报告题目:
Time-domain measurement technique of second harmonic of ultrasonic Lamb waves using mismatch of group velocities
作者:邓明晰

    摘要:Taking into account the fact that there is an inevitable influence of the transmitting and receiving transducers on the time-domain second-harmonic signal of the ultrasonic Lamb waves, a time-domain measurement technique of second harmonic has been proposed using mismatch of group velocities between the fundamental and double frequency Lamb waves. When there is a phase velocity matching but group velocity mismatching between the fundamental and double frequency Lamb waves, the second-harmonic signal of the ultrasonic Lamb wave propagation can be separated in the time domain from that generated by the wedge transducers used for generating and receiving the ultrasonic Lamb waves. The present technique uses the integrated amplitude of the time-domain second-harmonic signal that is only produced by the fundamental Lamb wave propagation to quantify the efficiency of the second-harmonic generation. The measurement procedure of the time-domain second harmonic has been demonstrated by an experiment where a fundamental Lamb wave propagates in an aluminum sheet. It is known that, through the measurement technique proposed in this paper, the condition for measurements of the second harmonic of the ultrasonic Lamb waves can be relaxed, and the influences of the wedge transducers on the second harmonic can be deducted completely. The second-harmonic signal measured by the present technique is completely due to the effect of second-harmonic generation of the time-domain signal of the fundamental Lamb waves.                                         

作者简历:
    邓明晰,后勤工程学院教授,中国声学学会常务理事,国家自然科学基金委员会第12、13届学科评审组成员,教育部新世纪优秀人才,教育部近代声学重点实验室(南京大学)学术委员,重庆声学学会副理事长,重庆高校“巴渝学者”特聘教授,享受政府特殊津贴。近年来主持国家自然科学基金课题6项;在科学出版社出版学术专著1部;发表学术论文百余篇,其中被SCI收录38篇、被EI收录76篇;1篇论文荣获《声学学报》年度最佳优秀论文奖,以及第五届中国科协期刊优秀学术论文奖。