Void growth in cyclic loaded porous plastic solid

• In low-cycle fatigue, where plastic strains are of great importance, final ductile fracture depends upon the mechanisms of void growth and coalescence of voids. A cell model is used to simulate a periodic array of initial spherical voids and this model is subjected to different loads that include cyclic loading. Three different types of matrix material are simulated: elastic-perfectly plastic, isotropic hardening and kinematic hardening. The cell model results are compared with the approximate constitutive equations for a voided material suggested by Gurson. The simulations show that the unspecified parameters introduced by Tvergaard in the Gurson yield function depend on the hardening behavior of the matrix material. For a perfectly plastic matrix material, the parameters q1 = 1.5 and q2 = 1.02 provide very close predictions for a variety of loadings. However, for isotropic or kinematic hardening matrix materials these parameters result in an inferior agreement and a much closer accuracy is obtained by adopting q1 = 1.5 and q2 = 0.82. This suggests that the parameter q2 depends on the hardening behavior of the matrix material. For kinematic hardening of the Gurson model, it is shown that Ziegler's hardening rule is superior to Prager's hardening rule. Finally, the void shape change due to loading is studied and it is found that this change has an insignificant effect on the response.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering (hsv//eng)

Nyckelord

porous material

void growth

plasticity

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art (ämneskategori)

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