National Aerospace Laboratories

About: National Aerospace Laboratories is a facility organization based out in Bengaluru, India. It is known for research contribution in the topics: Coating & Corrosion. The organization has 1838 authors who have published 2349 publications receiving 36888 citations.

A Comprehensive Analysis on the Structural-Acoustic Aspects of Various Functionally Graded Plates

Abstract: The vibration, sound radiation and transmission characteristics of plates with various functionally graded materials (FGM) are explored and a detailed investigation is presented on the influence of specific material properties on structural–acoustic behavior. An improved model based on a simplified first order shear deformation theory along with a near-field elemental radiator approach is used to predict the radiated acoustic field associated with a given vibration and acoustic excitation. Various ceramic materials suitable for engineering applications are considered with aluminum as the base metal. A power law is used for the volume fraction distribution of the two constitutive materials and the effective modulus is obtained using the Mori–Tanaka homogenization scheme. The structural–acoustic response of these FGM plates is presented in terms of the plate velocity, radiated sound power, sound radiation efficiency for point and uniformly distributed load cases. Increase in both vibration and acoustic response with increase in power law index is observed for the lower order modes. The vibro–acoustic metrics such as root-mean-squared plate velocity, overall sound power, frequency averaged radiation efficiency and transmission loss, are used to rank these materials for vibro–acoustically efficient combination. Detailed analysis has been made on the factors influencing the structural–acoustic behavior of various FGM plates and relative ranking of particular ceramic/metal combinations.

Bending behavior of piezo-hygrothermo-elastic smart laminated composite flat and curved plates with active control

Abstract: The actuation and sensing behavior of piezo-hygrothermo-elastic flat and curved plates with active control is presented. A finite element procedure involving coupled piezoelectric field with hygrothermal strain is derived using first order shear deformation theory and is implemented in a nine-noded Lagrangian plate element. The accuracy of the element to model the piezoelectric, pyroelectric, hygroelastic, and thermoelastic behaviors of flat and doubly curved plates is validated with standard benchmark problems. The directional actuation that represents the piezoelectric anisotropy is introduced in the analysis and a comparison is made with isotropic actuation to control the thermal and moisture induced deformation in the laminated plates. Numerical studies are carried out with different fiber orientations to capture the influence of piezoelectric anisotropy on the actuation and sensing characteristics of the active lamina. The directionally actuated piezoelectric lamina that has a reduced piezoelectric capability in transverse direction is efficient, if properly tailored along the fiber directions. However, it is observed that the isotropic actuation has the potential to control the thermal and moisture developed deflection in angle-ply and cross-ply laminates. The actuator lamina is efficient if placed on the top of curved laminates in controlling the deflection.