Condition Monitoring of structurally loaded polymers and composites is of crucial importance in many applications. It provides information about the current status of the material as measured by certain important material parameters.
The condition which limits the lifetime of the structure should be measured in a non-destructive manner if replacement of the test piece is undesired. Furthermore, the structures under investigation are generally difficult to reach with conventional measurement equipment. Therefore part of the research is focussed on in-service monitoring.
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This research focuses on the identification of a material parameter that can be identified sufficiently accurate by ultrasonic technologies. It must also be possible to assess the condition and the remaining life time of asbestos cement pipes employing this material parameter.
Remko Akkerman, Richard Loendersloot, Roy Visser
In a previous PhD research project the framework of a non-destructive lifetime assessment method with physical ageing as the predominant factor limiting the lifetime of uPVC pipes was developed. Before the method can be put into practice, the framework has to be extended and refined, putting an emphasis on increasing the resolution of micro-indentation measurements. Furthermore, the research focuses on incorporating the influence of gelation, molecular weight, additives, injection moulding, bi-axial stretching in the existing framework
Ton Bor, Roy Visser
Cogas, Enexis, Liander, Stedin, Bureauleiding, Delta, Rendo, Vitens
With only a measurement technique the residual lifetime of a structure cannot be determined. A translation between the measurement results and the current and future condition of the structure is required to determine the residual lifetime. This translation step from ultrasound measurements towards the residual lifetime of uPVC pipes is the main focus of this research project. The ultrasound measurement technique itself is under development in a separate research project.
Vibration based damage identification methods are promising as an alternative for the time consuming and costly Non Destructive Testing methods currently available. These methods also offer the potential to be used in a real-time Structural Health Monitoring system.
Cleansky, Fokker, NLR, AgustaWestland, Applied Mechanics Group of the University of Twente.
Development of an ultrasound measurement technique to determine the residual lifetime of uPVC water pipes
Ultrasonic measurement techniques are one of the most frequently used techniques for inspection of engineering structures. In this project a new ultrasonic measurement technique to evaluate the (physical) ageing state and crack growth in uPVC water distribution pipes is developed.
Applus Rtd, Vitens.
The consequences of physical ageing limit the lifetime of uPVC gas distribution pipes. The focus of the research project is therefore on the influence of physical ageing on the mechanical behaviour of uPVC gas pipes. The procedure of determining the residual lifetime is based on these findings and is split into four aspects/chapters: the choice for the yield stress as a measure for the condition of the pipe material, characterisation of the change of the yield stress time (its ageing kinetics), determining the critical condition and development of a method of measuring the current condition.
Roy Visser, Ton Bor
Cogas Infra & Beheer BV, Enexis, Liander, Stedin, KWR, Eindhoven University of Technology