## 3 Machinability of AM Ti6 Al4V Alloy
### Finite Element Analysis
Some reports indicated the degradation in the mechanical behavior of a composite material that was caused by the initiation of damage using FEA, and the results were affected significantly by the depth of cut and fiber orientation rather than the tool edge and rake angle [118]. The J-C model shows that chip morphology depends considerably on the adiabatic shear zones, which rely intensely on cutting parameters such as cutting forces and temperature [110]. Another researcher used optimized J-C model parameters to calculate the flow stress under different conditions; the calculated results showed excellent agreement with the experimental results reported, with less than 4% error [108]. Tables 9 and 10 provide the required material constants and mechanical and physical properties for numerical analysis using the J-C model. The crack initiates at the free surface of the chip and propagates toward the tool, developing into micro-cracks during the machining operation as reported [119]. J-C model captures the essential characteristics required to simulate cutting forces, chip morphology, and flow stress accurately. It emerges from this model that while accounting for material thermal softening is necessary, it is not sufficient that the model should also incorporate strain-softening to represent a material's behaviours as reported by many researchers [120; 121; 122; 123]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Model** & **Formula** & **Coefficients** & **Investigated Parameters** & **Type of Material** & **Reference** \\ \hline Johnson-Cook & \(\sigma=(A+B^{\alpha})\Big{(}1+\text{Cl}\,\frac{\epsilon}{\epsilon}\Big{)} \Big{[}1-\Big{(}\frac{T-T_{0}}{\pi\pi\cdots T_{0}}\Big{)}^{\alpha}\Big{]}\) & A, B, C, m, n & Flow stress & Wrought Ti6 Al4V & [114; 115] \\ Johnson-Cook & \(\sigma=(A+B^{\alpha})\Big{(}1+\text{Cl}\,\frac{\epsilon}{\epsilon}\Big{)} \Big{[}1-\Big{(}\frac{T-T_{0}}{\pi\cdots T_{0}}\Big{)}^{\alpha}\Big{]}\) & A, B, C, m, n & Cutting forces and chip morphology & Al 6061-T6 & [68] \\ Johnson-Cook & \(\sigma=(A+B^{\alpha})\Big{(}1+\text{Cl}\,\frac{\epsilon}{\epsilon}\Big{)} \Big{[}1-\Big{(}\frac{T-T_{0}}{\pi\cdots T_{0}}\Big{)}^{\alpha}\Big{]}\) & A, B, C, m, n & Cutting temperature & Wrought Ti6 Al4V & [56] \\ Johnson-Cook & \(\sigma=(A+B^{\alpha})\Big{(}1+\text{Cl}\,\frac{\epsilon}{\epsilon}\Big{)} \Big{[}1-\Big{(}\frac{T-T_{0}}{\pi\cdots T_{0}}\Big{)}^{\alpha}\Big{]}\) & A, B, C, m, n & Chip morphology and adiabatic shear banding & Refractory Ti6 Al4V & [110; 111] \\ Johnson-Cook & \(\sigma=(A+B^{\alpha})\Big{(}1+\text{Cl}\,\frac{\epsilon}{\epsilon}\Big{)} \Big{[}1-\Big{(}\frac{T-T_{0}}{\pi\cdots T_{0}}\Big{)}^{\alpha}\Big{]}\) & A, B, C, m, n & Strain (\(\epsilon\)), strain rate (\(\epsilon\)), and temperature & Brass & [112] \\ Power Law (PL) & \(\sigma=\omega_{0}\pi^{\alpha}\Big{(}\frac{\epsilon}{\epsilon}\Big{)}^{\alpha} \Big{(}\frac{\epsilon}{\epsilon}\Big{)}^{\alpha}\Big{(}\frac{\epsilon}{\epsilon }\Big{)}^{\alpha}\Big{(}\frac{\epsilon}{\epsilon}\Big{)}^{\alpha}\) & \(\omega_{0},m,n,0\) & Cutting forces, cutting temperature, and flow stress & AIS1 1045 & [113] \\ Oxley Strain & \(\sigma=\omega_{0}\Big{(}T,\,\epsilon\Big{)}\Big{(}\frac