Design of Outfit Elements in Ships for Fatigue Technical ... - EWF

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Page 4 of DVS 3501 Comments Description of Type of connection Detail category ∆σR Equipment Detail Sketch of connection with fatigue crack and stress considered σ Fillet weld to plate panel loaded in bending Assessment in individual cases by means of hot spot stress concept with ∆σSR = 90 2.3 Holder in unsupported plate panel with or without doubling plate Application of a doubling plate can be necessary depending on the local stiffness resulting from the dimensions of plate panel, holder and doubling plate and from the position of the holder within the plate panel. Example: Holder 60 mm × 15 mm, position of the holder in the center of the plate panel Permissible acceleration forces F 2 in [N] for 1 m lever arm, (F 1 = 0) Location of crack initiation Plate panel 1800 mm × 600 mm with t = 10 mm 15 mm 20 mm Variant without doubler 1090 N 2680 N 5340 N plate to holder 1940 N 4400 N 8000 N plate to doubler (1) 2000 N 2120 N 2150 N doubler to holder (2) with doubler ∅ = 100 mm t = 10 mm While the permissible force for a 10 mm thick plate panel is increased by a factor of about 2 if a doubling is fitted, the permissible force for a 20 mm thick plate panel is by a factor of about 2,5 higher for the holder without doubling plate. incomplete circumferential weld may be applied in dry spaces only. Unloaded overlapped plate fillet welded to longitudinally loaded structural member 2.4 Holder at stiffener Alternative 1 For R > 150 mm ∆σR to be downgraded by one category, for R 50 mm ≤ ∆σR can be upgraded by one category 56 50 – at bulb flat profile or flat bar – at angle bar For structural members loaded by bending ∆σR to be downgraded by one category For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by one category, however not beyond 56. Plate welded to an edge of a plate or girder flange R ≤ 50 mm 50 mm < R ≤ 150 mm 150 mm < R ≤ 300 mm R > 300 mm 2.5 Holder at stiffener Alternative 2 For plates or girder flanges loaded in inplane bending ∆σR to be downgraded by one category 56 50 45 40
Comments Description of Type of connection Detail category ∆σR Equipment Detail Sketch of connection with fatigue crack and stress considered σ Holder to be arranged in neutral axis of stiffener if possible Stiffener welded to a plate in load direction R ≤ 50 mm 50 mm < R ≤ 150 mm 150 mm < R ≤ 300 mm R > 300 mm 2.6 Holder at stiffener Alternative 3 For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by one category, however not beyond 80 80 71 63 56 80 The detail category is also valid for not fully circumferential welded holders (see 2.4). Fillet-welded stiffener transverse to loading direction (valid for short and long stiffeners) 2.7 Holder at stiffener Alternative 4 For stiffeners loaded in bending ∆σR to be downgraded by one category. In way of the rounded corner of an opening with the radius r a minimum distance x from the edge to be kept (hatched area): 2.8 Holder at cut-out or opening Holder welded in way of an opening and arranged parallel to the edge of the opening. x [mm] = 15 + 0.175 ⋅ r [mm] 100 mm ≤ r ≤ 400 mm In case of an elliptical rounding the mean value of both semi-axes to be applied R ≤ 150 mm not valid for hatch corners Circular doubler plate with max. 150 mm diameter. tD ≤ 0.8 t 2.9 Doubler plate for holder in unsupported plate panel Page 5 of DVS 3501 71 63 56 0.8 t < tD ≤ 1.5 t tD > 1.5 t
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Design of Outfit Elements in Ships for Fatigue Technical ... - EWF

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