A multilayer structure shear lag model applied in the tensile fracture characteristics of supersonic plasma sprayed thermal barrier coating systems based on digital image correlation

We developed a multilayer structure shear lag model used in analyzing tensile fracture behavior of supersonic plasma sprayed 8 wt% yttria-stabilized zirconia thermal barrier coatings (TBCs). The closed-form solutions of plane and shear stresses were deduced by using the shear lag model. Dynamic strain fields, cracking nucleation and propagation features of TBCs during tensions were in-situ monitored by non-contact digital image correlation (DIC) measurement system. The evolutions of plane and shear stresses in TBCs were estimated by the above closed-form solutions. Using in-situ measurement results of DIC, we further obtained the fracture strengths, interface shear strengths, fracture energy and fracture toughness of TBCs, and summarized the whole tensile fracture mechanisms of TBCs. This shear lag model with the aid of DIC is useful for measuring the mechanical properties of other novel multiple-layer structure brittle coating/ductile substrate systems.