Observations of acoustic emission activity during gear defect diagnosis.

It is widely recognised that acoustic emission (AE) is gaining ground as a non- destructive technique (NDT) for health diagnosis on rotating machinery. The source of AE is attributed to the release of stored elastic energy that manifests itself in the form of elastic waves that propagate in all directions on the surface of a material. These detectable AE waves can provide useful information about the health condition of a machine. This paper reports on part of an ongoing experimental investigation on the application of AE for gear defect diagnosis. Furthermore, the possibility of monitoring gear defects from the bearing casing is examined. It is concluded that AE offers a complimentary tool for health monitoring of gears

An initial investigation on the potential applicability of Acoustic Emission to rail track fault detection.

In light of recent accidents in the rail industry, the assessment of the mechanical integrity of rail-track is of vital importance. This encompasses the integrity of the track due to rolling contact fatigue and surface wear. Whilst numerous techniques are employed for crack detection, several defects have clearly been missed. In Europe, more than 100 rails are broken each year and rail maintenance costs within the European Union is estimated at 300-million Euros annually [Inst Mech Engrs 216 (2001) 249]. The derailment of a train at Hatfield in October 2000 is a tragic example of a fractured rail going undetected. This paper presents an experimental study on the applicability of Acoustic Emissions (AE) for rail-track defect diagnosis. An experimental test- rig was employed for this programme. This allowed for a surface defect to be seeded onto the test-rig. The investigation presented is part of an on-going attempt to develop the non-destructive technique of AE for assessing the surface integrity of rail-track. The AE technique is not new but the application in this particular instance is unique. It is concluded that the AE technique offers a complementary tool for rail track defect detection

Mechanical evolution of the rotating biological contactor into the 21st century.

This paper presents a review on the evolution of the mechanical design of rotating biological contactors (RBCs) within the UK. The findings documented have been taken from the biggest mechanical survey on RBCs ever undertaken worldwide and focuses on 300 operational units. The paper looks at the main components of the RBC and discusses the evolution of each member. Mechanical deficiencies associated with each design are briefly presented, giving an insight into reasons for improvements. This is the only known document that details changes in design philosophy employed over the last 30 years, with illustrative examples. For the purpose of this review, the mechanical evolution of the RBC is focused on three primary sections: media panel designs, media support structures, and auxiliary support systems including bearings, power units, and transmission systems. It is shown that the evolution of media panels has largely been directed by economies of manufacture and operational requirements. However, advances in the mechanical design of the RBC supporting structure, while dependent on media type, are largely influenced by overcoming known mechanical deficiencies as well as increasing operational life. This paper depicts the current technology and practice of UK-based manufacturers and details reasons for mechanical deficiencies