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概要
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Among many shell expansion methods, "The Base Line Method" is the most simple and practical. We can draw the expansion of shell plates on the flat steel plates immediatly after the frame and seam battens are provided. The other methods need the complete expansions on the mould loft before marking on the steel plates. But the base line method cannot be applied to such twisted plate that the angle between frame lines and seam lines are far from right angle. Because the base line on the Body Plan does not correspond to the straight line on a flat steel plate used in marking. Assuming that a shell plate is divided into small parts by many planes parallel to the frame line, the line, straight or curved, which passes through middle points of every frame, will work as an axis of torsion of each part. We have to expand twisted shell plates relying on this line. We cannot obtain good expansion of these irregular plates by any other method without consideration of the matters above-mentioned. There is to be a special curve on the twisted plate that was straight when the plate was flat. Authors found out the simple practical way to draw this special curve on the Body Plan. It needs only five or ten minutes to draw the curve. We name this curve "The Corrected Base Line". Using the corrected base line we can expand most accurately in the same way as the ordinary base line method. We applied this method to almost all shell plates of ordinary cargo ship. The results were satisfactory and we could cut down the labour to expand shell plates.
- 社団法人日本船舶海洋工学会の論文