Learning Forum

[vamsi]

I am working on simulation of fatigue crack growth in CT sample (chevron notch) using SMART crack growth load ratio, R = 0.1 and maximum load 6000 N.nCase 1:n taking pre- meshed crack. Boundary conditions are nFixing one face of CT sample.nApplying bearing load, 6000 N on pin hole surface.nI am not seeing any crack growth.nnCase 2:nI tried with taking a surface in the crack growth path and defined a Arbitrary crack and tried to run the solution by taking same boundary conditions. But, fatigue crack is not propagating.nnIn both the cases I am seeing an error message stating crack is under static loading in the solution information.nnKindly, help me out.Thanks for your time.n

[danielshaw]

Are you solving in 1 loadstep/substep? To predict fatigue crack growth using SMART, you must solve multiple loadstep/substeps?n

[vamsi]

I am using single load stepsl and 50 sub steps in analysis setting option.n

[danielshaw]

Did you define a crack growth law (e.g. Paris's Law) and the crack growth parameters. Something like:nn! Paris' Law Constants (units of delta-K in MPa.mm0.5, da/dN in mm/cycle) nC=2.29E-10nM=2nn! Fatigue crack growth law specificationntb,cgcr,2,,,PARISntbdata,1,C,Mnn! crack growth calculationsncgrow,new, 1ncgrow,cid, 1ncgrow,method,smartncgrow,fcg,meth,LC t! life-cycle methodncgrow,fcg,damx,0.5 t! maximum crack growth increment, mmncgrow,fcg,srat,0 tt! stress-ratio ncgrow,fcoption,mtab,2 t! material table data (Paris law)nn

[vamsi]

No, I am defining Paris law constants (C and m) in the engineering data, keeping the units in m, Nn

[vamsi]

C and m values are corrected and fatigue crack is propagating in sample. But, the number of cycles are very large compared to experimental for similar crack length. Help me in the optimizing this number of cycles.n n