Simulation of Slamming on a Fiber Reinforced Composite Structure Using the ALE/Eulerian Numerical Approach

Abstract

Slamming impact on marine structures constitutes a major concern for designers. Characterized by severe impulsive loads with short duration, this highly non-linear fluid-structure interaction can lead to significant structural damage. Several analytical models have been developed to predict the loads generated on slamming events. However, existent models are still not sufficiently accurate to be applied on industrial level. This thesis presents a numerical slamming model developed with the ALE/Eulerian approach on LS-DYNA. Primarily, the classical two-dimensional rigid wedge is used for an overview on the functioning of the applied penalty contact algorithm and calibration of its governing parameters. The model is validated through comparison with experimental results of the vertical slamming force available on the literature. Sensitivity analyses on parameters such as the penalty factor, damping coefficient and number of coupling points are performed. Additionally, simulations with a three-dimensional version of the rigid wedge are presented with the objective of demonstrating the influence of 3D flow effects on the resulting force. The models produce satisfactory results, reproducing fairly well the slamming force and the free-surface behavior on the rigid structure. On a third stage, the model is applied to an elasto-plastic flat plate. Good agreement with experimental results is found for the hydro-elastic behavior of the plate. Accurate measurements of the local pressure, however, could not be obtained. The model is finally extended to a practical application proposed by the company Calcul- Méca, a fiber reinforced composite sonar dome subjected to slamming. As a preliminary approach, a two-dimensional model with an approximated parabolic rigid body is developed. However, results obtained are not conclusive. Severe leakage occurs on the Lagrangian structure and could not be properly fixed. The slamming force seems to be incoherent with the expected physical behavior. These issues are probably associated to the low deadrise angle of the parabola combined with the high imposed constant velocity, which create extreme conditions for the penalty contact algorithm.