Periodic Reporting for period 1 - ViFoMeTi (Virtual hot Forming and Mechanical design of beta Titanium alloys: towards a sustainable process)
Reporting period: 2022-03-01 to 2024-02-29
Beta-titanium alloys are highly valued in biomedical, aerospace and marine applications for their high structural properties, excellent corrosion resistance, light weight and biocompatibility. Given their increasing use, finding more sustainable forming methods is key. Factors such as the forming temperature and the chemical composition of the beta-stabiliser have been proven to influence the material deformation response and thus affect the forming processes. To address this issue and contribute to more sustainable processes, the main goal of the ViFoMeTi project is to develop an innovative numerical model capable of predicting the thermomechanical behaviour of such alloys, considering temperature and chemical composition for improved accuracy. Additionally, the project intends to provide an environmental and business view of the topic being addressed.
At a first stage of the ViFoMeTi project, the ER has started by gathering all the available digital image correlation (DIC) data from IRDL lab own database which consisted in tensile tests performed using a Gleeble machine on Ti-xMo alloys (x=10, 12, 15 and 18 % wt as the available different compositions of the alloy) at 2 different applied strain rates (10-3 and 10-4 s-1) and 2 different temperatures (250 and 350 ºC). Then, numerical models intended to replicate the Gleeble tensile tests have been developed using input data extracted from the experimental DIC data post-processing (temperature fields, hardening curves, displacements curves and material elastic properties). Finally, a user subroutine has been implemented to include the occurrence of plastic instabilities in the numerical models using the Estrin-Kubin-McCormick (EKMC) constitutive model. To validate this subroutine and ensure the reliability of results, the results of numerical models using the subroutine (without considering the plastic instabilities) have been compared with the results of the same Abaqus models (1) using the material data in a tabular format and (2) using an equivalent Abaqus built-in material model. Additionally, a sensitivity analysis on the influence of the EKMC model parameters to reproduce the plastic instabilities has been performed to provided better insights on the methodology and to facilitate the required model adjustments to replicate the different thermo-mechanical material behaviours for the different temperatures, strain rates and compositions.
From the ViFoMeTi project’s performed work, the main innovative outputs that go beyond the state of the art are (1) the specific experimental data post-processing of heterogeneous tests to be suitable for the extraction of data required for the numerical simulation of the strain localised bands from the PLC effect; (2) the strain-rate analysis along the specimen length performed to the simulated thermomechanical tensile tests; and (3) the numerical modelling considering plastic instabilities that was accompanied by a sensitivity analysis to the parameters of the implemented constitutive model.
The work carried out also enhances innovation capacity in terms of new research that can be performed in continuation of this project. The IRDL own database has been reorganised to be made FAIR (findable, accessible, interoperable and re-usable), and the python codes and excel spreadsheets developed by the ER are made publicly available.
The work carried out also enhances innovation capacity in terms of new research that can be performed in continuation of this project. The IRDL own database has been reorganised to be made FAIR (findable, accessible, interoperable and re-usable), and the python codes and excel spreadsheets developed by the ER are made publicly available.