Energy absorbing apparatus
Described herein are energy absorbing apparatuses and methods of their use that utilize varying energy absorbing relationships between the apparatus members to absorb an energy input. The energy absorbing process occurs via a material forming process.
1. An energy absorbing device, comprising:
a line having a first end that extends and retracts from the energy absorbing device, and an opposing end of the line coupled to at least one energy absorbing member,
wherein, when the first end of the line extends from the energy absorbing device at a rate below a predefined threshold, the first end of the line is free to move relative to the at least one energy absorbing member, and when the first end of the line extends from the energy absorbing device at a rate beyond the predefined threshold, the at least one energy absorbing member engages the line and applies a retarding force on the line, transferring kinetic energy from the line into work energy by plastic deformation of the at least one energy absorbing member, plastic deformation being by tube drawing wherein the energy absorbing member includes a tube, and
the tube is plastically deformed during tube drawing by pulling the tube through a die.
2. The energy absorbing device as claimed in claim 1 , wherein the retarding force results in a halt in movement of the first end of the line.
3. The energy absorbing device as claimed in claim 1 , wherein an external force imposes motion to the first end of the line.
4. The energy absorbing device as claimed in claim 1 , wherein the first end of the line moves in a linear direction and the retarding force applied to the first end of the line is a linear force.
5. The energy absorbing device as claimed in claim 1 , wherein the retarding force is applied in a direction substantially opposite a direction of travel of the first end of the line.
6. The energy absorbing device as claimed in claim 1 , wherein a rate at which kinetic energy is absorbed by the at least one energy absorbing member is related to:
a force or torque applied to the at least one energy absorbing member by the line; and/or
a distance travelled or rotated by the first end of the line.
7. The energy absorbing device as claimed in claim 1 , wherein the at least one energy absorbing member has substantially uniform material characteristics resulting in a substantially linear retarding force being applied to the first end of the line.
8. The energy absorbing device as claimed in claim 1 , wherein the at least one energy absorbing member has non-uniform material characteristics resulting in a non-linear retarding force being applied to the first end of the line.
9. The energy absorbing device as claimed in claim 1 , wherein the energy absorbing device is a self-retracting lifeline.
10. The energy absorbing device as claimed in claim 1 , wherein the first end of the line rotates and the retarding force applied to the first end of the line applies a torque to the first end of the line.
11. The energy absorbing device as claimed in claim 1 , wherein the plastic deformation by tube drawing comprises plastic deformation by tube inversion.
12. The energy absorbing device as claimed in claim 1 , wherein the tube has a first diameter before being pulled through the die, and a second diameter after being pulled through the die, the first diameter being different to the second diameter.
13. A method of absorbing energy using an energy absorbing device comprising:
a line having a first end that extends and retracts from the energy absorbing device, and an opposing end of the line coupled to at least one energy absorbing member,
wherein, when the first end of the line extends from the energy absorbing device at a rate below a predefined threshold, the first end of the line is free to move relative to the at least one energy absorbing member, and when the first end of the line extends from the energy absorbing device at a rate beyond the predefined threshold, the at least one energy absorbing member engages the line and applies a retarding force on the line, transferring kinetic energy from the line into work energy by plastic deformation of the at least one energy absorbing member,
the method comprising:
applying a motion causing energy input on the first end of the line that exceeds the predefined threshold thereby triggering the at least one energy absorbing member to absorb at least part of a kinetic energy of the first end of the line by:
a tube drawing process wherein the energy absorbing member includes a tube, and the tube is plastically deformed during tube drawing by pulling the tube through a die.
14. The method as claimed in claim 13 , wherein the tube drawing process comprises a tube inversion process.
15. The method as claimed in claim 13 , wherein the tube has a first diameter before being pulled through the die, and a second diameter after being pulled through the die, the first diameter being different to the second diameter.