Fig. 4

Comparison of simulations (a, b) with friction force measurements. Simulation parameters are \(\varepsilon _1{:}\; 3.1 \times \varepsilon _0\,{\text{F}}/\text{m},\) \(\varepsilon _2{:}\; 1.0 \times \varepsilon _0\,{\text{F}}/\text{m},\) \(\sigma _1{:}\; 1.4 \times 10^{-15}\,{\text{S}}/\text{m},\) \(\sigma _2{:}\; 2.0 \times 10^{-12}\,\,{\text{S}}/\text{m},\) \(d_1{:}\; 16\ \upmu \text{m},\;\) \(d_2{:}\; 9\ \upmu \text{m},\) (at t = 0), \(A{:}\; 7.1 \times 10^{-4}\) m\(^2\), and m (mass of layer 1): \(1.0 \times 10^{-3}\) kg