This thesis involves the derivation of a constitutive model under large deformationtheory using Updated Lagrange method applied on an orthotropic material.Thefollowing aspects are included in this thesis work: introduction, theory, FEM implementation, derivation of constitutive model, calibration, result, discussion, conclusion and the future work. This thesis studies the deformation behavior of wood, which is widely used as aconstruction material, in an advanced and more detailed way by analyzing the mechanical properties of wood from both, the application in laboratory and theoreticalcalculation under large deformation theory. A non-linear elastic constitutive model is proposed, derived and calibrated using asimple inverse analysis procedure. The calibration process was performed to identify8 constitutive parameters A1 − A8 of the constitutive model by performing inverseanalysis against relevant experimental data acquired using the Aramis system. Theresults in the comparison were extracted from the specimen when it is both intangential orientation and radial orientation. The project work will be dedicated to the development of a Finite Element Method(FEM) code implemented in MATLAB scripts which was directly used to study themechanical properties of the orthotropic wood material when hyper-elastic behavioris assumed. The results will contain three parts: 1) study of the influence of pith location onthe load required to deform the specimen specimen, 2) reaction force comparisonof the model results against experimental results, and, 3) comparison of the GreenLagrangian strain pattern over the specimen between the experimental data and themodel’s results.