Energy-absorbing structure with defined multi-phasic crush properties

An impact-absorbing structure, comprising:

• a plurality of pre-formed sheets stacked and coupled in an alternating arrangement, wherein the plurality of pre-formed sheets comprises sheets of a first amplitude alternating with sheets of a second lower amplitude, wherein a series of cells are defined by the plurality of pre-formed sheets stacked and coupled in the alternating arrangement and each cell of the series of cells has at least a first sidewall and a second opposing sidewall, an open space there-between, and a longitudinal axis passing through the open space, at least a portion of the first and second sidewalls being shared between one or more adjacent cells of the series of cells, and
• an ordered series of geometric perturbations uniformly distributed within the structure and located in the first and second sidewalls imparting a controlled stiffness response having a lower compressive stiffness under initial compression and a subsequent higher compressive stiffness under further compression, wherein each sidewall of the first and second sidewalls has a single geometric perturbation, the single geometric perturbation of each sidewall of the first and second sidewalls collectively forms the ordered series of geometric perturbations,
• wherein the ordered series of geometric perturbations are oriented in a direction that is not parallel to the longitudinal axis and project out of a plane of the first and second sidewalls without an applied load, wherein at least one of said single geometric perturbation of the ordered series of geometric perturbations is concave relative to a first cell of series of cells and convex relative to a second cell of the series of cells adjacent to the first cell, wherein compression of the series of cells is initiated at the ordered series of geometric perturbations in response to the applied load.