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冷却水系统在日常运行过程中常常会发生一些事故,若不能及时发现和妥善处理,会迫使冷却水系统和有关生产装置停止运行,造成经济损失。 冷却水系统中事故的处理包括:找出事故的部位及原因、消除事故产生的后果、使冷却水系统迅速恢复到正常运行状态、提出防止事故的方案、采取相应的措施以及善后处理等几个方面。从工厂的全局考虑,冷却水系统中事故的处理应尽可能在不停车的情 相似文献
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比较了冶金机械设备在停电故障下几种事故驱动方式,重点介绍了新兴的EPS(Emergency Power Supply)事故驱动电源,并倾向于采用EPS作为冶金设备的主要事故驱动。 相似文献
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目的研究钢制安全壳内外壁面无机富锌涂层在极限设计基准事故工况下的特性,为设计验证和非能动安全壳冷却系统热工水力试验边界条件的确定提供数据支持。方法参照大破口失水事故工况下可能形成的物理环境设计试验:试件置于恒温炉加热至160℃,待整体温度均匀后,迅速浸入20℃冷水中冷却,待冷却至常温后,再浸入100℃沸水中加热60 min。测试涂层经过事故工况前后的导热性、干膜厚度、表面形貌和附着力,分析事故工况对这些性能的影响。结果模拟事故工况前后,涂层的干膜厚度在70~130μm范围,附着力在8.5~13.5 MPa范围,热导率升高了6.8%,表面形貌无明显变化。结论模拟事故工况前后,涂层的干膜厚度、表面形貌和附着力无明显变化,涂层热导率有微升趋势。 相似文献
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通过事故现象,分析了事故原因是10kV系统发生单相间歇性弧光接地引起的。同时,分析了作为单相接地保护的消弧变压器,在事故发生时未起作用的原因。根据10kV中性点非直接接地系统的特点,提出了对10kV供电系统接地保护的改造建议。 相似文献
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针对弹性悬臂梁的裂纹识别问题,探讨了谐响应分析在含裂纹梁损伤识别中的应用。首先结合连续介质弹性梁动力学方程和有限元方法,建立了含裂纹梁的受迫振动方程。然后,基于Abaqus平台建立了若干种含V型表面裂纹的悬臂梁有限元模型,在此基础上通过施加外部激励进行谐响应理论分析。最后,探讨了裂纹几何参数和加载位置对谐振频率及谐响应幅值的影响。结果表明,裂纹深度、裂纹位置、裂纹数量以及加载位置对谐响应变化规律有明显影响,为悬臂梁的裂纹识别提供了思路。 相似文献
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因在外部载荷的作用下,梁构件内部结构容易发生裂纹的萌生和扩展,甚至导致梁构件发生断裂从而引发灾难性事故,研究一种基于模态振型的圆截面梁裂纹识别等高线法。先推导无裂纹单元与含裂纹单元的刚度矩阵,然后求解含裂纹圆截面梁振动微分方程,发现裂纹工况对模态振型有一定的影响。在此基础上,研究不同裂纹位置比和不同裂纹深度比之下前三阶模态振型突变的响应曲面,提出基于模态振型的裂纹识别等高线法。结果表明:对于单裂纹圆截面梁裂纹识别,裂纹深度和裂纹位置的预测结果误差为0;对于双裂纹圆截面梁裂纹识别,裂纹深度预测最大误差不超过2%,裂纹位置预测最大误差不超过2%。 相似文献
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为避免复杂型面的汽车前保险杠防撞梁本体拉深成形中易起皱和拉裂等缺陷,提出了以微元离散圆形拉深的方法计算弧长方向的压边力变化曲线.首先分析了工件的几何物理性质和技术要求,在此基础上建立了塑性方程.然后对拉深成形过程进行近似假设,建立拉深的某一瞬间凸缘起皱后的波纹表面模型,建立压边力的方程,并获得沿弧长方向的分布曲线.结果表明,该压边力计算方法可以有效避免自由曲面拉深中的缺陷. 相似文献
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平面压边拉深中消除内皱的可靠性计算与实验研究 总被引:1,自引:1,他引:0
平面压边下增加压边力可以消除内皱,但会发生拉裂现象。根据平面压边下拉深的变形特点,对增加压边力消除内皱进行了可靠性分析计算,获得了不发生拉裂的临界起皱条件,并对增大压边力消除内皱进行了实验研究。结果表明,用正常消除外皱的压边力消除内皱作用微小,而增加压边力确实可以消除内皱。 相似文献
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The sensitivities of the conventional damping test and a particular implementation of the emerging vibro-acoustic modulation NDT technique have been compared on three types of cracked specimens: (1) a set of mild steel beams cracked in the laboratory, (2) a perspex beam also cracked in the laboratory and (3) an industrial component made of a nickel-based alloy. The latter was forged and cracked in the forging process. The comparison showed very similar performances on the specimens used. Both techniques work best for lightly damped specimens and in setups such that the influence of the support can be minimised. Their sensitivity is severely affected when these two conditions are not satisfied which significantly lower their appeal for many practical situations. 相似文献
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Mehdi Namazi Yusuf Altintas Taro Abe Nimal Rajapakse 《International Journal of Machine Tools and Manufacture》2007,47(9):1333-1341
The majority of the chatter vibrations in high-speed milling originate due to flexible connections at the tool holder–spindle, and tool–tool holder interfaces. This article presents modeling of contact stiffness and damping at the tool holder and spindle interface. The holder–spindle taper contact is modeled by uniformly distributed translational and rotational springs. The springs are identified by minimizing the error between the experimentally measured and estimated frequency response of the spindle assembly. The paper also presents identification of the spindle's dynamic response with a holder interface, and its receptance coupling with the holder–tool stick out which is modeled by Timoshenko beam elements. The proposed methods allow prediction of frequency-response functions at the tool tip by receptance coupling of tools and holders to the spindle, as well as analyzing the influence of relative wear at the contact by removing discrete contact springs between the holder and spindle. The techniques are experimentally illustrated and their practical use in high speed milling applications is elaborated. 相似文献
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Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were carried out.Microstructures of the joints were examined by scanning electron microscope.The properties were evaluated by microhardness and tensile strength.It was shown that electron beam welding is not feasible due to the brittle Ti-Fe intermetallics with high hardness.Increase of vanadium content in base metal can restrain but can’t avoid the formation of cracks.When vanadium content was too large,the joint was embrittled by FeTi compound with supersaturated V and also cracked after welding.Crack free joint was achieved by using vanadium transition portion which can prevent the contact of Ti and Fe elements.However,the formation of brittle σ intermetallics reduced the tensile strength of the joint,only up to 134MPa. 相似文献
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介绍材质为灰口铸铁的横梁断裂修复焊接工艺,采用冷焊补焊灰口铸铁,综合使用镍基焊条、普通碳钢焊条、常用奥氏体不锈钢焊条进行交叉过渡焊,提高焊接质量,简化修补工艺,降低修补成本。 相似文献