Re: anisotropic material, experiment

[EMAIL PROTECTED] (dave martin) wrote in message news:<[EMAIL PROTECTED]>...
> [EMAIL PROTECTED] (Sergey Litvinov) wrote in message news:<[EMAIL PROTECTED]>...
> > Is it possible to measure constants of linear anisotropic material by
> > experiments?
> > 
> > Material is elastic. And we are interesting in the general case of
> > anisotropy (21 constants).
> 
> Yes it is possible.  There is no ambiguity in the physical meaning of
> the relationships.

........

While determining all 21 constants must be possible by imposing
strains and measuring responses it is not easy to do. In the most
general case a large number of difficult measurements will be
required.

You might consider meaurements that involve photoelastic coatings to
gather a lot of data with a single experiment. For example, one might
drill a deep hole in a sample's surface, then impose a well defined
stress (or strain) state far from the hole. A photoelastic coating
will show the local strain state around the hole. The details of the
local strain state are determined by the local boundary conditions,
elastic constants, and remote strain field.

As a simple example, consider cutting a square sample from a plate and
drilling a small hole in the center. Impose a uniaxial deformation at
the sample boundaries. The local strain field expected around the hole
for an ideal isotropic material is well known; deviations from that
field must be due to non-zero elastic constants.