Stability Performance of Perforated Stiffened Laminated Composite Plates Under the Influence of Environmental and Operational Loading Conditions Using FE Approach

Abstract

Eccentrically stiffened plates are widely used as a structural component in many engineering applications. However, these structures are exposed to complex loading conditions, resulting in strength reduction leading to failure. This research aims to examine the stability performance of the perforated stiffened laminated composite plate subjected to non-uniform edge load under the influence of environmental conditions. Towards this, a robust and computationally efficient finite element (FE) formulation has been developed, where the plate is modeled using a 9-noded heterosis element to avoid the shear locking of the plate element and a 3-noded isoparametric beam element is adopted to model the stiffener by applying a displacement compatibility condition at the skin-stringer interface. A torsion correction factor is introduced in the beam formulation to account for the twisting of the stiffener. A unique dynamic technique is utilized to obtain the buckling load by employing two types of boundary conditions due to the non-uniform stress distribution in the perforated plate under environmental and operational loading conditions. An analysis is performed on the unstiffened plate to determine a suitable cutout shape, loading pattern and lamina scheme based on its improved stability performance. Unlike previous studies, several stiffener configurations are considered to comprehend the influence of temperature and moisture on the stability behavior of centrally placed cutout plates and obtain a stiffener configuration with improved performance. It is noticed that when the perforated stiffened plate is exposed to thermal or hygroscopic load close to a critical temperature or moisture, the buckling capacity drops suddenly in the plate attached to a stiffener of greater depth. Moreover, it is observed that when the stiffened plate is exposed to higher intensity of hygrothermal load, the plate’s buckling capacity drops significantly as the thickness of the plate reduces.