PSI - Issue 14

S.C.S.P. Kumar Krovvidi et al. / Procedia Structural Integrity 14 (2019) 855–863 S.C.S.P. Kumar Krovvidi / Structural Integrity Procedia 00 (2018) 000–000

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3.3. Detailed inelastic analysis using nonlinear isotropic kinematic hardening model

By entering the isotropic and kinematic hardening parameters, detailed inelastic analysis of the bellows is carried out in ABAQUS. The geometry and the boundary conditions are as given in Fig. 3. Roy et.al (2012) derived the properties of SS316LN for carrying out the inelastic analysis using combined isotropic-kinematic hardening model, which are used for carrying out the detailed inelastic analysis. The material properties for carrying out the detailed inelastic analysis of the bellows are given in Table 4 . Table 4: Elastic and hardening properties for inelastic analysis of bellows using nonlinear isotropic-kinematic hardening model for SS316LN

Young’s Modulus (E) in GPa

Poison ratio (ᶹ)

Yield stress in MPa

Kinematic hardening parameters

Isotropic hardening parameters

C (MPa)

γ

Q (MPa)

b

200

0.3

211

57805

619.04

42.30

21.6

The strain range at the root of the bellows (range computed between maximum positive and maximum negative displacement) is given in Figure 9. The strain range computed by combined isotropic kinematic hardening model is 0.31%. The number of cycles computed as per RCC-MR design curve is 19000 cycles. The number of cycles computed based on the linear elastic analysis, elasto-plastic analysis using cyclic stress strain diagram are given in Table 5 .

Figure 9: Strain at maximum positive displacement (+0.5 mm) and maximum negative displacement ( -0.5 mm) of the bellows convolute