Structural-acoustic modal analysis of cylindrical shells: application to MRI scanner systems
Structural-acoustic modal analysis of cylindrical shells: application to MRI scanner systems
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DOI：
10.1007/s10334-009-0185-z
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发表时间：
2009-12-01
影响因子：
2.3
通讯作者：
Mechefske, Chris K.
中科院分区：
文献类型：
--
作者：
Li, Gemin;Mechefske, Chris K.
磁共振成像 (MRI) 扫描仪孔中的声学噪声主要是由梯度线圈的振动引起的。扫描仪孔中的声学模式与线圈结构中的结构模式之间的相互作用导致结构声耦合。为了实现安静的MRI设计，需要充分研究MRI机器中的结构声学耦合机制。首先利用Love的经典壳理论实现结构分析。 “虚拟封闭腔”的概念被用于梯度线圈管道的声学模态分析。色散曲线和每个频带的模式数量用于揭示结构模式和声学模式的模态分布特性。通过结构波和声波的色散图的叠加来识别结构-声耦合模式。结构分析和声学分析分别进行了实验验证。在各种边界条件下计算了高达 3000Hz 的独立结构模态和声学模态及其分布模式。使用本文提出的分析程序清楚地揭示了耦合模式，并且发现与实验测量中确定的耦合模式一致。这些方法对于 MRI 扫描仪系统的耦合和非耦合模态分析是有效的，并且可用于安静 MRI 设计或现有 MRI 系统的吸声器设计。
The acoustic noise in a magnetic resonance imaging (MRI) scanner bore is mainly introduced by the vibration of gradient coils. The interaction between acoustic modes in the scanner bore and structure modes in the coil structure leads to structural-acoustic coupling. In order to implement quiet MRI design, the structural-acoustic coupling mechanism in MRI machines needs to be fully investigated.Structural analysis was first implemented using Love's classical shell theory. The concept of a "virtually closed cavity" was used in the acoustic modal analysis of the gradient coil duct. The dispersion curves and the number of modes per frequency band were used to reveal modal distribution properties for both structural modes and acoustic modes. Structural-acoustic coupling modes were identified by superposition of the dispersion diagrams of the structural waves and acoustic waves. Experimental validation was implemented separately for the structural analysis and acoustic analysis.Independent structural modes and acoustic modes and their distribution patterns were calculated up to 3000Hz with various boundary conditions. Coupling modes were clearly revealed using the analysis procedures presented in this paper and were found to be in agreement with the ones identified from experimental measurements.These methods are effective for coupled and uncoupled modal analysis of MRI scanner systems and can be used for quiet MRI design or sound absorber design for existing MRI systems.