Air-coupled ultrasonic plane stress detection method for composite material based on dual-modal sound-time ratios of lamb wave

An air-coupled ultrasonic plane stress detection method for a composite material based on dual-modal sound-time ratios of a Lamb wave, comprising the following steps:

• S1:
• configuring a detection device to emit a signal to a detection point of the composite material in the form of the Lamb wave;
• S2:
• receiving a reflected signal by the detection device;
• measuring unidirectionally loaded stress;
• based on the reflected signal and the dual-modal sound-time ratios of the Lamb wave in S1, and using unidirectionally loaded stress to obtain different stress coefficient relations;
• S3:
• based on the stress coefficient relations in S2, solving stress coefficients;
• S4:
• based on the stress coefficients in S3, acquiring three sound-time ratios;
• S5:
• based on the three sound-time ratios in S4, describing a stress state of the detection point;
• and
• S6:
• repeating S4 and S5 till completing detection and scanning of all points.