420 CHAPTER 14 Fatigue
The crack length at failure is given by Eq. (14.30) in whichα=1, K=1708N/mm3/2,and
S=175N/mm^2 :
af=17082
π× 1752=30.3mmAlso,n=4sothatsubstitutingtherelevantparametersinEq.(14.44)gives
Nf=1
40 × 10 −^15 [175×π^1 /^2 ]^4(
1
0.1
−
1
30.3
)
fromwhich
Nf=26919cyclesReferences
[1] ESDUDataSheets,Fatigue,No.80036.
[2] Knott,J.F.,FundamentalsofFractureMechanics,Butterworths,1973.
[3] McClintock, F.A., and Irwin, G.R., Plasticity aspects of fracture mechanics. In:Fracture Toughness Testing
anditsApplications,AmericanSocietyforTestingMaterials,ASTMSTP381,April1965.
[4] Dugdale,D.S.,J.Mech.Phys.Solids,8,1960.
[5] Rice,J.R.,andJohnson,M.A.,InelasticBehaviourofSolids,McGraw-Hill,1970.
[6] Paris,P.C.,andErdogan,F.,Acriticalanalysisofcrackpropagationlaws,Trans.Am.Soc.Mech.Engrs.,85,
SeriesD(4),1963.
[7] Rice, J.R., Mechanics of crack tip deformation and extension by fatigue. In:Fatigue Crack Propagation,
AmericanSocietyforTestingMaterials,ASTMSTP415,June1967.
[8] Paris,P.C.,Thefracturemechanicsapproachtofatigue.In:Fatigue—AnInterdisciplinaryApproach,Syracuse
UniversityPress,1964.
[9] Forman, R.G., Numerical analysis of crack propagation in cyclic-loaded structures,Trans. Am. Soc. Mech.
Engrs.,89,SeriesD(3),1967.
Further Reading
Freudenthal,A.M.,FatigueinAircraftStructures,AcademicPress,1956.Problems..............................................................................................
P.14.1 Amaterialhasafatiguelimitof±230N/mm^2 andanultimatetensilestrengthof870N/mm^2 .Ifthesafe
rangeofstressisdeterminedbytheGoodmanprediction,calculateitsvalue.
Ans. 363N/mm^2.