In this study, a mechanistic model was developed for the Elmendorf tear energy of paper based on the fundamental physics of the tear process. In the model, the tearing energy was calculated as the sum of fibre fracture energy and fibre pull-out energy since both energies were found to be significant in a series of single fibre pull-out experiments. The model also included statistical considerations, such as the distribution of fibre lengths.

Through dimensional analysis, a "dimensionless tear index" was identified and was found to be a universal function of three dimensionless parameters:​ α, β and ϵ. α is fibre strain and β is equal to the ratio of frictional resistance to the debond force. ϵ is proportional to the ratio of fibre length to the critical length and depends on the bond strength and sheet density for a given furnish. When the dimensionless tear index was plotted against ϵ at given α and β, almost all of the tear index data used to test the model fit on a single curve. This universal plot of the dimensionless tear index versus dimensionless bonding was divided into three regions. Simple approximation equations for these regions can be used to give rough estimates of the tear energy, based on a few measurements of fibre and paper structure.

Using a bond strength obtained through non-linear regression analyses on a particular experimental data set, the model was validated with other sets of data. It was found that the model gave good quantitative predictions of tear energy without the need for adjustable fitting parameters. With a slight modification to account for the role of fines in the furnish, the model was also successfully applied to handsheets made by artificially blending fibres and high specific surface area fines of mechanical pulps.