A program stored in a storage medium directs a computer to perform the processes of: receiving a three-dimensional geometric model; referring to attribute information about fastening between the parts; extracting a fastening portion at which a first and second parts are fastened based on the attribute information and the three-dimensional geometric model; dividing each of the first and second parts into a first geometry in proximity of the fastening portion and one or more second geometries corresponding to a remaining portion in the three-dimensional geometric model; and with respect to each of the first geometries obtained by dividing the first and second parts respectively, referring to a parameter depending on the attribute information and a property value depending on a material of the part, calculating an equivalent property value reflecting fastening based on the parameter and the property value, and assigning the equivalent property value to the first geometry.