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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - TEST-inn (TEST-INNOVATIVE LOAD APPLICATION MONITORING SYSTEMS)

Teaser

Summary

The main objective of TEST-inn is to reduce product development time risks and costs thanks to the development of a test rig equipped with a combination of state of the art load application system in combination with the innovative monitoring methods proposed for first damage detection, stress-strain events, overloads and hot spot detection and quantification as well as overall deformation measurement. The proposed test configuration will reduce a 33 % the number of tests needed for new product development and a 25 % of recurrent costs saving.

The technical goals are, the development of a test rig equipped with a combination of state-of-the-art load application system in combination with the innovative monitoring methods proposed in order to demonstrate the torsional and bending stiffness of the HLFC Leading Edge configurations by experimental testing an obtain the equivalent beam.

The innovative contributions are the development of the test monitoring system based on novel technologies for specimen control during torsion and bending tests. These are the innovative load application systems with (SMA) Shape Memory Alloys morphing technology to apply tuneable elastic strain. And Innovative innovative SHM Structural Health Monitoring Systems, (AE) Acoustic Emissions for first damage detection, (DIC-3D) Digital Image Correlation for stress-strain events detection and quantification, (FORS) Fibre Optic Rayleigh Scatter for continuous strain measurements for internal areas and (LS) Laser Scanner for overall deformation measurement.

Work performed

It has been developed a test rig equipped with a combination of state-of-the-art load application and innovative monitoring methods proposed. Test rigs have been designed and are under construction.
Tests rigs are divided into two different configurations.

Test case 1, composed of a clamping part and the load application system for the bending and torsion test necessary to obtain the component torsional and bending stiffness by experimental testing an obtain the equivalent beam. In this test rig, conventional monitoring systems like strain gauges, inclinometers. LVDTs, and innovative SHM Structural Health Monitoring Systems will be applied, (AE) Acoustic Emissions for first damage detection, (DIC-3D) Digital Image Correlation for stress-strain events detection and quantification, (FORS) Fibre Optic Rayleigh Scatter for continuous strain measurements for internal areas and (LS) Laser Scanner for overall deformation measurement.

For the obtention of the component torsional and bending stiffness, it has been developed an automated procedure Ansys FEM program based. Through the input of deformed sections measured during the tests by means of the laser scanner technology, and thanks to an iterative optimization process, after several loops the equivalent beam is obtained.

For the test case 2, test rig it is expected to reproduce a real load case representative of in-flight conditions by experimental testing by means of a test loading system based on (SMA) Shape Memory Alloys technology.

It has been developed an innovative load application system based on SMA morphing technology to apply tuneable elastic strains. It consists on pre-strained SMAs attached to the surface wanted to be deformed. By heating only a few degrees, and thanks to the austenitic transformation related to the of the shape memory effect, SMAs can transfer the load to the attached component with a very high power/weight ratio without the need for external actuators. Developments carried out show that we are able to generate with an only 1 mm SMA commercial sheet, more than 10.000 Âµstrains in low stiffness coupon samples, up to 1.000 Âµstrains at local level at components level, and up to 350 Âµstrains at global level for this kind of components, close to nominal strains of nominal load cases wanted to be reproduced.

For the Innovative SHM systems it has been developed an (AE) Acoustic Emissions technique for the first damage detection. We can detect and locate the first incipient damage in a loaded 3D structure remaining the specimen globally undamaged. It has been demonstrated and corroborated with FEM models, that the Palier criteria is the most accurate procedure to find the first damage. Palier effect says that when a structure is kept at a certain load level, during the first 2 minutes some hits are recorded, but the next 2 minutes hits should no longer be recorded unless the structure is permanently damaged. This procedure can be used during the design development phase, when testing prototypes in order to find weak points and reduce the number of redesign loops reducing product development time risks and costs.

We also have tuned up the innovative SHM systems of (DIC-3D) Digital Image Correlation and (FORS) Fibre Optic Rayleigh Scatter techniques for the stress-strain events detection and quantification during experimental test. More concretely it has been tuned up the DIC system in order to detect and quantify hot spots & stress-strain events for external areas during tests of 3D specimens close to final one to be tested. The set-up has been developed specially for high depth of fields necessary for industrial components when they are tested. On the other hand, it has been tuned up the FORS technology for continuous strain measurements for internal areas. We can detect and quantify hot spots & stress-strain events for internal areas in 3D components difficult to be measured with other techniques. Fiber optic has been calibrated corroborating t

Final results

For the Innovative LOAD APLICATION SYSTEMS, It has been demonstrated that it is possible to apply tuneable real strain loads, on up to 350 Âµstrains (this is on the order of nominal loading cases); with (SMA) Shape Memory Alloys morphing technology, in real 3D leading edge components.

(AE) Acoustic Emissions for first damage detection has been considered the SHM technology that during the project has shown a beyond state of the art development. We can detect and locate first incipient damage in a real 3D representative structure. Procedure developed match very well with FEM model with strain criteria implemented. After the damage location, the component remains undamaged and is ready to be used for other tests, reducing the number of complex and cost final components.

Moreover, the combination of developed technologies, allows to test components during the development process showing the first damage point, the internal and external hot spot stress concentrations in order to reduce the number of tests needed for new product development and the recurrent costs.

These results have been proved in a similar component of the final HLFC specimen in size, stiffness and materials. From this point until the project is finished it is expected to replicate these results with the final HLFC component.