Kenny Shen 的博客
A New Four-dimensional Ratcheting Boundary: Derivation and Numerical Validation
2018-3-4 Kenny Shen
Abstract


A new four-dimensional ratcheting boundary is derived analytically for the first time considering the interaction among four types of stresses: constant mechanical membrane stress, mechanical bending stress, cyclic thermal membrane stress, and thermal bending stress. A uniaxial beam model is used to derive the closed-form ratcheting boundary for these combined cyclic and constant loadings.  The Tresca yield condition and elastic-perfectly plastic behavior are assumed. A novel two-plane FE model is proposed for numerical validation and the results predicted by analytical solution agree very well with that obtained by two-plane FE model. The solution of the classical Bree problem is the one of special cases when this new four-dimensional ratcheting boundary is reduced into two-dimensional style. The relationship between the three-dimensional ratcheting boundary adopted by the newly implemented ASME VIII -2 Pressure Vessel Code and the proposed four-dimensional ratcheting boundary is also discussed.






Key words



Ratchet boundary; Shakedown; Two-plane model; Plastic FEA; Noncyclic method捕获.JPG



 

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