کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
798049 1467096 2012 23 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Acoustic radiation force in tissue-like solids due to modulated sound field
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی مکانیک
پیش نمایش صفحه اول مقاله
Acoustic radiation force in tissue-like solids due to modulated sound field
چکیده انگلیسی

The focus of this study is the sustained body force (the so-called acoustic radiation force) in homogeneous tissue-like solids generated by an elevated-intensity, focused ultrasound field (Machnumber=O(10−3Machnumber=O(10−3)) in situations when the latter is modulated by a low-frequency signal. This intermediate-asymptotics problem, which bears relevance to a number of emerging biomedical applications, is characterized by a number of small (but non-vanishing) parameters including the Mach number, the ratio between the modulation and ultrasound frequency, the ratio of the shear to bulk modulus, and the dimensionless attenuation coefficient. On approximating the response of soft tissues as that of a nonlinear viscoelastic solid with heat conduction, the featured second-order problem is tackled via a scaling paradigm wherein the transverse coordinates are scaled by the width of the focal region, while the axial and temporal coordinate are each split into a “fast” and “slow” component with the twin aim of: (i) canceling the linear terms from the field equations governing the propagation of elevated-intensity ultrasound, and (ii) accounting for the effect of ultrasound modulation. In the context of the focused ultrasound analyses, the key feature of the proposed study revolves around the dual-time-scale treatment of the temporal variable, which allows one to parse out the contribution of ultrasound and its modulation in the nonlinear solution. In this way the acoustic radiation force (ARF), giving rise to the mean tissue motion, is exacted by computing the “fast” time average of the germane field equations. A comparison with the existing theory reveals a number of key features that are brought to light by the new formulation, including the contributions to the ARF of ultrasound modulation and thermal expansion, as well as the precise role of constitutive nonlinearities in generating the sustained body force in tissue-like solids by a focused ultrasound beam.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of the Mechanics and Physics of Solids - Volume 60, Issue 10, October 2012, Pages 1791–1813
نویسندگان
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