Effect of cavitation on the plastic deformation and failure of isotactic polypropylene

To clarify the effect of cavitation, which is mostly induced by crystalline phase, on the plastic deformation and failure of isotactic polypropylene, solid‐state annealing at 160°C for 1.5 h is adopted to change the crystalline phase only while the amorphous phase keeps nearly intact. With aid of a special video setup, the relation of true stress and strain as well as the evolution of volume strain with axial strain has been derived. Enhancing crystalline phase due to annealing increases the yield stress and volume strain simultaneously. Moreover, the strain corresponding to steep increasing of volume strain is comparable with that related to yield, indicating that cavitation at early stage is accompanied with process of yield. With knowledge of toughness derived from impact tensile stretching and essential work of fracture (EWF), respectively, the relationship between cavitation and toughness has been correlated to some degree. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

超声促进聚合物合成研究进展

从超声波作用下的自由基聚合反应、开环聚合反应等不同聚合反应的诸方面综述了超声波在聚合反应中的应用，认为超声波的空化作用导致分子链分解或破裂产生自由基，引发聚合反应，促进聚合物合成。阐明超声波能够提高反应速率、产率，提高相对分子质量，控制相对分子质量分布等，而进一步研究超声聚合反应进程中的复杂问题尤其重要。     

熔体超声处理对7055铝合金显微组织和性能的影响

通过对7055铝合金棒材浇铸前作超声处理,研究了超声作用对其显微组织和力学性能的影 响。研究结果表明:超声波在熔体中产生空化作用,对7055铝合金熔体作超声处理能细化晶粒, 提高强度,并能大幅度提高其塑性。     

三峡船闸末级闸首超长泄水廊道中阀门水力学关键问题研究（3）—事故动水关闭情况下改善阀门工作条件的措施

针对三峡船闸末级闸首泄水廊道阀门事故动水关闭的情况下，阀门段存在大范围的脱空和空化，提出了封堵检修门井＋廊道顶有控制地通气，以及门楣自然通气的综合工程措施，以改善阀门的工作条件。物理模型试验和数学模型计算结果论证了该综合工程措施是有效的。     

浅谈天湖水电站水轮机运行故障及处理措施

简述天湖水电站投运以来各种故障的表现形式，分析其原因，提出了相应的处理方法及措施，并对合理利用国内外设备提出建议。     

栅格翼和雷体组合体的空泡水动力计算与分析

该文采用商用软件FLUENT计算了栅格翼在雷体上应用时的水动特性.采用气泡两相混合介质模型研究空化现象.计算结果表明,栅格翼作为一种水下航体的承力稳定面和控制面具有良好的性能.空泡的产生将降低栅格翼的升/阻比,从而降低其性能.     

渣浆泵过流部件破坏的原因分析

分析了渣浆泵过流部件破坏的主要原因，并提出提高渣浆泵过流部件使用寿命的措施。     

A metallurgical approach to improved cavitation-erosion resistance

Although cavitation erosion in hydraulic systems is an old problem, the damage mechanism that culminates in material loss was not known with certainty until recently. An investigation is described that aimed at clarifying the damage mechanism in cavitation erosion and applying that knowledge to make hydraulic equipment more resistant to cavitation. Strong correlations were established between cyclic deformation (fatigue) parameters and cavitation-erosion rates. This identification facilitated the search for more resistant materials. Finite element modeling confirmed that localized impacts on metal surfaces produce fatiguelike deformations and damage accumulation. Among available materials, near-equiatomic alloys of nickel and titanium are anomalously resistant to low-cycle fatigue and thus should be very resistant to cavitation erosion. Experiments confirmed the expected erosion resistance. Building large machines entirely out of NiTi is impractical, however, and a way of selectively cladding common constructional materials is required. Because NiTi has not been fusion welded successfully to other alloys, explosive bonding of thin NiTi plates to structural steel was investigated. Excellent welds were achieved, and the erosion resistance of the resulting clads has been demonstrated. Comparisons are made to other erosion processes and to other erosion-resistant materials, and some applications to hydraulic devices are suggested.     

表面张力对铝材料空蚀的影响

在磁致伸缩仪上，研究了５种不同表面张力系数的液体中铝试件的空蚀过程。结果发现在试验范围内，虽然液体的表面张力系数有所不同，但铝试件的空蚀过程仍包括４个阶段；得出前人文献中均未得到过的、铝试件的失质率及总失质量与液体表面张力系数呈线性增长的试验结果。并用空泡生命周期随液体表面张力系数增长呈线性减小的试验研究结果对上述现象从理论上加以说明。     

水压阀关键技术的研究

基于水压阀的研究现状和本文所进行过的相关研究得出结论：从摩擦学的角度选择合理“阀芯-阀套”相互适宜的材料配对和设计有利于抑制空化产生的合适的阀口几何结构形式是研制水压阀的关键技术难点。基于这两方面的技术问题，还介绍了目前可能的技术解决方案。