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Data for Designers

Data for Designers Aircraft Engineering THE MONTHLY SCIENTIFIC AND TECHNICAL ORGAN OF THE AERONAUTICAL ENGINEERING PROFESSION VOL XXIV No 275 JANUARY 1952 that it revolutionized the investigation of the problems arising from the subjection of highly-stressed materials to elevated temperatures. T will be recalled that among the several papers read at the 1948 Congress of Applied Mechanics which we subsequently repro­ Giving a Lead Iduced in full in these pages was one entitled 'The Plastic, Creep As we have already mentioned, various theories had been deve­ and Relaxation Properties of Metals' by M R A. E. JOHNSON of the loped to estimate in more or less accurate degree the allowable Engineering Division of the National Physical Laboratory. This working stresses involved. Experimental confirmation of the truth appeared in our January 1949 issue and it was followed in September of these was, however, lacking until the series of practical tests, of of the same year by another paper directly contributed by M R R. which the work reported by M R JOHNSON is part, was with great JOHNSON to these columns on 'The Behaviour of Metals under foresight put in hand in the Engineering Division of the National Multiaxial Stress Systems'—a related subject. Physical Laboratory. It is gratifying indeed to know that here is another instance of British scientists setting the pace for the world A Sequel by being first in the investigation of a new field of experiment. We are glad to welcome now, two years exactly after his first appearance in AIRCRAFT ENGINEERING, a third paper by him—this Simplifying the Problem time reprinted here by kind permission of THE INSTITUTION OF MECHANICAL ENGINEERS—dealing with 'Creep under Complex Stress Apart from the question of temperature, the detailed components, such as the rotor blades, of the new gas-turbine were, of course, Systems at High Temperatures', which is in some sense a continua­ subject to a complicated series of interrelated stresses which made tion of the Congress paper. To the two materials covered in the original paper (a low-carbon steel and the well-known Hiduminium detailed investigation of them an extremely complex matter which R.R. 59 alloy) are now added a magnesium alloy and a nickel- might well have daunted the most ingenious inquirer. The problem chromium alloy, No. 75 in the Nimonic range. was however approached, on the classic lines of such researehes, of seeking for some simplification by resolving the complex stress systems as far as possible into their component elements. In this Feeding the Hopper particular case, the assumption was adopted that the systems could, While the author is careful to point out that the results produced by making certain additions or subtractions, be resolved and replaced by the experimental work carried out are only strictly applicable to by an equivalent system of simple tension combined with simple the materials tested, these are none the less of such a wide variety torsion. The soundness of this assumption has been confirmed that others will hardly feel that this cautious acceptance of them is experimentally for at any rate the magnesium alloy investigated, as strictly necessary. Engineers will indeed, we believe, welcome them is detailed in an appendix to the paper published in this issue. as indicating which of the various criteria of failure that have been evolved by classic theorists in the past they can adopt in future Selecting the Samples calculations. Though the caution he displays in confining the applicability of his conclusions on these lines in each case to the A further desideratum was obtaining each of the materials to be particular material concerned because of their differing character­ subjected to test in a closely isotropic condition in regard to their istics is justifiable and understandable, they are none the less of creep properties. This necessitated using a different method of considerable general interest as being, we apprehend, adaptable to selection for each material—either by carefully choosing the precise calculations in regard to materials of similar type. method of cutting the test pieces from the ingot, or by specifying the use of cast or forged material. We do not propose—and indeed we are not qualified—to discuss A Tribute the tests or the results of them in detail, but we have we hope The experiments exemplify in a striking manner the extraordinary written enough to emphasize the importance and remarkable quality ingenuity which metallurgists have evinced in the last two or three of a brilliant example of experimental researeh carried out in the decades in developing their science. They would, we think, readily highest British tradition. admit that, as in so many other branches of engineering, the principal spur has come from the aeronautical engineer whose advances have Index for 1951 nearly always been one step ahead of those providing the necessary materials. There is, we suppose, little doubt that one of the principal It is desired to call the attention of readers to the fact that the obstacles to the development of the internal combustion, now known Index for last year was loosely inserted in each copy of the Decem­ as the gas, turbine lay in the apparent impossibility of finding ber 1951 issue. Where this is missing an extra copy can be supplied, materials capable of withstanding the exceptionally high tempera­ but as there is only a small stock of these it is hoped that a check tures involved. We do not know when, historically, the pheno­ will be made to make sure that a copy is not already available menon of creep was first recognized but it is, we suppose, true to say before application is made for a replacement. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Data for Designers

Aircraft Engineering and Aerospace Technology , Volume 24 (1): 1 – Jan 1, 1952

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb032119
Publisher site
See Article on Publisher Site

Abstract

Aircraft Engineering THE MONTHLY SCIENTIFIC AND TECHNICAL ORGAN OF THE AERONAUTICAL ENGINEERING PROFESSION VOL XXIV No 275 JANUARY 1952 that it revolutionized the investigation of the problems arising from the subjection of highly-stressed materials to elevated temperatures. T will be recalled that among the several papers read at the 1948 Congress of Applied Mechanics which we subsequently repro­ Giving a Lead Iduced in full in these pages was one entitled 'The Plastic, Creep As we have already mentioned, various theories had been deve­ and Relaxation Properties of Metals' by M R A. E. JOHNSON of the loped to estimate in more or less accurate degree the allowable Engineering Division of the National Physical Laboratory. This working stresses involved. Experimental confirmation of the truth appeared in our January 1949 issue and it was followed in September of these was, however, lacking until the series of practical tests, of of the same year by another paper directly contributed by M R R. which the work reported by M R JOHNSON is part, was with great JOHNSON to these columns on 'The Behaviour of Metals under foresight put in hand in the Engineering Division of the National Multiaxial Stress Systems'—a related subject. Physical Laboratory. It is gratifying indeed to know that here is another instance of British scientists setting the pace for the world A Sequel by being first in the investigation of a new field of experiment. We are glad to welcome now, two years exactly after his first appearance in AIRCRAFT ENGINEERING, a third paper by him—this Simplifying the Problem time reprinted here by kind permission of THE INSTITUTION OF MECHANICAL ENGINEERS—dealing with 'Creep under Complex Stress Apart from the question of temperature, the detailed components, such as the rotor blades, of the new gas-turbine were, of course, Systems at High Temperatures', which is in some sense a continua­ subject to a complicated series of interrelated stresses which made tion of the Congress paper. To the two materials covered in the original paper (a low-carbon steel and the well-known Hiduminium detailed investigation of them an extremely complex matter which R.R. 59 alloy) are now added a magnesium alloy and a nickel- might well have daunted the most ingenious inquirer. The problem chromium alloy, No. 75 in the Nimonic range. was however approached, on the classic lines of such researehes, of seeking for some simplification by resolving the complex stress systems as far as possible into their component elements. In this Feeding the Hopper particular case, the assumption was adopted that the systems could, While the author is careful to point out that the results produced by making certain additions or subtractions, be resolved and replaced by the experimental work carried out are only strictly applicable to by an equivalent system of simple tension combined with simple the materials tested, these are none the less of such a wide variety torsion. The soundness of this assumption has been confirmed that others will hardly feel that this cautious acceptance of them is experimentally for at any rate the magnesium alloy investigated, as strictly necessary. Engineers will indeed, we believe, welcome them is detailed in an appendix to the paper published in this issue. as indicating which of the various criteria of failure that have been evolved by classic theorists in the past they can adopt in future Selecting the Samples calculations. Though the caution he displays in confining the applicability of his conclusions on these lines in each case to the A further desideratum was obtaining each of the materials to be particular material concerned because of their differing character­ subjected to test in a closely isotropic condition in regard to their istics is justifiable and understandable, they are none the less of creep properties. This necessitated using a different method of considerable general interest as being, we apprehend, adaptable to selection for each material—either by carefully choosing the precise calculations in regard to materials of similar type. method of cutting the test pieces from the ingot, or by specifying the use of cast or forged material. We do not propose—and indeed we are not qualified—to discuss A Tribute the tests or the results of them in detail, but we have we hope The experiments exemplify in a striking manner the extraordinary written enough to emphasize the importance and remarkable quality ingenuity which metallurgists have evinced in the last two or three of a brilliant example of experimental researeh carried out in the decades in developing their science. They would, we think, readily highest British tradition. admit that, as in so many other branches of engineering, the principal spur has come from the aeronautical engineer whose advances have Index for 1951 nearly always been one step ahead of those providing the necessary materials. There is, we suppose, little doubt that one of the principal It is desired to call the attention of readers to the fact that the obstacles to the development of the internal combustion, now known Index for last year was loosely inserted in each copy of the Decem­ as the gas, turbine lay in the apparent impossibility of finding ber 1951 issue. Where this is missing an extra copy can be supplied, materials capable of withstanding the exceptionally high tempera­ but as there is only a small stock of these it is hoped that a check tures involved. We do not know when, historically, the pheno­ will be made to make sure that a copy is not already available menon of creep was first recognized but it is, we suppose, true to say before application is made for a replacement.

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Jan 1, 1952

There are no references for this article.