IIW History 1948-1958

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of three or four members of the Commission have been appointed to deal with specific well-defined t asks. In this way it h as been possible to keep the number of persons a ctively involved in the work of the Commission and required to attend Corn mission meetings quite small. The Commission has never appointed a perma nent secret a ry, the minutes being prepared by a drafting committee which for many yea rs has consisted of the v ice-chairman, Professor SOETE, and lVIr. AuDIGE as French speaking delegates, Dr. HARRIS and Dr. BENSON as English speaking delegat es. It is entirely clue to their untiring effort s that concise records of the Commission's activities over the past ten years exist. The work of an international Commission cannot be measured only by results which it has produced in the fo rm of published documents. The problem of residual stresses has exercised the minds of engineers responsible for welded construction for many years, and an enormous amount of research work has been undertaken in many different countries in order to elucidate the effect of residual stresses on the service behaviour of welded structures. Some aspects of these problems are still unsolved , in particular the effect of residual stresses on brittle fracture and on fatigue. Neverthele s, appreciable advances have been made during the last ten years, and much of the n ork carried on during this period in different countries has been stimula ted by the discussion and exchange of information which have taken place \Yithin the Commission. It h as been the co nstant endeavour of the Commission to integrat e work in the field of it activ– ities throughout the participating countrie · so tha t different investi gations carried out in different countries would be complementary to each other to an ever increasing degree. This h as been no easy task b ut a stage has now been reached where it can be said that no important investigation is initiated in any of the participating countries " ·ithout being discussed first ,,·ithin the Com– mi. ion. In fact, at the last meeting of the Commission in Essen, a n ext ensive American programme concerned " ·ith the study of the effect of residual . tresses on the initiation of brittle fracture and the inhibition of brittle fracture by various stress relieving methods in pressure vessels \ \'aS distributed by the American delegation t o all participating countries with the invitation to comment ; com– ment were received from a large number of countries and it is hoped t hat they may have been helpful to the American im·estigat or. . It was reali:' ecl by the Commission very early in its work that the meas ure– ment of residual stresses wou ld play an important part in all its work; it was also realised that there were wide difference· in the methods used for residual stress meas urements in different countries a nd that, if the results of researches carried out in these countries \\·ere to be cons ide red on a common basi , it \\·as necessary to en ure that either one and the same method \Yas used every \\·here for the measurement of residual stresse , or that at any rate , " ·here different methods "·ere used, they \Yould give comparable results. The Commission therefore devoted an app reciable part of its efforts in the early years to the study of different methods available; on the basis of t his study, it recommended that the method de\ eloped by Dr. Gu~NERT of \\·eden should b e used for residual stress measurements in preference t o other methods. Comprehensive instruc– tions for the procedures t o be adopt ed were ,1·orkecl out and the design of a suitable instrument cle,·eloped in Sweden \l'aS made freely available to all participating countries. ,' ince then the Commission h as revie,\'ed from time t o time other methods of measurement, but has not fo und it necessary t o change its origin al recommen– dati ons. E ndeavours have rather been direct ed, under the leadership of Dr. GuNXER'l', t o,Ya rds the expansion of the usefulness of the method t o permit the det erminati on of residual stresses as a function of the thickness co-ordinate . 3 . WORK ACCOMPLISHED.