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A combined parameter for graphic evaluation of the load capacity of fuselage
Published in Vladimír. Socha, Lenka Hanáková, Andrej Lališ, New Trends in Civil Aviation, 2018
Typical aircraft thin-walled metal structures are stiffened semi-monocoque, which are widely employed in the aeronautical industry. These characteristic structures are composed of a number of longitudinal stringers stiffening the outer thin stressed skin. An example of the semi-monocoque fuselage structure is presented in Figure 1. A critical stage of the structural integrity is the global load capacity. After this stage, the structure cannot significantly support the outer load and total collapse of the structure will occur. Determination of the global load capacity is a complex process, where particular element failures are investigated according to the detailed stress analysis. The critical point of the evaluation is the decision of when the limiting stage will be reached and which element failure will start the avalanche propagation of the following failures. Standard geometric parameters are utilized in the graphic evaluation of changes in structural integrity per load increment. In this paper, we describe the design of new specific parameters for more efficient and faster determination of the structural load capacity.
Effect of bimodularity and thermomechanical stresses from composite curing on mixed-mode fracture behavior of functionally graded skin-stiffener runout
Published in The Journal of Adhesion, 2023
Saumya Shah, Saroja Kanta Panda
Modern aero-space structures are primarily of the semi-monocoque structure are mainly constituted by thin skin and stiffeners. The newest generation of massive traveler aircraft and civil and military transports are primarily made up of graphite-fibre composite materials as their chief component, and generally, the adoption of assembling of subcomponents has been done through mechanical fastening. Contemporary design philosophy requires some modification in the model of these stiffeners. Due to the intersecting structural parts and inspection cut-out, the loading in the stiffener gets scattered towards the skin, which leads to complicated three-dimensional stress states. The reliable virtual component test has been evolved to design composite aerospace structures that significantly reduce the cost. This reliability requires an exhaustive knowledge of the destruction process and fracture operations in realistic aero-structures, especially in critical and dangerous regions such as stiffener runouts.
Experimental and finite element numerical studies on the post-buckling behavior of composite stiffened panels
Published in Mechanics of Advanced Materials and Structures, 2021
S. Nadeem Masood, Kotresh M. Gaddikeri, S. R. Viswamurthy
Cocured composites structures are gaining popularity in airframe applications as they allow large-scale integration of stiffeners to skin without using expensive fasteners. This technique results in a superior structure along with the reduction in assembly time and associated costs. Such semi-monocoque composite structures such as stiffened panels when subjected to compressive/shear loading can carry loads well beyond the local skin buckling. This phenomenon is accompanied by instantaneous loss of axial stiffness, albeit marginally thereby signaling the onset of non-linear structural response in the post-buckled regime. The panel will start to experience out-of-plane deformations and the cocured interface between skin and stiffener is stressed severely. This is not an ideal situation for composites in general and cocured construction in particular because of their poor inter-laminar properties. This has forced the designers to operate in the ‘safe linear range’ and restrict the design ultimate load to be below the local skin buckling. The reserve strength of stiffened panel beyond skin buckling is unutilized due to lack of understanding of nonlinear post-buckled response and ability to accurately predict collapse load.
Fabrication of solar energy UAV
Published in International Journal of Ambient Energy, 2020
M. Saleem, E. Gopi, R. Ramesh Kumar
The aim of the design was to accommodate more solar panels to generate power. The wing is rectangular shaped comprising of SD 7032 aerofoil, covering an area or 1.35 m2. The type of construction for the entire aircraft is semi-monocoque. The tail has a V-like design and weight elimination is done with NACA 0006.The fuselage is of rectangular structure with position for circuits and battery. The fuselage narrows down to a tapered tail boom section. Solar panel of Silicon type is fixed along the wings. The entire structure is made of balsa wood (Tables 1–2).