No abstract

The use of vibration to reduce residual stress levels in fabrications is potentially an attractive alternative to thermal annealing. The application of the process has hitherto been limited by the lack of coherent theory of operation. In this study, residual stresses were introduced into a low-alloy steel EN3b by rolling. It was shown that prolonged low-amplitude vibration at 100 Hz induced a stress relaxation of as much as 40 per cent, where the original level was close to yield. A model has been developed to explain the diverse effects resulting from low-amplitude vibration; the model involves the motion of dislocations under the influence of the combined residual and external cyclic stress fields. This model, which has been validated by detailed X-ray line profile analysis and elasticity measurements, is an extension to the currently available explanation for VSR (vibratory stress relief). The standard model, which assumed the need to exceed the local yield stress, only comes into operation at the higher levels of applied stress amplitude. The development of accurate and validated methods for the application of VSR may now be contemplated.

No abstract

A comparison has been made between the fatigue lives of welded specimens a) in the as welded condition b) after heat treatment, and c) after post-weld vibration. By comparison with the aswelded specimens, the fatigue lives of the thermally relieved specimens were found to decrease by 43%, while the vibration treated specimens showed an increase of between 17% and 30%. While these findings are interesting in that they offer a way of extending the fatigue lives of welded joints, they confirm the view that the mechanism of residual stress relieving in the vibratory stress relief (VSR) method, and its relationship with fatigue life is poorly understood.Tel: 0 I4 I 577 6297, Fax: 0 I 4 I 577 628 I

Factor analysis of FIRO-B data obtained from new software product teams had led to a reformulation of Schutz's ideas on team compatibility. The concept of Group-Warmth as a derivative of the FIRO-B Inclusion and Affection scales was developed and shown to be related to the commercial effectiveness of teams. In a like manner, the FIRO-B constructs of Control-Expressed and Control-Wanted were explored through concurrent factor analysis of 16 PF data. A new interpretation has been given to both FIRO-B Control scales, namely, Assertive-Impulsive.