title: An inverse method for determining the spatially resolved properties of viscoelastic-viscoplastic three-dimensional printed materials.
abstract: A method using experimental nanoindentation and inverse finite-element analysis (FEA) has been developed that enables the spatial variation of material constitutive properties to be accurately determined. The method was used to measure property variation in a three-dimensional printed (3DP) polymeric material. The accuracy of the method is dependent on the applicability of the constitutive model used in the inverse FEA, hence four potential material models: viscoelastic, viscoelastic-viscoplastic, nonlinear viscoelastic and nonlinear viscoelastic-viscoplastic were evaluated, with the latter enabling the best fit to experimental data. Significant changes in material properties were seen in the depth direction of the 3DP sample, which could be linked to the degree of cross-linking within the material, a feature inherent in a UV-cured layer-by-layer construction method. It is proposed that the method is a powerful tool in the analysis of manufacturing processes with potential spatial property variation that will also enable the accurate prediction of final manufactured part performance.
authors.affiliation: Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering , University of Nottingham , NG7 2RD, UK.
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.affiliation: Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering , University of Nottingham , NG7 2RD, UK.
authors.forename: I A
authors.initials: IA
authors.lastname: Ashcroft
authors.affiliation: Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering , University of Nottingham , NG7 2RD, UK.
authors.forename: R D
authors.initials: RD
authors.lastname: Wildman
authors.affiliation: Additive Manufacturing and 3D Printing Research Group, Faculty of Engineering , University of Nottingham , NG7 2RD, UK.
authors.forename: C J
authors.initials: CJ
authors.lastname: Tuck
keywords: inverse finite-element analysis; nanoindentation test; reactive inkjetting; viscoelastic–viscoplastic