PICASSO improved reliability inspection of Aeronautic structure through Simulation Supported POD

Transcription

1 4th International Symposium on NDT in Aerospace Th.1.A.3 PICASSO improved reliability inspection of Aeronautic structure through Simulation Supported POD Nancy MALÉO Snecma (Safran Group), Villaroche site, Rond-point René Ravaud, Réau, Moissy- Cramayel, France Telephone : Tel : / Fax : nancy.maleo@snecma.fr Abstract. PICASSO is a research collaborative project registered in the Seventh Framework Programme of the European Commission and coordinated by Snecma (Safran Group). The aim of PICASSO is to build a new and original concept of simulation supported Probability of Detection (POD) curves based on Non Destructive Testing (NDT) simulation in addition to existing experimental data base. The POD method of analysis is generally used for quantitative NDT process capabilities assessment. NDT performances must be evaluated in order to ensure the desired level of safety and the POD curve provides a very useful method of quantifying the performance capability of an NDT technique. POD curves are thus used as a basis for: establishing design acceptance requirements, setting inspection maintenance intervals. Nowadays POD curves are obtained by expensive fully experimental campaigns and are even technically often impossible to realize. The objectives of PICASSO are : to have more accurate and reliable POD curves in order to get appropriate damage tolerance assessments for critical parts to address the potential risk of failure from induced anomalies (from material, manufacturing or service) within the Approved Life of the part, to overcome cost issue of the Probability of Detection campaign with Non Destructive Testing simulation techniques. This challenge is particularly important for metallic parts within the engine and aircraft industry. This paper presents PICASSO project: partners, objectives, overall strategy and results exploitation. Introduction PICASSO is a research collaborative project registered in the Seventh Framework Programme of the European Commission. The aim of PICASSO is to build a new and original concept of simulation supported Probability of Detection (POD) curves based on Non Destructive Testing (NDT) simulation in addition to existing experimental data base. Licence: 1

2 1. Technical context Most aeronautical components have to be designed on damage tolerance concept. The damage tolerance design assumes that aeronautical structures contain flaws. This means that the potential existence of component imperfections as the result of inherent material structure, material processing, component design, manufacturing or usage is recognized and this situation is addressed through the incorporation of fracture resistant design, process control and Non-Destructive Testing (NDT) inspections. Therefore, periodic maintenance intervals are defined by the design office on the base of maximum size of defect potentially present in the component and material properties (crack growth rate). This process requires to perfectly know the minimum size of indication that can be reliably detected during manufacturing and in-service inspections. This information is obtained through Probability of Detection (POD) campaigns (see MIL-HDBK-1823A (1) for recommendations concerning POD determination). A POD campaign consists in applying the NDT procedure associated to the part by several NDT operators on a large panel of samples with and without defects representative of possible damage on the part. Statistical studies are performed on NDT results. The objective is to determine the curve which calculates the probability to detect a defect type in the proposed configuration (probability vs. defect size). An example of POD curve is given hereafter (see figure 1). Probability of Detection 100% 90% POD(a) 50% POD(a) 95% 0% a a Size of defect :a Figure 1 : Example of POD curve Design offices generally use the minimum detectable defect size with a probability of 90% with a confidence interval of 95%. : a Innovation context Today s conventional methodology for POD campaigns is too much cost and time consuming and configurations equivalence, which could avoid new POD campaigns, are not available. In the framework of PICASSO project, the benefits of an innovative concept will be evaluated. This concept is the simulation supported POD based on using NDT simulation tools for future POD determinations. The simulation supported POD approach constitutes very promising solution for the evaluation of aeronautic NDT inspection. By incorporating simulated data to the experimental statistical campaigns it becomes possible to reduce the cost and time while increasing the reliability of POD evaluations. The use of quantitative and validated numerical models will allow investigating more representative samples population than the 2

3 usual purely experimental POD campaigns, to cross more completely the effects of the different influential parameters and to reduce the a priori hypothesis done today on the statistical models. The table 1 hereafter illustrates the main advantages of the innovative simulation supported POD concept proposed by PICASSO over the traditionally used experimental approach: Table 1. Description of the main advantages of the innovative simulation supported POD concept over the traditionally used experimental approach Sample manufacturing NDT inspection campaign Experimental POD Simulation supported POD - Difficult to manufacture real defects - simulation of complex defect geometries, easy positioning by modelling - Limited number of samples - Large number of samples - Limited number of defects - Large number of defects - Several operators needed - NDT procedure is respected - Respect of the NDT procedure (sometimes operators change parameters for a better detection) - Find equivalence between artificial and real defects by modelling (in order to manufacture only easy defects) - Human factor will not be treated in the framework of this project POD data exploitation New POD configuration - Data collection - Need to do a new POD campaign - Automatic data exploitation can be implemented with simulation tools - Use simulation to find transfer function to find equivalence between POD configurations - Reduced POD campaign sufficient for a new configuration 3. Objectives The objectives of PICASSO are : to have more accurate and reliable POD curves in order to get appropriate damage tolerance assessments for critical parts to address the potential risk of failure from induced anomalies (from material, manufacturing or service) within the Approved Life the part, to overcome cost issue of the Probability of Detection campaign with Non Destructive Testing simulation techniques. The main result of PICASSO will be the validation of the concept of simulation supported POD by initial realistic results, implementation and methodologies. 4. Partners involved in PICASSO project The technology breakthrough developments proposed in PICASSO rely on a cooperation of 14 organisations, comprising European leading engine manufacturers, the engine-industry supply chain, key European research institutes and small and medium enterprises (SMEs) with specific expertise. The consortium gathers 6 large partners from industry, 3 SMEs, and 5 from university and research organisations. In total, 5 countries (France, Germany, Poland, Sweden, United Kingdom) are represented, all of them being members of the European Union. Snecma is the coordinator of this project. 3

4 The members of the PICASSO Consortium are listed here-under : Universities and Research Organisations : Bundesanstalt für Materialforschung und -prüfung / Nondestructive Testing/Radiology (BAM) Commissariat à l Energie Atomique (CEA) Chalmers tekniska hoegskola AB Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.v. Fraunhofer Institute for Nondestructive Testing, Dresden Branch (IZFP-D) TWI Ltd SMEs : Hoch Technologie Systeme GmbH (HTS) Phimeca Engineering S.A. Technic Control Industries : Snecma (Safran Group) EADS France (Innovation Works Department) (EADS) MTU Aero Engines GmbH Rolls-Royce plc Turbomeca (Safran Group) VOLVO AERO AKTIEBOLAG 5. Overall strategy of the work plan The PICASSO project has started on July 1str, 2009 and will last three years and a half. It is organised in six work packages: four technical work packages (WP1 to WP4), one dedicated to management and coordination (WP5), and one to Exploitation and Dissemination (WP6). The following diagram (see figure 2) presents the overall strategy of the work plan : WP1 Initial input WP5 Management and coordination Validation cases used to validate the simulation supported POD methodology WP4 Assessment of new POD methodology Description of material properties, defect geometries and equipment for the development of models WP2 Modelling Models available for the development of the simulation POD software platform Influent parameters description WP3 Simulation supported POD Common prototype software for simulated supported POD determination WP6 Exploitation and dissemination Figure 2 : Overall strategy 4

5 5.1. Initial input (WP1) Reliable NDT simulations models are based on initial input depending on material properties (noise, grain size, anisotropy,..), defect description (cracks, inclusions, ), and data from equipment (sensors, detectors).the initial real conditions of the component must be precisely known to determine representative modeling inputs. The results of the NDT inspections may be strongly affected in function of the material characteristics (grain size, noise, anisotropy ), the real shape and knowledge of the (un)expected defects, and data from equipment. The aim of this WP1 is to identify the case studies that simulation supported POD method will be develop against and generate all the necessary material property, defect shape and Non Destructive Evaluation (NDE) method data that will be needed as input into the simulation software. Objectives of WP1 : Selection of validation cases by the industrial partners Description of material properties, defects geometries (crack and volumetric defects) and equipment Description of the influential parameters 5.2. Modelling - NDT simulation software (WP2) Simulation tools already exist in Europe for NDT techniques, as Ultrasonic Testing (UT), Radiographic Testing (RT) and Eddy Current Testing (ET). The figure 3 presents the simulations softwares involved in PICASSO : Eddy Current Testing VIC-3D X-Ray Testing Owner : HTS CIVA RT Ultrasonic Testing NDT technic concerned : EC Owner : CEA List Elastodynamic Finite Simulation of EC technique NDT simulation software which Integration Technique offers the user physics based (EFIT) VAC models for the X-Ray technic. Owner : IZFP-D Owner : Chalmers / Volvo Analytical RT inspection Numerical 1-D, 2-D, and 3-D Simulation software of EC simulation tool (artist ( artist) simulation modules for elastic technique to build simulated Owner : BAM wave propagation problems data base. Simulation of radiographic CIVA UT CIVA EC imaging. Modeling of the real Owner : CEA List Owner : CEA List inspection scenario by defining a virtual setup. NDT simulation software which NDT simulation software which offers the user physics based offers the user physics based models for UT technic. models for EC technic. Figure 3 : Simulation softwares involved in PICASSO The simulations tools are adapted to aeronautical needs and their maturity is now enough to start working on simulation supported POD. Nevertheless, their performance must be improved to ensure the maximal reliability on simulation for POD calculations. The simulation supported POD approach is based on the application of these quantitative NDT models which have to take into account the complexity of real situations, the influential parameters and their possible fluctuations. In particular, models have to be 5

6 able to consider the phenomena induced by the complexity of parts and materials (texture, microstructure, structural noise ), the complexity of geometries, of defects, and the fluctuations coming from a large number of influential parameters. Objectives of the WP2 : Models have been highly improved by developers to achieve accurate, reliable and numerically efficient simulation tools Simulation supported POD - POD methodology (WP3) WP3 is the core of the PICASSO project since it focuses on Probability of Detection (POD) issues and deals with the introduction of simulated data in POD studies. This WP develops a simulation supported POD methodology which includes : the modelling of uncertainties in order to develop a methodology to generate appropriate simulated data including uncertainties (Design of numerical Experiment) ; the combination of experimental measurements and modelling data and the feasibility of delta-pod (transfer function approach - study of extrapolation procedure on defects response or NDT parameters in different contexts) ; the improvement of POD estimation models. Objectives of the WP3 : The goal of WP3 is to provide common methodologies and tools for low cost POD determination using a simulation supported strategy. The major expected result is the development of a prototype POD software platform Assessment of new POD methodology (WP4) In the framework of the WP4, the models have been tested to verify if the specificity of aeronautical metallic parts providing sensitivity of inspection is taken into account and if models are reliable enough for an intensive use for POD calculations. It have been performed using the validations cases defined in WP1 by the comparison of the experimental and the simulated data. WP4 assesses and validates the new simulation supported POD methodology developed in the framework of the WP3 by the comparison between experimental and simulation POD data. Objectives of the WP4 : WP4 has 4 objectives: Production of POD data ; Calculation and comparison of POD curves, conventional and simulation supported; Capability criteria for simulation supported POD curves ; Recommendations and training curses. 6. Results exploitation The PICASSO exploitation roadmap targets the following objectives : Prepare the European aircraft industry and its supply chain for integration of PICASSO technology in products, 6

7 Disseminate widely the PICASSO technology within the scientific NDT community, Draw a common roadmap for concept adoption with the different stakeholders to be able to produce engines and airframes incorporating the PICASSO innovative simulation supported POD concept through future and closer to market research and development activities Approval of the concept at regulation Authorities level The new concept of Simulation Supported POD developed in the framework of PICASSO will have to be approved and qualified by the European regulations authorities (EASA/FAA). During the lifetime of the project, the PICASSO consortium has been in contact with the RISC Group and has performed some presentations of the progress of the project. The RISC group has the responsibility to propose to the FAA and EASA recommended practices to guarantee the damage tolerance of the critical parts of turbojets (rotors). The NDT and their POD curves are an ingredient of the probabilistic methods suggested to contain the risk of rupture on defects. The members of the RISC Group are representatives of EASA, FAA, GE, PW, Honeywell, Snecma, MTU, RR, 6.2. Contact with Model-Assisted POD (MAPOD) Working Group The Simulation Supported POD approach also arise interest in the United States. Based on the similar recognition that the use of physics-based models has the potential to assist the determination of POD, a working group (Model-Assisted POD Working Group) has been created with the support of the Air Force Research Laboratories and NASA Langley Research Centre. The MAPOD working group is a discussion forum led by the Centre for Non Destructive Evaluation at Iowa State which gathers industrial companies and universities. During the course of the project, the PICASSO consortium has been in contact with this MAPOD working group in order to explain the European Simulation supported POD approach and to keep them informed of the progress of the project. It has been agreed to make a common communication on the Simulation Supported POD concept after the completion of PICASSO. 7. Conclusions The simulation supported POD concept improves the reliability of POD calculations by increasing the population of POD samples with defects and by enabling the simulation of sub-components configurations. The main result of the project will be the validation of the concept of simulation supported POD by first realistic results, implementation and methodologies. Its intensive use and the building of a future European standard on simulation supported POD will be the next step towards the entry into service of such tools. 7

8 Acknowledgements The author would like to thanks the members of the consortium of PICASSO project who have participated to this paper. Reference [1] MIL-HDBK-1823A, Non-Destructive Evaluation system reliability assessment, USA Department of Defense Hadbook, April 7th,