The excellent works referred to use the scientific approach of 'consider an element'. A further understanding of the operation of a drum can be found by considering the radial pressure distribution on the shell. Seam weld behaviour has been overlooked in the rush to eradicate diaphragm failures. We don't hear much, or even anything?, about seam failures so pehaps the issue is an also ran until someone looks at the metal saved in making the thinnest possible shell. I should live that long! ■

The seam weld has not been overlooked. Read through the Modified Transfer Matrix Method. Hoop, bending, radial and tangential loads and strain are considered. The type of weld along the seam must be matched with the weld stress limit criteria.

Having said this, I acknowledge the problem with the seam weld analysis in defining the backing bar influence. To my knowledge, this can only be evaluated using FEA.

We have done so in an attempt to understand the local notch sensitivity and weld irregularities. Others have also made such a study. In this analysis and with locking pressure analysis, plasiticity must also be considered. Confirmation must include physical testing of specimens as was done by the British to confirm the many weldment configurations and types.

Today, CDI has not expanded these techniques. I believe this will only come from academic research. Dr. Qiu's work was offered, by CDI, to the industry as an informational guide as to the difficulties when investigating large and highly loaded pulley designs. ■