Dynamic numerical prediction of plasticity and damage in a turbofan blade containment test

For the light designs of new aircraft engines, constitutive plasticity and fracture models sensitive to strain rate and temperature are essential for the accurate prediction of deformations and internal stresses of the components during simulations of impact and explosion events. The work described in this article consists of the development and numerical analysis by finite elements of the blade containment test of a commercial aircraft turbofan engine, conducted to evaluate the structural integrity of the casing after being impacted by a detached fan blade. Two simulation models of the test are proposed, in which the resistance behavior of the strain rate-dependent material is described by isotropic laws of strain hardening and Johnson-Cook damage. The strength analysis is based on the numerical field results of equivalent stresses and deformations, along with the internal damage rates of the casing. The first simplified model considers half of the casing impacted by a blade at different speeds and angles of impact. The second model consists of a complete discretization of casing and rotating turbofan, with the initial detached condition of a blade simulated at different rotating speeds of the fan. The material used in this study is the Ti-6Al-4V alloy. The results analysis and advances obtained make it possible to approach an efficient computational tool with more accurate calculations to study a casing redesign with a safe reduction in mass and that fulfills the certification requirements using the blade containment test.