where A is the cross-sectional area, h is the height of the insulation,e is the strain, r is the stress, and a and b are constant values. Without considering the hysteresis of the stress-strain curves, the mean values of compression/decompression measurement were used, and the suggested values of a and b are
a = 1.5e7 Pa and b = 2.9e8 Pa for the pressboard and
a = 1.0e6 Pa and b = 4.5e8 Pa for the insulation paper,
respectively.