cnclite1,
ad_bfl was planning on working on the vibratory spectrum although he is a bit quiet of late.
The sizes that you have specified for ceramic spheres are much too large for optimum modulus and compressive strength and the size range is much too small. To keep the aggregate percentage up, one needs 4 orders of magnitude of difference between the biggest and smallest sizes. We have been thinking of using 3M zeeospheres which are tiny ceramic spheres for the smaller sizes.
There are published results in the A.J. Kinloch book that explain that increased aggregate size leads to larger critical flaws vis-a-vis griffith critical flaw size. Also, with the low size range, you'll have so much epoxy that the resultant material will not be very rigid. Epoxy is strong but has an abysmal modulus compared to aggregate.
Would recommend the strong glass fiber, s glass if I remember right. Also, make sure that the fiber length is about 1 inch as rule of thumb shows that this is almost as strong as full length fibers if they are aligned.
Most of the work we've done is with reichhold 37-127/37-606 available from shopmaninc as their low viscosity slow setting formulation. Neither is ideal due to low strength, low modulus, deairing problems and slightly higher viscosity than some other choices. I haven't been able to run to ground the other choices.
For aggregate, see
http://www.cnczone.com/forums/showpo...postcount=3241
For the relationship between epoxy percentage and stiffness aka modulus see:
http://www.cnczone.com/forums/showpo...postcount=3119
Regards all,
Cameron