ETD Collection

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Subject: search.filters.subject.Buckling (Mechanics)

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    Optimisation of no sway plane rigid frames against buckling
    (2019) Naidoo, Devveena
    The report proposes a simple method which optimises the design of plane, rigid no sway frame structures based on the system buckling load. It is centred on either maximising the buckling load or minimising the weight of the structure, or both; and to have all stories buckling at the same time. The method is applied to various frames examples and the results are compared to that obtained from a system buckling analysis performed in the ANSYS Finite Element Analysis (FEA) software. The proposed optimisation procedure proved successful for no sway multi-story rigid frames, as validated by the acceptable percentage differences of below 5% from the FEA analysis. The optimisation method is however limited in its application to multi-story rigid no sway frames only. The methods attempted for the calculation of the system buckling load to account for the influence of adjacent stories of sway frames, was not successful and further development is required.
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    An extension to classical lamination theory for buckling and vibration of functionally graded plates
    (2019-08) Catanho, R.V.
    An extension to classical lamination theory (CLT) is presented to analyse the natural fre- quencies and critical buckling loads of simply supported functionally graded plates. The variation of the through-thickness properties of the plate is governed by a power law which is subsequently represented by a polynomial series of su cient order and varies according to the law of mixtures or the Mori-Tanaka Homogenization method. The sti ness matrices are found, from which the position of the neutral plane is established which allows for the governing equations for the natural frequency and critical buckling load to be derived using the Rayleigh-Ritz method. The natural frequency and critical buckling loads are determ- ined for various volume indices, aspect and span ratios and the accuracy thereof is validated against 2D, 3D and quasi-3D solutions found in literature. A comparison with CLT found that the present study produces natural frequencies and critical bucking loads which are more accurate and which converge faster than CLT.