A geometric algorithm to evaluate the thickness distribution of stretched sheets through finite element analysis

Industry 4.0 aims to digitalize the manufacturing process to increase the productivity and the product quality of plants. A fundamental aspect of the digitalized manufacturing processes is the simulation of the manufacturing process in order to develop its virtual representation, known as digital twin, whose purposes may be monitoring, and control. Algorithms to elaborate the simulated data in order to improve the control of the manufacturing process are very important and they need to be developed. Sheet metal forming is a widely used process to manufacture parts with a high production rate and a low cost. The thinning of the stretched sheet needs to be controlled in detail, because it is strongly connected with the product quality. This work presents a simulation model and a geometric algorithm to evaluate the thickness distribution of a sheet stretched through a forming process. In order to accurately evaluate the thickness trend, a geometric algorithm was proposed which, on the basis of the position of the nodes of the internal and external surface of the sheet, was able to evaluate the thickness value. It enables finding of the minimum value of the stretched sheet thickness. The geometric algorithm was slightly modified, in a second step of the work, to experimentally evaluate the thickness trend of a sheet stretched by a forming process; it was applied to the measurement points obtained through a coordinate measurement machine on the inner and outer surfaces of the sheet. The numerical–experimental comparison of the results shows the appropriateness of the proposed algorithm for numerical data.