Analytical and Numerical Modeling of Stress Field and Fracture in Aluminum/Epoxy Interface Subjected to Laser Shock Wave: Application to Paint Stripping

Abstract

In this paper, analytical and numerical models have been developed to compute the stress field and predict fracture of the aluminum/epoxy interface subjected to laser shock loading, in the frame of the investigation of the paint stripping process. An explicit finite element (FE) model combined with the cohesive zone modeling (CZM) method, an analytical stress analysis model, and a spall fracture model have been developed. The numerical model has been calibrated and validated against tests in terms of the stripping pattern, while the analytical models have been compared with the numerical model. The models were combined to generate computational tools for decreasing computational effort. The FE model with the CZM is the most accurate tool although it is the most computationally expensive. The spall fracture model gives trusted estimations of the spall strength of the interface which are very sensitive to the interface thickness and when incorporated into a continuum FE-based damage model can predict the stripping initiation faster than the FE model with the CZM. The analytical stress analysis model can be used to efficiently describe the shock wave propagation into the material system, but it can give only a rough estimation of the tensile stress at the epoxy, which when combined with the spall strength does not give reliable predictions of the stripping initiation. The three models require as input different material properties, some of which are very difficult to determine. Nevertheless, the availability of accurate material parameters and properties of the aluminum, the epoxy, and, especially, their interface can significantly improve the efficiency of the developed models.

Numerical Simulation of the Symmetric Laser-Shock Disassembly Process for Adhesively Bonded Ti/CFRP Parts

“…It is worth noting that the loading configuration utilized in the FE model was consistent with that employed in the experiments, whereby both surfaces of the specimen were loaded, and the bottom surface was delayed by 3.55 μs. This is in accordance with the experimental procedure described in reference [7]. Figure 7 presents the mesh for the second FE model indicating the overlapping areas of load application.…”

“…When the release wave interacts with the elastic precursor shock wave, it creates high localized tensile stresses. The most cost-effective way to optimize a complex experimental procedure is to simulate the process and numerus simulation studies have been conducted to investigate and characterize the laser-shock phenomenon [7][8][9][10]. This study aims to create an accurate model of the specimen that is used in experimental work, using LS-Dyna FE explicit code.…”

A Laser Shock-Based Disassembly Process for Adhesively Bonded Ti/CFRP Parts

“…Laser shock has been used in the industry for material processing, improving fatigue strength of metallic materials, by creating residual compressive stresses [13,14]. Recent research has been able to use the ability of the technique to generate high tensile stresses for non-destructive purposes in the form of an adhesion test called LASAT [15][16][17][18], and for the purpose of damage creation, as it is the case for selective paint stripping [19][20][21], and the formation of controlled delaminations in composites [22].…”