Creation and verification of computational models for analysis of the mechanical behaviour of jet engines composite components under high-velocity impact: main problems and basic recommendations

Abstract

Currently, modern CAE programs like ANSYS, LS-DYNA, ABAQUS, Simcenter 3D etc. are widely used to develop each engineering product. CAE reduces development costs and speeds up product launches. Computer modelling allows eliminating unsuccessful design options at early design stages and minimising or eliminating critical design changes at the prototype testing stage. Computer simulations are especially needed for the development of high-performance perfection designs like jet engines. The use of composites in the engines requires the availability of appropriate design tools to assess the mechanical behaviour of structural elements made of such materials under operational loads and in an emergency. Predictive modelling of the deformation and fracture of the composite fan blades and fan case subjected to dynamic loading cause considerable interest of engineers. As in the case of simulation of shock loading of metals, a model of a composite material must be verified. However, the problem is that the fibrous composite material itself is already a structure and can be modelled in various ways: without considering the layered structure (homogeneous approach) taking the mesostructure into account (at the ply-level or at the yarn-level) taking the microstructure into account (at the filament level). The requirements for the initial data, the number of parameters determined during the verification process, the complexity of creating geometric models will differ in each case. This paper briefly describes the main approaches to the numerical simulation of composite elements under highvelocity impact loading. The main advantages and disadvantages of these approaches are also considered. On the example of the meso-scale approach, the main parameters of the computational models that affect the results of calculations are shown. Based on the obtained data, the main recommendations were formulated on the validation of meso-scale models of composites.

Simplified Approach to Verification of Numerical Models for Deformation and Fracture Analysis of Structural Composite Subjected to High-Velocity Impact

“…This suggests that the force increase is associated primarily with the composite strength. Thus, the hypothesis mentioned in [12] about the possibility of taking into account the strain rate during high-velocity impact by introducing a correction factor for the material strength was confirmed.…”

“…The MAT_054/MAT_ENHANCED_COMPOSITE_DAMAGE orthotropic material model was used in calculations to describe the mechanical behaviour of the composite. A more detailed description of the material model is presented in [12].…”

“…During the determination of the strength parameters and interlaminar contacts, it was found that the use of the previously proposed approach (see [12]) in the calculation of low-velocity impact made it possible to achieve an adequate prediction of the load corresponding to the onset of failure, but led to a non-physical prediction of the crack development and delamination in the specimen. Figure 3 shows that when the maximum load is reached, it drops sharply, which was not observed in the experiments.…”

“…The mesoscale and combined approaches are the most suitable for practical use [5][6][7][8][9][10][11]. It was shown in [12] that in both cases extensive verification of computational models (mesh model and material model) using high-velocity impact test data is required. However, carrying out a large number of instrumented high-velocity impact tests is a laborious and costly process.…”