Energy-dissipating cover and methods for making the cover

An energy dissipation system, comprising:

• a component sensitive to mechanical impulse, the component comprising one of a battery, an engine component, a transmission component and an exhaust component;
• and
• an energy-dissipating cover disposed so as to cover the component, the energy-dissipating cover comprising:
• a sheet of metal selected from a ferrous alloy having a yield strength of at least 900 MPa, a ferrous alloy having a strain hardening index of at least 0.15 and an aluminum alloy having a yield strength of at least 200 MPa, the sheet defining in-plane and orthogonal out-of-plane directions and having a top surface facing the component, a bottom surface, an outer perimeter, an overall area within the outer perimeter and a nominal thickness of no more than 2.5 mm, wherein the sheet is configured for connection with one or more external structures at a plurality of connection points within the outer perimeter, wherein the overall area comprises a plurality of supported areas and at least one unsupported area that does not overlap any of the supported areas, wherein each of the supported areas runs along the outer perimeter, surrounds at least one of the plurality of connection points, surrounds one or more folds formed in the sheet, and/or surrounds one or more reinforcements attached to the sheet;
• and
• a plurality of embossments formed within the at least one unsupported area and extending outward from the bottom surface, wherein the embossments are shaped, sized and arranged so as to be effective for dissipating in-plane a substantial portion of a kinetic energy of a mechanical impulse of 85 J having a duration of no more than 10 ms directed normal to the bottom surface of the sheet at the plurality of embossments and for limiting orthogonal deflection of the sheet from the mechanical impulse to no more than 12 mm;
• wherein each of the plurality of embossments is generally hemisphere-shaped, generally pyramid-shaped, generally delta (Δ)-shaped, generally frusto-hemisphere-shaped, generally frusto-pyramid-shaped or generally sigma (Σ)-profiled.

A method of forming a plurality of embossments in a sheet of metal selected from a ferrous alloy having a yield strength of at least 900 MPa, a ferrous alloy having a strain hardening index of at least 0.15 and an aluminum alloy having a yield strength of at least 200 MPa, the sheet defining in-plane and orthogonal out-of-plane directions and having a top surface, a bottom surface, an outer perimeter, an overall area within the outer perimeter and a nominal thickness of no more than 2.5 mm, wherein the sheet is configured for connection with one or more external structures at a plurality of connection points within the outer perimeter, wherein the overall area comprises a plurality of supported areas and at least one unsupported area that does not overlap any of the supported areas, wherein each of the supported areas runs along the outer perimeter, surrounds at least one of the plurality of connection points, surrounds one or more folds formed in the sheet, and/or surrounds one or more reinforcements attached to the sheet, the method comprising:

• placing the sheet on a first surface of a female die, the first surface having a plurality of embossment cavities arranged thereon;
• inductively heating the sheet at one or more loci on the sheet which correspond to respective locations of a selection of the plurality of embossment cavities;
• positioning a male die over the sheet and the female die, wherein the male die has one or more embossment protrusions which correspond in size, shape and arrangement to the selection of embossment cavities, such that the one or more embossment protrusions are disposed in registration with the selection of the plurality of embossment cavities;
• and
• pressing the sheet at the one or more loci with the one or more embossment protrusions so as to form the plurality of embossments in the sheet, wherein the embossments are formed within the at least one unsupported area and extend outward from the bottom surface, wherein the embossments are shaped, sized and arranged so as to be effective for limiting to no more than 12 mm an orthogonal deflection of the sheet from a mechanical impulse, wherein the mechanical impulse is directed normal to the bottom surface of the sheet at the plurality of embossments and has a kinetic energy of 85 J and a duration of no more than 10 ms.