scholarly journals THE RESPONSE OF CYLINDRICAL SHELLS TO EXTERNAL BLAST LOADING

1963 ◽  
Author(s):  
Jr Schuman ◽  
William J.
Keyword(s):  
Cylindrical Shells ◽  
Blast Loading ◽  
External Blast Loading

Using Explicit Finite Element Analysis to Simulate the Structural Damage Associated With an Internal Detonation in a Heat Exchanger

2014 ◽  
Author(s):  
Phillip E. Prueter
Keyword(s):  
Finite Element ◽  
Heat Exchanger ◽  
Structural Damage ◽  
Real Life ◽  
Blast Loading ◽  
Process Equipment ◽  
Computational Techniques ◽  
Explicit Finite Element ◽  
Blast Analysis ◽  
External Blast Loading

Developing the realistic blast loading associated with an internal detonation occurring within a pressure vessel or heat exchanger is challenging. Unlike evaluation of external blast loading on structures due to far-field explosions, where typical overpressure-time histories can be reasonably defined based on empirical data, investigating confined detonations presents additional complications. The subsequent impulsive peak reflected overpressure from confined detonations acting on a structure can be extremely high due to the close proximity of the blast source to the vessel wall or pressure boundary. This establishes the possibility of significant structural damage for process equipment subjected to an internal detonation, even for relatively modest amounts of concentrated explosive products. This paper discusses the underlying theory of blast analysis and examines the practical application of non-linear, finite element based, explicit computational techniques for simulating the load acting on a structure due to internal and external blasts. The investigation of a recent, real-life industry failure of a heat exchanger due to a suspected internal detonation is discussed. Explicit, three-dimensional blast analysis is performed on the heat exchanger in question, and an internal detonation is simulated to reasonably replicate the considerable damage actually observed in the field. This analysis permits the determination of an approximate amount of concentrated product that caused the accidental explosion; that is, the plausible equivalent amount of explosives is back-calculated based on the predicted damage to the finite element model of the equipment in question. Computational iterations of varying charge amounts are performed and the predicted amount of permanent damage is documented so sensitivity to the hypothesized charge amount can be quantified. Furthermore, explicit blast analysis of nearby equipment is performed. In this investigation, computational results for both the heat exchanger (subjected to internal blast loading) and surrounding equipment (subjected to external blast loading) are in good agreement with the measured plastic deformations and failure modes that were actually observed in the field. Commentary on the likely detonation event that caused the significant damage observed is provided. Additionally, an advanced finite element failure criterion that is driven by plastic yielding is employed where portions of the computational model are removed from the simulation once a user-defined strain threshold is reached. This approach facilitates simulation of the gross heat exchanger pressure boundary failure actually observed in this case. The explicit finite element based analyses discussed in this study reasonably predict the structural response and damage characteristics corresponding to a recent, real-life industry failure.

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

2021 ◽  
Vol 9 (11) ◽  
pp. 1297
Author(s):  
Zhan-Feng Chen ◽  
Hui-Jie Wang ◽  
Zhiqian Sang ◽  
Wen Wang ◽  
He Yang ◽  
...  
Keyword(s):  
Mechanical Model ◽  
Dynamic Pressure ◽  
Cylindrical Shells ◽  
Solution Process ◽  
Blast Loading ◽  
Nonlinear Mechanics ◽  
Pressure Equation ◽  
Blast Pressure ◽  
Mechanics Model ◽  
Internal Blast 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.

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

2008 ◽  
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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