Table 2 Material definitions for Lead White and Red Iron Oxide; Based on the tests at Smithsonian Institution
From: Numerical modelling of mechanical degradation of canvas paintings under desiccation
Material Name | Property | Definition (Relaxation State) | Calculated Values at 50% RH |
|---|---|---|---|
Lead White | Elastic, Ep [MPa] | –0.0083* RH2- 0.3*RH + 125.65 | 89.9 |
Yield Strain | 3.82E-7*RH2 – 4.22E-5*RH + 2.41E-3 | 0.0013 | |
Plastic, Pp | \(\mathrm{\alpha }*\mathrm{ln}\left(\upvarepsilon \right)+\upbeta\) \(\mathrm{\alpha }=0.275{\mathrm{E}}^{-0.014*\mathrm{RH}}\) \(\upbeta =1.995{\mathrm{E}}^{-0.015*\mathrm{RH}}\) | – | |
Moisture Expansion Coefficient, αp [/% RH] | 7.414E-7*RH + 1.435E-5 | 0.00005 | |
Max. Principal Stress [MPa] | 3.91E-5*RH2 – 1.32e-2*RH + 1.22 | 0.66 | |
Red Iron Oxide | Elastic Modulus, Erio [MPa] | –0.0082*RH + 0.828 | 0.42 |
Moisture Expansion Coefficient, αrio [/% RH] | 1.5E-7* RH2- 3.74E-6*RH + 8.095E-5 | 0.00029 | |
Max. Principal Stress [MPa] | –1.05E-5*RH2 + 6.11E-4RH + 3.89E-2 | 0.043 |