Design and optimization of a plasma facing component calls for dedicated constitutive laws which can handle the non linear behaviour typical of composite materials when applying this class of materials. This paper depicts the different phases of characterization and modelling which are required. Compared to a classical elastic analysis, this approach provides a more realistic estimate of the stress distribution within a thermally loaded PFC as demonstrated by finite element computations performed on a plasma facing component with a macrobloc[registered trademark] geometry.