Progressive damage modeling in laminate composites under slamming impact water

What is it about?

The use of composite materials begin to normalize in various sectors, however, these structures are very susceptible to degradation of their properties and consequently a catastrophic failure. The response of deformable composite subjected to water-entry impact can cause a phenomenon called hydro-elastic effect due to water-flexible laminate interaction. This phenomenon may be large enough to cause the damage in composite panels. This paper employs the finite element method to simulate the behavior of composite wedges under slamming impact with presence of damage. To investigate this situation, the hydro-elastic influence has been analysis as both kinematic effect due to deflection of the composite panel and dynamic effect caused by the interaction between the water and the structure. On the other hand, damage modeling was formulated based on continuum damage mechanics for intra-laminar damage. A user-defined material subroutine VUMAT has been incorporated into explicit Abaqus FE software to enhance the damage simulation, which includes Hashin criteria for degradation of the panel stiffness with failure onset criteria and fracture mechanics. To reinforce the methodology adopted, numerical results are compared with the previous experimental data. A good agreement was observed. Effects of impact velocity and the panels flexibility on the damage have been investigated.

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Why is it important?

This paper presents a finite element analysis of the water entry problem for deformable wedge composite with the establishment of a subroutine for the consideration of the existence of damage. The study deals with the mechanical behavior and the identification of damage initiation and its development in dynamic tests. Two different stiffness panels, with 8 mm and 13 mm, are used with different constant impact velocities; namely 6, 8 and 10 m/ s. Multi-materials Eulerian-Lagrangian model builds in finite element code (ABAQUS 14.6) was exploited to represent the water domain which more feasibility of modeling and allows high deformation in the fluid. The considered model was initially validated with experimental results in the literature. Kinematic effects along water-panel interface exhibited a larger elastic influence due to flexibility and the change in local deadrise angle. Consequently, these effects can be reducing the panel response which significantly appeared in higher velocity impact, especially in the center and the end of the panel. Based on the Continuum damage mechanics and fracture mechanics, a 3D damage model was formulated using user-materials routine VUMAT to enhance the damage simulation, and implemented into the finite element code. The more serious damage have been observed in the matrix close to the edges and in the center of the panel that assist ship designers to give more attention in these locations. The fiber damage needs more high impact energy to occur. The interlaminar damage for the sandwich panels is not addressed here and it will be the objective of the next investigation. The improved understanding of these phenomena and the development of predictive tools are part of an ongoing effort to improve the long-term integrity of composite structures for naval applications.

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