排序方式: 共有82条查询结果,搜索用时 421 毫秒
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建立了一个基于VC++的超声信号处理与分析系统。该系统集信号采集、处理和特征参量的计算与提取,特征参量的统计与综合以及材料的表征和评价于一体,不但能够完成常规信号处理,而且能够对超声波信号进行全方位、多种类型的特征参量自动计算、提取与分析。用该系统对检测碳纤维增强复合材料(CFRP)孔隙率时的超声回波信号进行了处理和分析,提取了有效频带能量(ELFB)和主频对应的能量(EPF),并把它们与孔隙率之间的关系进行数值拟合,发现在拟合曲线上存在临界孔隙率的现象,为CFRP孔隙率检测提供了有效途径。 相似文献
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用真空葛氏扭摆研究了CuZnAl 形状记忆合金平衡状态试样的内耗。在室温至500℃温度范围内,观测到两个弛豫型内耗峰,峰温分别为240℃和345℃(f≈1.7Hz)。通过改变频率测得240℃峰的弛豫激活能为27kcal/mol,345℃峰的弛豫激活能为42kcal/mol。计算了两个峰的τ_0值,确定345℃峰为α相中Zener 弛豫峰,240℃峰则是由β有序相内反向畴界某种点缺陷运动所产生。 相似文献
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Pores,microcracks and density of plasma sprayed Cr2O3 coatings before and after high-intensity pulsed ion beam(HIPIB) irradiation were investigated using the ultrasonic reflection coefficient spectroscopy(URCS).The URCS was analyzed based on an acoustic transmission model for the multi-layered structure.The longitudinal velocity in the coatings was calculated from the experimental URCS,and the attenuation coefficient expression was deduced by comparing the experimental and numerical fitting amplitude spectral lines.The longitudinal velocity of as-sprayed Cr2O3 coating is 2 002 m/s,and increases to 2 099 and 2 148 m/s after being irradiated by HIPIB with 1 and 5 shots.Correspondingly,the factor A changes from 0.046 to 0.026 and 0.020 and n from 1.702 to 1.658 and 1.649 in the attenuation coefficient expression of α=Af n.It is observed that the surface morphology of Cr2O3 coatings changes from rough and porous to smooth and uniform with the increase of shot number,which accords with the ultrasonic analyses reasonably.The URCS seems to provide a convenient and nondestructive method to characterize surface modification of the plasma sprayed coatings. 相似文献
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基于随机介质理论的热障涂层随机孔隙模型构建 总被引:3,自引:1,他引:2
基于随机介质理论、采取统计学方法,将热障涂层(TBCs)中孔隙和裂纹引起的局部密度和弹性模量起伏用空间自相关函数及某些统计参数来描述,借助极值搜索法对连续随机介质模型进行改造,并针对涂层孔隙率及各向异性取向等进行模型参数优化,提出并建立了TBCs随机孔隙模型。将模型模拟结果与ZrO2涂层SEM观察结果进行对比表明,所建立的模型能够较好地描述热障涂层中的孔隙、裂纹形貌特征。本研究对于确定TBCs孔隙特征与涂层性能的理论关系以及涂层性能计算研究具有较大意义。 相似文献
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