Weld Fatigue - Ansys
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Weld Fatigue [email protected]
Transcript of Weld Fatigue - Ansys
Weld Fatigue - Overview
• Weld Fatigue
• Target application: Mechanical
• Description: Post processing tool based on IIW recommendations to evaluate weld fatigue according to Nominal, Hot-Spot and Effective Notch method. Linearized stress method is also included. Shell and solid models are supported. Load cases from single step, load case combination or load case scanning. Cumulative damage from several load cases can be calculated. S-N curves from IIW and DNV GL RP-C203 are included.
• The version of the App and the supported versions of ANSYS are the ones indicated on the App Store.
ACT App Store
• https://appstore.ansys.com/shop/ACTApps_act%20apps
• Great place to get started
− A library of helpful extensions available to any ANSYS customer
− New apps added regularly
− Applications made available in either binary format (.wbex file) or binary plus scripted format (Python and XML files)
− Scripted extensions are great examples
− Documentation and training materials available on the ANSYS Customer Portal: https://support.ansys.com/AnsysCustomerPortal/en_us/Downloads/ACT+Resources
Information
• Please pay attention to paragraph 9 of the CLICKWRAP SOFTWARE LICENSE AGREEMENT FOR ACS EXTENSIONS regarding TECHNICAL ENHANCEMENTS AND CUSTOMER SUPPORT (TECS): “TECS is not included with the Program(s)”
• To report any issue or provide feedback related to this app please contact:
Binary App Installation (1)
Installing from the ACT Start Page:
1. From the project page, select the“ACT Start Page” option
2. Click on “Extension Manager”
3. Press “+” symbol in the top right corner
4. It will open a file dialog to select theappropriate “*.wbex” binary file
5. The extension is installed
Loading the extension:
1. From the Extension Manager,click on your extension and choose‘Load Extension’
2. The extension is loaded
Notes:• The extension to be installed will be stored in the following location: %AppData%\Ansys\[version]\ACT\extensions (Example for [version]: v180)• The installation will create a folder in this location, in addition to the .wbex file
Binary App Installation (2)
Installing from the Extensions menu:
1. From the Extensions menu, select the “Install Extension…” option
2. It will open a file dialog to select the appropriate “*.wbex” binary file
3. Click “Open” to install the extension
Loading the extension:
1. From the Extension Manager,click on your extension and choose ‘Load Extension’
2. The extension is loaded
Notes:• The extension to be installed will be stored in the following location: %AppData%\Ansys\[version]\ACT\extensions (Example for [version]: v180)• The installation will create a folder in this location, in addition to the .wbex file
Binary App Installation (3)
Define additional folders in which ACT will search for extensions in order to expose them in the Extension Manager
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Notes:• During the scan of the available extensions, the folders will be analyzed according to the following order:
1. The application data folder(e.g. %AppData%\Ansys\[version]\ACT\extensions)2. The additional folders defined in the “Additional Extension Folders” property3. The installation folder4. The “extensions” folder part of the current Workbench project (if the project was previously saved with
the extension)• If an extension is available in more than one of these locations, the 1st one according to the scan order is used
• Once the binary extension is installed at default location, one can move the *.wbex and the folder to any other location– Default path: %AppData%\Ansys\v180\ACT\extensions– New path: Any location on your machine, shared drive etc.
• All users interested in using the extension need to include that path in their Workbench Options1. In the “Tools” menu, select the “Options…”2. Select “Extensions” in the pop up panel3. Add the path under “Additional Extensions Folders”
Weld Fatigue
• Background
– Weld fatigue evaluation usually requires a lot of manual work in order to extract weld fatigue stresses in a correct local coordinate system and evaluate the life or damage according to S-N curves.
• Solution
– The Weld Fatigue app can create results for life, damage, safety factor and stress range along all the weld sections in the model.
– Nominal, Hot-Spot and Effective Notch method are supported based on the IIW recommendations.
– Linearized stress method for solids.
– Results are plotted on the geometry and listed in a csv text file.
– The cumulative damage for multiple load cases can be calculated.
Weld Fatigue
• News in V180.2
– Linearized Stress method for solids (using PRSECT) [6]
– User defined S-N curves can be defined in the preference file
– IIW S-N curves (Nominal, Hot-Spot and Effective Notch) [1]
– DNV GL S-N curves (Tab. 2-1, 2-2 & 2-3 and High strength Steel Eq. 2.4.6) [5]
Weld Fatigue Usage
• Build the FE-model as normal [2].
Linearized Stress Method must be used on a solid model. [6]
Nominal Method can be used for base material as well as for different weld joints (Structural Details Table 3.1 [1])
Hot-Spot Method can be used for fillet and butt welds (Structural Details Table 3.3 [1])
Effective Notch method must be used on a solid model with the weld and notch modelled, usually in a sub model.(Fig. 2.19 & Table 2.4 [1])
Cumulative Damage can be used to sum the damage from several load cases for a selected group of weld results and also calculate the safety factor in stress and life.
Help button opens up this documentation.
Method Shell Solid
Linearized n/a OK
Nominal OK OK
Hot-Spot OK OK
Effective Notch n/a OK
Weld Fatigue Properties, Linearized Stress
• Top faceScoping Method: [Geometry Selection/Named Selection]Geometry: Edges, Faces or Nodes of solids (By using a sub set of the face nodes the evaluation time is greatly reduced. Avoid large face selections)
• Bottom faceScoping Method: [Geometry Selection/Named Selection]Geometry: Edges, Faces or Nodes on the “Bottom” side. For each “Top face” node a path is created to the closest “Bottom face” node and the linearized stress is evaluated.
• Stress OptionsStress Type: Linearized Stress of type [Absolute Principal/Maximum Principal/Middle Principal /Minimum Principal/Stress Intensity/Equivalent]Stress Item: [Membrane/Bending/Membrane+Bending/Peak/Total]Result Side: Selects the result side from the path results to display [Top/Bottom]Corner Nodes Only: [Yes,No] To speed up evaluation corner nodes are used by default.
Note: “Absolute Principal” is “max(abs(S1), abs(S2), abs(S3))”Note: You may “Duplicate” a Linearized Stress object to quickly display a different stress or results item or use a different S-N curve or FAT-factor (no evaluation time needed).Note: The output from the path evaluation is saved in a text file for each result object ”linearizedStress_XXX.lis” in the solution folder:...
***** POST1 LINEARIZED STRESS LISTING *****
INSIDE NODE = 4748 OUTSIDE NODE = 9880
** MEMBRANE PLUS BENDING ** I=INSIDE C=CENTER O=OUTSIDE
S1 S2 S3 SINT SEQV
I 164.6 34.26 -1.138 165.8 151.2
O 66.98 8.061 -16.26 83.24 74.14
Weld Fatigue Properties, Nominal, Hot Spot & Eff Notch
• Base Material Face (Nominal Method)Scoping Method: [Geometry Selection/Named Selection]Geometry: Edges or Faces of shells or solids. (Evaluation limited to the surface of the part)Shell face: [Top/Middle/Bottom] Used only for shell bodies
• Hot Spot SectionScoping Method: [Geometry Selection/Named Selection]Geometry: Edges along the weld hot-spot (weld toe).
• Reference FaceScoping Method: [Geometry Selection/Named Selection]Geometry: Faces connected to the hot-spot edges. The hot-spot stress is calculated from node results on this face.Shell face: [Top/Middle/Bottom] Used only for shell bodies
• Hot Spot MethodWeld Stress: [Normal/Principal] Stress type to use. Default = NormalExtrapolation: [Linear/Quadratic] Extrapolation method. Default = LinearMaterial thickness: Thickness, t, used to calculate the hot-spot extrapolation points, X. Default t = 0.0 mm. Must be greater than zero!a: First extrapolation point coefficient. Xa = a*t. Default a = 0.4b: Second extrapolation point coefficient. Xb = b*t. Default b = 1.0 (If “Quadratic” b = 0.9)c: Third extrapolation point coefficient. Xc = c*t. Default c = 1.4 (Used only for “Quadratic”)Offset: Hot-spot edge offset on reference face normal to edge tangent. Default = 0.0 mm
• Effective Notch FaceScoping Method: [Geometry Selection/Named Selection]Geometry: Cylindrical notch faces of solid bodies.
Weld Fatigue Properties, Common
• S-N curveFAT Class: List of available S-N curves (from “weldFatiguePref.py”, see page 32). Use “User defined” to edit S-N curve properties manually (otherwise the properties are in read only mode).FAT: Weld fatigue class. Stress range at Nfat cycles. Default S-N curve for Nominal, Hot-Spot and Effective Notch method are plotted on next page.FAT factor: Scale factor for FAT value. E.g. to apply a thickness or temperature modification factorNfat: Number of cycles for defining FAT. (IIW: Default = 2e6 cycles.)Nc: Break point between slope m1 and m2. (IIW: Default = 10e6 cycles.)Slope m1: S-N curve slope for N < Nc. (IIW: Default = 5 for Nominal, 3 for Hot-Spot and Eff. Notch)Slope m2: S-N curve slope for N > Nc. (IIW: Default = 22)
• Load case definitionLoad Type: [Zero Based/Fully Reversed/Load Combination/Load Scanning] Default = “Fully Reversed” See following slide for description.First time: List of time steps in the analysis. Default = 1.000 Last time: List of time steps. Visible for Load Combination and Scanning. Default = 2.000 Load scale factor: Fatigue stress scale factor. Can be used for sensitivity analysis. Default = 1.0Cycles per block: Number of cycles used to calculate damage and safety factors. Default = 1
• Fatigue ResultResult Item: [Life [N]/log10(Life) [N]/Damage per block [-]/Safety factor life [#blocks]/ Stress range/Safety factor stress [-]/Life Quality/Stress max/Stress min/First time/Last time/Path pos] Result to display on the model. Default = “Life [N]”. Definitions shown in S-N curve on next page.
• DefinitionBy: Default = “Time” (Cannot be changed)Display Time: Time step selected from “First Time” in Load case definition (Read only).
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S-N curve
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Default S-N Curves and Result Items
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Result ItemsLife [N]: N(DS)log10(Life) [N]: log10(N(DS))Damage per block [-]: Nb/N(DS)Safety factor life [#blocks]: N(DS)/NbStress range: DSSafety factor stress: DS(Nb)/DS
Ncut-off, Maximum calculated life(Default 1.E+10)
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Load Case Definition
• Zero Based
− Calculates a pulsating stress range (R = 0) by scaling load step “First time” with “Load scale factor”
• Fully Reversed
− Calculates an alternating stress range (R = -1) by scaling load step “First time” with “Load scale factor”
• Load Combination
− Calculates the stress range between step “First time” and “Last time” and scale with “Load scale factor”
• Load Scanning
− Calculates the maximum stress range between step “First time” and “Last time” and scale with “Load scale factor”. The identified critical time steps are available as results.
Note: The three first methods are similar to ANSYS Fatigue Tool. Load Scanning is not available for Linearized Stress Fatigue.
T1 T2
DS
T1 T2
DS
Load step defines range
Load step defines amplitude
Nominal Method
• Calculates the maximum principal stress range on the surface of the model.For base material this is similar to the ANSYS Fatigue Tool except that you also have the option for load case scanning over multiple load cases (Same as in the app: “Fatigue Scanning”) and can define the S-N curve direct in the result object and not in Engineering Data.
• For weld joints the user must read the stress at the correct location according to the weld class and not at the weld location and also to find correct FAT value. (Structural Details Table 3.1 [1]). It is recommended to use Hot-Spot and/or Effective Notch method for weld evaluation.
FAT = 50 MPa (Table 3.1, No 721 [1])Life N = 2e6*(50/102)^3 = 2.35e5
DS = 102 MPa
Note: Verification in model “WeldFatigue_V180.2.wbpz” [2]
Nominal Method, Load Scanning
• Load scanning performs all possible load case combinations from the selected range of time steps in order to find the true maximum principal stress range.
• The number of combinations increase fast with number of load steps, which is why this feature should be used with care to avoid long evaluation times.
• For Hot-Spot and Effective Notch method the stress orientation is constant (perpendicular to the weld) for all steps so min and max stress are found direct from the individual load steps.
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Hot-Spot Method
• Calculates the maximum stress range at the weld hot-spot (weld toe) by extrapolation of the normal stress perpendicular to the hot-spot edge from the reference surface. The principal stress can also be used. If the angle between the principal stress and extrapolation normal is greater than 60 degrees the normal stress is automatically used. The linear and quadratic method can be used and the extrapolation points, a, b & c, can be edited based on weld code and model thickness, t.
• The mesh must be fine enough to allow one or two elements between the hot-spot and the first extrapolation point as well as between the two (or three) extrapolation points.The app will use a polynomial interpolation to calculate the stress at the extrapolation points, hence the mesh does not need to be a perfect mapped mesh with nodes at the extrapolation points.
• Different weld types and corresponding FAT values are found in Table 3.3 [1].
Xa = a*t Xb = b*t
Extrapolation normal, X
Note: Verification in model “WeldFatigue_V180.2.wbpz” [2]
Hot-Spot Method, Extrapolation comparison
• In [1] recommendations are made for mesh size, L, and extrapolation options for type A and B geometry.An additional reference model with mesh size L=2mm, “Extra Fine”, is included in the comparison.
• For Type A the three models gives the same Hot-Spot stress but for Type B the coarse result differ and will give un-conservative results.
Type A, Fine (a)a=0.4t, b=1.0tL= 4mm, t=10mm
Type A, Coarse (b)a=0.5t, b=1.5tL=10mm, t=10mm
Type B, Fine (c)a=4 mm, b=8mm, c=12mmL=4mm
Type B, Coarse (d)a=5mm, b=15mmL=10mm
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Extrapolation comparison
Fine Coarse Extra Fine
Note: Verification in model “HotSpot_V180.2.wbpz” [3]
Hot-Spot Method, Life Quality
• The result “Life quality” is an empirical factor of the ratio between the calculated life and the “true life”. The quality is based on the distance, d, between the closest node to each extrapolation point. Optimal quality is 1.0. If the same node is found for all extrapolation points the quality is set to 0.0. Quality = 1 - (da/Xa)^2 - (db/(Xb-Xa))^2 - (dc/(Xc-Xb))^2 (Linear extrapolation uses a and b only)
• The singularity at the Hot-Spot influence the stress at the first extrapolation point. A coarse mesh will usually result in a higher Hot-Spot stress and lower predicted life.
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Stress vs. Element size L
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SX L=5mm
Hot-Spot Method, Life Quality cont.
• A parameter study of the element size, life and quality for a short segment of a tetrahedron mesh shows the following two graphs for linear and quadratic extrapolation [3].
• For increasing element size the variation of life and quality increases but the trend is that the result “Life quality” follows the calculated life. For thickness 10 mm the recommended element size is 2 mm in order to have two elements before the first extrapolation point.
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Life quality (Linear)
Life min rel.
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Life avg. lin.
Quality min
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Life quality (Quadratic)
Life min rel.
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Quality min
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Thickness, t=10 mm, a=0.4, b=1.0 Thickness, t=10 mm, a=0.4, b=0.9, c=1.4
Note: Verification in model “HotSpot_V180.2.wbpz” [3]
Effective Notch Method
• Calculates the tangential stress range in the effective notch (cylindrical fillet). Fillet radius R = 1 mm is valid for thickness 5 mm [1]. For thinner parts R = 0.05 mm may be used but other recommendations may exist. The app will not check the notch radius.
• The mesh must be fine enough to allow at least four second order elements for a 90 degree segment, e.g. element length 0.4 mm. Use inflation layers to get good element quality.
• Note: You may use the Nominal Method to obtain the maximum principal stress range if the fillet is not a perfect cylinder, e.g. a torus, or if you do not want to use the tangential stress.
Tangential direction
Material R = 1 mm R = 0.05 mm
Steel FAT 225 FAT 630
Aluminium alloys FAT 71 FAT 180
Magnesium FAT 28 FAT 71
Effective Notch Method, Life Quality
• The expected life is highly sensitive to the stress range. A stress convergence study shows that 2nd order brick elements requires 24 elements/360 degrees and first order elements requires 40 elements/360 degrees.
• The result “Life quality” is the ratio between the calculated life and the “true” life as a function of normal angle difference, phi, over the element. A coarse mesh over predicts the life so dividing the calculated life with the quality is a rough estimate of the “true” life.
• Second order tetrahedron elements tends to give higher stress compared to brick elements for the same mesh resolution and are therefore conservative. First order tetrahedron elements must never be used.
• Using inflation layers on a tetrahedron mesh improves the result and is recommended practice.Note: The Nominal method uses the same definition for “Life quality” for solid models.
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Relative Life Brick
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Note: Verification in model “EffNotch_V180.2.wbpz” [4]
Linearized Stress Method
• Calculates the linearized stress through the thickness of a solid using the “PRSECT” command [6].
• Many codes uses ”Linearized Stress” to evaluate fatigue. With the ”Linearized Stress” feature you don’t have to define a path to do this evaluation. Instead you may plot the results along edges, faces or node groups and perform the fatigue calculation direct.
• Note: When using “Load Combination” the order of “First time”, T1, and “Last time”, T2, influence the sign of “Maximum Principal” and “Minimum Principal”. Load combination is always done by “LCT1 – LCT2”. Using the “Linearized Absolute Principal Stress” will always use the absolute maximum.(You may also switch and use T2 for “First time” and T1 for “Last time”.)
Linearized (Face)Linearized (Edge) Linearized (Nodes)
Linearized Stress Method vs. Nominal Method
• The “Linearized Maximum Principal Stress” based on “Membrane+Bending” (“Structural Stress”) corresponds to the stress in a shell model using the “Nominal Stress Fatigue”.
Linearized (Solid model)Nominal (Shell model)
Note: Verification in model “WeldFatigue_V180.2.wbpz” [2]
Linearized Stress Method vs. Hot-Spot Method
• The Linearized Stress at the edge of a weld toe (Hot-Spot) is very similar to the results using the “Hot-Spot Method” but without the need of a very detailed mesh along the “Hot-Spot”.With a coarse mesh local effects may be missed resulting in an un-conservative result!
Hot-SpotLife_min = 240900
LinearizedLife_min = 217500
Linearized coarseLife_min = 342000
Note: Verification in model “WeldFatigue_V180.2.wbpz” [2]
Comparison of methods
• The four methods shows similar result where Hot-Spot method has 9% higher life, Effective Notch method has 17% lower life and Linearized has 7% lower life compared to the Nominal method respectively.
• For a shell model (2nd order) the Hot-Spot method life is only 3 % lower compared to Nominal.
• The Hot-Spot result is very sensitive to the mesh method, size and quality at the hot spot , e.g. solid vs. shell, contact vs. multi-body, with or without weld elements. In this example the Hot-Spot life could differ as much as 50% compared to the Nominal life.
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Life Comparison
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Cumulative Damage
• Grouping result objects of the same type with the same geometry scoping but different load cases together with a “Cumulative Damage” object will sum the damage from the grouped objects and calculate the total damage and results. You may have several “Cumulative results” in the same group.
Note: Do not group different results of the same load case, e.g. Life, Damage and Stress range, since this will sum the damage for each one!
Note: Verification in model “WeldFatigue_V180.2.wbpz” [2]
Cumulative Damage
• GeometryScoping Method: [Geometry Selection/Named Selection]Geometry: Edges or Faces from grouped result objects.
• Load Group PropertiesLoad Group Properties: [Apply/Cancel] Click to load Geometry , Load case and S-N Curve from grouped objects.Total #Cycles: Total number of cycles from grouped objects (Read Only)
• S-N curveFAT Class: Fatigue S-N curve. (Read Only)FAT: Weld fatigue class stress. (Read Only)FAT factor: Scale factor for FAT value (Read Only)Nfat: Number of cycles for defining FAT (Read Only)Nc: Break point between slope m1 and m2. (Read Only)Slope m1: S-N curve slope for N < Nc. (Read Only)Slope m2: S-N curve slope for N > Nc. (Read Only)
• Fatigue ResultResult Item: [Cumulative Damage [-]/Safety factor life [#blocks]/Equivalent Stress range/Safety factor stress [-],Life quality [-]]Definitions shown in S-N curve on next page.
• DefinitionBy: Default = “Time” Display Time: Time step to use for deformed shape. Does not influence result.
• ResultsMinimum: Minimum value from displayMaximum: Maximum value from display
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Cumulative Damage, Result Items
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Result ItemsCumulative Damage [-]: Nb/N(DSeqv)Safety factor life [#blocks]: N(DSeqv)/NbEquivalent Stress range: DSeqvSafety factor stress [-]: DS(Nb)/DSeqv
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Weld Fatigue Result listing
• In the solution folder, a result summary csv text file for each result object is created with the same name as the result object
(and an Id number). See example below.
• The text file can be used in e.g. Excel and also with the free app “CSV-Plot”.
Node Id: Node numbers from result object
Life: Number of cycles, N, until damage = 1.0 for calculated stress range, DS. Cut off limit N = 1010
log10(Life): Log10(Life)
Damage per block: Damage for calculated stress range, DS, repeated Nb times (Nb: cycles per block). Nb/N(DS)
Safety factor life: Number of blocks to get damage = 1.0. N(DS)/Nb
Stress range [MPa]: Calculated stress range, DS, at node Id
Safety factor stress: Factor to scale stress range, DS, to get damage = 1.0 for one block of cycles. DS(Nb)/DS. Cut off limit 100
Life quality: Relative Life based on mesh curvature (Nominal, Effective Notch). 1.0 optimal quality
Relative measure of node distance from Hot-Spot extrapolation point. 1.0 exact node locations
Stress max Maximum principal stress (Nominal) or maximum normal stress (Hot-Spot, Effective Notch)
Stress min Minimum principal stress (Nominal) or minimum normal stress (Hot-Spot, Effective Notch)
First time First and last load step used in stress range calculation. For Load Scanning this can be different than the
”First time” and ”Last time” in Load case definition. See figure on slide ”Load Case Definition”Last time
Edge Id Hot-Spot edge Id number. Sort table on Edge Id and Path pos to do graphs in Excel
Path pos [mm] Hot-Spot path position
Note: The csv file name will not change if the result is renamed. Clear and evaluate to re create the csv file.
Weld Fatigue Default Preference
• In the extension folder, e.g. ~\AppData\Roaming\Ansys\v180\ACT\extensions\WeldFatigue_V180.2\
there is a preference file that defines the default
properties for Hot-Spot method, S-N Curve and load
case when adding a new results to the model tree.
This can be used to define settings for a specific design
code.
• Custom S-N curves can be added to the app using the
new API found below “# FAT Class Dictionary”.
Curves for IIW and DNV are included and shown in the
following pages [1], [5].
One additional feature when defining a S-N curve in the
preference file is the possibility to include a second
break point, N0, and a corresponding slope, m0. This is
used for IIW and DNV to “limit” a curve at low N.
IIW S-N curves, Nominal & Hot-Spot Method (Steel)
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IIW S-N curves Nominal & Hot-Spot Method (Steel)
FAT160 steel
FAT125 steel
FAT112 steel
FAT100 steel
FAT90 steel
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FAT71 steel
FAT63 steel
FAT56 steel
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IIW S-N curves, Nominal & Hot-Spot Method (Alu.)
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IIW S-N curves Nominal & Hot-Spot Method (Aluminium)
FAT71 aluminium
FAT50 aluminium
FAT45 aluminium
FAT40 aluminium
FAT36 aluminium
FAT32 aluminium
FAT28 aluminium
FAT25 aluminium
FAT22 aluminium
FAT18 aluminium
FAT16 aluminium
FAT14 aluminium
FAT12 aluminium
IIW S-N curves, Effective Notch
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IIW S-N curves Effective Notch Method
FAT225 R1 steel
FAT71 R1 aluminium
FAT28 R1 magnesium
FAT630 R0.05 steel
FAT180 R0.05 aluminium
FAT71 R0.05 magnesium
DNV Table 2-1 S-N curves in air
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DNV Table 2-1 S-N curves in air
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DNV Table 2-2 S-N curves in seawater (cathodic)
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DNV Table 2-2 S-N curves in seawater with cathodic protection
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C1
C2
D
E
F
F1
F3
G
W1
W2
W3
T
DNV Table 2-3 S-N curves in seawater for free corrosion
10
100
1000
1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08
Stre
ss r
an
ge [
MP
a]
#Cycles
DNV Table 2-3 S-N curves in seawater for free corrosion
B1
B2
C
C1
C2
D
E
F
F1
F3
G
W1
W2
W3
T
Validity of the fatigue results
• The nominal stress range should be within the limits of the elastic properties of the material. The IIW recommendations are not applicable to: [1]
1. low cycle fatigue (strain based fatigue) wherenominal stress range Dsnom > 1.5fy or max stress snom > fy
hot spot stress range DsHS > 2fy or max stress sHS > fy
2. corrosive conditions
3. elevated temperature operation in the creep range
• Use the results “Stress range” and “Stress max/min” to verify that condition one is fulfilled. Also verify the fatigue resistance of the parent material.Note: All IIW or DNV GL S-N curves are limited by the parent material (FAT160 & B1)
• It is the user’s responsibility to ensure that the FE-model, chosen fatigue method, input values and results obtained by this application is suitable for his/her intended purpose, e.g. to evaluate according to a specific design code or to apply fatigue modification factors due to misalignment etc.
Known issues and limitations
• The “First time” and “Last time” can’t be changed from the default values until the analysis has been solved in order to find all available time steps.
• Cumulative damage result will not change status to “Need update” if another group member is edited and updated. You must manual click on the “Load Group Properties” field to load any changes in the Cumulative Damage result and evaluate the result again.
• Cumulative damage result may fail to evaluate or show zero value if it is solved at the same time as the other group members. Use “Clear Generated Data” on the Cumulative damage result and “Evaluate All Results” again to see the correct results.
References
• [1] Recommendations for Fatigue Design of Welded Joints and Components, Second Edition. A.F. Hobbacher. International Institute of Welding (IIW)
• [2] Demo model “WeldFatigue_V180.2.wbpz”
• [3] Demo model “HotSpot_V180.2.wbpz”
• [4] Demo model “EffNotch_V180.2.wbpz”
• [5] RP-C203: Fatigue design of offshore steel structures DNVGL-RP-0005:2014-06
• [6] ANSYS Help Viewer R18
The demo models are included in the installation package. These projects are used to demonstrate and verify the features of the app.
