共查询到19条相似文献,搜索用时 140 毫秒
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《振动与冲击》2019,(18)
为研究叶片型线对射流离心泵水力性能及旋转噪声特性的影响,提升射流离心泵叶轮设计水平,应用高阶Bezier曲线对叶片型线进行参数化控制,采用Plackett-Burman方法进行参数的显著性分析和筛选,基于响应面法对敏感性较强的3个控制变量进行中心复合试验设计,建立射流离心泵叶片型线与效率、扬程、轴功率及旋转噪声之间的多元回归模型,确定水力性能和声学性能之间的映射关系。结果表明:叶片包角、叶片出口安放角、叶片进口直径对射流离心泵的水力性能和声学性能影响最为显著;方差分析法和系数法检验结果证明回归模型高度显著,能够反映叶型控制参数与响应目标之间的客观关系;较小的包角、较大的出口安放角、较小的进口直径有助于改善射流离心泵的水力性能,设计空间水力性能最优参数组合为包角φ=52.5°,出口安放角β_2=50°,叶片进口直径D_j=14.5;叶型各控制参数编码靠近0水平时有助于改善声学性能,设计空间声学性能最优参数组合为包角φ=76°,出口安放角β_2=33°,叶片进口直径D_j=18;声学性能和水力性能在叶片型线的样本空间内具有逼近Pareto解的能力,Pareto前沿解沿一条呈下的凸形曲线分布。 相似文献
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分别应用定量金相法、wRC-1992组织图法和X射线衍射物相定量方法对铬镍奥氏体不锈钢的焊缝铁素体的含量进行测定。在定量金相法中,考虑了铁素体含量分布的均匀度;在X射线衍射物相定量方法中,分析了试样择优取向对测定结果的影响,考虑了测定结果的分散性。最后,对三种方法的测定结果进行了比较。结果表明:在一定条件下,应用类似于X射线衍射仪测定残余奥氏体含量的方法对焊缝铁素体含量进行测定,也能得到与金相法和WRC-1992组织图法比较一致的结果。 相似文献
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采用金相法、化学法和磁性法对308奥氏体不锈钢焊缝中δ铁素体含量(质量分数)进行了检测.结果表明:采用金相法中的网格数点法、网格截线法和八线法时,在500倍显微镜下测得δ铁素体含量均为7.6%,是较为可信的结果;采用化学法中的Schaeffler图法时,测得δ铁素体含量约为8.5%,和金相法的测量结果接近;采用磁性法测... 相似文献
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本文试验研究了五种晶体取向(0°、15°、30°、45°、90°)和三种试验温度(900 20℃、1000 20℃、1100 20℃)对DZ-22定向铸造高温合金热应力疲劳裂纹扩展速率的影响,并观察了金相断裂特征,给出了五种晶体取向材料的裂纹扩展曲线的拟合方程式。 相似文献
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采用金相法测量了某镀镍铜线的镀镍层厚度,从试验重复性、金相试样镶嵌的垂直度以及光学显微镜标尺的校准等方面对影响镀层厚度测量结果的不确定度进行了分析和阐述,并对各不确定度分量进行了计算和合成,最终给出了镀镍层厚度测量的不确定度报告。结果表明:该镀镍铜线的镀镍层厚度为16.57μm,扩展不确定度U=1.68μm,包含因子k=2。 相似文献
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选取定向凝固镍基高温合金DZ444不同方向片状试样,利用电子背散射衍射等技术表征晶体取向和微观组织,利用脉冲回波技术分析纵波声速和声衰减系数。结果表明:两声学特性呈各向异性,随着试样平面法向与凝固方向之间夹角φ由0°到45°再到90°,纵波声速由5533m/s增大到6595m/s后又降至5634m/s,而声衰减系数逐渐增大,变化约0.19dB/mm;对信号频谱分析发现,表面回波与一次底波的主频差值、主频幅值差值及表观积分反射系数均逐渐增大,这主要是由微观组织和晶体取向差异造成的。 相似文献
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本文主要介绍氟化锂(LiF)分光晶体的定向、研磨和弯曲工艺。用塑性弯曲方法,弯曲成50×50×1mm,曲率半径 R=200mm 的晶体;用弹性弯曲方法,弯曲成15×10×0.3mm,R=100mm的晶体。文中并对定向和弯曲过程中常出现的问题进行初步分析和讨论。 相似文献
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Structure and orientation development in simultaneous biaxial stretching of gelation-crystallized ultra-high molecular weight polyethylene (UHMWPE) was examined by means of X-ray pole figures. The dry gel film exhibits a stacked lamellar structure similar to single-crystal mats with preferential crystalc-axis orientation normal to the film surface. The biaxially stretched gelationcrystallized films reveal a complex crystal orientation of (1 1 0), (2 0 0) and (0 2 0) planes. The detailed analysis of these pole figures manifests the occurrence of crystal twinning in addition to the orientation of crystallites. Crystal transformation of orthorhombic to monoclinic structure was not observed during biaxial stretching. The orientation distribution functions of crystallites were calculated assuming affine deformation. The orthogonality of crystal 1 1 0-c axes and crystala-c axes was further assumed to be conserved during the crystal twinning and biaxial orientation, respectively. Model simulation with contributions of 30% crystal twinning and 70% crystal orientation yields the best fit with the X-ray pole figures of biaxially stretched UHMWPE films. The affine model appears to be valid up to a biaxial draw ratio of 1.8×1.8, after which the results deviate from ideality with increasing draw ratio.On leave from Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya, Japan. 相似文献
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Zhixin Qin Masakazu Kobayashi Akihiko Yoshikawa 《Journal of Materials Science: Materials in Electronics》1999,10(3):199-202
X-ray diffraction reciprocal space maps and pole figures were used to analyse the cubic GaN epitaxial layers grown on (0 0 1) GaAs by r.f. plasma source MBE; the presence of hexagonal phase in cubic GaN layers was detected by high resolution x-ray analysis and the relationships among various crystal axes of cubic and hexagonal phase GaN were analysed with respect to V/III source-supply ratio. As for the growth conditions of the epitaxial layers, the V/III ratio was found to drastically affect the quality of the layers. High-temperature growth under near-stoichiometric conditions was necessary to obtain high quality epitaxial layers. It was found that inclusion of the hexagonal phase in the cubic GaN layers could be less than 0.4%, though previously reported typical c-GaN epitaxial layers included as much as 10–20% hexagonal phase GaN. On the basis of the measurements and analyses of reciprocal space maps and pole figures, it was revealed that the orientation of crystal axes of the hexagonal phase was unique in the present GaN epitaxial layers and they were different from those of previously reported c-GaN epitaxial layers. 相似文献
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In this work the magnetic induction in grain orientated ultra-thin silicon steel sheets (with a thickness of 0.08 mm) was
calculated by employing the crystal orientation distribution function and the formula for the anisotropy of energy for a single
crystal of cubic symmetry. The incomplete pole figures of {110}, {200} and {112} were measured and the corresponding orientation
distribution function was determined. On the basis of the texture data and the corresponding magnetic anisotropy energy, the
magnetic induction in the ultra-thin silicon steel sheet was calculated. The calculation results are in good agreement with
the experimental measurement. 相似文献
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《Materials Characterization》2007,58(7):617-622
The objective of this study is to investigate the possibility of improved drawability of AZ31 magnesium alloy sheet produced by equal channel angular rolling process at room temperature. Although with similar optical microstructure, the limiting drawing ratio of AZ31 magnesium alloy sheet is improved from 1.2 to 1.6 for the specimens before and after equal channel angular rolling, which is due to the changing crystal orientation that induces shear deformation through this process. The enhanced drawability in AZ31 magnesium alloy sheet provides the possibility for drawing at ambient temperature by controlling the crystal orientation in AZ31 magnesium alloy sheet. 相似文献
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Keith J. Bowman Jason Jenny Steven Kim Ronald D. Noebe 《Materials Science and Engineering: A》1993,160(2):201-208
Three B2 structure aluminide sheet materials produced by hot-rolling of alloys from compacted powders were evaluated for crystallographic texture. Two essentially binary NiAl alloys showed strong components in the plane of the sheet. A NiFeAl alloy had dramatically different texture which consisted of a strong components in the plane of the sheet. In addition to microstructures, measured pole figures and the orientation distribution function are reported and compared with textures produced in similar materials via extrusion. 相似文献
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Single-pass equal channel angular extrusion (ECAE) experiments of an extruded Mg–Zn–Y–Zr alloy with an intense initial basal texture were performed in two inter-perpendicular billet orientations and at 473 and 623 K. The study was aimed to determine the effects of ECAE temperature and billet orientation on the microstructure, texture evolution and mechanical properties of the ECAEed alloy. It was found that the grain refinement achieved through the single-pass ECAE in the Orient-I billet orientation (the normal direction (ND) of the extruded plate parallel with the ECAE exit direction) was more effective than that in the Orient-II billet orientation (the ND of the extruded plate perpendicular to the ECAE exit direction). The average grain sizes after ECAE at 473 K were much smaller than those after ECAE at 623 K. The pole figures of the alloy ECAEed at 473 K showed that most of the basal planes in the Orient-I and Orient-II samples were inclined about 40° and 35°, respectively, with respect to the longitudinal direction of the ECAE extrudate. However, for the alloy ECAEed at 623 K, most of the basal planes were parallel with the longitudinal direction of the ECAE extrudate. It was remarkable that the yield strengths of the alloy ECAEed at 473 K were lower than those at 623 K. The peculiar relationship between ECAE temperature and the mechanical properties of the alloy was ascribed to the texture evolution during ECAE. 相似文献