International Shipbuilding Progress - Volume 4, issue 39

Authors: Rothemund, M.

Article Type: Research Article

Abstract: This paper was first published in the M.A.N. Forschungsheft No. 6/1956. We consider, however, that information on the new M.A.N. radial type high-pressure supercharger is of sufficient interest to shipbuilders, shipowners and others who may not be readers of the Forschungshefte to warrant a reprint in the M.A.N. Diesel Engine News. No. 30/1954 of the Diesel Engine News covered the design features of high-pressure superchargers originally used in conjunction with M.A.N. 4-stroke diesel engines of the K6V45/66 m.H.A. type. This unit was comprised of a 3-stage axial type reaction turbine and a 14-stage axial flow compressor. The axial type …had been chosen because our axial compressors at that time were more advanced from the viewpoint of efficiency than were radial compressors. In the meantime the radial compressor has caught up and is, therefore, preferably used in new power-plant designs. The present article deals with the new M.A.N. high-pressure supercharger of the radial type installed in the m.s. Tannstein and her sister ship Torstein . Show more

DOI: 10.3233/ISP-1957-43901

Citation: International Shipbuilding Progress, vol. 4, no. 39, pp. 561-571, 1957

Authors: Burghgraef, B.

Article Type: Research Article

Abstract: A method to evaluate the maximum deflection and maximum stresses in a simply supported plate subjected to water pressure and compressive forces in the middle plane is discussed. It is based on a comparison of the results obtained from Marguerre’s theory of large deflections and from de Saint Venant’s linear equation for small deflections of plates. A magnification factor is derived by means of a similar procedure as used by F. Bleich . However a more accurate result is aimed at by taking into account a term neglected by F. Bleich . Charts are given from …which a rapid computation of maximum deflection and stresses may be made. Limitations to the use of the magnification factor are discussed and a numerical example is given. In an appendix the method to prepare the chart from which the magnification factor can be determined, is described. It is shown that a simple construction and only a minimum of numerical work are necessary. Finally some references are given. Show more

DOI: 10.3233/ISP-1957-43902

Citation: International Shipbuilding Progress, vol. 4, no. 39, pp. 572-578, 1957

Authors: Shepheard, Victor

Article Type: Research Article

Abstract: Scientific and technical developments are revolutionizing weapons, equipment, and the warship hulls which carry them into service. Of the many problems which these changes are bringing to warship design, two particular aspects, namely developments in hull structural design and structural steels, are dealt with in this lecture. It describes some of the special problems in the hull strength of surface warships and submarines — particularly those due to the dynamic loading set up by underwater explosions — which led to the inauguration of the Naval Construction Research Establishment and the provision of special facilities, some of which are unique. …Reference is made to the theoretical and experimental research work which is being undertaken to obtain a better appreciation of the way various design features of warship hulls resist the static and dynamic forces imposed upon them, and special emphasis is given to the post-war research on steel materials, welding, and the phenomenon of brittle fracture. These researches are being undertaen with the principal objects of avoiding brittle fracture in normal structural steels and of developing high-yield steels for special applications in warship construction. The difficulties that have been met in the development of these steels are discussed, including the problems of welding them under shipyard conditions. The discussion also brings out the need for more modern plant in our steelworks. This research work is directed not only towards the building of warship hulls that are capable of withstanding the forces of nature and enemy attacks, but also towards achieving these aims with minimum hull weight, in order that the largest military loads may be carried. Show more

DOI: 10.3233/ISP-1957-43903

Citation: International Shipbuilding Progress, vol. 4, no. 39, pp. 579-595, 1957

Authors: Norén, T.M.

Article Type: Research Article

Abstract: A certain property of steel called the “nominal cleavage of strength” can be determined by means of tensile test pieces on the edges of which a brittle alloy has been welded. On exposing these test pieces to an increasing tensile stress, cracks are continuously formed in the brittle layers of welding. At a certain critical stress a fracture will be initiated at one of the sharp crack fronts. A characteristic property of a steel, the nominal cleavage strength is defined as the highest nominal tensile stress a steel can withstand in the presence of a crack without the initiation of …fracture at the crack front. The nominal cleavage strength decreases continuously as the temperature decreases just as the conventional yield point increases continuously with decreasing temperature. If curves of these strengths are drawn the point of intersection would appear to be a transition temperature for the steel, defined as the temperature above which plastic deformation can occur in a large volume of material despite the presence of a crack, but below which only minor local plastic deformation is possible immediately in front of the crack. By means of the testing method called “NC-testing” (NC = nominal cleavage) results have been obtained that show a certain correlation to the results of impact tests as well as to those of other brittle-fracture tests, e.g. Tipper, Van der Veen and others. Moreover, the critical stresses for initiation and propagation of brittle fractures are shown by means of NC-curves as well as the influence of residual welding stresses. It is also shown that the quality of a steel with regard to its brittle-fracture tendency cannot be simply expressed by an impact transition temperature as the critical stresses quoted above are not directly connected with the position of this temperature. Show more

DOI: 10.3233/ISP-1957-43904

Citation: International Shipbuilding Progress, vol. 4, no. 39, pp. 596-609, 1957