Laser Phase Array Generation of Ultrasound for On-Line Weld Quality Control

本研究的目的是开发一种新的、高效的非接触式激光相控阵超声产生技术，用于固体和过程的无损评估(NDE)。这项新技术使用的是一组激光，而不是单一的光束。这项研究将包括评估相控阵性能和开发相控阵分析模型的基础研究。在气体保护焊(GMAW)过程中，将致力于非接触式无损检测在线控制熔透深度和气孔的具体应用。电磁换能器将被用作非接触式接收器。研究分为五个阶段：(1)建立激光相控阵产生超声的分析模型，(2)对相控阵模型进行实验验证，(3)将相控阵应用于非接触式无损检测，实现熔深和气孔的在线控制；(4)开发了声在熔池中传播的分析模型；(5)开发了数据采集系统和算法。从超声信号中提取的熔池熔深和气孔信息将被用于系统反馈，用于焊接电源、电流或速度控制，以实现所需的熔深和气孔。

The purpose of this research is to develop a novel, efficient technique of noncontacting laser phased array generation of ultrasound, for the nondestructive evaluation (NDE) of solids and processes. The new technique uses an array of laser beams in place of a single beam. The research will include a basic study to evaluate the performance of and develop an analytical model for the phased array. Specific applications to noncontact NDE on-line control of the depth of penetration and porosity during a gas metal arc welding (GMAW) process will be pursued. An electromagnetic acoustic transducer will be used as a noncontact receiver. The research has five phases as follows: (1) development of an analytical model for predicting the generation of ultrasound by a laser phased array; (2) experimental verification of the model for the phased array; (3) application of phased array to noncontact NDE on-line control of the depth of weld pool penetration and porosity; (4) development of an analytical model for propagation of sound through the weld pool; and (5) development of the data acquisition system and algorithms. The information on weld pool penetration and porosity extracted from the ultrasonic signal will be used in the system feedback for the welding power-supply, current, or speed control, to achieve the desired penetration and porosity.