Fragmenting tube energy absorber

Claim 2

A frangible tube energy absorber comprising: a frangible tube; a die at one end of said tube and including a die radius for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward said die; means for applying an inwardly directed force against the outside of said tube adjacent said die radius, said means including a surface portion temporarily movable longitudinally with said tube opposite the die during fracturing of said tube, and wherein said surface portion is temporarily movable longitudinally in a direction opposite to the direction of said tube stroking, whereby propagation of longitudinal cracks above the die portion is inhibited for preventing premature failure of said tube; and comprising an elastically stretchable torus around said tube and having an internal surface portion engaging said tube.

Claim 3

An absorber as defined in claim 1 wherein said torus comprises an elastomeric ring having sufficient elastic elongation to roll along said tube.

Claim 4

A frangible tube energy absorber comprising: a frangible tube; a die at one end of said tube and including a die radius for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward said die; means for applying an inwardly directed force against the outside of said tube adjacent said die radius, said means including a surface portion temporarily movable longitudinally with said tube opposite the die during fracturing of said tube, and wherein said surface portion is temporarily movable longitudinally in a direction opposite to the direction of said tube stroking, whereby propagation of longitudinal cracks above the die portion is inhibited for preventing premature failure of said tube; and comprising a plurality of rollers around said tube each of said rollers having a concave tube engaging face with a constricted center portion and enlarged ends.

Claim 5

A frangible tube energy absorber comprising: a frangible tube; a die at one end of said tube and including a die radius for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward said die; means for applying an inwardly directed force against the outside of said tube adjacent said die radius, said means including a surface portion temporarily movable longitudinally with said tube opposite the die during fracturing of said tube, and wherein said surface portion is temporarily movable longitudinally in a direction opposite to the direction of said tube stroking, whereby propagation of longitudinal cracks above the die portion is inhibited for preventing premature failure of said tube; and comprising a plurality of rollers around said tube each of said rollers having a concave tube engaging face with a constricted center portion and enlarged ends.

Claim 6

An absorber as defined in claim 3 wherein said rollers each comprise a plurality of raised portions on said concave face for controlling fracture patterns of said tube.

Claim 7

An absorber as defined in claim 4 wherein said raised portions include ridges arranged transverse to the axis of said tube for inhibiting propagation of longitudinal fractures of said tube above said die.

Claim 8

An absorber as defined in claim 5 wherein said ridges are continuous substantially entirely along the length of the roller face.

Claim 9

An absorber as defined in claim 5 wherein said ridges are intermittent along the length of the roller face and are arranged in rows with raised portions in successive rows being staggered from raised portions in preceding rows.

Claim 10

A frangible tube energy absorber comprising: a frangible tube; a die at one end of said tube and including die radius for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward said die; means for applying an inwardly directed force against the outside of said tube adjacent said die radius, said means including a surface portion temporarily movable longitudinally with said tube opposite the die during fracturing of said tube, and wherein said surface portion is temporarily movable longitudinally in a direction opposite to the direction of said tube stroking, whereby propagation of longitudinal cracks above the die portion is inhibited for preventing premature failure of said tube; and said means for applying a force comprising a plurality of balls bearing on said tube.

Claim 11

A frangible tube energy absorber comprising: a frangible tube; a die at one end of said tube and including die radius for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward said die; means for applying an inwardly directed force against the outside of said tube adjacent said die radius, said means including a surface portion temporarily movable longitudinally with said tube opposite the die during fracturing of said tube, and wherein said surface portion is temporarily movable longitudinally in a direction opposite to the direction of said tube stroking, whereby propagation of longitudinal cracks above the die portion is inhibited for preventing premature failure of said tube; and said means for applying a force comprising a plurality of balls bearing on said tube.

Claim 12

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force including a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and a plurality of balls around said tube and bearing on the outside thereof.

Claim 13

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force including a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and a plurality of balls around said tube and bearing on the outside thereof.

Claim 14

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force includes a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and an elastically stretchable torus in tight engagement around said tube.

Claim 15

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force includes a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and an elastically stretchable torus in tight engagement around said tube.

Claim 16

A frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force including a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and a plurality of rollers around said tube and bearing on the outside thereof.

Claim 17

A frangible tube energy absorber having a frangible tube and a die at one end of said tube for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: means for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; said means for promoting transverse cracks and inhibiting longitudinal cracks comprising means for applying an inwardly directed force against the outside of said tube adjacent said die radius; said means for applying a force including a surface portion temporarily movable longitudinally with said tube during fragmenting thereof; and a plurality of rollers around said tube and bearing on the outside thereof.

Claim 18

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube including a die portion for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: indentations formed on the surface of said tube and disposed at an angle to the tube axis for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; and said indentations are stress-raising indentations in a tube surfacE, said indentations each extending no more than a short length.

Claim 19

In a frangible tube energy absorber having a frangible tube and a die at one end of said tube including a die portion for fracturing said tube into a plurality of discontinuous fragments upon longitudinal stroking of said tube toward such die, the improvement comprising: indentations formed on the surface of said tube and disposed at an angle to the tube axis for both promoting formation of cracks transverse to the tube axis and for inhibiting propagation of cracks parallel to the tube axis; and said indentations are stress-raising indentations in a tube surfacE, said indentations each extending no more than a short length.

Claim 20

A frangible tube energy absorber as defined in claim 12 wherein said indentations are formed as said tube is stroked into said die.

Claim 21

A frangible tube energy absorber as defined in claim 12 wherein said indentations are formed before said tube is assembled onto said die.

Claim 22

A frangible tube energy absorber as defined in claim 14 wherein said indentations are on the outside surface of said tube.