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The Effects of Engineering Assumptions when Designing a Plate Panel/Stiffener System Under a Uniformly Distributed Load. Bernard Nasser Master of Engineering in Mechanical Engineering. Rensselaer Polytechnic Institute Hartford, Connecticut December, 2011 (For Graduation May, 2012) . Purpose.
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The Effects of Engineering Assumptions when Designing a Plate Panel/Stiffener System Under a Uniformly Distributed Load Bernard Nasser Master of Engineering in Mechanical Engineering Rensselaer Polytechnic Institute Hartford, Connecticut December, 2011 (For Graduation May, 2012)
Purpose • Study focuses on the effect of engineering assumptions made when designing a plate panel/stiffener system under a uniformly distributed load. • Initial engineering assumptions design the panel using Classical Deflection Theory (small deflection theory) for a flat rectangular plate under a uniformly distributed load that is either fixed or clamped around the edges. • Stiffeners are initially designed as beams under a uniformly distributed load that are either simply supported or fixed at the ends. • Initial panel and stiffener sizes generated are an approximation, as a finite element analysis is required to evaluate and authorize the final configuration. • Final configurations can be very different from the simple initial closed form evaluations, as stress issues and fabrication constraints are accounted for. • Comparative analysis between the closed form solutions (stress and deflection for a fixed or pinned rectangular plate with a uniformly distributed load) and the values generated by a finite element analysis. • How close are FEA results to initial assumptions?
Panel System Figure 1: Pressurized Tank with top plate stiffened
Panel System Figure 3: Section view showing stiffener design “butting” into shell side plate Figure 4: Section view showing stiffener design sniped prior to reaching shell side plate Figure 5: Section view showing stiffener design wrapped around plates
Numerical Analysis Clamped Rectangular Plate Under Uniformly Distributed Load α = 0.0138 (given, for a/b = 1) po = 100 psi b = 30in E = 30 x 106 psi t = 0.75in β1 = 0.3078 (given, for a/b = 1) po = 100 psi b = 30in t = 0.75in
Numerical Analysis Simply Supported Plate Under Uniformly Distributed Load α = 0.0444(given, for a/b = 1) po = 100 psi b = 30in E = 30 x 106 psi t = 0.75in β1 = 0.2874 (given, for a/b = 1) po = 100 psi b = 30in t = 0.75in