Theoretical and Numerical Analysis of Blasting Pressure of Cylindrical Shells under Internal Explosive Loading

Cylindrical shells are principal structural elements that are used for many purposes, such as offshore, sub-marine, and airborne structures. The nonlinear mechanics model of internal blast loading was established to predict the dynamic blast pressure of cylindrical shells. However, due to the complexity of the nonlinear mechanical model, the solution process is time-consuming. In this study, the nonlinear mechanics model of internal blast loading is linearized, and the dynamic blast pressure of cylindrical shells is solved. First, a mechanical model of cylindrical shells subjected to internal blast loading is proposed. To simplify the calculation, the internal blast loading is reduced to linearly uniform variations. Second, according to the stress function method, the dynamic blast pressure equation of cylindrical shells subjected to blast loading is derived. Third, the calculated results are compared with those of the finite element method (FEM) under different durations of dynamic pressure pulse. Finally, to reduce the errors, the dynamic blast pressure equation is further optimized. The results demonstrate that the optimized equation is in good agreement with the FEM, and is feasible to linearize the internal blast loading of cylindrical shells.

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Investigation on the Mechanisms of Strain Growth in Cylindrical Containment Vessels Subjected to Internal Blast Loading

Volume 5: High Pressure Technology; Nondestructive Evaluation Division; Student Paper Competition ◽

10.1115/pvp2008-61016 ◽

2008 ◽

Cited By ~ 3

Author(s):

Q. Dong ◽

Q. M. Li ◽

J. Y. Zheng

Keyword(s):

Cylindrical Shells ◽

Blast Loading ◽

Elastic Response ◽

Mode Shapes ◽

Local Dynamic ◽

Element Simulation ◽

Growth Phenomenon ◽

Modal Coupling ◽

Internal Blast Loading ◽

Elastic Responses

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the earlier stage. In order to find out the possible mechanisms of the strain growth phenomenon, the natural frequencies and mode shapes of various vibration modes in cylindrical shells with different boundary conditions are obtained theoretically and numerically. The dynamic elastic responses of cylindrical shells subjected to internal blast loading are studied by theoretical analysis and finite element simulation using LS-DYNA. It is found that strain growth in cylindrical containment vessels is mainly caused by linear modal superposition and nonlinear modal coupling. The effects of the reflected blast shock waves and structural perturbation are discussed. The proposed theory for the strain growth mechanisms may guide the safe design of cylindrical containment vessels.

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Numerical analysis of the processes of deformation and fracture of closed cylindrical shells under internal blast loading

Strength of Materials ◽

10.1007/bf02767595 ◽

1997 ◽

Vol 29 (2) ◽

pp. 179-187

Author(s):

I. A. Volkov ◽

M. B. Prokopenko ◽

I. Yu. Gordleyeva

Keyword(s):

Numerical Analysis ◽

Cylindrical Shells ◽

Blast Loading ◽

Deformation And Fracture ◽

Internal Blast Loading

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Discovering Sequenced Origami Folding Through Nonlinear Mechanics and Topology Optimization

Journal of Mechanical Design ◽

10.1115/1.4041782 ◽

2019 ◽

Vol 141 (4) ◽

Cited By ~ 4

Author(s):

Andrew S. Gillman ◽

Kazuko Fuchi ◽

Philip R. Buskohl

Keyword(s):

Topology Optimization ◽

Design Space ◽

Optimization Algorithms ◽

Element Model ◽

Evolutionary Optimization ◽

Nonlinear Mechanics ◽

Design Problems ◽

Mechanics Model ◽

Highly Nonlinear ◽

Evolutionary Optimization Algorithms

Origami folding provides a novel method to transform two-dimensional (2D) sheets into complex functional structures. However, the enormity of the foldable design space necessitates development of algorithms to efficiently discover new origami fold patterns with specific performance objectives. To address this challenge, this work combines a recently developed efficient modified truss finite element model with a ground structure-based topology optimization framework. A nonlinear mechanics model is required to model the sequenced motion and large folding common in the actuation of origami structures. These highly nonlinear motions limit the ability to define convex objective functions, and parallelizable evolutionary optimization algorithms for traversing nonconvex origami design problems are developed and considered. The ability of this framework to discover fold topologies that maximize targeted actuation is verified for the well-known “Chomper” and “Square Twist” patterns. A simple twist-based design is also discovered using the verified framework. Through these case studies, the role of critical points and bifurcations emanating from sequenced deformation mechanisms (including interplay of folding, facet bending, and stretching) on design optimization is analyzed. In addition, the performance of both gradient and evolutionary optimization algorithms are explored, and genetic algorithms (GAs) consistently yield solutions with better performance given the apparent nonconvexity of the response-design space.

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