共查询到20条相似文献，搜索用时 156 毫秒
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应用应变疲劳能量损耗的理论和弹塑性断裂力学的J积分理论,初步探讨了钢材的应变循环加载对延性断裂韧度JIC的影响。通过对20G钢和16Mn热轧钢板两种钢材的应变循环加载前、后两种状态的延性断裂韧度JIC测试数据的比较,考察了这种影响的存在。测试结果表明,±0.3%全应变控制的循环加载,经历500周次后可使两种钢材的JIC数值产生15%以上的改变量。对于20G钢,这种变化与Rice给出的循环加载变形功与J积分之间的函数关系相对应;而对于16Mn钢则有较大的差异,其原因有待于进一步的研究。 相似文献
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冲击试验中同样试样中的冲击吸收功与冲击速率之间的关系在许多人的认识中存在着误解，本通过在冲击试验中使用不同质量的摆锤，从实验和理论上揭示了上述两之间的关系。 相似文献
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16Mn热轧钢板延性断裂韧度JIC的相关性研究 总被引：1，自引：0，他引：1
探讨了热处理和应变循环加栽对16Mn延性断裂韧度JIC的影响.实验结果表明:16Mn热轧钢板正火后延性断裂韧度JIC约是正火前的3倍,应变循环加栽对钢材的延性断裂韧度JIC的影响很明显,钢材单调拉伸0.3%应变后,延性断裂韧度JIC均比未经单调拉伸0.3%应变时降低了11%.控制±0.3%全应变的循环加栽500周后,延性断裂韧度JIC比未经单调拉伸0.3%应变时钢的延性断裂韧度JIC提高了15%,产生相反差异的原因还有待于进一步的研究. 相似文献
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统计了国内四家钢轨生产企业近几年生产的60kg/m U71Mn和U75V钢轨的室温冲击功。U71Mn钢轨轨头、轨腰和轨底的冲击功平均值分别为15.65J、8.69J和19.57J,U75V钢轨轨头、轨腰和轨底的冲击功平均值分别为14J、9.03J和16.28J。轨底冲击功最高,轨头次之,轨腰最低。各钢厂生产的U71Mn和U75V冲击功的均值和波动范围相似。U71Mn钢轨轨头和轨底的冲击功高于U75V钢轨,轨腰的冲击功与U75V钢轨基本相同。U71Mn和U75V钢轨全断面各部位的冲击功的变化规律相似,越靠近钢轨边部,压缩比越大,冷却速度更快,冲击功越高;而轨腰部位受铸坯中心区域的偏析、疏松等缺陷的影响越小,冲击功最小。 相似文献
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以新一代超低碳贝氏体桥梁用钢为研究对象,从冲击韧性、J积分和CTOD三个方面进行试验研究与分析,讨论了试验温度对冲击裂纹起始功Wi、扩展功Wp及冲击总功Wt的影响,绘制出CTOD和J积分阻力曲线。结果表明:裂纹起始功Wi、扩展功Wp和冲击总功Wt都随温度的降低而减小,在-80℃时,冲击总功为310J,材料没有发生韧脆转变。利用阻力曲线计算出δ0.2BL为0.31mm,J0.2BL为273.75kN/m。 相似文献
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冲击功异常是影响管线钢性能稳定性的重要因素之一.针对本钢1700mm热轧生产的管线钢存在冲击功异常问题,对管线钢冲击功进行了检测,并对其的低倍组织和金相检验结果进行了分析,通过冶炼工艺和轧制工艺的调整,解决了管线钢的冲击功异常的问题. 相似文献
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薛若宸 《数理天地(初中版)》2004,(6)
1.利用线段之间的关系例1 如图l,已知GD⊥CB,AC交GD于F,AE⊥CB,又∠G=∠GFA. 求证:AE平分∠CAB. 证明由GD⊥CB,AE⊥CB,得GD∥AE.则∠CAE=∠GFA=∠G.由∠FAG=180°-2∠G,知图1 相似文献
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王会 《乐山师范学院学报》1991,(1)
在美国英语(American English,简称AE)和英国英语(British English,简称BE)中,某种表达方式常被大多数美国人采用,但却不被大多数英国人采用;反之英国人喜欢采用的某种表达方式,美国人却往往避免而另有所好,这就形成AE与BE在语法上的差别。为了正确使用英语,我们应该了解和认识它们。本文拟就AE和BE之间在语法上所存在的明显差别进行分析探讨。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献