Test method

Abstract

A test method for determining suitable parameters for the mathematical representation of the characteristic performance of a material. The test method comprises: a contact test, where two bodies are pressed together and deformation occurs which can be measured. Computational modelling of the contact test takes place, initially using estimated material characteristic parameters and finally optimising the choice of the material characteristic parameters to minimise the difference between the real test measurement results and the computational analysis results. The intention is to use simple test equipment, such as material hardness test machines, together with computational analysis, to obtain high quality materials characterisation for parameters, for example for a Johnson-Cook representation of steel, to model ratchetting (plastic strain accumulation under cyclic loading), to model creep performance, or materials loaded under high strain rates.

Claims

1. A test method in which two bodies of any shape which are pressed together in mechanical contact, to the extent that at least one of the bodies becomes deformed and that deformation can be measured, and a computational modelling process of the pressing together of those bodies that can be repeated with different material characteristic parameters corresponding to the material properties of one or both bodies, and an computational scheme that can optimise the material characteristic parameters so that the difference between the computational model prediction and the measurements from the real test are minimised.

2. A test method as in claim 1, where either or both bodies has at least one internal void, which is positioned in sufficient proximity to the point of contact that the void has a measurable change in shape during the mechanical contact test.

3. A test method as in claim 2, where there is a multiplicity of internal voids.

4. A test method as in claim 2, where at least one of the voids is of circular cross-section.

5. A test method as in claim 2, where at least one of the voids is elongated in cross-section, withvariable width.

6. A test method as in claim 5, where at least one of the elongated voids has a non-straight form.

7. A test method as in claim 5, where at least one of the elongated voids has a branchedstructure.

8. A test method as in claim 2, where at least one void extends through the surface.

9. A test method as in claim 1, where the shape of the contacting region of at least one of the bodies is segmented about a central axis, where the shape of each segment is a partial solid of revolution.

10. A test method as in claim 1, where the shape of the contacting region of at least one of the bodies is that of a complete solid of revolution.

11. A test method as in claim 1, where the shape of the contacting region of at least one of the bodies is polyhedral based pyramid, where the apex of the pyramid is the point of first contact.

12. A test method as in claim 1, where the shape of the contacting region is a 2D extrusion.

13. A test method as in claim 12, where the contacting region is domed at the point of contact14. A test method as in claim 12, where there is at least one void in sufficient proximity to the point of contact that the void has a measurable change in shape during the mechanical contact test.

15. A test method as in claim 14, there at least one void is a complete 2D extrusion passing through the entirety of the body.

16. A test method as in claim 15, where at least one void is cylindrical.

17. As in claim 12, where the contacting region has two flat sides which meet at a point at the point of contact.

18. A test method as in claim 17, where there is at least one void in sufficient proximity to the point of contact that the void has a measurable change in shape during the mechanical contact test.

19. A test method as in claim 18, where there at least one void is a complete 2D extrusion passing through the entirety of the body.

20. A test method as in claim 19, where at least one void is cylindrical.

21. A test method as in claim 12, where the contact region is undulating.

22. As in claim 21, where there is at least one void in sufficient proximity to the point of contact that the void has a measurable change in shape during the mechanical contact test.

23. A test method as in claim 2, where the mathematical form of the material characteristic for which the parameters are to be determined is the Johnson-Cook plasticity model.

24. A test method as in claim 2, where the mathematical form of the material characteristic for which the parameters are to be determined models kinematic strain hardening.

25. A test method as in claim 2, where the mathematical form of the material characteristic for which the parameters are to be determined include parameters for strain-rate effects.Application No: GB2400713.0Claims searched: 1-25Examiner: Mr Joe McCannDate of search: 17 June 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-25 WO 2012 / 168404 Al (VENEZIA TECNOLOGIE SPA)- See abstract, page 13, line 24 to page 14, line 3 and figures 7 and 8 X 1-25 US 2020 / 0249138 Al (SCHMALING et al.) - See abstract and paragraph 13 X 1-25 GB 2607931 A (PLASTOMETREX LTD) - See abstract, page 10, lines 14-23 and figure 2 X 1-25 GB 2615332 A (PLASTOMETREX LTD) - See abstract, page 1, lines 24-34 and figure 6 X 1-25 US 6731996 Bl (MACEWEN et al.) - See abstract and figure 5 v A 1-25 CN 116664531 A (SHENZHEN INSTITUTE OF NORTHWESTERN POLYTECHNICAL UNIV) - See whole documentCategories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if combined with one or more other documents of same category. P Document published on or after the declared priority date but before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From G06T 0007 / 00 01 / 01 / 2017 G06F 0030 / 20 01 / 01 / 2020 GOIN 0003 / 08 01 / 01 / 2006 GOIN 0003 / 40 01 / 01 / 2006

Images