PSI - Issue 52

124 Quaiyum M. Ansari et al. / Procedia Structural Integrity 52 (2024) 122–132 Quaiyum M. Ansari/ Fernando Sánchez/Luis Doménech-Ballester/ Trevor M. Young / Structural Integrity Procedia 00 (2019) 000 – 000 3 that the failure modes can be complex, requiring X-ray microtomography to explain interfacial failure initiation and progression.

Fig. 2. (a) Whirling Arm Rain Erosion Rig (WARER) at University of Limerick (b) Rin erosion damage of sample (C) CT scan of rain erosion sample at a perpendicular cross-section at failure location [19] Domenech et al. [20] investigated the anti-erosion performance of a wind turbine blade's leading edge top coating. The viscoelastic material models are considered in this work for coating layer impedance characterisation, with ultrasound measurements used to generate the input data for the modelling. Cortés et al. [21] studied the effect of adhesion properties on the rate of rain erosion. Accelerated rain erosion testing [22], pull-off testing and peeling adhesion testing of individual coating configuration cases are all part of the experimental investigation. The use of nano indentation testing by O'Carroll et al. [6] was followed soon afterwards by Ouachan et al. [23] with their own study. The inclusion of the primer layer was discovered to significantly improve adhesion and reduce delamination. Zhang et al. [24] investigated the effects of low velocity impact on impact forces on a solid surface. Using high speed images, they discovered that droplets have symmetric shapes during the initial process, even when they impact an inclined surface. Furthermore, the impulse increases quadratically with normal velocity, whereas the peak impact force increases directly with normal velocity. Mishnaevsky [25] optimised the erosion strength of wind turbine blade coating using a toolbox. He discovered that the erosion rate increases as the hardness of the coating surface increases. In contrast, higher hardness on the top surface was found to provide better erosion resistance under low angle impact. Zhang et al. [26] conducted accelerated rain erosion testing on wind turbine blade coatings and discovered that substrate curvature has no effect on rain erosion rate and that flat panels, which are easy to manufacture, can be used to investigate erosion rate. Furthermore, nozzle-coating distances less than 100 mm do not affect the rain erosion rate. Petersen et al. [27] demonstrated a contactless and non-destructive method of detecting defects inside wind turbine blade LEPs using optical coherence tomography (OCT). However, due to the highly scattering nature of these coatings, particularly the putty layer with a high filler particle content, OCT is currently limited to surface defects and penetration depth is limited to 4 μm. Mitchell et al. [28] investigated the impact dynamics of low velocity water droplets using numerical and experimental methods. They discovered from high velocity impact photography that the droplet spreads faster in high velocity impact than in low velocity impact. Furthermore, the impact time duration is inversely proportional to the impact velocity. In this study, the mesh distortion is controlled using Arbitrary Lagrangian-Eulerian (ALE). There are several other impact simulation methods such as Smoothed Particle Hydrodynamics (SPH) and Coupled Eulerian – Lagrangian (CEL) that is discussed by Doagou-Rad and Mishnaevsky Jr. [29] for large deformations. In SPH, where nodes act as particles to represent the body. In the Eulerian-Lagrangian contact formulation which is based on the enhanced immersed boundary method where interaction between fluid and structure is important such as water droplet impact on LEP coating surface. Nassiri et al. [30] investigated the wavy pattern in the welding process using the ALE Finite Element (FE) method as well. Adler [31] used FE analysis to investigate the impact of water droplets on deformable targets. He discovered that the finite element method can include damage to the failed element. It will then help in predicting the extent of damage caused by the impact of water droplets. Verma et al. [32] used a parametric study for offshore wind turbine blades to conduct a numerical investigation of rain droplet impact. They discovered that the maximum impulse, stress, or damage occurs during normal droplet impingement on the coating surface. The contact force history is distinguished by two distinct stages: a water hammer stage followed by lateral jetting. This stage transmits the maximum amount of load to the coating system and is primarily responsible for erosion.