Mechanics of Metallic Materials (M3S)
M3S investigates the non-linear behavior and integrity of metallic materials and structures in the aerospace domain when they are submitted, in use, to severe multiaxial and/or thermo-mechanical loads. With the objective of constantly improving the design process, the unit conducts research to model the manufacturing part processes in order to assess their impact on the fatigue service life. The modeling is based on strong interaction with experimental mechanics, ranging from fine characterization of the physical mechanisms up to the development of multi-instrumented technological tests with the purpose to validate new proposed approaches on representative test structures.
Technological fatigue tests with heat gradient of surfaces for validating the modeling tools
(behavior law and damage model) which are developed for estimating the service life of a
high-pressure turbine blade
Functionalization, Durability, Multi-Materials (FD2M)
FD2M activities are partly devoted to the joining and repair of metallic materials systems which are already in service. Another part of activities deals with the development of new functional materials for higher performance and sustainability in aeronautical environment.
By using both thermodynamic and physico-chemical approaches, multi-materials systems are investigated in order to meet the requirements of future generations of aircraft and related engine systems (thermal barriers, protective coatings, architectured materials obtained by additive manufacturing).
Thermal barrier system for turbine blades (SEM micrography and EBSD mapping)
Metallic Materials, Microstructures and Processes (M3P)
The scope of the M3P unit is the development of metallic and intermetallic materials. The unit studies in particular, with the support of thermodynamic and kinetic models, the phase transformations in structural alloys in view of optimizing the production / transformation processes and defining new alloy compositions for better mechanical properties of use. To this end, the unit benefits from major specific technical resources in terms of production and characterization of microstructures. It is also responsible for sharing, maintaining and developing those resources for the entire department and, more generally, for ONERA.
a) Atomization tower (EIGA / VIGA) for manufacturing metallic alloy powders. Photo credit: ALD Vacuum Technologies GmbH
b) Turbine disk made of N18 nickel-based superalloy using powder metallurgy
c) Associated microstructure
Computational structural mechanics unit (MS2)
The researchers of the Computational Structural Mechanics (MS2) unit develop algorithms, mathematical models and innovative computational solutions concerning mechanics of materials and structures. Its field of activity covers the following scientific topics: structural dynamics, multi-scale approach of failure, stochastic phenomena, optimization, multi-physical numerical simulation, high-performance calculation, surrogate model, applied mathematics, coupled experimental-numerical studies, etc.
Numerical simulation of crack propagation, conducted with Z-set/Z-cracks, in an
aeronautical engine combustion chamber under thermo-mechanical fatigue loading
Manufacturing and non-destructive inspection of composite materials (ETC2)
The activities of ETC2 deal with three fields of research, corresponding to (i) the design and development of new functional materials associated with exceptional properties (multifunctional thermostructural and ceramic composites: eutectic, ultra-refractory, transparent, etc.); (ii) the simulation of composite materials manufacturing processes (mainly liquid channel processes such as RTM or infusion; and (iii) the development of health monitoring techniques for materials and structures (integrated and non-integrated), with the goal of reducing maintenance times and control periods.
a. Detection of cracks in turbine blades by ultrasonic vibrothermography and "Flying Spot" photothermic radiometry
b. Development of processes for producing low-cost ceramic matrix composites for missile nose cones
c. Production of ZnGeP2 single crystals for non-linear optics
d. Tracking damage in composite structures under mechanical load by IR thermography
e. Non-destructive control by laser vibrometry of Rafale radomes in operational conditions
Modeling and mechanical characterization of composites (MC2)
The research work conducted by MC2 aims at proposing constitutive equations to predict the behavior, damage and fracture which are specifically developed for composite materials, such as laminates with unidirectional plies or 3D woven materials. To improve the insight into the damage and failure mechanisms, MC2 is interested in the experimental characterization methods for composite materials using multi-instrumented tests on samples and structures, and also in the development of tools to ensure consistency between tests and simulations. Lastly, the advanced design activities for composite structures focus on the optimization of stacking sequences taking account manufacturing constraints, as well as topological optimization for composite structures.
Forecasting crack density on mesoscopic scale in 2D Glass/Epoxy woven composite and experimental validation
Design and dynamic resistance (CRD)
- Numerical simulation of the crash and impact strength of aeronautical structures combined with the development of experimental tools and methods. These tools and methods aim at studying the dynamic behavior of materials and structures at high deformation speeds (modeling of impactors such as ice, bird, tires, etc.), and fluid-structure coupling in order to improve numerical simulations.
- Development of new aeronautical structure concepts comprising, on the one hand, the development of numerical tools for predicting structural mass balances for evaluating in the early design phase the relevance and feasibility of new aircraft concepts and, on the other hand, the development of technological solutions (active materials and structures).
Crash tower: 15 m tall drop tower for full-scale aeronautical structures crash testing
Laboratory for microstructural investigations (LEM)
LEM, a joint CNRS-ONERA research unit, conducts fundamental research aimed at establishing the link between physical mechanisms operating at the small scale and the macroscopic behavior of materials (non-equilibrium microstructures; mechanical, electronic, optical properties, etc.). The approach combines experiments (synthesis, electron microscopy, X-ray diffraction), theoretical developments, and modeling on different scales (electronic structure, atomic-scale simulations, phase field methods, dislocation dynamics).
These activities are spread across two areas:
- Microstructures: morphology, plasticity and transport
- Small-sized carbon and boron nitride-based materials
LEM is also in charge of the renewal and updating of the fleet of transmission electron microscopes to meet the evolving needs of all researchers working at ONERA.
Modeling microstructures: growth of a carbon nanotube, nickel-based superalloy, crack-front plasticity