Modelling of Young's modulus of foams

The uniaxial compressive modulus of foams has been studied using models for cellular solids, These models predict that the modulus is a function of the relative density of the foam. However, experimental data show a large degree of scatter, which is investigated. Two factors are considered: density variation within the foam, and the shape and geometry of the cell edge cross-section. The results show that density variation within the foam does not contribute significantly to the difference. However, the geometry of the cell, and especially the cell edge cross-section, plays an important role and is the likely cause of the large variations in modulus at low densities. The fraction of solid material contained in the cell edges, as opposed to the walls, is a key component of cell geometry, which becomes increasingly important as the relative density decreases.