Response of moist paperboard during rapid compression and heating

The response of moist paperboard exposed to extensive compression and heating in short periods of time is investigated. A generic framework describing this response, in a thermodynamically consistent manner, has been derived previously. The present paper provides explicit formats of the necessary constitutive relations specific to moist paperboard exposed to extensive compression and heating in short periods of time. The transient transports of mass, momentum and energy, as well as specific interaction terms are considered for orthotropic paperboard. The elasto-plastic response is taken into account in a large strain setting. The exchange of mass between the water bound to the fibers and the water vapor during the sealing is also considered. Simulations of an idealized sealing of two sheets of paperboard are performed and the predicted distributions of temperature, vapor pressure, out-of-plane stress and Forchheimer number are studied. The discussion related to the results from the simulations provides a deeper insight to how the different transport processes will affect the paperboard and how these are coupled. The closed system of equations, including the explicit formats of constitutive relations, provided in this paper makes it possible to set up suitable experiments for validation of the model.