The aim of the paper was to compare experimentally measured values and bending test simulations. Specimens was created by 3D printing. Material for specimens is composite Onyx. The samples were different in the internal structure. The inner structure has a different shape and size. Flexural test measured stress from the force required to bend a beam under three points loading conditions.  Aim this paper was to find out the data, which will used to select choice size and shape of the inner structure dimensions for parts that will loads with flexing.  By optimizing the size and shape of the inner structure to ensure the choice of the right structure for a given issue with regard to material consumption. The samples are sized according to ISO 178. The test was carried out according to ASTM D790 and next ISO 178. Test measured the force required to bend the specimen he test is stopped when the specimen reaches 5 % deflection or the specimen breaks before 5 %. If the sample can withstand the desired deflection, the test will continue by norm ISO 178 and the test is stopped when the specimen breaks. The same was simulated in Ansys workbench using the FEM calculation method. These data processed in tables and graphs and mutually compared with boundary values. The lower limit or value will be a hollow sample. The upper limit was a solid sample where the highest stiffness is expected.

Acknowledgements: This work was supported by the Slovak Research and Development Agency under the contract No. KEGA 037ŽU-4/2018.