Hanuman N S V N, Roy Subhankar, Bose Tanmoy
Department of Mechanical Engineering, National Institute of Technology Meghalaya, Shillong 793003, India.
Department of Mechanical Engineering, National Institute of Technology Meghalaya, Shillong 793003, India.
Ultrasonics. 2020 Aug;106:106138. doi: 10.1016/j.ultras.2020.106138. Epub 2020 Mar 23.
In this paper, an analytical framework is presented to understand the generation of different intermodulation frequencies under dual excitation which is also verified with experiments. One single periodic frequency (SPF) excitation along with one variable frequency excitation, varying from local defect resonance (LDR) frequency and its superharmonics to subharmonic, are used. The flexural wave propagation in an orthotropic composite plate containing a delamination is analytically derived considering quadratic nonlinearity. Both analytical and experimental results are presented for glass fibre reinforced plastic (GFRP) plates with single and double delaminations. Two different types of intermodulation peaks are observed, that is local defect resonance intermodulation (LDRI) and single periodic frequency intermodulation (SPFI), out of which SPFI is found to be generated only during superharmonics and subharmonic excitation. At LDR frequency excitation, only its higher harmonics are found and no SPFI peaks are observed. The acoustic nonlinearity parameters are found increase with order of harmonics and delamination diameter.
