Fig. 1. Geometry of the model.

Fig. 2. Comparison among curves of ARF function Yp₁versuskR₁ for different models: rigid/elastic sphere, single thin elastic shell.

Fig. 3. Effects of separation distance on relation between ARF function Yp₁ and kR₁ for the frontal shell, showing comparison (a) among the cases d/R₁ = 2, 2.5, and 4, (b) between the case d/R₁ = 4 and single shell, and (c) among d/R₁ = 4, 10, 20, 50, 100.

Fig. 4. Effects of radius ratio on relation between ARF function Yp₁ and kR₁ for frontal shell, showing (a) comparison among the case R₂/R₁ = 1 and single shell, (b) between the cases R₂/R₁ = 1, 2, and (c) between the cases R₂/R₁ = 0.5, 2, 5.

Fig. 5. Effect of shell thickness on relation between ARF function Yp₁ and kR₁ for frontal shell.