Method for controlling three-dimensional deep-buried crack size in brittle material by ultrasonic excitation

Abstract

The invention provides a method for controlling three-dimensional deep-buried crack size in a brittle material by ultrasonic excitation, a three-dimensional deep-buried crack is prefabricated in a transparent brittle material, an ultrasonic excitation gun is placed on the surface of the transparent brittle material, an ultrasonic wave is generated by an ultrasonic generator, the ultrasonic wave passes through the surface of the material to transfer into the interior of the material, and penetrates the entire body of the material, when the ultrasonic wave pass through the crack, medium transition occurs at the crack and at both sides, mechanical vibration at the crack is different from that of the surrounding, mechanical turbulence of the crack is caused, the mechanical vibration of the ultrasonic wave is transformed into mechanical energy at the crack, the mechanical vibration effect of the tip of the crack expands and cracks the crack until the size of the crack is cracked to meet requirements, and ultrasonic wave input is stopped. The method is simple, reasonable, rapid, efficient, simple in operation, accurate in control and economical in use, and the characteristics of the rack is consistent with that of the natural brittle material.

Description

technical field [0001] The invention belongs to the field of fracture mechanics research and engineering safety prediction and evaluation of brittle solids (such as metal, rock, concrete, ceramics), and relates to a method for controlling the size of three-dimensional deep-buried cracks inside brittle materials by ultrasonic excitation, which can be specially applied to engineering fracture mechanics In the field, materials containing cracks inside are used to study the disasters caused by various natural environments. Such as: low-stress brittle fracture of steel caused by internal crack expansion, which in turn leads to explosion of cutting-edge aerospace and national defense products; severe fracture of internal cracks in deep rocks under the extrusion of plates and shells causes earthquakes and tunnel accidents; internal crack expansion of metal and concrete Cause accidents such as project collapse and bridge damage; internal defects and cracks cause great damage. The old ...

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Problems solved by technology

However, there are many deficiencies in the pouring method as follows: 1) Insufficient simulation process: the crack making process is complicated and time-consuming, and the manufacturing process includes mold making, prefabricated crack making, mixed liquid making, and repeated baking and freezing of the solidified test piece. , high cost and low efficiency; 2) Insufficient brittleness: the brittleness of the transparent brittle material prepared by pouring method can only reach about 1 / 7-1 / 8 at low temperature, while the brittleness of rock is above 1 / 10, Sometimes it is as high as 1 / 20; 3) Insufficient test conditions: the pouring method needs a low temperature environment to be realized, and the test conditions are demanding; 4) Insufficient cracks: the pouring method uses metal sheets or mica sheets as prefabricated cracks, which are not really cracks without thickness, simulation Insufficient; 5) Insufficient transparency

Adams M and other papers (Crack extension from flaws in arittle material subjected to compression.) etc. use this method to make three-dimensional internal closed cracks, but the cutting-paste method has the following disadvantages: 1) "grooves" are used to represent cracks, which are different from real cracks 2) Insufficient integrity of the test piece: the sample is bonded by glue and is no longer a complete object

However, the realization of glass 3D printing did not have a substantial breakthrough until 2017, and it was published in the world's top journal "Nature" (2017, volume 44, doi:10.1038 / nature22061). For the use of 3D printing technology to make internal three-dimensional cracks, now This technology has not yet been implemented

At the same time, the 3D printing method has the following disadvantages: 1) 3D printing technology needs to heat the quartz sand to 1600-1800°C to melt, which requires high equipment, complicated technology and operation; 2) 3D printing of brittle materials has low uniformity and transparency

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