Study on the Shear Lag Effect

Abstract

Shear lag effect increase as we move away from the section thereafter, the effects becomes predominant especially for the unsymmetric structures. The force transmission between the structure and patch occurs through bond layer, via shear mechanism, invariably causing shear lag. In the present study, an attempt is made to correlate the average shear stress in the bond layer obtained using the Bhalla & Soh model (2004) & BSC(Bhatt Saxena Chaudhary) model. In BSC model overall deformation of the bond layer is considered. It is simplified model of the complex shear lag phenomenon as with force transmission among PZT (lead zirconate titanate) patch and host structure .PZT is one of the world’s most widely used piezoelectric ceramic materials. When fired, PZT has a perovskite crystal structure, each unit of which consists of a small tetravalent metal ion in a lattice of large divalent metal ions. PZT is used to make ultrasound transducers both for loudspeakers and microphones and other sensors and actuators, as well as high –value ceramic capacitors and FRAM chips. PZT is also used in the manufacture of ceramic resonators for reference timing in electronic circuitry. PZT has a high dielectric constant, ferroelectric, piezoelectric, & pyroelectric properties. The ideal properties of PZT have made its application to transducer, sensor and actuator devices ubiquitous. Piezoelectric ceramics, when mechanically activated with pressure or vibration, have the capacity to generate electric voltages sufficient to spark across an electrode gap. Piezoelectric energy harvester has good compression performance, fatigue resistance and waterproof performance. Piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. The word Piezoelectric is derived from the Greek piezein , which means to squeeze or press ,& piezo , which is Greek for “push”. The main advantage of BSC model is that it does not involve solving the complex differential equations. Shear stress distribution is practically independent of excitation frequency except near pressure. BSC model can be made use of for carrying out the preliminary design in structural control related problems.