Jingde Li

Energy Absorption Analysis of Density Graded Aluminium Foam

A numerical approach is carried out to investigate the energy absorption efficiency of density graded aluminium foam. Effects of blast load impact velocity, loading duration and sample thickness on the input energy density and output energy density of the graded foam are investigated. The stochastic meso-scale aluminium foam structure is generated by adopting a 2D Voronoi technique and the commercial software ANSYS/LS-DYNA is used for the FE modelling. Parametric study shows that the density graded aluminium foam is effective in improving energy absorption capability while keeping a lower stress transmitted to the substrate or the protected structure if it is properly designed.

Design of Metal Foam Cladding Subjected to Close-Range Blast

AbstractThe response of a blast mitigation cladding consisting of a face sheet and metal foam core subjected to a close-range blast is predicted. Whereas the cladding is sufficiently wide compared to the standoff distance between the explosion center and the cladding, the boundary of the blast induced bulge is released. The face sheet is considered as a rigid perfectly plastic membrane as the deformation of the sheet always exceeds half its thickness. A procedure predicting the depth and extent of the bulge is proposed with energy method. Subsequently, the minimum thickness of the foam layer is calculated based on the bulge depth. This design-oriented approach, in a ready-to-use manner, can be straightforwardly applied, facilitating the preliminary design of blast mitigation claddings with metal foam core.

Gas explosion analysis of safety gap effect on the innovating FLNG vessel with a cylindrical platform

After investigating gas dispersion on a cylindrical Floating Liquefied Natural Gas (FLNG) platform [1], this second article focuses on assessment of gas explosion by using Computational Fluid Dynamics (CFD). Gas explosion simulations are carried out to evaluate the explosion overpressure mitigating effect of safety gap. The Datadump technique, which is an effective tool in resetting turbulence length scale in gas explosion overpressure calculation, is applied to ensure simulation accuracy for the congestion scenario with safety gap. Two sets of different safety gaps are designed to investigate the safety gap on the cylindrical FLNG platform, the overall results indicate that the safety gap is effective in reducing overpressure in two adjacent congestions. However, for the explosion scenario where the flame is propagating through several safety gaps to the far field congestion, the safety gap mitigates overpressure only in certain explosion protecting targets. Two series of artificial configurations are modelled to further investigate the explosion scenarios with more than two safety gaps in one direction. It is concluded that the optimal safety gap

Evaluation of gas explosion overpressures at configurations with irregularly arranged obstacles

AbstractRapid analytical methods for the calculation of gas explosion overpressures in confined and congested regions are of great value where a benchmark value is sought rather than a time consuming detailed analysis obtainable by computational fluid dynamics (CFD). While earlier correlations have been compared directly to experiments, the geometries used were often simplistic and displayed homogeneity in confinement and congestion. Realistic geometries typically display a high degree of inhomogeneity in confinement and congestion. Here the authors examine geometries where the confinement and congestion were deliberately varied such that some of the geometries possessed inhomogeneity of both parameters. Little experimental data exists for such configurations and hence the authors examine these configurations using CFD. The CFD overpressure predictions at various target locations for 400 scenarios are compared with the results from a newly derived correlation and the correlation of the guidance for the ap...