an anti - intrusion beam for incorporation into a vehicle door assembly is manufactured from an outer skin formed from laminated layers of composite materials having fiber reinforcement oriented in a directional pattern in each respective layer . the anisotropic beam includes body members having an interior core formed of high density foam plastic . the transversely corrugated beam includes attachment areas that have the same corrugated configuration which are fastened to mounting lugs of an inner door panel arranged in a corresponding corrugation . variations in the thickness and formation of the layers of the outer skin can be used to control the failure of the beam during impact to provide a progressive predicable failure pattern for the beam . a frame catcher can be inserted into the body portions of the anti - intrusion beam to permit the transfer of impact forces to the frame of the vehicle .