Allows the user to select a named database on any path accessible to the user. This would normally be the company's or the department's own preferred materials, either copied from MSC.Fatigue supplied standard database, or their own test results.
In the case of the user created database, a password, previously defined by the User at the creation stage, must be entered to add/remove or modify properties. Note that both a User database and a local (nmats) database can co-exist in the run directory and selection is made by using the Select User Database button. However it is recommended that the users create their own (company) named database and do not rely on the local nmats copy, for reasons of good data management.
S-N Material Parameters
The following tables explain each of the possible materials input of the spreadsheets for each of the fatigue analysis types.
Parameter Description
Material When this cell is selected a listbox of available S-N curves appears at the bottom of the form. These are the available S-N curves that are defined in the MSC.Fatigue material database. Selecting one of these curves from the listbox will fill the active cell with the material name and make the adjacent cell active. Although the cell and listbox refer to these curves as materials, they are actually S-N curves. All datasets stored in the MSC.Fatigue materials database are referred to as materials. Datasets which have strain data (
ε
-N) associated with them also appear in the listbox since S-N curves can be synthesized from strain data. Care must be taken if both S-S-N ande
-N datasets have been defined in the same material entry. S--N datasets takeprecedence. There are two types of S-N curves, component and material. See Component vs. Material S-N Curves(p. 121) for more details.
Finish The possible surface finish choices are No Finish, Polished, Ground, Good Machined, Ave. Machined, Poor Machined, Hot Rolled, Forged, Cast, Water Corroded, Seawater Corr., and User Defined. Unless modified, the User Defined, Polished, and No Finish picks are the same. The No Finish simply treats the material properties ‘as-is’ with no modifying effects as does Polished. To modify the User Defined surface finish use theLoading Management(Ch. 4) module and load in the filecsuser.surdelivered with the MSC.Fatigue system in theptimedirectory where it can then be modified.
This file defines the relationship between the notch sensitivity and the UTS of the material for a particular surface finish. The editedcfuser.surfile must then be copied to thematsdelivery directory before MSC.Fatigue will recognize its
presence. In certain instances, the surface treatment and surface finish menus may not be applicable. See Treatment below.
Treatment A surface treatment may also be specified. This is a process which may be used to enhance the fatigue life as opposed to the surface finish which is normally a result of the manufacturing process. In certain instances, the surface treatment and surface finish menus may not be applicable. This is dependent on the type of material used.
For instance, certain types of metals do not have data to support surface treatment and finish, and therefore are not allowed by the program. For these materials, a Polished finish and No Surface Treatment is assumed no matter what the user has set.
Also certain surface finishes (Water Corroded and Seawater Corr.) do not allow surface treatment and therefore suppress the surface treatment menu assuming no
treatment. The user will be informed of any inconsistencies at submit time.
Available options are No Treatment, Nitrided, Cold Rolled, and Shot Peened.
Component S-N curves ignore surface finish and treatment.
Region When this cell is active a listbox will appear in which all existing groups will be listed. There is always one group called the default_group. Other groups must be created and/or modified using the Group facilities available from the main menu bar in either MSC.Patran or MSC.Fatigue Pre&Post. The groups selected for a fatigue analysis must have the nodes or elements of interest defined in them. For fatigue analyses which use more that one material dataset, care must be taken to ensure that there are no overlapping or duplicately defined nodes or elements. If multiple materials and surface finish/treatment combinations are used and there is an overlap in the defined regions, the last material combination will take
precedence for that node or element. FE results at these nodes or elements will be used in the subsequent fatigue analysis. Only results for 2D and 3D elements are supported. For this reason, these groups should not reference entities of any other type. Important Note: Even though groups names allow spaces, for use with fatigue regions they cannot have any spaces in the name, either leading, trailing or
anywhere in between.
Temperature This cell is only available on the spreadsheet when the "Temp. Type" optionmenu is set to "Region". It allows the users to specify temperatures on the analysis groups.
Kf A concentration factor can be specified for each material and surface
finish/treatment combination. The default is 1.0 (no modification) and must be a number greater than zero.
Weld If a fatigue analysis based on the British Standard BS5400 standard is being prepared, the S-N dataset name will be one of the weld classes, (e.g., CLASSC or CLASSF2). BS5400 also makes a further distinction between welded and
non-welded details. Consequently, if an S-N data set name beginning with the word CLASS is supplied, an option menu will appear. If a weld is to be analyzed, the response should be Yes. Answering No implies that the actual detail is not a welded connection but is classified correctly by BS5400 under the S-N data set name supplied. (This can be confirmed by using the weld classification option in the materials database manager, PFMAT.) Weld S-N curves are considered component S-N curves. SeeComponent vs. Material S-N Curves(p. 121) for more details.
Parameter Description
Main Index
Multiplier A multiplier can be specified for each material and surface finish/treatment combination. The default is 1.0 (no modification). The multiplier and the offset below are useful when applying a correction over a region, e.g. for a residual stress or preload corresponding to a particular group that is not modelled or taken into account in the FE analysis.
Offset An offset can be specified for each material and surface finish/treatment combination. The default is zero (no modification). See Multiplier.
Parameter Description
Note: For a material, the scaling is applied to the local response in the materials units. For an SN calculation, it will be applied in Stress, in the units used in the FE analysis, subject to the scaling factor if used. The offset is applied after the scaling factor.