Decisions on life-cycle reliability of flood defence systems

Many countries rely on flood defence systems to prevent economic damage and loss-of-life due to catastrophic floods. Asset managers of flood defence systems need to cope with the consequences of structural degradation, and changing societal and environmental conditions, in order to satisfy performance requirements and optimize societal value of...

Extensive testing on PVC sewer pipes towards identifying the factors that affect their operational lifetime

Polyvinyl chloride (PVC) sewer pipes have operated for decades in a hostile environment, raising concern among sewer managers over the longevity of their drainage systems. Inspection data (CCTV and Panoramo®) reveals that severe defects have already surfaced, yet it is unknown if the material properties of PVC sewers have been affected. In...

Sewer asset management: state of the art and research needs

Sewer asset management gained momentum and importance in recent years due to economic considerations, since infrastructure maintenance and rehabilitation directly represent major investments. Because physical urban water infrastructure has life expectancies of up to 100 years or more, contemporary urban drainage systems are strongly influenced...

Committee III.2: Fatigue and Fracture

Concern for crack initiation and growth under cyclic loading as well as unstable crack propagation and tearing in the ship and offshore structures. Due attention shall be paid to the suitability and uncertainty of physical models and testing. Consideration is to be given to practical application, statistical description and fracture control...

Value of information in levee monitoring and inspection (poster)

Potential of Laser Scanning for Quantification of Sediment Deposits in Sewer

There is still a long way to go in understanding the behaviour of solids in sewers due to the difficulties in obtaining sufficient monitoring data to be able to understand the dominant processes. Laser profilers have shown to be capable of measuring the pipe interior, with a high accuracy, which is sufficient to be able to detect and quantify...

Performance assessment of housing associations

This article analyzes the function, design, and effects of a method to assess the performance of housing associations in the Netherlands. First, the roles of performance assessment are discussed from three perspectives: the association as an agent for the central government; the association as a facilitator of local stakeholders’ needs; and the...

Renovation techniques for fatigue cracked orthotropic steel bridge decks

This dissertation presents the research into renovation techniques for orthotropic steel bridge decks. These techniques are needed to solve fatigue problems in the decks of these bridges, as several fatigue cracks have been detected in the deck structure of these bridges the last decade. A well-known example of fatigue cracks are those observed...

Aircraft corrosion and fatigue damage assessment (USAF ASIP Publication)

This paper reviews currently available information on corrosion and fatigue in aircraft as a background to discussing the assessment of corrosion and fatigue damage. The main topics are: - aircraft operating environments and loads - corrosion - fatigue - corrosion and fatigue - corrosion and fatigue damage assessment. Aircraft structures are...

Gebruiksbewaking bij de marine luchtvaartdienst

The RNLN Fleet Air Arm (Marine Luchtvaartdienst) has recently implemented a series of usage monitoring procedures for optimisation of Orion and Lynx operation. Goal is an enhancement of efficiency, economy and safety of the usage of both aircraft systems. Compared to the benefits, the efforts for achieving useful usage monitoring are relatively...

Some tests to assess the effect of crack stoppers on the fatigue life of centre-notched sheetspecimens

Several simple crack stopping methods were evaluated In fatigue crack propagation tests on 2024-T3 Alclad sheet specimens. After precracklng until a crack of 40 mm was obtained crack stoppers were Installed and the fatigue test was continued. Crack stoppers Installed In stop holes were: a blind rivet, a hard driven rivet, a heavily tightened...

Reliability of nondestructive inspection

This report describes the concept of reliability of nondestructive inspection (NDI) and reviews the different aspects involved. First, the probability of detection (POD) of flaws in flawed specimens is discussed. To provide a measure of confidence in an estimated POD, lower botind values of this probability at a given confidence level are...

Evaluation of non-destructive inspection methods applied to milled step-down areas

The present report describes how fatigue cracks were produced in 102 specimens. After cracking these specimens were inspected non-destructively by means of eddy currents, ultrasonics. X-rays and penetrants, and the indications were recorded. Successively the specimens were exposed to corrosion whereafter the inspections were repeated. Upon...

The effect of gust alleviation on fatigue in 2024-T3 Alclad

Fatigue tests under flight simulation loading were done on simple notched 2024-T3 Alclad sheet specimens. Reduction of the gust load amplitudes resulted in an increase of crack initiation life but hardly influenced crack propagation. Reduction of the overall stress level increased both initiation and crack propagation life. The observed...

De toepassing van schade-onderzoek in de luchtvaart

Following an introduction about the methods of failure smalysis the present paper illustrates by meaJis of actual case histories the role of service failure analysis in defining new inspection procedures and the adapting of existing ones. It appears that in some cases this leads to a different design or choice of material. The examples are all...

The requirement of damage tolerance: An analysis of damage tolerance requirements with specific reference to MIL-A-83444

Fail-safety or damage tolerance i s generally considered as a highly desirable and in some countries as anobligatory property of transport aircraft structures. Recently the USAP issued a detailed requirement on damage tolerance. In the present report various aspects of damage tolerance are discussed with specific reference to the USAP...

Preliminary investigation into the application of magnetic ruhher inspection (M.R.I.)

The present report gives a brief description of the principles and probable advantages of the magnetic rubber inspection technique. The results of a first demonstration of the method at the NLR are discussed. It is concluded that the method needs further evaluation.

Present and possible future applications of neutron radiography in aviation in the Netherlands

The present report reviews some of the literature on neutron radiography, its principles and its applications especially as conducted by the Energieonderzoek Centrum Nederland ECN on behalf of the National Aerospace Laboratory NLR. It is concluded that neutron radiography already is a valuable inspection tool and in addition to that it offers...