A constitutive model for Ti6Al4V considering the state of stress and strain rate effects

Abstract

The predictability of manufacturing process simulation is highly dependent on the accuracy of the constitutive model to describe the mechanical behavior of the work material. The model should consider the most relevant parameters affecting this behavior. In this study, a constitutive model for Ti6Al4V titanium alloy is proposed that considers both material plasticity and damage. It includes the effects of strain hardening, strain-rate and the state of stress to represent the mechanical behavior of Ti6Al4V titanium alloy in metal cutting simulation. To generate states of stress and strain rates representative of this process, mechanical tests were performed using a specific experimental setup. This included a specimen geometry designed to generate different states of stress, as well as a digital image correlation technique to obtain the strains during the mechanical tests. For the determination of the coefficients of the constitutive model, the yield stress and fracture locus obtained from these tests were used in an optimization-based procedure. To verify the accuracy of the proposed constitutive model to represent the mechanical behavior of the Ti6Al4V alloy under different states of stress, force-displacement curves obtained using this model and the Johnson-Cook model are compared with the curves obtained experimentally.

Johnson–Cook Parameter Identification for Commercially Pure Titanium at Room Temperature under Quasi-Static Strain Rates

“…As previous authors have already identified the JC model parameters for commercially pure titanium (CP-Ti) [ 10 ] or Ta6V [ 14 ], this paper does not claim originality. The present study aimed to provide a complete set of mechanical parameters for the elastic and plastic behavior of the CP-Ti and to evaluate the influence of quasi-static strain rates and sandblasting.…”

“…In the finite element analysis with Radioss © for an intracranial implant subjected to impact, the constitutive model is simplified to an engineer’s tool, such as the isotropic Johnson–Cook (JC) model [ 13 ]. Cheng et al [ 14 ] published the identified parameters of this model for Ti-6Al-4V. Hereafter, JC parameters were identified on samples made of commercially pure titanium (CP-Ti), and the influence of sandblasting and quasi-static strain rate variation were analyzed.…”

Inverse Identification of the Ductile Failure Law for Ti6Al4V Based on Orthogonal Cutting Experimental Outcomes

“…At the same time, the flow stress models with coupled ductile failure models started to be developed. For instance, Chen et al [49] used a two-stage ductile failure model, which was stress triaxiality-dependent, coupled with the Johnson-Cook flow stress model, to predict chip segmentation when carrying out orthogonal cutting on Ti6Al4V using the finite element software Abaqus. Additionally, Liu et al [50] analyzed the feasibility of using different ductile failure models in machining when the orthogonal cutting 2024-T3 aluminum alloy also used Abaqus.…”

Machining simulation of Ti6Al4V using coupled Eulerian-Lagrangian approach and a constitutive model considering the state of stress

“…The results of their modelling show that, for a cutting speed of 60 m/min, the simulated chip is continuous, whereas the serrated chip was obtained experimentally [19]. Moreover, it is worth noting that the simulated plastic strain in the shear band of the chip is extremely high compared to the strain at fracture of the Ti6AL4V obtained in the material testing [20].…”

“…However, only a few constitutive models used in metal cutting considers the state of stress. Cheng et al [20] proposed a constitutive model that considers the effect of strain hardening, strain-rate, and the state of stress on the mechanical behavior of Ti6Al4V alloy. The accuracy of this model is verified for different samples geometry and loading conditions (thus different state of stress), by comparing the predicted force-displacement curves obtained using this constitutive model and the experimental curves.…”