%0 Journal Article
%T The Effect of Perforation on the Dynamics of a Flexible Panel
%A A. Putra
%A Y. M. Cheah
%A N. Muhammad
%A A. Rivai
%A C. M. Wai
%J Advances in Acoustics and Vibration
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/526045
%X Introduction of holes into plate-like structures is commonly found as one of the practical noise control measures to reduce sound radiation. However, perforation also reduces the panel stiffness and hence increases its vibration. The discussion on this effect is lacking and hence this paper discusses the dynamics of a perforated panel from the results obtained from Finite Element (FE) model. Different hole geometries and arrangement are simulated to investigate their effect on the plate mobility. In general, it is found that increasing the perforation ratio increases the plate mobility. For a fixed perforation ratio, the mobility increases at high frequency (above 1£¿kHz) for a smaller hole density in the plate. The plate with holes concentrated at the middle shows the largest increase of vibration around the plate centre compared to those uniformly distributed or away from the middle and concentrated at the plate edges. This is because as the hole separation becomes smaller, the reduction of the global stiffness around the mid area of the plate becomes greater. This also corresponds to the finding here that the mobility is greater at the vicinity of the hole. Different conditions of the plate edges are found to give consistent trend of the effect of perforation. 1. Introduction The vibration of engineering structures, particularly those consisting of thin plate-like members, can be a significant source of noise in many situations. It is common in noise control technique to reduce the sound radiation of such structures directly by constructing them from perforates. This technique is known to be capable of reducing considerable noise radiation and has found many practical applications, including safety guard enclosures over flywheels and producing collection hoppers. However, the effect of perforation on the plate dynamics is rarely discussed, at least in terms of change in the vibration level due to perforation. The recent models [1, 2] to calculate the sound radiation from a perforated panel also ignore this effect. The investigation of the effect of perforation on dynamic properties of plates began in the early 1960s in order to determine an accurate stress analysis of perforated panels used to support the tubes in a heat exchanger [3, 4]. To obtain equivalence with the actual properties corresponding to a solid plate, the effective material properties were defined, namely, effective Young¡¯s modulus, effective Poisson¡¯s ratio, and effective density. Soler and Hill [5] later proposed an analytical formula to calculate the bending stiffness of a
%U http://www.hindawi.com/journals/aav/2014/526045/