Method and system to model materials for use in articles, such as tampons

A modeling method for a fibrous material to be made into a product, which may be but one example of a family of such modeling methods, includes analyzing processes and conditions under which the fibrous material is made into the product, determining that moisture, temperature and rate conditions should be tested according to the analysis of the processes and conditions, and testing the fibrous material under at least one of moisture, thermal or rate conditions similar to those under which the fibrous material is made into the product to obtain test results. The modeling method further includes defining a constitutive model for the fibrous material according to the test results. A computing device may be programmed to perform simulations using the model.