PVP2010-25749 PLASTIC RESPONSE OF THIN-WALLED TUBES TO DETONATION

Elastic and plastic deformation of tubes to internal deto-nations and the shock waves produced by their reflection were investigated. The study included experimental measurements as well as computational modeling. Tests with stoichiometric ethylene-oxygen mixtures were performed at various initial pres-sures and strain was measured on thin-walled mild-steel tubes. The range of initial pressures covered the span from entirely elas-tic to fully plastic deformation modes. A model for the pressure load on the tube wall was developed and tested against exper-imental measurements. This model was applied as a boundary condition in both a single degree of freedom model of the tube cross section and a finite element model of the entire tube. Com-parison of computational and experimental results showed rea-sonable agreement if both strain-rate and strain-hardening effects were accounted for. A unique mode of periodic radial deforma-tion was discovered and explained through modeling as the result of flexural wave interference effects. NOMENCLATURE c Speed of sound in gas f Temporal frequency of oscillation h Thickness of tube wall u Fluid velocity x Change in tube radius CJ Theoretical Chapman-Jouget, post-detonation state E Young’s modulus ∗Address all correspondence to this author. P Internal pressure of tube R Undeformed tube radius UCJ, UR Detonation and reflecting shock velocities X Axial location of reflected shock γ Ratio of specific heats ν Poisson ratio ρ Density of tube material τ Time decay constant in pressure model ω Angular frequency of oscillatio