Pits in Metals Caused by Collision With Liquid Drops and Rigid Steel Spheres

Area of Science:

• Materials Science
• Impact Dynamics
• Solid Mechanics

Background:

• Understanding impact dynamics is crucial for material design and failure analysis.
• Previous models for pit formation have limitations when considering projectile flow and target material properties.

Purpose of the Study:

• To validate an existing pit-depth-versus-velocity equation.
• To investigate the influence of projectile type (flowing vs. non-flowing) and target material properties on impact pit formation.

Main Methods:

• Experimental testing using target plates of copper, 1100-O aluminum, and 2024-O aluminum.
• Projectile impacts were generated using mercury drops, water drops, and steel spheres.
• Static strength properties of target materials were measured via tensile testing.

Main Results:

• The pit-depth-versus-velocity equation showed good agreement with experimental data for flowing projectiles (mercury, water).
• Numerical constants differed for flowing versus non-flowing (steel sphere) projectiles.
• An exception was observed for steel spheres impacting 2024-O aluminum, where work-hardening affected pit formation.

Conclusions:

• The validated equation is effective for flowing projectiles but needs refinement for non-flowing projectiles.
• Target material work-hardening can significantly alter impact pit morphology, necessitating model adjustments.