Finite element modeling for designing and optimizing lightweight titanium aerospace components requires advanced simulation tools with adequate material modeling. In this sense, a hybrid strategy is proposed in this work to identify the parameters of the Johnson–Cook plasticity and damage laws using a combined direct-inverse method. A direct calibration method for plasticity law is applied based on the literature-reported data of strain-stress curves from experimental tensile tests at different temperatures and strain rates. The triaxiliaty-dependent fracture parameters of the Johnson–Cook damage law at reference conditions of strain rate and temperature (d₁, d₂, and d₃) are calibrated with the direct method based on new data of experimental evolution of computed average fracture strain with the average stress triaxiality. The validation is performed with numerical results from an accurate micromechanics-based Ti64 model. The inverse calibration method is used to determine the strain rate and temperature-dependent damage parameters (d₄ and d₅) through large strain simulations of uniaxial tensile tests. The numerical results, including average strain and necking profile at fracture, are then utilized to calculate stress triaxiality by the Bridgman criterion for adjusting parameters d₄ and d₅. The calibrated model yields a 2.1% error for plasticity and 3.4% for fracture predictions. The experimental and simulated load-bearing capacity using the micromechanics damage model differed by only 1%. This demonstrates that the SC11–TNT model of Ti64 is reliable for identifying the Johnson–Cook damage law through the accurate use of inverse methods. The hybrid calibration strategy demonstrates the potential capability of the identified Johnson–Cook model to accurately predict the design load-carrying capacity of Ti64 aerospace components under different deformation rates and temperatures while accounting for material damage effects.

Titanium alloys, such as Ti-6Al-4V, are crucial for aeroengine structural integrity, especially during high-energy events like turbine blade-out scenarios. However, accurately predicting their behavior under such conditions requires the precise calibration of constitutive models. This study presents a comprehensive sensitivity analysis of the Johnson-Cook plasticity and progressive damage model parameters for Ti-6Al-4V in blade containment simulations. Using finite element models, key plasticity parameters (yield strength (A), strain-hardening constant (B), strain-rate sensitivity (C), thermal softening coefficient (m), and strain-hardening exponent (n)) and damage-related parameters (d1, d2, d3, d4, and d5) were systematically varied by ±5% to assess their influence on stress distribution, plastic deformation, and damage indices. The results indicate that the thermal softening coefficient (m) and the strain rate hardening coefficient (C) exhibit the most significant influence on the predicted casing damage, highlighting the importance of accurately characterizing these parameters. Variations in yield strength (A) and strain hardening exponent (n) also notably affect stress distribution and plastic deformation. While the damage evolution parameters (d1–d5) influence the overall damage progression, their individual sensitivities vary, with d1 and d4 showing more pronounced effects compared to others. These findings provide crucial guidance for calibrating the Johnson-Cook model to enhance aeroengine structural integrity assessments.

The prevention of catastrophic fracture during fan blade-out (FBO) events is a critical requirement for aero-engine safety certification. While the suppression of void growth under triaxial compression is a known mechanical principle, this research establishes how macroscopic geometric compliance can be used to actively control the local triaxiality history during high-strain-rate impacts. Rather than treating parameter sensitivity and structural mass as isolated variables, this study shows that increasing global structural flexibility physically forces the local dynamic stress tensor into a compressive state, preventing fracture. Utilizing a finite element model of a Trent 1000-class turbofan, an iterative geometric refinement was performed to minimize casing mass without compromising energy absorption capability. The Johnson–Cook (J–C) plasticity and damage laws for the Ti-6Al-4V alloy served as the baseline, with a conservative limit model developed to account for identified ±5% calibration uncertainties in thermal softening ( m ) and strain rate sensitivity ( C ). Numerical results demonstrate that a 6.3% reduction in casing mass is achievable while maintaining a factor of safety (FS) of 1.25 under nominal loading and 1.66 under conservative material assumptions. The analysis reveals that the optimized, more compliant geometry facilitates beneficial cycles of triaxial compression near −0.7, which suppresses void nucleation and prevents catastrophic perforation. This study provides a validated engineering framework for the design of lightweight, damage-tolerant containment systems that remain resilient even under unfavorable constitutive calibration scenarios.