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Undergraduate Thesis
Journal Paper (in preparation)
Thermomechanical Analysis of Composite Structures Under Spatially-Varying Internal Heat Generation
Thesis Partner: Md. Rakibul Islam, Department of Mechanical Engineering, BUET.
Thesis Supervisor: Dr. Shaikh Reaz Ahmed, Professor, Department of Mechanical Engineering, BUET.
Summary
The thermomechanical behavior of a sandwich composite plate, consisting of an isotropic aluminum core and orthotropic aluminum-aluminate composite skins with perfectly bonded interfaces, was investigated under non-uniform thermal loading and mixed physical boundary conditions using the Displacement Function Approach (DFA) with a plane-stress approximation.
A total of 36 distinct configurations were studied - three mechanical boundary conditions, six thermal loading conditions and two fiber orientations in the composite skins - to probe into their effect on stresses and deformations within the plate.
Longitudinal edges clamped, shown by hatched lines / / / /
Variable boundary conditions in lateral edges, shown in red
All edges thermally insulated
Thermal convection and radiation out of plane
Six different patterns of internal heat generation
Two orientations of fibers in skin
Solution Method: Displacement Function Approach
Commercial tools utilize numerical methods such as the Finite Element Method (FEM), whereas DFA employs Finite Difference Method (FDM) for numerical differentiation.
Both FEA and DFA discretizes the structure into numerous nodes.
FEA solves for two displacement components at each node, and subsequently calculates the stress components at each node.
DFA packs the two displacement components into a single scalar variable called the displacement potential function, ψ.
Solving for a single variable instead of two can considerably reduce computational time and memory usage.
Displacement and stress components can be subsequently calculated at each node by partial differentiation of the displacement potential function.
To learn more about the analytical formulation of DFA and how it is numerically implemented, I recommend going through a couple of papers listed below which guided me throughout my thesis:
Results
Clockwise from top:
Effect of changing direction of heat generation fluctuation in core
Temperature distribution under various heat generation patterns
Color maps showing stress components for across the structure for a particular configuration of thermal loading and physical boundary conditions
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