Liquid drop collisions on deformable media

Abstract

The spatial and temporal distributions of the transient stresses generated in elastically deformable bodies with the elastic properties of zinc selenide, polymethylmethacrylate, and soda-lime glass have been evaluated for an idealized representation of a water drop impacting a plane surface. The development of regions of significant tensile stresses within the target material is clearly shown which can be related to fracture initiation in brittle materials. The analytical approach used has its inherent shortcomings which include the lack of obtaining the stresses at the surface in the vicinity of the Rayleigh wave front and the fact that it is only applicable to the earliest stages of the impact event before lateral outflow dominates. However, the idealized model reasonably approximates the results from numerical analyses with regard to the water drop shape profile in the initial stage of the impact when the compressibility of the water in the drop is most significant. It does appear that the period of the collision covered by the analysis is where the damage within the material originates, whether due to the deformations within the impact zone or by the transient stress distribution established after the passage of the shear wave into the target material.

Nanoengineered Graphene-Reinforced Coating for Leading Edge Protection of Wind Turbine Blades

“…Thus, the hottest and also the most deformed regions are within the contour line of the contact area of the impacting ball. This is in line with many models and observations reported elsewhere [4,50,55,56].…”

Leading edge erosion of coated wind turbine blades: Review of coating life models

“…The relevance of the analytical results in relation to surface damage of uncoated materials is demonstrated by Adler [33] and Hackworth [34], based on experimental results with zinc selenide, zinc sulphide, and gallium arsenide. Single water drop impacts are generated with 0.7, 2.0, and 2.5 mm diameter drops and impact velocities of 222 and 341 m/s.…”

Multiple liquid impact of single-crystal lithium fluoride

“…The cracks shown are variable in length, the largest emanating from the centre of impact that, unusually, has a subsidiary crack running in the h110i direction. Referring to type (III) cracks, Adler (1977) had shown that substantial surface and near± surface tensile stresses developed ahead of the shear wave in polycrystalline zinc sulphide just before the Rayleigh surface wave begins to develop. However, there was no evidence in the case of single-crystal lithium¯uoride of subsurface tensile cracking associated with bulk waves.…”

“…Figure 2 shows the intersections of these cracks from two quadrants. They are typically W-shaped cracks and are associated with liquid impact on single-crystal materials, particularly magnesium oxide (Adler andJames 1981, Jackson andField 1999b). The increase in the number of W-shaped cracks occurred beyond the damage threshold limit of the material and was largely associated with the appearance of cracks in the h100i radial directions within the impact zone.…”