SUMMARY
The realistic estimation of the ply stiffness parameters of polymer composite laminates is a big challenge nowadays in industrial practice. In this paper a new, innovative concept is introduced that is based on the backward use of Classical Laminate Theory (CLT). The innovation in this new concept is (amongst others): possibility to infer the stiffness constants from the simple mechanical tests of specimens with multidirectional ply stack-up identical to the part to design. In addition the new method is manifested in a form of a compact equation that surely returns the measured deformation of the tested specimen on laminate level. The mathematical background of this concept is slightly more complex than what the conventional techniques offer, however its explicit form allows to code it in any automatic systems (e.g. user script) that can be run in Finite Element environment or as part of the software of a mechanical testing frame.