Effect of the secondary slip system on early fatigue damage

Lin, S. R.; Lin, T. H.

doi:10.1016/0022-5096(74)90024-6

Cited by 14 publications

(4 citation statements)

References 10 publications

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“…This e'12 has a strain component e^a which adds to the e^^ in causing the difference in resolved shear stress x^n in P and Q. This increases the rate of sliding in P,Q thus accelerating the extrusion growth at the free surface as reported by Lin and Lin [26]. This additional e^^ caused by 6^2 in the second slip system in R causes the extra length of slice R to be more than the initial static extrusion.…”

Section: Effect Of Secondary Slip On Primary Slipmentioning

confidence: 86%

“…This induces large resolved shear stress (initial plus residual) of opposite signs in P and Q, causes a higher rate of extrusion growth, and explains why the fatigue initiation growth rate is higher for f.c.c metals than for hexagonal metals. Some calculations of this secondary slip effect were reported by Lin and Lin [26] Mughrabi, et. al.…”

Section: Materials Defects and Initial Stress Fieldmentioning

confidence: 94%

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Interaction of Two Slip Planes on Extrusion Growth in Fatigue Band

Lin¹,

Lin²,

Wu³

1987

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Micromechanic theory of fatigue crack initiation by Lin and his associates is reviewed. Intrusions and extrusions have been observed in fatigue specimens. An initial stress field favorable for the growth of extrusion or intrusion can be produced by arrays of dislocation dipoles as shown by Lin (1969). These dipoles cause an initial tensile strain giving an elongation which is called the static extrusion. It has been suggested tiiat after extrusion reaches the height of static extrusion, extrusion growth terminates. Along the direction of an extrusion, tensile strain and tensile stress occurs. This tensile stress causes the resolved shear stiess to reach critical and slide in a secondary slip system. The slip causes plastic tensile strain which increases significantiy the extrusion growth. Similarly tiie same mechanism exists for the growth of intrusions. This explains why extrusion grows much more tiian the static extrusion.

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Section: Effect Of Secondary Slip On Primary Slipmentioning

confidence: 86%

Section: Materials Defects and Initial Stress Fieldmentioning

confidence: 94%

Interaction of Two Slip Planes on Extrusion Growth in Fatigue Band

Lin¹,

Lin²,

Wu³

1987

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“…Figure 3 shows a schematic illustration of intrusion and extrusion within a PSB. At the same time the growth of intrusion (extrusion) changes the stress state in the slice R. This stress variation in R can activate another slip system, the secondary slip system (Lin and Lin 1974;Lin, 1992;Basinski and Basinski, 2004) in R when combined with the applied and initial stresses. The strain due to the second slip on the other hand also has a contribution along the first (primary) slip direction which provides more favorable initial stresses in both P and Q.…”

Section: Pqr Micromechanical Modelmentioning

confidence: 99%

PQR Model-based Micromechanical Analysis of Hysteresis Loops for Single Crystal Fatigue: Aspects of Multi-Axial Loading, Geometric Effects and Creep

Wang

Lin

2008

International Journal of Damage Mechanics

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The micromechanical theory of fatigue crack initiation, namely the PQR model with a gating mechanism proposed by Lin (1992), is systematically summarized and further generalized to arbitrary loading conditions which may occur in reality. All possible loading cases and slip mechanisms are considered for a FCC single crystal. The Schmid factors for both primary and secondary slip systems are presented. A 3D boundary element method is adopted to compute the stress influence coefficients for the residual stress field. The hysteresis loops, which are due to a general two phase sequential loading process, i.e., a uni-axial loading followed by a multi-axial loading applied by combined shear and axial loadings, are given to illustrate the fatigue development and demonstrate the proposed methodology. The results show that the two stage loading may increase the magnitudes of intrusion and extrusion. Subsequently the geometry influence for intrusion is studied. The effect of geometry variation caused by intrusion is taken into account through updating the stress influence coefficients as well as the applied resolved stress when intrusion grows. This process is continued until the saturated state of fatigue crack initiation is reached. Comparison of geometry influence on intrusion growth is shown as well. It turns out that the geometric change could become an important factor for the intrusion growth. Finally by replacing the plastic strain with creep strain the present model is easily extended to investigate the steady hysteresis loops for single crystal creep at elevated temperature. The results compare favorably with the available experimental data.

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“…We consider three thin slices in a most favorably oriented crystal at the free surface of the polycrystal as shown in Fig.4 (Lin, 1974). An initial tensile strain e l is assumed to exist in the slice R. This ea causes an initial compressive stress in R, a positive resolved shear stress T in P and a negative I~ in Q (Lin and Lin, 1988).…”

Section: T = Tu + Ta + T R ='Cc( 7 (17)mentioning

confidence: 99%

Reciprocal Theorem of Residual Stress and Inelastic Strain

Lin¹,

Lin²,

Wu³

et al. 1988

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Effect of the secondary slip system on early fatigue damage

Cited by 14 publications

References 10 publications

Interaction of Two Slip Planes on Extrusion Growth in Fatigue Band

Interaction of Two Slip Planes on Extrusion Growth in Fatigue Band

PQR Model-based Micromechanical Analysis of Hysteresis Loops for Single Crystal Fatigue: Aspects of Multi-Axial Loading, Geometric Effects and Creep

Reciprocal Theorem of Residual Stress and Inelastic Strain

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