Method for improving the energy absorbing characteristics of automobile components

• US 6,907,391 B2
• Filed: 03/02/2001
• Issued: 06/14/2005
• Est. Priority Date: 03/06/2000
• Status: Expired due to Fees

• Current Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Original Assignee: Johnson Controls Technology Company (Johnson Controls International plc)
• Inventors: Lambrecht, Martin, Van Poolen, Lambert J., Bellora, Val A., Krauss, Ryan W., Thoma, Paul E.
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Ferris, Fred
• Application Number:
  US09/797,925
• Publication Number:
  US 20020013686A1
• Time in Patent Office: 1,565 Days
• Field of Search: 703/8, 703/7, 703/6, 706/45
• US Class Current: 703/8
• CPC Class Codes: B60R 2021/0048 Head
• CPC Class Codes: B60R 21/04 Padded linings for the vehicle interior ; Energy absorbing structures associated with padded or non-padded linings

Abstract

A method is disclosed for designing an energy-absorbing impact zone for a vehicle interior, including acquiring test data representative of an occupant, determining a force versus deflection curve for the vehicle impact zone, analyzing the force versus deflection curve, and utilizing the analysis to adjust the stiffness of the energy-absorbing impact zone and to shape the force versus deflection curve so that a constant area under the force versus deflection curve has the minimum deflection possible without exceeding a certain force limit and a certain head impact criterion.

Claims

1. A method for designing an energy-absorbing impact zone for a vehicle interior, comprising:

acquiring test data representative of an acceleration versus time relationship for a head of an occupant impacting the impact zone;

determining a force versus deflection curve for the impact zone based on the test data;

determining a total deflection of the energy-absorbing impact zone; and

shaping the force versus deflection curve to minimize a deflection by selecting a countermeasure material having a thickness and adjusting the a stiffness of the material without exceeding a certain force limit and a certain head impact criterion.

2. The method of claim 1, wherein the force versus deflection curve represents data resulting from one or more dynamic head impact tests.

3. The method of claim 2, wherein the head impact criterion has an upper design limit of approximately 1000 hu.

4. The method of claim 2, wherein the dynamic head impact tests include a simulated human head traveling at a speed representative of approximately 6.7 meters per second.

5. The method of claim 2, wherein the dynamic head impact tests include a simulated human head traveling at a speed representative of a published automotive industry standard.

6. The method of claim 1, wherein the force versus deflection curve corresponds to a substantially constant amount of energy absorption representative of approximately 102 joules.

7. The method of claim 1, wherein the force versus deflection curve corresponds to a substantially constant amount of energy absorption corresponding to a simulated human head traveling at a speed representative of a published automotive industry standard.

8. The method of claim 1, wherein the force versus deflection curve is derived from an acceleration versus time curve.

9. The method of claim 8, wherein the force versus deflection curve is evaluated for one or more of an initial slope limit, a shape criteria, an energy absorption amount, a peak deflection criteria and a peak force criteria.

10. The method of claim 9, wherein the initial slope limit applies for generally linearly-ramping force versus deflection curves.

11. The method of claim 10, wherein the initial slope limit for the generally linearly-ramping or concave force versus deflection curve is within the range from 175 to 260 N/mm.

12. The method of claim 9, wherein the initial slope limit does not apply to force versus deflection curves having a trapezoidal shaped curve or a square shaped curve.

13. The method of claim 1, wherein the step of shaping the force versus deflection curve includes minimizing deflection.

14. The method of claim 1, wherein the force versus deflection curve has an upper force limit representative of approximately 6.2 kN.

15. The method of claim 1, further comprising the step of modeling the energy-absorbing impact zone as a group of springs in series, wherein the springs are representative of a vehicle sheet metal portion, a countermeasure and a free motion headform.

16. The method of claim 1, wherein adjusting the stiffness of the energy-absorbing impact zone includes changing one or more of the countermeasure material and the countermeasure structure.

17. The method of claim 16, wherein the countermeasure material is selected from the group consisting of metal, glass, ceramic, polymer, paper, cardboard, synthetic fiber and natural fiber.

18. The method of claim 17, wherein the countermeasure structure has a form selected from the group consisting of solid, solid with a void pattern, porous, foamed, honeycombed, wave-shaped, ribbed, woven, corrugated, compressed, composite and layered.

19. A method of designing a vehicle impact zone that reduces the severity of injury to an occupant during a collision, comprising:

establishing a head impact criterion for quantitatively representing the severity of impact;

selecting a design threshold for the impact criterion;

conducting one or more dynamic impact tests;

using the dynamic impact test data to prepare one or more force versus deflection curves;

analyzing the force versus deflection curve data using a series spring analogy;

adjusting the stiffness of the impact zone;

shaping the force versus deflection curve without exceeding a certain force limit and the established head impact criterion.

20. The method of claim 19, wherein the dynamic impact tests include one or more dynamic head impact tests.

21. The method of claim 20, wherein the design threshold for the impact criterion has an upper limit of approximately 1000 hu.

22. The method of claim 20, wherein the dynamic head impact tests include a simulated human head traveling at a speed representative of approximately 6.7 meters per second.

23. The method of claim 20, wherein the dynamic head impact tests include a simulated human head traveling at a speed representative of a published automotive industry standard.

24. The method of claim 19, wherein the force versus deflection curves corresponds to a substantially constant amount of energy absorption representative of approximately 102 joules.

25. The method of claim 19, wherein the force versus deflection curve corresponds to a substantially constant amount of energy absorption corresponding to a simulated human head traveling at a speed representative of a published automotive industry standard.

26. The method of claim 19, wherein the force versus deflection curves are derived from one or more acceleration versus time curves.

27. The method of claim 26, wherein the force versus deflection curve is evaluated for one or more of an initial slope limit, a shape criteria, an energy absorption amount, a peak deflection criteria and a peak force criteria.

28. The method of claim 27, wherein the initial slope limit applies for generally linearly-ramping force versus deflection curves.

29. The method of claim 28, wherein the initial slope limit for the generally linearly-ramping force versus deflection curve is within the range from 175 to 260 N/mm.

30. The method of claim 27, wherein the initial slope limit does not apply to force versus deflection curves having a trapezoidal shaped curve or a square shaped curve.

31. The method of claim 19, wherein the step of shaping the force versus deflection curve includes minimizing deflection.

32. The method of claim 19, wherein the force versus deflection curves have an upper force limit representative of approximately 6.2 kN.

33. The method of claim 19, further comprising the step of modeling the energy-absorbing impact zone as a group of springs in series, the springs corresponding to a vehicle sheet metal portion, a countermeasure and a free motion headform.

34. The method of claim 19, wherein the step of adjusting the stiffness of the impact zone includes changing one or more of the countermeasure material and the countermeasure structure.

35. The method of claim 34, wherein the countermeasure material is selected from the group consisting of metal, glass, ceramic, polymer, paper, cardboard, synthetic fiber and natural fiber.

36. The method of claim 35, wherein the countermeasure structure has a form selected from the group consisting of solid, solid with a void pattern, porous, foamed, honeycombed, wave-shaped, ribbed, woven, corrugated, compressed, composite and layered.

37. A system for designing a countermeasure for an impact zone within a vehicle, comprising:

means for establishing a force versus deflection curve representing data from one or more impact tests between a free motion headform and the countermeasure;

means for establishing a head impact criterion;

means for analyzing the force versus deflection curve data using a series spring analogy;

means for shaping the force versus deflection curve to minimize deflection of the countermeasure based on the head impact criterion without exceeding a certain force limit.

38. The system of claim 37, wherein the head impact criterion is a maximum of approximately 1000 hu.

39. The system of claim 37, wherein the dynamic impact tests include a simulated human head traveling at a speed representative of approximately 6.7 meters per second.

40. The system of claim 37, wherein the countermeasure is tested using one or more of a static flat platen test, a dynamic flat platen test, a static round platen test, a dynamic round platen test, and a dynamic test using the free motion headform and the countermeasure, wherein the countermeasure is placed against a rigid background.

41. The system of claim 37, further comprising the step of selecting the countermeasure according to the countermeasure'"'"'s packaging space, cost, and energy absorption and deflection properties.

42. A system for designing a countermeasure for a vehicle comprising:

means for acquiring test impact data representative of one or more impacts of an occupant against an interior component of the vehicle;

means for identifying design criteria for limiting injury to the occupant during an impact against the interior of the vehicle;

means for representing the test impact data in a force versus deflection relationship;

means for selecting a material for the countermeasure including a structure characteristic having an impact performance that satisfies the design criteria.

43. The system of claim 42 further comprising means for determining a packaging space within which the countermeasure may be provided.

44. The system of claim 42 further comprising means for determining a deflection of the interior component using a series spring model.

45. The system of claim 42 further comprising means for determining a total deflection at a certain force limit.

46. The system of claim 45 wherein the total deflection comprises a deflection budget for deflection of a headform and deflection of the countermeasure and deflection of a vehicle component.

47. The system of claim 45 further comprising means for determining a package space for the countermeasure based on the total deflection.

48. The system of claim 42 further comprising means for shaping a curve representative of the force versus deflection relationship in one of a convex shape and a trapezoidal shape.

49. The system of claim 42 further comprising means for converting flat platen-based material test data to reflect impact by a rounded headform.

50. The system of claim 42 further comprising means for determining an effective radius to account for a geometry of a vehicle component.

51. A system for designing a head impact countermeasure for a vehicle component comprising:

means for developing a force versus deflection curve representative of an impact between a head form and the vehicle component;

means for establishing a total deflection based on a certain force limit;

means for determining a packaging space adjacent to the vehicle component within which the head impact countermeasure may be provided; and

means for selecting a material for the head impact countermeasure.

52. The system of claim 51 further comprising means for transforming flat platen material test data for use with a rounded headform.

53. The system of claim 51 further comprising means for determining a structural shape of the material.

54. The system of claim 51 further comprising means for modeling the total deflection as a sum of individual springs.

55. The system of claim 51 further comprising means for shaping the force versus deflection curve to minimize deflection within a maximum force threshold.

56. The system of claim 51 further comprising means for selecting the material for the head impact countermeasure using a deflection budget.

57. The system of claim 51 further comprising means for selecting the material for the head impact countermeasure using an energy budget.