How i can estimate the properties of 4D composites? Has anyone had to deal with the tests of carbon-carbon composites 4D? Can anyone suggest a method of assessing their properties in different directions without destruction? Non-destructive method. Macroindentation shows that in all directions the properties are the same. Material is like isotropic. I think this is due to the fact that the load is applied to the the entire frame and the shear strains are almost none. The compression test shows that the properties differ in 3 times ( strength and modulus). Properties of different components - pitch, fibers - are different (they were determined by micro- and nanoindentation).
I haven't really understood about what material there is a speech. But in the 80th years 4-d materials called composites with laying of fibers in the directions of a tetrahedron. They have no naturally "fourth measurement", and there is a cubic symmetry and they are described by three modules of elasticity instead of two at isotropic bodies. I with work then was helped by "The theory of elasticity" Landau and Lifshits, in her there are ready formulas for cubic crystals.
The problem is that if we carry out the macroindentation GOST R 8.748— 2011 (ISO 14577-1:2002) in various directions along the axes of the reinforcement, we get absolutely identical results. If we carry out the compression test (destructive testing), the values of strength and elastic modulus are different. What could be the reason?
I doubt a possibility of application a microindentorah for determination of properties of materials with such structure. As the size of a cell of material will be more than the size an indentorah. We defined properties on the usual macrosamples which are cut out in various directions. Once, i was determin properties of all block, by wire strain gages and Instron of 120 tons. I obtained 3 modules of elasticity
If we carry out the compression test (destructive testing), -why destructive ???
But we carry out MACROindentation. The radius of the indenter is about 10 mm. The indentation depth is about 2 mm. Load - 5000 N.
I personally, wouldn't begin to apply a similar technique to anisotropic materials. The result can't be interpreted correctly M. Friedman from НИИГрафит tried to develop such technique for isotropic graphite. For your materials all characteristics precisely are defined by standard methods and without destruction. To material in your drawing about 50 years, on him it is possible to find data.
- Badges
- Science topic