Non-linear Lamb wave mixing method for measuring stress distribution in metal sheet

Abstract

The invention relates to a non-linear Lamb wave method for measuring stress distribution in a metal sheet, and discloses a stress distribution detection method based on the non-linear Lamb wave mixingtechnology. The stress distribution detection method is suitable for stress distribution detection and positioning of a stress concentration area in plate structures, and belongs to the field of non-destructive detection. The non-linear Lamb wave method comprises the steps that firstly excitation frequencies of two fundamental frequency waves are determined according to a measured object and thenon-linear Lamb wave mixing resonance conditions; two rows of A0 mode waves are excited in opposite directions at the left end and the right end of the specimen, and a sum-frequency S0 signal is received at a certain position between the excitation signals to detect the non-linear mixing stress of the plate structure; by changing the excitation delay of the excitation signals, different positionsof the specimen are swept and checked in mixing, and the amplitude of the mixing wave is extracted; and finally, according to the change rule of sum-frequency difference signal amplitude with mixing position, the stress distribution of the metal plate can be detected, and the stress concentration area can be positioned.

Description

technical field [0001] The invention relates to a non-linear Lamb wave mixing detection method for stress distribution of a plate structure, which is suitable for stress distribution detection and location of a stress concentration area in a plate structure, and belongs to the field of non-destructive testing. Background technique [0002] As a common structural form, metal plate structures are widely used in various major infrastructures due to their good formability and weldability, such as ship shells, aircraft fuselages and hatches, and large oil storage tank shells. wait. Under the joint action of static force and cyclic load, internal medium and external working environment during use, metal components are prone to stress concentration at sudden changes and rigidly constrained parts, and evolve into fatigue cracks or fractures, resulting in failure of structural components. resulting in catastrophic accidents. Therefore, in order to eliminate potential safety hazards...

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Problems solved by technology

However, the research on stress detection using nonlinear ultrasonic mixing technology in domestic and foreign literature is still in the exploratory stage.

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