Circuit-field coupled finite element analysis method for an electromagnetic acoustic transducer unde

来源 :Chinese Physics B | 被引量 : 0次 | 上传用户:shinobu1314
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
This paper presents an analytical method for electromagnetic acoustic transducers (EMATs) under voltage excitation and considers the non-uniform distribution of the biased magnetic field. A complete model of EMATs including the non-uniform biased magnetic field, a pulsed eddy current field and the acoustic field is built up. The pulsed voltage excitation is transformed to the frequency domain by fast Fourier transformation (FFT). In terms of the time harmonic field equations of the EMAT system, the impedances of the coils under different frequencies are calculated according to the circuit-field coupling method and Poynting’s theorem. Then the currents under different frequencies are calculated according to Ohm’s law and the pulsed current excitation is obtained by inverse fast Fourier transformation (IFFT). Lastly, the sequentially coupled finite element method (FEM) is used to calculate the Lorentz force in the EMATs under the current excitation. An actual EMAT with a two-layer two-bundle printed circuit board (PCB) coil, a rectangular permanent magnet and an aluminium specimen is analysed. The coil impedances and the pulsed current are calculated and compared with the experimental results. Their agreement verified the validity of the proposed method. Further- more, the influences of lift-off distances and the non-uniform static magnetic field on the Lorentz force under pulsed voltage excitation are studied. This paper presents an analytical method for electromagnetic acoustic transducers (EMATs) under voltage excitation and considers the non-uniform distribution of the biased magnetic field. A complete model of EMATs including the non-uniform biased magnetic field, a pulsed eddy current field and the The acoustic field is built up. The pulsed voltage excitation is transformed to the frequency domain by fast Fourier transformation (FFT). In terms of the time harmonic field equations of the EMAT system, the impedances of the coils under different frequencies are calculated according to the Then the currents under different frequencies are calculated according to Ohm’s law and the pulsed current excitation is obtained by inverse fast Fourier transformation (IFFT). Lastly, the sequentially coupled finite element method (FEM) is used to calculate the Lorentz force in the EMATs under the current excitation. An actual EMAT with a two-layer two-bu The coil impedances and the pulsed current are calculated and compared with the experimental results. Their agreement verified the validity of the proposed method. Further- more, the influences of lift-off distances and the non-uniform static magnetic field on the Lorentz force under pulsed voltage excitation are studied.
其他文献
近年来,国内外均对常见的婴幼儿秋季腹泻患儿进行病原体研究。也报导了婴儿腹泻主要病原体是人类轮状病毒(HRV)。我院于1986年5月至1987年4月一年内首次在柳州市对腹泻患儿5
急行跳远不仅需要很好的弹跳力、速度、灵敏柔韧性,而且还要有象短跑运动员那样合理的跑的技术。 要想在35—40米内发挥较高的水平速度,而且要准确的踏在起跳板上,这就要求
赤塔是赤塔州的首府,距离莫斯科6074公里。位于赤塔河与国戈达河的交汇处。气候为典型的大陆性气候,冬季平均气温为-27℃、夏季平均气温为18℃、年降水量为324毫米。西伯利亚大铁路通过该市
对我国男子体操队参加6次世界大赛的成绩和我国七运会决赛的情况,与苏联、德国、日本等体操强国进行了比较,分析了我国男子自由体操的现状、实力水平,并对6个单项与团体成绩的关
以浦东开发开放为龙头,进而推动长江经济带的开发开放,是我国实施第三步战略目标的一项重要措施。十年来,浦东开发开放的效应逐步向长江流域辐射,对中西部地区的经济发展产生了重
虽说夫妻本是同欢鸟,但也偶有争吵。前些天为购物,和老公在专卖店争论起来。不许我买那身有点夸张的衣服,而我,本性有点倔,越不让买,越要买。我知道,老公不是不许我买,只是他不想因我不听婆婆话而引家庭战争。  好几次,都因我喜欢时新东西而惹得婆婆唠叨半天。不是在她儿子面前尽说我不是,就是责备她儿子也不管管,任由我被那些时新货给宠坏。生性耿直的老公,每听一回婆婆唠叨,就会不分青红皂白地在房间里对我吼起来,
圣旨,作为古代帝王权力的展示和象征,无论措辞还是格式,都是严肃而生硬的。可是,在如此严谨的“红头文件”中,偏偏出现了一个另类:这道特殊的圣旨有着谜一样的外表,背后却隐
几年来的教学实践使我们深刻地体会到:教学效果的好与坏,除了取决于教师的理论知识、技术、技能水平和课堂的教学组织能力外,在很大程度上也取决于有效的教学方法。教学中只
大部分人和我一样,没有一个有钱的爸爸,因此在大学毕业之后,需要自己去找一份工作,首先是要能够养活自己。因为母亲的关系,大学毕业之后,我放弃了在外资公司的工作,到深圳母
我科于1986年10月至1987年3月,试用国际腹泻病研究中心推广的米粉——口服补液盐(Rice—ORS)治疗小儿肠炎伴脱水50例。总结如下。临床资料观察对象均为急性肠炎(?)轻或中皮