Constitutive model and experimental study of molded pulp material

Molded pulp products can improve the utilization of recycled paper by achieving close to zero waste emission and a 100% recycling rate, while satisfying the national goals for recycled packaging materials of various countries. Molded pulp products are often designed using finite-element simulations to optimize their performance, which requires the input of accurate material properties. However, studies on the constitutive model, an essential factor related to material properties, are still rare. This study investigated the mechanical behavior of the molded pulp material to simplify the parameters and improve the accuracy of the constitutive model. The fiber distribution and connection within the molded pulp material were investigated; treating the pores of the molded pulp as a virtual material enhances the meso-mechanical model and gives a transversely isotropic constitutive model. The elastic modulus in the thickness direction was calculated as 1.5997 MPa, and the experimentally measured value is 1.5368 MPa. The error of proposed model is 4.1%, but significantly smaller than treating molded pulp as an isotropic material, the error of which is ~80 times larger of experimental result.