Accession Number : ADD000730

Title :   Crack Detection Apparatus and Method.

Descriptive Note : Patent,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON D C

Personal Author(s) : Sessler,John G ; Weiss,Volker

Report Date : 25 Feb 1975

Pagination or Media Count : 5

Abstract : The patent describes an apparatus and method for non-destructively detecting the presence and the location of crack in materials, using low frequency mechanical vibrations. The material specimen or structure having a crack to be detected is subjected to tensile or compressive forces due to excitation caused by low frequency sound waves or mechanical vibrations from a generator, thus changing the opening and thereby changing the effective size of the crack in the specimen. An ultrasonic search unit is used to follow modulations of reflected energy at the crack interface due to variations of the effective size of the crack. The search unit is controlled by an ultrasonic pulser-receiver which displays the amplitude of echo from the crack on an oscilloscope.

Descriptors :   *Ultrasonic tests, *Ultrasonic inspection, *Nondestructive testing, *Patents, Cracks, Detection, Pulse generators

Subject Categories : Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE