A computer-aided tool to quickly analyse variabilities in flexible assemblies in different design scenarios

In automotive and aeronautic fields, within the common context of manufacturing and assembly of flexible products, such as sheet metal parts, controlling the final shape of the assembly is a key issue. Even assuming as known the shape errors in single manufactured parts, the assembly process can cause wide variability due to the flexibility of parts and to the choice of fixture and clamping frames as well as to the fastening technique adopted. Variations at part level propagate through the assembly due to both assembly sequence and process variability; therefore it is strategic to analyse different assembly configurations at the beginning of the design phase and chose the one that assures less variability on the key characteristics to be achieved. The paper presents a computer tool, based on finite element analysis, which is able to statistically analyse variations occurring in assembly processes of flexible parts. The tool offers a graphical environment to import finite element shell meshes and pre-process them by assigning fixtures, clamping points as well as fastening joints and related statistical variability. Contacts between parts can be also assigned. The output is given in terms of statistical variability of the key characteristics both graphically and numerically. The linear model behind the tool allows to quickly spam a variety of design solutions predicting failures and controlling final variations. Therefore, the tool could be used to anticipate the analysis of flexible assemblies providing useful and necessary information related to joint configurations and positions of fixtures as well as to assembly sequences