A METHOD TO ASSESS IMPACT DAMAGE USING A SMOOTHED PARTICLE HYDRODYNAMICS AND FINITE ELEMENT COUPLED APPROACH

摘要

Following the highly unlikely event of a pressurised component failing, it is important to know the indirect consequences of failure. These include the effects of missiles generated from the failed component hitting other components within the plant. Methodologies such as the R3 assessment procedure provide formulae to calculate the missile velocity, as well as the energy required to penetrate a target. In this paper, a multi physics model is presented which enables calculation of missile velocity based on a coupling between Smooth Particle Hydrodynamics (SPH) and Finite Element Method (FEM). Investigations were performed using air as the fluid at different pressures; this enabled optimisation of the model so that it could be used to assess high pressure steam as the process fluid. A comparison between a simple hand calculated maximum acceleration, and the peak obtained from the simulation, provided a means of validating the model. Velocities obtained from the numerical method were found to be considerably lower than R3. Several reasons are suggested as to why this is the case and are justified with results from numerical simulations. In addition to this, the impact of a missile on a target was simulated using FEM with a special material model based on strain rate hardening and shear failure. The R3 impact assessment method was found to be in closer agreement with the numerical results, providing evidence that these empirical formulae are still acceptable to use in assessments. However, in order to get an accurate evaluation of missile velocity, more sophisticated methods should be used to avoid overly conservative assessments.