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非线性拟合方法用于透射式脉冲红外技术测试碳/碳复合材料的热扩散系数 被引量:1
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作者 李晓丽 Sun Jian-Gang +4 位作者 陶宁 曾智 赵跃进 沈京玲 张存林 《物理学报》 SCIE EI CAS CSCD 北大核心 2017年第18期268-275,共8页
为了测试碳/碳复合材料的热扩散系数,本文提出了非线性拟合用于透射式脉冲红外检测的数据处理方法.非线性拟合通过循环迭代的方法持续调整拟合参数,让理论值不断逼近实验值,直至获得最佳结果.传统的透射式脉冲红外成像技术利用半高时间... 为了测试碳/碳复合材料的热扩散系数,本文提出了非线性拟合用于透射式脉冲红外检测的数据处理方法.非线性拟合通过循环迭代的方法持续调整拟合参数,让理论值不断逼近实验值,直至获得最佳结果.传统的透射式脉冲红外成像技术利用半高时间法测试材料的热扩散系数,但通常会受到采集时间不足和信噪比差的限制.本文提出的非线性拟合方法可以有效消除或减弱这两种影响.在使用该方法之前,首先选用常见的304不锈钢评估了该方法的测量精度及拟合长度对测试结果的影响.结果显示304不锈钢的测量精度达到0.3%,且当拟合长度不小于半高时间法采集时间的1/5时,拟合长度对非线性拟合结果影响很小.随后使用该拟合方法测试了不同厚度的碳/碳复合材料试件,并通过热扩散系数测量结果分析了试件之间的热参数差异性和材料自身的均匀性. 展开更多
关键词 非线性拟合 透射式脉冲红外检测 碳/碳复合材料 热扩散系数
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Microstructural characterization of polycrystalline materials by synchrotron X-rays
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作者 Leyu n WANG Meimei LI +2 位作者 Jonathan ALMER Thomas BIELER Rozaliya BARABASH 《Frontiers of Materials Science》 SCIE CSCD 2013年第2期156-169,共14页
Third generation synchrotron X-rays provide an unprecedented opportu- nity for microstructural characterization of many engineering materials as well as natural materials. This article demonstrates the usage of three ... Third generation synchrotron X-rays provide an unprecedented opportu- nity for microstructural characterization of many engineering materials as well as natural materials. This article demonstrates the usage of three techniques for the study of structural materials: differential-aperture X-ray microscopy (DAXM), three-dimensional X- ray diffraction (3DXRD), and simultaneous wide angle/small angle X-ray scattering (WAXS/SAXS). DAXM is able to measure the 3D grain structure in polycrystalline materials with high spatial and angular resolution. In a deformed material, streaked diffraction peaks can be used to analyze local dislocation content in individual grains. Compared to DAXM, 3DXRD is able to map grains in bulk materials more quickly at the expense of spatial resolution. It is very useful for studying evolving microstructures when the materials are under deformation. WAXS/SAXS is suitable for studying materials with inhomogeneous structure, such as precipitate strengthened alloys. Structural informa- tion revealed by WAXS and SAXS can be combined for a deeper insight into material behavior. Future development and applications of these three techniques will also be discussed. 展开更多
关键词 differential-aperture X-ray microscopy (DAXM) three-dimensional X-raydiffraction (3DXRD) wide angle/small angle X-ray scattering (WAXS/SAXS)
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