技术问题语段：
The technical problem addressed in this patent is to provide an improved impact mitigating structure and method for designing it, to better protect the wearer from injury caused by impact. The invention is designed to optimize the load mitigation of the structure during an impact, by minimizing the force and peak acceleration experienced by the structure, while also considering the shape and other constraints of the structure. This helps to reduce the likelihood of injury and improve the safety and comfort of the impact mitigating structure.
权利要求：
Claims
1. A method of designing an impact mitigating structure; the method comprising:
determining the force exerted by an object on the impact mitigating structure as a function of the distance by which the object displaces an outer surface of the impact mitigating structure during an impact of the object onto the outer surface of the impact mitigating structure;
calculating a ratio of the integral of the force exerted by the object on the impact mitigating structure with respect to the distance by which the object displaces the outer surface of the impact mitigating structure during the impact to the product of the maximum force exerted by the object on the impact mitigating structure during the impact and the total distance by which the object displaces the outer surface of the impact mitigating structure during the impact; and
determining the respective values of one or more characteristic variables of the impact mitigating structure that maximise the ratio for use in designing the impact mitigating structure. 2. A method as claimed in claim 1 , wherein the impact mitigating structure comprises a cellular structure or a lattice structure.
3. A method as claimed in claim 2, wherein the cellular structure comprises a plurality of tessellating cells, wherein the plurality of cells each have a plurality of side walls that are shared with adjacent cells.
4. A method as claimed in claim 3, wherein the plurality of side walls extend perpendicularly to the surface of the impact mitigating structure. 5. A method as claimed in claim 3 or 4, wherein the cells each have a polygon shaped cross-section in a direction substantially perpendicular to the direction in which the side walls extend.
6. A method as claimed in claim 3, 4 or 5, wherein the one or more
characteristic variables comprise one or more of: the thickness of the side walls, the characteristic width of the cells, the height of the cells and the shape of the cells.
7. A method as claimed in claim 6, wherein the characteristic width of the cells is between 10 mm and 50 mm.
8. A method as claimed in claim 6 or 7, wherein the thickness of the side walls of the cells is between 0.4 mm and 5 mm.
9. A method as claimed in claim 6, 7 or 8, wherein the height of the cells is between 10 mm and 30 mm.
10. A method as claimed in any one of claims 6 to 9, wherein the shape of the cells has a hexagonal cross-section.
11. A method as claimed in any one of claims 6 to 10, wherein a relative density of the cells is between 0.025 and 0.07, wherein the relative density is approximately 2t/w, where t is the thickness of the side walls of the cells and w is the characteristic width of the cells.
12. A method as claimed in claim 2, wherein the lattice structure comprises a plurality of struts extending between a plurality of vertices.
13. A method as claimed in claim 12, wherein the one or more characteristic variables comprise one or more of: the length of the struts, the thickness of the struts and the geometry of the struts.
14. A method as claimed in any one of the preceding claims, wherein the impact mitigating structure comprises a curved outer and/or inner surface.
15. A method as claimed in claim 14, wherein the radius of curvature of the impact mitigating structure is between 60 mm and 140 mm.
16. A method as claimed in any one of the preceding claims, the method further comprising impacting an object on the impact mitigating structure to determine the force exerted by the object on the impact mitigating structure as a function of the distance by which the object displaces the outer surface of the impact mitigating structure during an impact of the object onto the outer surface of the impact mitigating structure.
17. A method as claimed in any one of the preceding claims, wherein the step of determining the respective values of one or more characteristic variables of the impact mitigating structure that maximise the ratio comprises repeating the steps of determining the force exerted by an object on the impact mitigating structure and calculating the ratio for a plurality of different respective values of the one or more characteristic variables.
18. A method as claimed in any one of the preceding claims, the method further comprising setting one or more constraints and determining the respective values of one or more characteristic variables of the impact mitigating structure that maximise the ratio within the one or more constraints.
19. A method as claimed in claim 18, wherein the one or more constraints comprises a maximum allowed deceleration of 250 g when using the impact mitigating structure.
20. A method of designing an impact mitigating structure; the method comprising:
determining the acceleration of the impact mitigating structure during an impact of an object onto the outer surface of the impact mitigating structure;
calculating, using the acceleration, an objective measure of the ability of the impact mitigating structure to mitigate the impact of the object on the impact mitigating structure; and
determining the respective values of one or more characteristic variables of the impact mitigating structure that optimise the objective measure for use in designing the impact mitigating structure.
21. A computer readable storage medium storing computer software code which when executing on a data processing system performs a method as claimed in any one of the preceding claims.
22. An impact mitigating structure designed according to the method of any one of claims 1 to 20.
23. A method of manufacturing an impact mitigating structure, the method comprising designing the impact mitigating structure according to the method of any one of claims 1 to 20, and manufacturing the impact mitigating structure using the respective values of the one or more characteristic variables of the impact mitigating structure that have been determined.
24. A method as claimed in claim 23, wherein the impact mitigating structure is manufactured using Additive Manufacturing.
25. A method as claimed in claim 23 or 24, the method further comprising generating a set of Additive Manufacturing instructions using the respective values of the one or more characteristic variables of the impact mitigating structure that have been determined; and manufacturing the impact mitigating structure according to the Additive Manufacturing instructions.
26. A method as claimed in claim 23, 24 or 25, wherein the impact mitigating structure is manufactured from and/or comprises a polymer, e.g. a polyamide, e.g. polyamide 11 , e.g. an elastomer, e.g. a thermoplastic elastomer, e.g. a polyether block amide (PEBA), e.g. ST PEBA 2301.
27. An impact mitigating structure manufactured according to the method of any one of claims 23 to 26.
28. An impact mitigating structure as claimed in claim 22 or 27, wherein the impact mitigating structure comprises a cellular structure comprising a plurality of tessellating cells, wherein the plurality of cells each have a plurality of side walls that are shared with adjacent cells, wherein the characteristic width of the cells is between 10 mm and 50 mm, wherein the cell wall thickness is between 0.4 mm and
5 mm, wherein the cell height is between 10 mm and 30 mm, wherein the ratio of twice the cell wall thickness to the cell width is between 0.025 and 0.07, and wherein the shape of the cells has a hexagonal cross-section. 29. An impact mitigating structure as claimed in claim 22, 27 or 28, wherein the impact mitigating structure is curved and the radius of curvature of the impact mitigating structure is between 60 mm and 140 mm.
30. An impact mitigating structure for protecting a user against an impact from an object, the impact mitigating structure comprising a cellular structure having a plurality of tessellating cells, wherein the plurality of cells have a plurality of side walls;
wherein the cellular structure comprises a curved inner surface having a radius of curvature between 60 mm and 140 mm;
wherein the width of each of the plurality of cells is between 10 mm and 50 mm ;
wherein the thickness of each of the plurality of side walls is between 0.4 mm and 5 mm; and
wherein the height of each of the plurality of cells is between 10 mm and 30 mm.