کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8129829 | 1523179 | 2018 | 26 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Nonlinear effects of micro-cracks on long-wavelength symmetric Lamb waves
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کلمات کلیدی
Non-destructive evaluation - ارزیابی غیر مخربLamb waves - امواج لامPerturbation theory - تئوری اختلالHertzian contact - تماس هرتزیانeffective material properties - خواص مؤثر موادNonlinear ultrasound - سونوگرافی غیرخطیPenny-shaped cracks - شکاف پنی شکلMicro-cracks - میکرو تراکمHarmonic generation - نسل هارمونیکFEM - پنج
موضوعات مرتبط
مهندسی و علوم پایه
فیزیک و نجوم
آکوستیک و فرا صوت
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
For an elastic medium containing a homogeneous distribution of micro-cracks, an effective one-dimensional stress-strain relation has been determined with finite element simulations. In addition to flat micro-cracks, voids were considered that contain a Hertzian contact, which represents an example for micro-cracks with internal structure. The orientation of both types of micro-cracks was fully aligned or, for flat micro-cracks, totally random. For micro-cracks with Hertzian contacts, the case of random orientation was treated in an approximate way. The two types of defects were found to give rise to different degrees of non-analytic behavior of the effective stress-strain relation, which governs the nonlinear propagation of symmetric (S0) Lamb waves in the long-wavelength limit. The presence of flat micro-cracks causes even harmonics to grow linearly with propagation distance with amplitudes proportional to the amplitude of the fundamental wave, and gives rise to a static strain. The presence of the second type of defects leads to a linear growth of all harmonics with amplitudes proportional to the power 3/2 of the fundamental amplitude, and to a strain-dependent velocity shift. Simple expressions are given for the growth rates of higher harmonics of S0 Lamb waves in terms of the parameters occurring in the effective stress-strain relation. They have partly been determined quantitatively with the help of the FEM results for different micro-crack concentrations.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Ultrasonics - Volume 90, November 2018, Pages 98-108
Journal: Ultrasonics - Volume 90, November 2018, Pages 98-108
نویسندگان
Marek Rjelka, Bernd Köhler, Andreas Mayer,