基于二次波的增材制造平板缺陷无损检测方法研究

DAMAGE DETECTION IN THE ADDITIVE MANUFACTURING PLATE USING THE SECOND ARRIVAL WAVE

在航天航空领域,增材制造板状结构因其优异特性而得到广泛应用.但是增材制造结构件在制造或者使用过程中极有可能会产生不同类型的缺陷,从而造成安全隐患.本文基于兰姆波在平板中具有多个路径的传播形式,提出了一种利用二次到达波的缺陷无损检测方法,并应用于增材制造平板的缺陷定位.首先,根据兰姆波的频散特性确定激励信号的中心频率和模式.设计兰姆波在板中的多种传播路径,通过预先设置的压电片传感器接收二次到达波.通过波速和消耗时间来计算从传感器到缺陷的距离,以传感器为中心、以测得的传感器到缺陷的距离为半径做圆,进而利用两圆交点定位缺陷.本文使用增材制造聚乳酸(PLA)板进行数值仿真和实验,以验证该方法的有效性,结果表明本方法可快速简捷地对直径为1mm的通孔进行缺陷定位.研究工作对增材制造结构缺陷检测具有参考意义.

Usually,only the first arrival wave is used for damage detection,and the resultant overlap of multiple wavepaths is ignored.In this paper,a simple damage detection method using the second arrival waves of multiple wavepaths is proposed for damage localization in an additive manufacturing(AM)plate.The frequency and mode of Lamb wave used for excitation are determined according to the dispersion characteristics.The wavepaths of Lamb wave propagation in the plate are designed for receiving the second arrival waves by a sparsely distributed sensor array.The distance from the sensor to the damage is calculated by multiplying the wave velocity by the consuming time.Then,the damage location can be determined by intersecting any two circles taking the sensor as the center and the calculated distance as the radius.Both numerical simulations and experiments of AM polylactice acid(PLA)plates are carried out to validate this method,which indicates that a through-hole damage with diameter of 1 mm can be detected with acceptable accuracy in a simple way.The results also confirm that the second arrival waves of multiple wavepaths can used to detect the damage with only three piezoelectric wafers.In addition,both the effects of the damage size and depth on the accuracy of the proposed method are studied by numerical simulations.