FOS 3 D

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Fibre Optic System for Deflection & Damage Detection

Project Funding:
Cleansky
Project Coordination:
AAC
Project Partners:
Integrated Microsystems Austria (IMA)
Duration:
24 months

The motiv­a­tion behind the devel­op­ment of morph­ing wings is biolo­gic­ally inspired by the flight capab­il­it­ies of birds. They are able to achieve a wide dynamic range missions through large shape changes to their wings. There are several examples in aircraft industry where morph­ing wing approach is already tested with good results in terms of tune­able aero­dy­namic prop­er­ties. However, a big chal­lenge in the art still exist how effi­ciency to control the flight by morph­ing wing concept without damages possible induced in the compos­ite mater­i­als such as carbon- or glass-fibre rein­forced plastics (CFRP and GFRP). In order to guar­an­tee the struc­tural integ­rity and airwor­thi­ness of such a compon­ent continu­ous inspec­tions with regard to damage evol­u­tion have to be done.

Currently all non-destruct­ive inspec­tions are performed on ground follow­ing a fixed time sched­ule where the number of inspec­tions per time increases signi­fic­antly with the age of the aircraft (Time Based Maintenance).

fos3d_1If the sensors and / or actu­at­ors of a non-destruct­ive inspec­tion and load monit­or­ing system could be perman­ently attached to the struc­ture of interest (self sens­ing struc­ture) and the system oper­ated online during service (Structural Health Monitoring), espe­cially in distrib­uted and diffi­cult to access areas, the way is open for a paradigm change to main­ten­ance on demand (Condition Based Maintenance). In this project we propose a new tech­nique based on low coher­ence inter­fer­o­metry performed in “all-in-fibre” sens­ing config­ur­a­tion, made of single mode optical fibre. The strain sens­ing element is a coil made of several turns of optical fibre, firmly fixed on the surface of the subjec­ted struc­tural part. These sensors will be used to acquire low frequency strains for the determ­in­a­tion of the deflec­tion and at the same time acquire the high frequency strains arising from the onset, growth and fric­tion of damages (AE events). In such config­ur­a­tion only a limited number of sensors is required to char­ac­ter­ize the damage as AE is the only pass­ive tech­nique that is able to cover larger areas with a suffi­cient size of detect­able damage.

In general, key ques­tions to be answered by the system developed in this project are:

fos3d_2

  • What is the direc­tion of deflec­tion of compos­ite wing?
    ( qual­it­at­ive aware­ness)
  • What is the magnitude of deflec­tion of compos­ite wing? (quant­it­at­ive aware­ness)
  • Does the damage exist at all? (qual­it­at­ive aware­ness)
  • Where is the damage? (quant­it­at­ive local­iz­a­tion); and
  • What is the size and sever­ity of damage? (quant­it­at­ive assess­ment of damage).