Publisher: Trans Tech Publications
E-ISSN: 1662-8985|2017|1142|371-377
ISSN: 1022-6680
Source: Advanced Materials Research, Vol.2017, Iss.1142, 2017-02, pp. : 371-377
Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.
Abstract
Perturbation method is used to resolve one-dimensional wave equation under the assumption of small strain conditions. The relationship of the second order relative nonlinear coefficients (SORNC) β', the third order relative nonlinear coefficient (TORNC) δ' as the functions of fundamental and harmonic amplitudes is determined. The specimens are loaded from-200 MPa to 320 MPa at increments of 40 MPa by the electron universal testing machines. The SORNC β' and TORNC δ' are detected by the nonlinear ultrasonic testing system when ultrasonic waves propagate in the specimens. Results show that the relative nonlinear coefficients increase with the stress. The SORNT β' is approximately linear with the stress when stress is lower than 84.6% of the yield strength. The TORNC δ' is approximately linear with the stress when stress is lower than 76.9% of the yield strength.