Numerical analysis of the ISF process on sheet with locally modified material flow stress

The strategies of product making are considering how they affect the environment. In this scenario, production is pushing to new strong and lightweight materials and to a more suitable mass distribution to use the right material in the right place. An optimal design can be reached by both a proper material selection and use considering the stress distribution on the parts during their life in service. Flexibility in production is essential to be able to shape the products as designed. Incremental sheet forming (ISF) is a flexible manufacturing process, which allows processing various lightweight alloys. Severe sheet thinning is one of the main ISF limitations hindering the quality of the formed components and the efficiency of the production. These limitations result in an appeal weakening of ISF for industrial purposes. To overcome that, the material flow during ISF should be directed considering the strain level of the formed areas. Herein, the research aims at incrementally forming sheets, whose properties were modified locally by heat treatments. For example, the sheet properties can be tailored by laser light, which goes to modify the microstructure of the alloy in specific areas, considering the strain path given to the sheet. The goal is the inhomogeneity reduction of thickness distribution of the sheet. To investigate the problem in a wide range of variability, a numerical model has been set up. Specifically, a flat mesh was first defined and, subsequently, the material properties have been assigned to shell elements considering the differences in the material flow stress ascribable to the grain structures. The material data were extracted by literature. Conical frustums with helical tool path were numerically produced. An intensive understanding on how the ISF mechanism is influenced, if the sheet properties are locally customized, is provided.