Nondestructive testing method for residual stress of sample surface

Abstract

The invention provides an ultrasonic surface wave velocity measurement system, which comprises an ultrasonic testing device connected with a control device and an oscilloscope separately, wherein the ultrasonic testing device is used for providing a focused transducer of which a probe is vertically downward with electricity, receiving a signal of the ultrasonic probe of the focused transducer and transmitting the signal to the oscilloscope; a sample cell is also arranged at the lower part of the focused transducer; the sample cell containing a liquid; the ultrasonic probe of the focused transducer is immersed into the liquid; and a drive mechanism is fixed on the sample cell and connected with the focused transducer. Only the ultrasonic surface wave velocity of an area of propagating an ultrasonic surface wave, namely the area opposite to the focused transducer is measured, and the propagation distance of the excited ultrasonic surface wave in the material is very small, so that detection of the residual stress of a local area is achieved; and the surface wave is excited by adopting the noncontact focused transducer, so that the residual stress of the surface of a curve structure can be measured, thereby achieving measurement of the residual stress of the curve structure.

Description

technical field [0001] The invention relates to a detection method of residual stress, in particular to a non-destructive detection method of surface residual stress. Background technique [0002] Residual stress is the stress that exists inside the object in an equilibrium state under the action of external force, and is sometimes called internal stress or locking stress. Changes in ambient temperature or mechanical processes such as rolling, forging, welding, etc. cause local plastic deformation of the material, resulting in residual stress. [0003] In industrial production, the process performance and service life of metal parts are often closely related to the residual stress inside the metal material. During the service process of the component, due to the superposition of residual stress and external load, the component will produce secondary deformation. This local uneven elastic-plastic deformation will change the material lattice, resulting in the redistribution o...

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Problems solved by technology

[0008] However, this method has certain limitations: (1) This method mostly uses the "one send, one receive" or "one send, two receive" type, and the measured results are often the average value in the acoustic channel, which makes it difficult to measure local areas (2) This method is a contact measurement method, which can only be applied to the measurement of plane surface residual stress, but for a wide variety of metal components, especially for complex structures or curved surface components such as aeroengine blades, It is difficult to obtain qualitative and quantitative results by applying traditional residual stress detection methods

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