Nonlinear ultrasonic guided waves for quantitative life prediction of structures with complex geometries

Material damage such as dislocations and microcracks are characteristic of early stages of fatigue. Accumulation of these nascent cracks leads to non-linear elastic response of the material. These non-linearities can be detected from harmonic generation for propagating elastic waves. The long term goal of this study is to investigate the non-linear elastic propagation in parts with complex geometry. Cellular Automata is introduced as a new simulation method, in order to develop new analysis on quadratic non-linearities. An existing linear code was progressively modified to take into account a different constitutive law. Also the boundary conditions need to be reviewed to ensure free stress with the non-linear behavior. The propagation of the longitudinal wave is investigated in detail. Numerical accuracy is validated from comparison with a closed, for both linear and non-linear code. The reflection of the non-linear P-wave gives confirmation for the correct treatment of the boundary condition. Finally the capabilities of the Cellular Automata code are underlined for reflection of Lamb waves for various boundary conditions.

Department dc:contributor.department

Mechanical Engineering

Grantor dc:publisher

Georgia Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Autrusson, Thibaut Bernard

Advisors dc:contributor.advisor

• Leamy, Michael J.
• Sabra, Karim G.

Committee member dc:contributor.committeemember

• Laurence Jacobs

• Accuracy
• Cellular Automata
• Numerical code
• Lamb wave

Handle dc:identifier.uri

http://hdl.handle.net/1853/37103

OAI identifier oai:identifier

oai:repository.gatech.edu:1853/37103