a energy absorbing structure is disclosed for the purpose of protecting human occupants of a vehicle from the damaging effects of sudden accelerative or decelerative forces by means of plastic deformation of the structure . the structure consists of a generally rectangular sheet of a stranded material , preferably expanded metal , which has nonisotropic properties and which is employed in the construction of the bottom or back of a seating structure for the vehicle occupant . the nonisotropic properties of the sheet allow it to be designed in such a way that it resists deformation when exposed to any force below a specified threshold ; beyond the specified threshold , the sheet absorbs the force through plastic deformation , thus attenuating damaging force to which the occupant may be exposed . such a device may be used in the seating apparatus of various vehicles , including aircraft , automobiles , space vehicles , helicopters , heavy machinery , tractors , military vehicles , and the like .