基于声发射特征参数的金属材料塑性变形研究

发布时间：2018-03-27 19:34

本文选题：声发射特征参数　切入点：塑性变形　出处：《西南石油大学》2017年硕士论文

【摘要】：从微观与宏观角度对材料各方面性能进行研究是目前研究材料领域中的一个重要手段和方法。在传统材料力学测量手段中仅能实现材料基本力学性能的测量,难以实时探究材料内部过程变化。材料在内力或者外力作用下会释放出弹性波,声发射源释放的弹性波携带有大量关于材料变形过程的相关信息,通过对声发射信号的分析能够追踪材料内部活动规律。本论文针对石油行业常用的两种金属材料(L360及35CrMo),使用声发射技术研究了单轴拉伸过程的力学性能与声发射特征参数的关系,建立了两种材料的声发射特征参数实验资料。使用声发射参数时间历程结合应力曲线,构建微观塑性变化机制与宏观力学响应之间的关系,分析了各声发射参数在描述材料拉伸过程的优缺点。在此基础上,进一步总结两种材料拉伸过程中声发射参数变化规律及特征。以参数变化规律及特征为依据,对拉伸过程进行了划分,该方法与传统应力应变曲线划分结果基本一致。对两种材料拉伸过程中的声发射参数进行相关性分析,引进了皮尔森相关系数以及斯皮尔曼秩相关系数对声发射参数相关性进行定量描述。通过相关性分析后得到:声发射振铃计数、幅值与能量在整个拉伸过程中表现出很强的相关性。目前关于声发射特征参数与力学性能之间定量研究的方法并不多,本论文通过神经网络与小波变换,使用特征参数得到了与应力时间历程吻合度很高的曲线,为研究声发射特征参数与材料力学参数的定量分析提供了一定的思路。
[Abstract]:It is an important means and method to study the properties of materials in the field of materials from the micro and macro aspects. In the traditional measurement methods of material mechanics, the measurement of basic mechanical properties of materials can only be realized. It is difficult to explore the internal process of materials in real time. Elastic waves are released by internal or external forces. The elastic waves released by acoustic emission sources carry a lot of information about the deformation process of materials. In this paper, the mechanical properties and acoustic emission of two metal materials commonly used in petroleum industry, L360 and 35CrMoO, are studied by acoustic emission technique. The relationship between characteristic parameters, The experimental data of acoustic emission characteristic parameters of two kinds of materials are established. Using the time history of acoustic emission parameters and the stress curve, the relationship between the microscopic plastic change mechanism and the macroscopic mechanical response is constructed. The advantages and disadvantages of various acoustic emission parameters in describing the tensile process of materials are analyzed. On this basis, the variation law and characteristics of acoustic emission parameters in the stretching process of two kinds of materials are summarized. The tensile process is divided, and the method is in good agreement with the traditional stress-strain curve. The correlation of acoustic emission parameters in the tensile process of two kinds of materials is analyzed. The Pearson correlation coefficient and Spelman rank correlation coefficient are introduced to describe the correlation of acoustic emission parameters quantitatively. The amplitude and energy show a strong correlation in the whole stretching process. There are few methods to quantitatively study the relationship between the characteristic parameters of acoustic emission and mechanical properties. In this paper, neural networks and wavelet transform are used to study the relationship between amplitude and energy. The curve with high consistency with the stress time history is obtained by using the characteristic parameters, which provides a certain way of thinking for the quantitative analysis of the acoustic emission characteristic parameters and the mechanical parameters of materials.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG115

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