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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MOTIVATE (Matrix Optimization for Testing by Interaction of Virtual And Test Environments)

Teaser

Summary

The MOTIVATE project is bringing about a step change in the way virtual and physical tests are used together in an industrial environment to reduce the cost, risks and time associated with product development. Enabling technologies, which have been demonstrated in laboratory conditions during a series of EU FP 5 and 7 projects, are being transitioned into the industrial environment and will be demonstrated in a structural test on an aircraft subcomponent (a 1 sq.m fuselage panel) and in an aircraft-scale structural test on a cockpit. The specific objectives of the project are:
i. to develop a robust and repeatable method for the quantification of uncertainties in measurements using digital image correlation in an industrial environment,
ii. to produce advanced structural test protocols with an associated methodology for validation of simulation data, and
iii. to deploy the validation methods and test protocols in a demonstration during a structural test case.

This project is a response to Innovation Action JTI-CS2-2016-CFP04-AIR-02-32 entitled \'Testing Matrix Optimisation by Interaction between Numerical Modelling & Innovative Non-Contact Measurement Technology\' within Work Package B 3.3.2 of Technology Stream B3: Advanced Integrated Structures in the ITD Airframe of the Clean Sky Joint Technology Initiative (JTI). Specifically, it is intended to improve and develop the existing methodologies for quantifying uncertainty in measurements of displacement and strain field, and in parallel, to progress and mature the current methodologies for correlating predicted and measured data fields in order to provide a simple-to-use and robust approach to validating computational models. Automated and robust protocols for validation will enhance confidence and credibility in computational simulations of structures, and thus, enable light-weight, elegant designs to be brought to the marketplace faster and at lower costs by reducing the number of tests required to develop high fidelity models of new designs of aircraft structures. Light-weight, elegant structures are essential in realising the Clean Sky goal of achieving major steps towards the ACARE (Advisory Council for Aeronautics Research in Europe) Environment Goals for 2020.

Work performed

At the mid-point in the project, the MOTIVATE project is on-schedule to complete all of its milestones and deliverables as described in the Grant Agreement and to achieve its objectives. The consortium is working together effectively and has a strong working relationship with its Topic Manager, Airbus, at whose facilities a major structural test will take place in the second half of the project, which will include the implementation and demonstration of the project outputs.

From a technical perspective, the project has already delivered (i) a draft protocol for a new validation metric that will provide the probability that a predicted field of surface displacements or strains belong to the same population as a corresponding field of measurements given a stated level of uncertainty in the measurements; (ii) two alternative methods for quantifying the level of uncertainty in measurements made in an industrial environment using digital image correlation; (iii) an enhanced flowchart for the validation process that incorporates these advances and allows the use of historical data; and (iv) a draft protocol for the implementation of the enhanced flowchart in the event that validation tests need to be undertaken.

The dissemination of the outputs from the project is underway. A number of conference presentations have been made and archived journal papers are being planned. A series of posts on an engineering blog have been published and video shorts of project demonstrations are being released. A workshop was held at Airbus in Toulouse in March 2018 and a second one is planned for January 2019 at Airbus in Filton. In addition, a knowledge exchange workshop, connected with the revision of the CEN Workshop Agreement on the Validation of Computational Solid Mechanics Models, is planned for November 2019 in Zurich.

Final results

The project is built around a new philosophy for the integrated use of test and simulation data based respectively on non-contact measurement technology and numerical modelling, both of which are capable of generating data fields that describe strain over the surface of engineering components and structures. It is common practice to compare the outputs from such experiments and simulations using data from hot-spots or along sections and this may lead to significant strain features being neglected or to a sub-optimal approach to a campaign of tests. Recently, it has been shown that a measured or predicted displacement or strain field in engineering structures can be represented by a feature vector using image decomposition [Wang et al, IJ Solids & Structures, 48:1644-1657, 2011 and Patki & Patterson, Exptl Mech, 1137-1149, 2011] and that this enables new techniques for quantitative comparisons of data-rich fields [Sebastian et al, J Strain Anal, 48:36-47, 2013 and CEN CWA16799:2014]. Such comparison techniques offer the potential to establish high levels of confidence in predictive tools which is required in order to optimise safety factors and generate the light-weight designs needed to enhance aircraft performance.

approaches to quantifying uncertainty in measurements of displacement and strain fields obtained using digital image correlation have been reviewed and a simple-to-use, robust methodology developed for use in industrial environments, which considers the entire measurement volume as well as the timescale of a structural test. In addition, recent advances in the validation of simulations, using image decomposition to compare predicted and measured data fields, are being incorporated into advanced structural test protocols taking account of uncertainties to provide statements on the extent to which the predictions represent reality, i.e. the validity of the simulations. Best practice guidelines are being developed to allow the test protocol to be optimised to minimize the costs and time required for physical tests while maximising the reliability and credibility of the simulations. The project outcomes will represent a significant and generic advance in the technologies and methodologies used to validate computational models of structures and this will benefit a wide range of industrial sectors, including the aerospace industry where it will support the introduction of disruptive technologies, such as highly-integrated structures, by enabling high-fidelity simulations.