Assuming a solid plate has a hairline fracture, in an unknown location and of unknown magnitude, how can we increase its presence to enable higher accuracy detection when using ultrasonic methods?
Is it related to non-linear acoustics where an excitation of a certain frequency is given to structure and it's response is studied in frequency domain? Damage is characterized by the presence of nonlinear frequencies, i.e. higher harmonics of the excitation frequency.
It depends on a number of factors. Quick points I can recall:
1) Frequency of the excitation; behavior is not predictable however it is recommended to use natural frequencies for excitation
2) Amplitude of excitation; more amplitude more non-linearity
3) Location of the output point; when measuring the response do it as close as possible to the damage.
4) Point of excitation; excite as close as possible to the damage
Basically the non-linearity is local in nature and if you measure the response far away from damage region, there won't be any non-linearity.
Hope this helps.
Thank you for your response - we're assuming that the damage is in an unknown location for the purposes of our study.
Suggestion: the generalized linear model maybe will be more simple but more natural one. Analysis of the model will be easier as nonlinear one and much more productive.
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