Dynamic stress intensity factors for ultrasonic fatigue test specimens

• Published in: Computers & structures Vol. 23; no. 6; pp. 795 - 806
• Main Authors: Blom, A.F., Glemberg, R.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1986; Elsevier Science
• Subjects: Exact sciences and technology; Fundamental areas of phenomenology (including applications); Measurement and testing methods; Physics; Solid mechanics; Structural and continuum mechanics; Fatigue test; Stress intensity factor; Crack; Ultrasonic method; Crack propagation
• ISSN: 0045-7949; 1879-2243
• DOI: 10.1016/0045-7949(86)90248-8

Ultrasonic fatigue test methods are increasingly being used to study crack growth and threshold behaviour of metallic materials. In such studies a particular problem is the accurate determination of the dynamic stress intensity factor range, ΔK. A direct time integration finite element analysis of a center cracked specimen tested at its lowest natural frequency is presented. The effects of opening and closing of the crack tip when the test specimen is subjected to a fully reversed load cycle, i.e. zero mean load, is investigated. Numerical results correlate well with experimental data. It is shown that old published data are in error with up to at least 20% due to insufficient evaluation of dynamic stress intensity factors.