Accession Number : AD0721729

Title :   The Use of High Power Ultrasonics (Macrosonics) in Studying Fatigue in Metals.

Descriptive Note : Technical rept.,

Corporate Author : GEORGE WASHINGTON UNIV WASHINGTON D C INST FOR THE STUDY OF FATIGUE FRACTURE AND STRUCTURAL RELIABILITY

Personal Author(s) : Mason,Warren P. ; MacDonald,Douglas E.

Report Date : MAR 1971

Pagination or Media Count : 22

Abstract : High power ultrasonics has been a useful tool in studying fatigue in metals since a large number of cycles can be obtained in a small time. In the case of brass and iron the mechanisms appear to be different since at the high frequencies fatigue occurs in isolated regions whereas at the low frequencies the slip is generally spread over the grains. The same mechanism can be produced at high frequencies by going to higher temperatures. In iron the stress required for fatigue at higher frequencies is considerably less than for low frequencies. Recent measurements in titanium have shown that the required stress is about the same for high and low frequencies. The crack propagation velocity, however, is much faster at the ultrasonic frequencies. This was proved by striation measurements with a scanning electron microscope. Thus, the high frequency fracture is not only localized, it is virtually catastropic in the localized area. (Author)

Descriptors :   (*METALS, FATIGUE(MECHANICS)), (*FATIGUE(MECHANICS), ULTRASONIC RADIATION), IRON, BRASS, TITANIUM, GRAIN BOUNDARIES, SOUND GENERATORS, FRACTURE(MECHANICS)

Subject Categories : Metallurgy and Metallography
      Test Facilities, Equipment and Methods

Distribution Statement : APPROVED FOR PUBLIC RELEASE