Elastic-Plastic Constraints Analysis for Hole-Edge Crack

This paper mainly conducts an elastic-plastic constraint analysis on rectangular plate specimens with hole-edge crack under remote uniaxial uniformly distributed load by usingJ-A2elastic-plastic fracture theory. In order to analyze the effect of orifice on elastoplastic stress field of hole-edge crack tip, this paper calculates a series of round hole-edge crack, diamond hole-edge crack and corresponding pure crack models. The interference effects of the orifice shape on elastic-plastic J integral and crack constraint parameterA2are discussed. The results show that: the orifice has an amplification effect on the fracture driving force (J-integral), and this amplification effect in elastic-plastic is smaller than that in elastic; the orifice has a shielding effect on the crack tip constraint (A2parameter), and this shielding effect gradually weaken with the crack increasing.

Constructal design applied to the elastic buckling of thin plates with holes

Elastic buckling is an instability phenomenon that can occur if a slender and thin plate is subjected to axial compression. An important characteristic of the buckling is that the instability may occur at a stress level that is substantially lower than the material yield strength. Besides, the presence of holes in structural plate elements is common. However these perforations cause a redistribution in plate membrane stresses, significantly altering their stability. In this paper the Bejan’s Constructal Design was employed to optimize the geometry of simply supported, rectangular, thin perforated plates subjected to the elastic buckling. Three different centered hole shapes were considered: elliptical, rectangular and diamond. The objective function was to maximize the critical buckling load. The degree of freedom H/L (ratio between width and length of the plate) was kept constant, while H0/L0 (ratio between the characteristic dimensions of the holes) was optimized for several hole volume fractions (ϕ). A numerical model employing the Lanczos method and based on the finite element method was used. The results showed that, for lower values of ϕ the optimum geometry is the diamond hole. For intermediate and higher values of ϕ, the elliptical and rectangular hole, respectively, led to the best performance.