エッジインデンテーション皮膜はく離強度評価法の破壊力学的検討

概要

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In order to discuss the delamination energy obtained by the edge-indentation method on a viewpoint of fracture mechanics, the crack initiation and propagation behavior were examined by the microscopic observation along interface under the indenter as well as the three dimensional finite-element stress analysis of the zone. The results show that the interfacial crack starts at a little distant position from the indentation center, and the triangular-shaped delamination of coating extends stably for a certain distance with increasing indentation load. When an apex of the triangular-shaped coating with partially-delaminated interfacial crack is pushed by the side of indenter, the critical value of interfacial strain-energy release rate or the interfacial fracture toughness, 2γ_<12> is expressed by the following equation : 2γ_<12>=1/(8π^2k^2B_1E_<e1>)(cos^2θ)/(tan^2α)((P_0)/χ)^2 where B_1 is coating thickness, E_<e1> is elastic constant of coating, θ is a half of delamination angle, α is apex angle of indenter, P_0 is indentation load at delamination, x is indentation distance from edge, and k is a constant. The interfacial fracture toughness, 2γ_<12> corresponds to the delamination energy, E_d, which has been defined experimentally from indentation load vs.displacement curve in the previous paper.
社団法人日本材料学会の論文
2000-05-15