle, the maximum equivalent stress on seal surface increased and the maximum contact pressure on seal surface decreased. And, under limited loads, contact pressure on torque shoulder is affected little caused by alternating load.
3569
Authors: Xia Yu, Wei Ming Zhang, Zhong Chao Qiu, Cheng Feng Chen
Abstract: Alternating current field Measurement is one of the important progresses about electromagnetic nondestructive testing in recent years. Alternating magnetic fields excitation testing model is established by using electromagnetic simulation software ANSOFT, a flat plate crack defects are simulated. By analyzing its principle, crack depth and the width change influence on test results, finally the simulation results are verified by the method of experiment. The experimental results are consistent with the simulation results. The results show that this differential probe has good effect on crack defects test.
452
Authors: Qing Du, Guang Yu Shi
Abstract: The Schwartz-Neuman alternating method is employed to analyze 3D cracks in structural components with complicated geometries.The SIFs of Mode I, II and III for the mixed-mode cracks under complicated stress state are obtained from the alternating computing scheme between finite element method solution for the uncracked body and the symmetric Galerkin boundary element method solution for the crack in an infinite body. The SIFs of the different surface cracks postulated at a regular pipe and elliptical surface cracks at the nozzle-cylinder intersection of a typical reactor pressure vessel are investigated by using the Schwartz-Neuman alternating method. The comparison with other analysis models and results reported in the literature shows that the Schwartz-Neuman alternating method can efficiently and accurately evaluate SIFs of surface cracks of different shapes and depths with much smaller computational models, which indicates that the Schwartz-Neuman alternating method is an efficient method in the evaluation of the SIFs of 3D cracks.
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