Modelling of piezo-structure elastodynamic interaction through bond layer for electro-mechanical impedance technique

As impedance tsansduccrs・tbc piczoelccu'ic ceramic(I、71)patches have eillei各ed as stiて)l1 C candidates for sti・uctural health flX)flitOi・ing(SlIM)of sti・し ictures in the recent \eals becaし Ise o1" their siia11 size and shape. eost-et"(し cliveness and ease of installation. 、 t、he research I bi・struct tarai identifleation and long-terni monitoring lias recently beconie an area of interest fbr a large numb ei・of academie and coniniet・eiai iahoi・atoi・jes.『 l'he associated techniques aim to enable struetut・es and equipment nionitot・theii・O\\n structural integrit》・ while in opei・ation. and shall be useful not only to impro×・ei・eiiabiiity, bしtt also to reduce maintenance and inspection costs・ This thesis is focused on the eleetro-mechanical impedance (FMI) technique Ihr SUM. ibe basic principle behind this technique is to use high frequencies (typically >50 kI-Iz) generated h》 surface-bonded PZT patch to detect changes in structural drive point inipedance caし I SCしI h\ internal! surface cracks. loose connections. delaminations or any other type of damage. Ube resultant electi・o-mechanieal intei・action. which is characteristic of the pai・ticし ilat・ st i・し ici ure. modulates the current flowing through the PZT patch. The modulation is a function of the mechanical interaction between the P/、U patch and the struetしire ovet・the considered t1'eqし ielicy range. The resし titani admittance signalし ire. \\liicii acts like a li・equency i・espouse function(ト R F). is used to detect changes or damages occしIl・1・ing in the host sti‘しicture. 『 1'he bond layer between ilie P/,I patch and host sii・し icture plays a signi Iicant iole in Pt Istructure interaction in the ENlI teciiniqし te. Fo Lindel・stand the neclianisiil of lbi・ce ti・aulstし1・ through the adhesive mediuii (which intl・oduce shear lag cfiセet) more precisely. ×aniotas niodcls have been proposed by i・esearchei・s iii ilie past. Some of those are based on static. dynamic. e眠eti×・e and simplitied interaction thi・。 しigh the bond layer. Ho'vever. these models still lack r lLO Ill・ifl tet・11-ts()r considei・ing all govet・ning paraliletel・s, especiall》・ both sheat・and mnet・tia tertils s'il-tし I llaneoし tsk. し j ild Cl・siandmng sheat・fllechanmsm phenonlena of the adhesive layer is vital for eflilailceぐI al)plicahilit》・ of the EMI technic1しte. I l-te main objeclive of this i・eseai・C h\\o i・k is to model the shea」・ lag phenonlena (between PZT patch and host sti・ucture) ana1vlicall》. achieving moi・e accurate model. The previous analytica' models have ignored the inertia term. which has been rigorously integrated in this research to ai.i・i\ C at l flC'\ i・el-tiled sheat・lag nlodel. l'be I1C\' model eonsidei・s both shear lag and inertia C f. 1しcts sililullaneoしisIv. The predictions of the new illodel are mしich better match 'vith expet・iillental obser×・alions as compai・ecl to the pt・evious models. Vai・ioしis pai・ameiric studies have also been cat・1・ied oしtt to stし idy the influence of the piezo and the structural properties on the adlilittance si. nlatし ti・es. -I he I・eseai・ch is liti・thet・extended by considering the mllet・tia eflbct of the adhesive mass (so 魚r neglected) in addition to that of the PTT patch. A continuum based admittance approach has been lt)t・illし tlaied \' het・e the 、“ equi\ aleilt and cliとctive itl1pedanc&' tet・Fns are replaced by CO ilt Iflし tutu d isplaceilient tci・ill de×・eloped at intet・ltcial adhesive hond. This model considers the hC)tld laきじ t. " s cOililcct ion het'veetl the patch and sit・netし tt・e thi・。 しtgllout the sensot・length, unlike the p i・C\ iOUs ilk)ぐlels \×hich \'C1・el・esti・icted to boundat・}・ intet・actions. Pai・a me t i・ie stしidies have 1c i lo\ \じし I lo sし Ip1)ort tile sustainahilit》・ and sし titahi lit' o t' proposed continuunl approach. Finally, t(_) ctlhaticc tile efliciencv of the proposed model in real ii比 application on Sl-IM and active co Ilti・oJ systetli ti-te study ofelectrical power consumption and energy e伍ciency has been carried oし tt. \Lri()し Is enei・g》 conversion ei石ciency ratios have been obtained by e'・aluating the total enel・() }しtsed loi・Illechallical I・esponse to the total enei・gy supplied. in overall, the study shows Sigilili cant intlしtence of the bond la)・et・On energy efliciencう・. A Illodified electro-mechanical