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Title: Postbuckling analysis of isotropic and anisotropic plate assemblies under combined loading
Author: Zhang, Chi
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2018
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Plated structures are used extensively in aerospace structures to reduce mass, while maintaining a high degree of stiffness. In many cases, such structures exhibit stable postbuckling behaviour and can carry loads far in excess of their critical buckling load. However, postbuckling behaviour is often complex and computationally expensive to determine particularly when anisotropic composite material is utilised. In aerostructure design, engineers require fast yet reliable software to extend the design envelope as far as possible into the postbuckling region. The exact finite strip computer program VICONOPT is a powerful tool for analysis and optimisation of prismatic plate assemblies but has some limitations particularly in conducting postbuckling analysis. For example, it gives conservative postbuckling results for structures subject to combined shear and compression because it assumes the mode shape varies sinusoidally in the longitudinal direction. Also, it unable to predict correct postbucked stress distribution patterns. This work is motivated by the need to address these limitations. A new postbuckling analysis procedure is proposed for analysis of isotropic and anisotropic plates under combined loading. This approach is based on a geometrical relationship between the postbuckling axial stiffnesses calculated from the actual mode shapes and those calculated under the sinusoidal assumption. This enables comparison studies to be conducted to correct the previous conservative postbuckling analysis. An 'Improved' method is also proposed to obtain an accurate stress distribution during the postbuckling analysis. Enhanced trigonometric functions are developed to that the inplane displacement field can be represented more adequately. The in-plane governing equilibrium equations are derived and solved analytically for both isotropic and general anisotropic plates. This Improved method is further extended to handle more complex problems, including stiffened panels for which some adjustments to the equilibrium equations are made. Each proposed method is presented alongside appropriate practical examples and numerical results, and a commercial finite element package is used to validate the results obtained.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available