聚乙烯管道电熔焊接接头超声检测特征线的形成机理研究

项目名称： 聚乙烯管道电熔焊接接头超声检测特征线的形成机理研究

项目编号： No.51305394

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 机械、仪表工业

项目作者： 施建峰

作者单位： 浙江大学

项目金额： 25万元

中文摘要： 冷焊是聚乙烯管道焊接接头中最常见、最危险的缺陷之一。申请人等发明的基于特征线的冷焊超声检测方法是目前国内外唯一有效可行的冷焊无损检测方法。特征线是超声相控阵B扫描实时成像图中能准确反映熔融区边界位置的超声反射信号线。本项目拟以聚乙烯管道电熔焊接接头为研究对象，综合运用聚合物焊接温度场数值模拟、聚合物热分析和显微观测、液浸聚焦超声检测等技术，对焊接接头中不同位置处材料经历的温度-时间历程进行精确预测，应用结晶动力学理论分析不同温度-时间历程下聚乙烯的微观组织结构，研究其对声速、声阻抗等声学性能参数的影响规律，建立超声波在声阻抗连续不均匀聚乙烯薄层中传播的声学模型，分析超声波在熔融区边界处的反射声压，从而揭示超声检测特征线的形成机理。通过本项目研究，解决塑料管道应用过程中冷焊缺陷超声检测技术的关键性基础问题，对提高塑料管道的本质安全性，推动塑料管道安全保障技术的发展具有重要意义。

中文关键词： 聚合物焊接；超声检测；特征线；温度场；热历史

英文摘要： Cold welding is one of the most common and hazardous defects in polyethylene (PE) pipe system. The Eigen-line method, which was invented by our research group, is the only available nondestructive detection method to detect cold welding in PE pipe system currently. Eigen-line is ultrasonic reflection signal line in the ultrasonic phased array B-scan image, demonstrating the exact location of the fusion zone boundary. In this project, the formation mechanism of Eigen-line in electrofusion joint of PE pipes will be studied. By applying the technology of numerical simulation of welding process and thermal analysis, microscopic observation, immersion ultrasonic inspection, etc for polymer, we plan to predict the thermal history in different region of electrofusion joint precisely, and utilize the theory of crystalline kinetics to analyze the microstructure of PE under different thermal histories. The relationship between microstructure of PE and acoustic properties such as acoustic impedance will also be investigated in detail. Then, an acoustic model will be developed to analyze the reflected acoustic pressure of ultrasonic signal on the fusion zone boundary, and to reveal the formation mechanism of Eigen-line. By solving the key fundamental problems of the ultrasonic inspection method when inspecting cold welding

英文关键词： polymer welding；ultrasonic inpsection；Eigen-line；temperature model；thermal history