1. 1(1) 1(2)[1] 1992 [2] 1992 [3] 100 100 比率 (%) 80 60 40 変形腐食亀裂 相対損傷数 80 60 40 変形腐食亀裂 20 20 0 0 5 10 15 20 25 船齢 ( 年 ) 0 0 5 10 15 20 25 船齢 ( 年 ) (1) Ratio of Each Damage (2) Number of Damage Fig.1 Relation between ship s age and damage[1] 1 ( 財 ) 日本海事協会 35 平成 14 年度 ClassNK 研究発表会
14 FEM 2. 2.1 1 14 [1] 1992 [3] 1(a)(b) 1(c) 2 2.2 2.3 [2] 2 ( 財 ) 日本海事協会 36 平成 14 年度 ClassNK 研究発表会
(a) Upper Portion (b) Middle Portion (c) Lower Portion (after Sandblasted) Photo 1 Pitting Corrosion on Hold Frames of Bulk Carrier Photo 2 Corrosion Pit and Heavy Rust 3 ( 財 ) 日本海事協会 37 平成 14 年度 ClassNK 研究発表会
2 3. 3.1 14 KA32 [4] Web 16 80mm A 1 200mm B184mm CShellWeb Face 1 Web 150 6.3mm10mm 10mm B 25mm C 29mm 3.2 2 3 3 8:110:1 4:1 3.3 4 ( 財 ) 日本海事協会 38 平成 14 年度 ClassNK 研究発表会
Table 1 Test Specimens T Width G.L. Number of Pits No. (mm) (mm) (mm) Side-A Side-B A1 8.0 A2 8.3 A3 8.6 Several Many A4 8.7 (**) (***) A5 7.1 A6 7.1 A7 10.0 0 0 A8 10.0 80 200 1 0 A9 9.9 1 0 A10 9.8 1 0 A11 9.5 10 4 A12 9.7 9 8 A13 9.8 6 8 A14 7.0 A15 7.6 Many Many A16 7.8 (***) (***) B 6.3 200 300 132 178 C 8.0 184 450* 113 80 * height ** more than 40% of surface is corrosion-pitted *** more than 80% of surface is corrosion-pitted (a) Hold Frame of Bulk Carrier (b) Bottom Shell of Tanker Fig.2 Cross-sectional View of Corrosion Pit Fig.3 Relationship between Diameter and Depth of Corrosion Pits 5 ( 財 ) 日本海事協会 39 平成 14 年度 ClassNK 研究発表会
A 4 0.53 7mm 3mm 25%=2.5mm[5] (200mm)(80mm) Fig.4 Relationship between Average Thickness and Area Ratio of Corrosion Pit 4. 16 A B 4.1 3(a)A8 200mm B 3(b) 4 4.2 5 6 ( 財 ) 日本海事協会 40 平成 14 年度 ClassNK 研究発表会
σ nominal =P max /A 0 P max A 0 A 0 10 mm 5 B 37% 56% 5 4.4 A15 A12 A8 sub-crack crack1 crack2 crack3 crack4 A7 (a) Test Specimen A(b) Test Specimen B Photo 3 Tensile Test Specimens after Test Fig.5 Relationship between Thickness Loss and Nominal Strength in Tensile Test 7 ( 財 ) 日本海事協会 41 平成 14 年度 ClassNK 研究発表会
Fig.6 Relationship between Thickness Loss and Total Elongation in Tensile Test Fig.7 Relationship between Thickness Loss and Local Strength at Fractured Area 4.3 6 1mm 1mm 4.4 7 σ nmax =P max /A f0 A f0 8 ( 財 ) 日本海事協会 42 平成 14 年度 ClassNK 研究発表会
409589MPa 527MPa KA32 440590MPa [4] 5. ShellWeb Face C Web α 2.44 β 0.99 α β σ y a b α = β = b t E abt σ y E t 8 Fig.8 Shape of Compression Test Specimen and Position of Extensometer Fig.9 Load Shortening Curve in Compression Test 9 ( 財 ) 日本海事協会 43 平成 14 年度 ClassNK 研究発表会
Fig.10 Relationship between Buckling Deflection and Load Table 2 Thickness of Compression Test Specimen Cross Section a b c d e Ave. 8.3 7.8 8.7 7.2 7.8 Ave. (all) 8.0 (mm) 5 9 10 No.1 No.5 No.24 10 No.3 11 240kN 240kN 280kN 75mm 2 8.0mm d 7.2mm FEM 10 ( 財 ) 日本海事協会 44 平成 14 年度 ClassNK 研究発表会
6.FEM 6.1 MSC.Marc MSC.Marc Element Library [6]Element Type 75Element Type 117 E =205,800MPaν=0.3σ y =387MPa H =1,940MPa σ y H (1) (2) 8:1 (3) C 29mm 40mm 11 2.5mm 4 40mm 16 10mm 6.2 6.2.1 2 model A : model B : model A 966 900 model B 73,305 57,600 10 10 model A model AB 11 ( 財 ) 日本海事協会 45 平成 14 年度 ClassNK 研究発表会
10 9 10 12 75mm 10 2.5 (unit : mm) Fig.11 Modeling Example of Corrosion Pit (Diameter:40mm) (a) Shell Model (model A)(b) Solid Model (model B) Fig.12 Calculated Deformation in Elasto-Plastic Analysis (Compression Test) 6.2.2 model A model B model C-1t = 10.0 mmmodel C-2t = 8.0 mm model C-3t = 7.2 mm 13 13 280kN model C-2 339kNmodel C-3247kN model A 374kNmodel B 12 ( 財 ) 日本海事協会 46 平成 14 年度 ClassNK 研究発表会
356N Fig.13 Relationship between Thickness Loss and Buckling Load D Original Surface Corrosion Pit Fig.14 Cross-sectional View of Overlapped Corrosion Pits 7. 14 14 D 13 ( 財 ) 日本海事協会 47 平成 14 年度 ClassNK 研究発表会
8. 14 FEM 1) 2) 8:1 10:1 3) 4) 5) 6) 7) 1) 01 pp.3-152001 2) No.219pp.79-1171992 3) No.224pp.381993 4) () K 2002 5) ()1999 6) MARC Analysis Research Corporation, MARC Volume B Element Library K7, 1997. 7) 1 14 14 ( 財 ) 日本海事協会 48 平成 14 年度 ClassNK 研究発表会