During frontal and rear end type collisions, very large forces will be imparted to the passenger compartment by the collapse of either front or rear structures. NCAP tests conducted by NHTSA involve, among other things, a door openability test after barrier impact. This means that the plastic/irreversible deformations of door openings should be kept to a minimum. Thus, the structural members constituting the door opening must operate during frontal and rear impact near the elastic limit of the material. Increasing the size of a structural member, provided the packaging considerations permit it, may prove to be counter productive, since it may lead to premature local buckling and possible collapse of the member. With the current trend towards lighter vehicles, recourse to heavier gages is also counterproductive and therefore a determination of an optimum compartment structure may require a number of design iterations.In this article, FEA is used to simulate front side door behavior. Ford guidelines require the side doors, hatches and lift gates to be designed to remain closed during 35 mph perpendicular front (fixed) barrier crash tests. These guidelines also require the side doors to be designed to be capable of being opened without tools after the impact. While earlier analytical techniques  to handle door openability were based on door aperture deformation computations, this work describes a technique that is based on more realistic approach which directly simulates the process of door openability itself, using a finite element simulation. Therefore, it enables the simulation of an actual door behavior during and after perpendicular fixed barrier impacts.