Multi-stage energy absorber

An energy absorbing liner system that is interposed between an incident surface that receives an impacting force and a mass to be protected from at least some of the impacting force, the energy absorbing liner system having

• one or more energy absorbing modules that offer a dual stage resistance to impacting forces, one or more of the energy absorbing modules having
• a basal layer between the incident surface and the mass to be protected;
• a first stage energy absorber extending from the basal layer toward the mass to be protected with one or more membranes that bend and /or collapse and have domed thin tops at least some of the membranes offering a first level of reaction to impacting forces that are low or high energy impact events normal to and inclined or tangential to the mass to be protected;
• a second stage energy absorber extending from the basal layer toward the incident surface the second stage energy absorber having one or more energy absorbing units, the energy absorbing units extending from the basal layer the energy absorbing units having a wall with an upper perimeter proximate the basal layer, the energy absorbing units providing a second level of reaction to what remains of the impacting forces after at least partial absorption by the one or more membranes, the one or more energy absorbing units at least partially absorbing energy generated by an impacting object by the wall bending inwardly or outwardly or inwardly and outwardly without rupture,
• ribs formed from the basal layer that extend between adjacent pairs of the energy absorbing units, the ribs forming a quadrilateral pattern, one of the membranes lying within the quadrilateral pattern;
• and
• wherein at least some of the membranes have a stiffness characteristic such that the second stage energy absorber is between 2 and 10 times stiffer than the membranes in the first stage, the first stage thereby at least partially absorbing low energy impacts and reducing shear and rotational forces experienced by the mass to be protected and thus providing an energy absorber that offers at least two levels of reaction to the impacting force.