S24-3 PAT318, Section 24, March 2005 Multiple S-N Mean Stress Curves n MSC.Fatigue V2005 allows fatigue analysis with multi- mean stress curves. These curves (S-N curves for different R-Ratios) which account for mean stress effects in S-N method by Goodman, Gerber or other empirical methods. n An ASCII Materials database (.mnd) is used, instead of the standard Materials database (.mdb)
S24-4 PAT318, Section 24, March 2005 Mean Stresses mean stress stress range stress max min mean stress ratio mean stress R ratioLoading condition R>1Smax and Smin are negative, negative mean stress R=1Static loading 0
S24-5 PAT318, Section 24, March 2005 R-ratio = -0.5 R-ratio = +0.5 Mean Stress Using Multiple S-N Curves nDamage is calculated from appropriate S-N Curve, or by interpolating between curves
S24-6 PAT318, Section 24, March 2005 Multiple S-N Mean Stress Curves
S24-7 PAT318, Section 24, March 2005 Multiple S-N Mean Stress Curves n See the example in Quick Start Guide ( Chapter 15) for details. n If SN data at different mean stresses does not exist, corrections to the stress range can be applied to allow the use of a S-N curve determined at R=-1. Methods include u Goodman u Gerber
S24-8 PAT318, Section 24, March 2005 Temperature Corrected Fatigue n Temperature Corrections u Fatigue Properties vary with temperature, especially for components operating at high temperatures u MSC.Fatigue V2005 enables a temperature map to determine material fatigue properties. u A set of fatigue curves is used to define fatigue material characteristics at different temperatures. u Stress-Life and Strain-Life is supported. u Temperatures are steady state (i.e. no time varying or creep effects) u Temperatures may vary spatially, across the FE model. u Temperatures are read from standard FE results files or ASCII table. u See the example in the Quick Start Guide ( Chapter 15)
S24-9 PAT318, Section 24, March 2005 Temperature Corrected Fatigue
S24-10 PAT318, Section 24, March 2005 Duty Cycle Analyzer n Duty Cycle enables a schedule of multiple events to be considered n Each event can have its own number of repetitions, and damage is linearly summed n Load time histories can be in DAC, or RPC, format or combination n Enables insight into contribution from individual events n Manages all the fatigue analysis runs and combine results n See the example in the Quick Start Guide ( Chapter 18)
S24-11 PAT318, Section 24, March 2005 Duty Cycle Analyzer nSelect Duty Cycle from: Job Setup (in Loading Information Form)
S24-13 PAT318, Section 24, March 2005 AEROSPACE SPECTRUM FILE SUPPORT n Stress Spectra are generated from information in ASCII editable Spectrum (extension.spe) and Load Control (extension.lcs) files. n See the example in the Quick Start Guide ( Chapter 16)
S24-14 PAT318, Section 24, March 2005 AEROSPACE SPECTRUM FILE SUPPORT n Invoked by selecting Load Spectrum from the Job Setup Menu (in the Loading Information Form)
S24-15 PAT318, Section 24, March 2005 jobname.fin - Job Control File (ASCII) written by Patran, when you press the "APPLY" button in the Job Control Form, with the Action" set to: "Full Analysis", "Partial Analysis", "Translate Only", Save Job Only". It defines the analysis setup as you fill out the various forms. jobname.fes - Input File (Binary) File for the Fatigue Solver modules. It contains information necessary to run a complete fatigue job. It is created by the Translator (PAT3FAT), which reads the file, jobname.fin, and the FEA results information (e.g. stresses) from the model database file (model.db). The "Full Analysis", or "Translate Only Action on the Job Control Form will create this file. MSC.Fatigue Files
S24-16 PAT318, Section 24, March 2005 jobname.fpp - This File (Binary) contains the result of the Rainflow Cycle Count (Preprocessing). The Action, "Partial Analysis", on the Job Control" Form will create all files upto this point, and stop. jobname.fef - Output File (ASCII) containing the Results of the Fatigue Analysis, when a Full Analysis is requested. It can be read into Patran to display the results. It is also used by the MSC.Fatigue Results module, PFPOST, to do tabular listing of Fatigue results. jobname.fef_tmpl - Template File (ASCII) used in reading the Fatigue Results into Patran. This contains infromation defining the meaning of the various results data in the jobname.fef file.
S24-17 PAT318, Section 24, March 2005 jobname.msg - Message File (ASCII) containing all messages during an analysis. If the job does not run, this is the file to look at, for clues. jobname.sta - Status File (ASCII), read by the Monitor action Job from the Job Control Form. This is updated constantly, as the Analysis progresses.
S24-18 PAT318, Section 24, March 2005 MSC.Fatigue Files