碩士 / 國立海洋大學 / 系統工程暨造船學系 / 90 / Large hatches usually appear in containerships. However, the geometrical discontinuity induced by deck opening will cause stress concentration at hatch corners. It is a very important task for containership designers to improve the stress concentration problem.
The characteristic of key groove together with a circular hole at hatch corner is discussed in this paper. The key groove has the shape of circular arcs with different center. The ameliorative efficiencies of key groove together with a circular hole are revealed. To compare the stress concentration at the hatch corner with original keyhole design and the new alternative key groove configuration of a 1092 TEU containership, the programs, WARSHP and ANSYS are used. The boundary conditions in the local structure of a hatch corner can be determined by WARSHP. While the design load is based on the LR rules. Then the stress concentration is characterized by ANSYS.
In designing key groove together with a circular hole, six parameters are used to represent the geometry. They are: initial groove width (A); orientation angle of the center circular arc of the key groove (THETA); radius of center circular arc (CR); radius of circular hole (r); radius of outside circular arc (R1); radius of inside circular arc (R2), etc.. By systematical approach to find out the sensitivity of these parameters to the stress concentration effect, the following data are taken:
A=0.3m, 0.4m and 0.5m
THETA= , and
CR=1.4m, 1.5m and 1.6m
r= 0.3m, 0.35m and 0.4m
R1=1.3m, 1.5m and 1.7m
R2=1.3m, 1.5m and 1.7m
From the results it can be said that r, CR and R1 will cause more contribution than A, R2 and THETA on the stress ameliorative efficiencies. However, the contribution coming from THETA is still more than that coming from A and R2.
Since the width of the key groove together with a circular hole is shorter than that of a keyhole, thus the scallop sizes on end hatch coaming for these two kind designs are much different. Therefore, hole type on end hatch coaming should be taken into account for the key groove with a circular hole on deck. In this paper, three different types of end coaming hole are selected, i.e.,
(1) TYPE1: ellipse hole with (longitudinal axis)/(transverse axis) = 0.5.
(2) TYPE2: circular hole with (longitudinal axis)/(transverse axis) = 1.0.
(3) TYPE3: ellipse hole with (longitudinal axis)/(transverse axis) = 1.5.
The results reveal that the key groove with a circular hole will attain more improvement than original keyhole design for the of stress concentration. The stress improvement is between the range 0.65% ~22.8%. Besides, the stress concentration at end hatch coaming and hatch corner will be effected by different types of holes. The end coaming hole, TYPE3 has best ameliorative efficiencies, and TYPE2 has most uniform distribution according to the standard deviation of stress distribution. The stress ratio has calculated for the case of key groove together with a circular hole, and the magnitude of stress ratio is also displayed.
| Identifer | oai:union.ndltd.org:TW/090NTOU0345015 |
| Date | January 2002 |
| Creators | Y. T. Cheng, 鄭義騰 |
| Contributors | W. H. Wang, 王偉輝 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 97 |
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