基于神经网络的摩擦焊工艺参数预测和接头性能缺陷检测研究

【作者】 冯静；

【导师】 王玉；

【作者基本信息】 西北工业大学 ， 机械设计及理论， 2003， 硕士

【摘要】 本文在对摩擦焊接头形成过程的分析和实验研究的基础上，用BP网络建立了摩擦焊主要工艺参数(摩擦时间、摩擦压力、顶锻压力)和接头性能(接头强度)的预测系统。在神经网络的训练过程中，以含有动量项和自适应学习率的快速BP算法为基础，又引入“再调整”系数β、误差函数系数α，形成了一种新的BP算法。实验结果表明，该系统得到的摩擦时间、摩擦压力、顶锻压力和接头强度的预测值与实际值吻合良好。 采用先进的超声扫描成像系统对高温合金摩擦焊接头进行超声无损检测，并记录下相应的超声扫描信号。用目前无损检测领域较为前沿的信号处理方法——小波包分析法对扫描信号进行处理。将信号进行多频段小波包分解，根据各相应频率、时间点的幅值大小绘出小波包分解系数灰度图。再由灰度图中不同的色块分布特征把信号分为三类：无缺陷信号、未焊合缺陷信号、弱结合缺陷信号。 利用基于小波包分析的“能量——故障”法和传统的幅频特性曲线法分别提取信号特征，作为缺陷识别神经网络模型的输入，用改进后的快速BP算法进行网络训练，建立了基于BP网络的摩擦焊接头超声波扫描信号的模式识别系统。该系统能够很好地区别各类信号，将信号自动识别分类为(0，0)、(1，0)、(1，1)三类，对应于无缺陷信号、弱结合缺陷信号、未焊合缺陷信号。 用编程语言VC将各部分内容集成、制作友好的人机交互界面，使之成为一个便于使用、便于改进的工程应用软件。该软件能够完成诸如样本集管理、参数预测、根据样本集的变化重新构建神经网络、进行小波包分析等多项相关功能。更多还原

【Abstract】 The friction welding-a modern connecting method is used in the various fields more and more widely and so the study of this field is now becoming more and more imperative.In this paper, on the base of analyzing and experimental studying on the process in the forming process of the friction welded joints, BP network is used to construct the neural network prediction system of the major technical parameters (friction-time, friction force and so on) and the capability of the friction welding joints. During the training of the neural network, the influence, which is caused by the various network parameters, on the error function is discussed emphatically and the traditional BP algorithm is improved by importing the re-adjusting coefficient fiand error function coefficient a. The forecast value can meet the actual value well.In addition, using ultrasonic testing machine test the friction welding joints and the modern analyzing method -wavelet packet analysis is used to class the reflected echo scan signal into three sorts: good welding, un-welding and weak defect. After classing, the selected characters of signal by wavelet packet analysis and amplitude-frequency analysis are used to construct the classing-prediction neural network.At last, in order to convenient for practice application, Visual C++ is applied to integrate these application programs into an application-software.更多还原