TABLE 4.

Coefficients of the experimental mean force-displacement curves (Figure 4). Each polynomial curve fit $\mathit{f}\left(\mathit{\delta }\right)$ describing this is defined for $\mathbf{0}\le \mathit{\delta }\le {\mathit{\delta }}_{\mathit{max}}$ with ${\mathit{f}}_{\mathit{max}}=\mathit{f}\left({\mathit{\delta }}_{\mathit{max}}\right)$ . The complete data set after curve fitting for the force-displacement measurements can be found in Supplementary Material S1.

Measurement region	${\mathit{\delta }}_{max}$ in mm	f max in N	Degree (n-1)	Polynomial curve fit $f\left(\delta \right)$
				Coefficients $f_n$						RMSE in N/mm
				f 1	f 2	f 3	f 4	f 5	f 6
R1	25	11.85	2	8.684e-03	2.462e-01	0	-	-	-	1.256
R2	30	13.33	4	−2.937e-06	2.590e-04	2.479e-03	2.163e-01	0	-	0.963
R3	30	11.52	2	8.604e-03	1.260e-01	0	-	-	-	0.512
R4	30	10.33	2	5.279e-03	1.859e-01	0	-	-	-	0.660
R5	25	11.41	4	5.359e-06	1.710e-04	3.677e-03	1.740e-01	0	-	1.025
R6	20	32.25	4	−2.765e-05	2.665e-03	2.231e-02	3.214e-01	0	-	2.639
A1	20	20.94	2	3.456e-02	3.556e-01	0	-	-	-	2.913
A2	25	29.51	5	−1.119e-05	−6.415e-04	4.969e-02	5.176e-02	4.619e-01	0	3.320
A3	25	27.01	5	9.067e-06	−5.547e-04	1.047e-02	−2.882e-02	3.835e-01	0	3.922
A4	25	22.44	3	−3.641e-04	2.890e-02	4.072e-01	0	-	-	4.682
A5	24	23.86	2	2.864e-02	3.068e-01	0	-	-	-	4.037
A6	14	55.98	4	−3.118e-04	−3.885e-03	3.465e-01	7.624e-01	0	-	10.959