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Design of Powered Rail Vehicles and Locomotives
Published in Simon Iwnicki, Maksym Spiryagin, Colin Cole, Tim McSweeney, Handbook of Railway Vehicle Dynamics, 2019
Maksym Spiryagin, Qing Wu, Peter Wolfs, Valentyn Spiryagin
The monocoque body has rigid link connections between elements such as the frame, roof and side walls, the tightening belt, etc. It enables collaboration of all elements of the design to resist loads acting on it. This also includes skin elements of the body shell such as the wall-covering sheets. Car bodies of this type are produced in the cowl unit style. The advantage of monocoque construction is the high rigidity and low weight. One of the designs of this type is shown in Figure 4.21.
Automotive Architecture
Published in Patrick Hossay, Automotive Innovation, 2019
Unibody designs are sometimes referred to as a monocoque structure, derived from the French term for a single outer shell. Monocoque construction relies on the outer skin as the key structural member that distributes and carries tensile and compression loads throughout the shell with no internal structure. Think of an eggshell. As you apply compressive or torsional force, the shell’s symmetrical structure sort of reinforces itself at any given point, providing impressive structural integrity for its weight. Clearly a unibody has some of these characteristics, but the boxed sections, subframes, and reinforcing structures in a unibody system define more of a semi-monocoque structure than a true monocoque. Still, some vehicles get closer to a true monocoque than others, relying more heavily on the outer shell for rigidity and less on major substructure components. The advantage is weight saving and stiffness. Yet the design must be careful to provide adequate strength and crashworthiness, as a true monocoque structure relies on its form integrity.
Are We Thinking Like Rocket Scientists and Engineers?
Published in Travis S. Taylor, Introduction to Rocket Science and Engineering, 2017
Monocoque (French for “single shell”) is a structure design technique where the structural integrity is supplied by the skin of the structure. A beer or soda can is an example of a monocoque structure. Because the structure of the can is nothing but the thin walls of the cylinder (its skin), the only structural integrity is supplied in these thin walls. A simple experiment of standing on a beer can will tell us some important information about how monocoque structures function. If the can is empty, it will collapse under much less loading than it will when it is full and unopened. The beer inside the can offers much more resistance to external pressure than unpressurized air in the empty can. So, why do rocket scientists care about this?
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.
Lightweight design of bus frames from multi-material topology optimization to cross-sectional size optimization
Published in Engineering Optimization, 2019
Shanbin Lu, Honggang Ma, Li Xin, Wenjie Zuo
In this part, the ordered SIMP method is applied to the multi-material topology optimization of a monocoque bus frame, completely made of steel materials and consisting of 358 beams (Figure 4). The length, width and height of this bus are 13.0, 3.2 and 3.5 m, respectively. In this article, three phase materials, namely void, aluminium alloy and steel, are used to design the bus frame; their properties are listed in Table 1. After 42 iterations, the convergence conditions are satisfied and the computational cost is 5.2 h. The optimized bus frame is shown in Figure 5, where 19 beams are deleted, i.e. corresponding to the void material, and almost half of the steel beams are changed to aluminium ones. All the convergence curves of the responses are shown in Figures 6–9. It can be seen that the mass objective continued to decrease, but the torsional, bending and frequency stiffness constraints were larger than or approximately equal to the specified lower bounds. The initial and optimal responses are compared in Table 2. The mass of bus frame is decreased by 39.65%.