ONERA’s Multiaxial and Anisothermal Lifetime Assessment for Engine Components


S. Kruch, P. Kanouté, V. Bonnand (ONERA)

This paper presents the calculation methods developed at ONERA to assess the lifetime of aeroengine structures subjected to multiaxial thermo-mechanical loadings. The complexity of the steps required in this process has grown over the past years, in order to take advantage of extremely accurate observations in materials and more precise experimental results.

Multiaxial Haigh Diagrams from Incremental Two Scale Damage Analysis


R. Desmorat LMT (ENS Cachan / CNRS / U. Paris Saclay)
A. du Tertre, P. Gaborit (Snecma)

In High Cycle Fatigue, plasticity and damage are localized at a microscale, a scale smaller than the Representative Volume Element (RVE) scale of continuum mechanics. An incremental two-scale damage model has been built on this basis by Lemaitre et al, and has been mainly applied to alternated loading with no plasticity at the RVE scale. A modified Eshelby-Kröner scale transition law is derived here, taking into account RVE mesoscale plasticity and also microscale plasticity and damage.

Development of an Incremental Model for Fatigue Crack Growth Predictions


S. Pommier LMT(ENS Cachan, CNRS, UPSaclay)

This paper presents an incremental approach for modeling fatigue crack growth with history effects. This approach is being developed at LMT since 2003, in collaboration with several industrial partners, mainly with Snecma, the SAFRAN Group, EDF and AREVA, and the SNCF. The first part of this paper presents the context, objectives and key assumptions on which the model is based.

Thermodynamic Modeling by the CALPHAD Method and its Applications to Innovative Materials


M. Perrut (ONERA)

Among the different steps leading to a multi-scale lifetime prediction for aero-engine components and other industrial components, one seems to be apart from the other mechanical engineering concerns: thermodynamic and microstructural modeling. Here is given an introduction to the CALPHAD method [19, 27], explaining how it actually models the thermodynamic properties of multicomponent systems.

Oxidation Assisted Intergranular Cracking in Alloy 718: Effects of Strain Rate and Temperature


B. Max (IRT Saint Exupéry)

Alloy 718 is the most widely used superalloy in industry due to its excellent mechanical properties, as well as its oxidation and corrosion resistance over a wide range of temperatures and solicitation modes. Nevertheless, it is a well-known fact that this alloy is sensitive to oxidation assisted intergranular cracking under loading in the temperature range encountered in service.

Issues Related to the Constitutive Modeling of Ni-based Single Crystal Superalloys under Aeroengine Certification Conditions


J.Cormier, F. Mauget (Institut Pprime-ISAE ENSMA)
J-B Le Graverend (ONERA-Institut Pprime-ISAE ENSMA)
C. Moriconi (Turbomeca-SAFRAN)
J. Mendez (Institut Pprime-ISAE ENSMA)

This paper presents a constitutive modeling approach (the Polystar model) used to compute the viscoplastic behavior and the durability of high pressure turbine blades and vanes of aeroengines during complex thermomechanical histories typically encountered during certification procedures.

Fatigue Damage Modeling of Composite Structures: the ONERA Viewpoint


M. Kaminski, F. Laurin, J.-F. Maire (ONERA)
C. Rakotoarisoa (Snecma, Safran Group)
E. Hémon (Safran Composites, Safran Group)

The aim of this paper is to present the fatigue damage modeling approach developed at ONERA for the fatigue life prediction of composite materials and structures. This paper is divided into five sections. The first one explains why the already developed and validated methods for fatigue life modeling of metals and alloys cannot be directly applied to composite materials.

Experimental and Numerical Simulation Strategies for the Prediction of the Macroscopic Behavior and Rupture of Structural Materials under Fast Dynamic Loadings


E. Deletombe, J. Berthe, D. Delsart, J Fabis, B. Langrand, G. Portemont (ONERA)

The presented research works have been done at ONERA – The French Aerospace Lab, in collaboration with many academic and industrial partners. They are aimed at improving the safety and protection of passengers and crew in aircraft transport, thanks to an increased resistance of structures and decrease of high energy impacts vulnerability. This paper gives an overview of recent progress made in the experimental and numerical fields to better predict the dynamic behavior and strength of primary structure materials.

On the Deformation Heterogeneities Described By Crystal Plasticity


E.P. Busso (ONERA)

The deformation fields within grains in polycrystalline materials are generally highly heterogeneous and can be the precursors to the nucleation of micro-cracks or cavities. Such behavior is conditioned by microstructural features, such as grain structure, texture, morphology, size, etc.

Physically Justified Models for Crystal Plasticity Developed with Dislocation Dynamics Simulations


B. Devincre, R. Gatti (ONERA-CNRS)

This article highlights how dislocation dynamics (DD) simulations provide a unique opportunity for establishing scale transitions in crystal plasticity. Recent progress in this numerical method is briefly reviewed. Based on the standard problem of plasticity in fcc crystals, we show that DD simulation insight provides guidelines for modeling material mechanical properties controlled by the collective behavior of dislocation microstructures.