Objectif To achieve a better capability to diagnose the actual safety conditions of steel structures by means of a new method based on the elastic wave propagation and reflection characteristics. aracteristics.Main results so far achieved can be summarised as follows:- The theoretical models of the waves propagation have furnished useful data for establishing the best conditions for exciting the structure; however the developed computer program cannot furnish a forecast of the wave propagation, as the finite elements calculations are to expensive to be used on a routine basis.- A new system for including elastic waves in the structure members has been studied and developed.The system is based on the magnetostrictive effects and eliminates all the problems related to the use of mechanical exciters.- A software for collecting, analysing and comparing the echoes from the structures discontinuities (nodes, cracks, etc. . .) has been developed.- The theory of the synchronous sampling for the signal analysis has been further developed.- A portable instrumentation system, housed in a standard container , has been designed and built. The system includes, besides the instrumentation systems (signal anlyzer, computer, amplifiers, etc . . . ), all the equipment necessary for on field operation (as umbilical cable, cable winch, underwater cage, exciter and accelerometers, etc. . . ).- The system has been tested at sea in order to verify its operability by divers.- Land and sea test of the system on a jacket model (simulating a real structure) are in course.- The results so far achieved demonstrate the capability of the method to detect damage corresponding to 1/4 cut (or less) of the structural members sections, when used as comparative local method .The basic principle of the proposed method is that an elastic wave propagating along a structure shares its energy between a transmitted wave and a reflecting one when it reaches a discontinuity in the structure (e. g. a crack). Measuring the time of return and the energy of the reflected wave, it should be possible to locate and quantify the discontinuity.The project is subdivided into the following main subjects:- acquisition of basic theoretical knowledge- theoretical and laboratory experimental study of the method- design and procuring of a subsea portable monitoring system- field test of the portable system on a jacket model- sea test of the portable system. Programme(s) ENG-HYDROCARB 1C - Programme (EEC) of Community projects in the hydrocarbons sector, 1973-1985 Thème(s) 1.6 - MISCELLANEOUS Appel à propositions Data not available Régime de financement DEM - Demonstration contracts Coordinateur TECNOMARE SPA - SOCIETA PER LO SVILUPPO DELLE TECNOLOGIE MARINE Contribution de l’UE Aucune donnée Adresse SAN MARCO 3584 30124 VENEZIA Italie Voir sur la carte Coût total Aucune donnée
