Scattering Of SH-type Guided Waves By A Band Piezoelectric Domain With Circular Inclusions And Semi-circular Depressions

Intelligent materials integrate driving and sensing functions.When they are applied to engineering structures,it will also have intelligent functions such as self-perception,self-repair and self-adaptation.As a kind of intelligent materials,piezoelectric materials are widely used in structural damage in civil engineering,sensors in local detection and intelligent dampers in shock absorption due to unique coupling effect of mechanical and electric field deformation and the realization of machine-electric conversion.The rise of intelligent materials provides technical support and new ideas for structural health monitoring in civil engineering.Single layer plate,multi-layer family core composite plate or sandwich beam made of piezoelectric materials will be damaged in the process of using.The scattering of elastic waves plays a great role in functional analysis of piezoelectric plates.SH-type guided waves are used in the theoretical model of band-shaped piezoelectric materials as a class of elastic waves,providing a theoretical basis for the non-destructive testing direction of piezoelectric elements in civil engineering.The research contents and conclusions of this article are as follows:Based on linear piezoelectric theory,the problems of circular inclusions and single semicircular depressions in the zonal piezoelectric domain are studied.When the inclusion and sag interact,the influence of a single semicircular sag on stressing concentration around circular inclusion is analyzed.The complex function method,multipolar coordinate method and mirror image accumulation principle are applied to solve the stress free and electrical insulation conditions at the boundary of belt shape domain.Based on continuity conditions of electric field and displacement field at the boundary with circular inclusions and a single semi-circular depression,an infinite linear equations are established;Truncating finite terms in system of equations is used to solve unknown coefficients in the scattered wave;In a specific example,the change of dynamic stress concentration factor and electric field intensity concentration factor of circular inclusion edge with relevant physical parameters is analyzed.Calculation examples show that: when the force-electricity coupling interaction,the electric field is more effective than the force field;The position of defect has a negligible effect on piezoelectric element.The stress concentration phenomenon is more obvious when the defect is directly above the inclusion;The relative media density of inner and outer sides in inclusions cannot be underestimated for analyzing stress which changes on circumference of inclusions.Researching on circular inclusions and multiple semi-circular depressions in a strip-shaped piezoelectric medium,the change of stress distribution map around circular inclusions under the action of multiple semicircular depressions is analyzed.Due to the existence of complex boundaries,the construction of scattered guided waves will also become more difficult.The more complicated the upper and lower boundary defects become,the more valuable for engineering research will be.Using the conditions of continuity about force field and electric field with circular inclusions and multiple semi-circular depression boundaries,an infinite linear equations system and interception of finite terms are established to further solve the unknown coefficients of scattered waves.The results of calculation examples show that the position of depressions on the upper and lower boundaries of the band domain,the frequency and order of SH-type guided waves,and piezoelectric parameters all have a great effect on the stress concentration on circumference of inclusion.The combination of multiple defect forms has more practical significance for the actual destruction with strip-shaped piezoelectric elements in engineering.According to the change law of stress concentration coefficient,the valuable conclusions in the project are summarized,so as to effectively reduce the damage of piezoelectric element.In this paper,the anti-plane dynamics of SH-type guided wave scattering in the band piezoelectric domain with circular inclusions and semicircle depressions is studied,which provides an important research direction for the application of SH-type guided wave to the reliability evaluation of seismic engineering structures and the health diagnosis of building structures,and also has a profound significance for the expansion of SH-type guided wave to non-destructive testing.