Field of research: Outfitting Design; Fatigue Strength
Project leader: Prof. Dr.-Ing. W. Fricke
Duration: 01.01.2002 – 31.12.2003
Funded by: Stiftung Stahlanwendungsforschung (FKZ AVIF A 183)
Pipes in engine rooms of ships are fastened according to the local conditions with partly rather simple supports as defined in DIN 86027, which consist of pipe clamps and connectors made of flat bars. These showed sometimes cracks already during the trial trip or early service period, requiring costly repairs and modifications of the pipe supports. The analysis of the status-quo showed that mostly the weaker fasteners with relatively narrow flat bars are affected, where usually the connection to the pipe clamp was damaged. In the present project, vibration measurements were performed at selected pipe systems and compared with computations. A relatively accurate prediction of the lowest natural frequencies, which is necessary for a resonant-free design, was shown to be possible only under consideration of the flexible end connection of those supports ending within plate fields. Notable vibration amplitudes and stresses occur only during resonant excitation, while forced vibrations between resonance peaks showed rather small stresses. Regarding the strength behaviour, five pipe support types were investigated experimentally and numerically. Apart from static measurements of the strains during fastening the screws, which showed over-elastic straining at different locations, fatigue tests under cyclic axial and bending load of the supports were performed. Here, the shape of the pipe support was optimised in view of good fatigue behaviour together with low material consumption. Stress results from finite element calculations were suitable only for comparisons, as the actual stresses were affected by pre-deformations and the resulting contact of the pipe clamp and by friction effects. Finally, a guideline was given for the designer, which summarizes the achieved results and experiences and which gives hints for the application of the different support types.
Fricke, W. und Bohlmann, B. (2004):Entwicklung von Standardrohrhaltern für den Schiffbau. CMT-Forschungsbericht 3/2004, Center of Maritime Technologies, Hamburg.
W. Fricke und B. Bohlmann: Entwicklung von Standardrohrhaltern für den Schiffbau. Jahrb. der Schiffbautechn. Ges. 99 (2005), Springer-Verlag, Berlin Heidelberg New York