Objective
Development and validation of methods and procedures for reliability assessment and lifetime prediction by knowledge representation and diagnostic techniques.
Progress to end 1990
Tests on 1:5 scaled vessels
- The tests on vessel A were ended and the final inspections executed,while the destructive testing is under way. The cladding residual stresses turned out to be of tensile type on the clad surface but compressive in the clad-ferritic interface, slowing down the propagation of the inner crack tip.
- JRC-CISE-EPRI collab.(validation of a superposition model for the environmental fatigue):the fractographic examination of cracks confirmed the plausibility of the model.
Pressurized Thermal Shocks
The test rig has been modified to optimize the experimental parameters.Some 500 thermal shocks have been performed so far and the collected data are being elaborated for lifetime assessment.
Dev.of RAMINO (Reliability Assessment for Maintenance and Inspection Optimization) KBS
Domain experts elicitation and knowledge representation did progress; inference engines and intelligent interfaces with standard engineering software have been realized.
A new option of the COVASTOL code has been developed by JRC and CISE for lifetime prediction of turbine shafts and disks.
NDE techniques
- Laser interferometry:a micro-endoscope for inspection of internals has been designed, built and tested.The real time mapping of damage on composite specimens (from SIAI-Marchetti) has been obtained, while a new, more powerful algorithm for fringe analysis has been implemented.
- First indications have been obtained from the study of the fractal structure of turbulence.
Publications
- Nuclear Engineering and Design 118 (1990)
- The Int.J. of Pressure Vessels and Piping, vol.41 (1990) 25-41
- Structural Reliability, Kluwer Academic Press, (1990)
- Fatigue Fract. Engng. Mater. Struct. Vol.13 N.5 pp.457-471 1990
Detailed description of work foreseen in 1991 (expected results)
Tests on 1:5 scaled vessel - The destructive testing of vessel A will be completed. Framatome is willing to buy the results for validating models of crack growth initiation. The test on vessel B is to be discussed with partners for best exiloitation in view of generation of norms and standards for life prediction of structures. - The JRC-CISE-EPRI collaboration will be completed.
Pressurized thermal shocks - Prosecution of experimentation, data analysis and life prediction exercise (aim: norms for thermal fatigue life prediction). The implementation of the BOSS KBS for plant management will be prosecuted (depending on personnel availability).
Development of RAMINO KBS - Final implementation of the prototype. - Study (with industrial partners) of the possibility to extend to composites the numerical code RELIEF.
NDE techniques - Use of pulsed laser for strain monitoring of operating structures. - Image processing: further research on fractal dimension of turbulent flow patterns for load diagnostics.
Short description of evolution of work in 1992
The experimental and theoretical activity on metallic components will be oriented to the development and/or validation of methods and techniques for standards setting in lifetime prediction and reliability index evaluation. According to the interest of our industrial partners, the research effort on composite material components will be increased. The cost/benefit ratio of organizing training courses in diagnostics and structural reliability is being investigated.
Topic(s)
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21020 Ispra
Italy