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101.
黄坛口水电站建于20世纪50年代。在第二次大坝安全定期检查中。发现钢闸门和启闭机存在许多缺陷。闸门和启闭机的更新改造已经进行,并取得良好效果。 相似文献
102.
103.
Fretting fatigue is one of the most important phenomena for inducing a significant reduction of fatigue strength and consequently,
leading to unexpected failure accidents of the engineering structures even at very low stresses. In the present study, both
plain and fretting fatigue tests with zero mean stress were carried out on two different types of steel, low-carbon steel
and martensitic stainless steel, by means of a reversed bending fatigue testing machine. The drop in the fatigue strengths
through fretting at vise clamp-specimen interface were significant for both tested steels. The fretting processes produced
a reduction in fatigue strength of about 27% for low-carbon steel and 16% for martensitic stainless steel. 相似文献
104.
ATH在无卤阻燃聚乙烯电缆料中的应用研究 总被引:12,自引:0,他引:12
何云南 《高分子材料科学与工程》1992,8(6):126-130
以EVA改性LDPE,以偶联剂改性ATH,通过一系列配方的研究和性能测定,认为可以设计出适合于电缆料用的无卤阻燃聚乙烯的配方。 相似文献
105.
本文研究了一种Zn-Ti合金新镀层,经盐水浸泡、中性盐雾和大气暴露试验结果试验,其耐蚀明显超过镀Zn层,并与镀Cd层相近,用缺口持久拉伸试验检验氢脆性,拉伸持续时间超过200h,达到原航空部部颁标准(HB5067-85),该镀层适用于高强度钢防护。 相似文献
106.
Naoki Takinami Takashi Chino Shotaro Yoshida Isao Miura Kazuo Watanabe Kazuo Amano 《Electrical Engineering in Japan》1994,114(6):1-12
When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test. 相似文献
107.
在辽宁省工业城市进行 A3钢大气暴露试验。两年后测出不同地点腐蚀率。依据所记录的各试验点的气象数据和污染数据,讨论了 A3钢的大气腐蚀规律。 相似文献
108.
For environmental considerations, the substitution of the conventionally used oil-based grinding fluids has nowadays become strongly recommended. Although several alternatives have been proposed, cryogenic cooling by liquid nitrogen is the non-polluting coolant that has been given relatively more attention because of its very low temperature. In this investigation, in order to contribute to developing this promising cooling mode, its beneficial effects on the ground surface integrity of the AISI 304 stainless steel and their consequences on the fatigue lifetime are explored. Results of this investigation show that grinding under cryogenic cooling mode generates surfaces with lower roughness, less defects, higher work hardening and less tensile residual stresses than those obtained on surfaces ground under oil-based grinding fluid. These surface enhancements result into substantial improvements in the fatigue behaviour of components ground under this cooling mode. An increasing rate of almost 15% of the endurance limit at 2 × 106 cycles could be realized. SEM analyses of the fatigue fracture surfaces have shown that the fatigue cracks observed on the specimens ground under cryogenic cooling are shorter (i.e., 30-50 μm) than those generated under oil-based cooling mode (i.e., 150-200 μm). The realized improvements in the surface integrity and in the fatigue behaviour are thought to be related to the reduction of the grinding zone temperature observed under cryogenic cooling, as no significant differences between the grinding force components for both cooling modes have been observed. 相似文献
109.
110.
V. E. Kahle 《Journal of Failure Analysis and Prevention》2006,6(4):23-28
Three reconditioned rail car couplers, arbitrarily identified as couplers, failed during service due to cracking of the front
face. The three couplers were reportedly upgraded by quenching and tempering to enhance strength and toughness. The objective
of this investigation was to determine the mode of crack propagation and the root cause of the observed failures.
Verl E. (Bud) Kahle, P.E., was a professional failure analyst for more than forty years. After receiving his Bachelor of Science
degree in physical metallurgy from Washington State University 1957, Bud was employed by the General Electric Company at a
facility in Hanford, Washington. He later was employed by the Aerojet General Corporation and eventually was head of the Southern
Pacific Materials Science Laboratory in Sacramento. After retirement from Southern Pacific he owned and operated his own firm,
Kahle Metallurgical Consulting Services, for fifteen years. He came to be known as “the man with the answers” to clients in
a variety of industries. Bud was a Life Member of ASM International.
Many of Bud’s clients remarked on the high quality of his failure analysis case histories and encouraged him to have them
published. After Bud passed away in 1999, his wife, Suzanne, approached ASM International to see if the society would be interested
in publishing any of his work. Mrs. Kahle was able to supply a large number of reports, which Bud had carefully archived over
the years. Journal of Failure Analysis and Prevention Associate Editor Michael Stevenson read through the collected case histories, selected the ones to be included in this issue,
and edited them for journal publication.
ASM International wishes to thank Mrs. Kahle for providing these case histories for publication. 相似文献