The understanding of the weld formation process in FSW is difficult due to: (1) the complexities resulting from coupled physical phenomenon’s (thermo mechanical and metallic process); (2) the difficulties characterizing exactly the interactions between the tool and the materials (friction, 3D material flow, …); (3) the collecting of complete and relevant information during the generation of the weld. Technological studies prove that FSW process is easy to realise. In addition to that, the welds may have good mechanical behaviours, in comparison with those resulting from traditional fusion welding as GMAW. The challenge is to relate the main and relevant parameters of the process (geometry of the tool, topologies of the assembly, others parameters such as axial force, torque, tool positioning, the nature of materials to be assembled,..) to the mechanical properties expected for that weld The study proposes an analogical simulation in a modeling clay (plasticine) workpieces environment. The goal is to obtain a better understanding of the joining creation in the case of butt join of homogeneous assembly of two flat plates made of aluminium alloy AA2017T351. By varying different parameters such as geometrical conditions of assembly, geometry of the tool, other kinematics parameters, we can measure the consequences on the dimensional morphology of the weld. The latter is then characterized by geometrical parameters such as penetration, area of the join, geometrical offset between tool axis and weld interface, and chromatic parameters… . A comparison between the assembly of two aluminium alloys sheets and the equivalent in plasticine workpieces will be discussed, so as to outline differences and analogies between them.