In situ evaluations of Young`s modulus and Poisson`s ratio using a cantilever beam specimen

Young`s modulus and Poisson`s ratio for thermal spray coatings are needed to evaluate properties and characteristics of thermal spray coatings such as residual stresses, bond strength, fracture toughness, and fatigue crack growth rates. Since coatings are used while bonded to a substrate, it is desirable to have a procedure to evaluate Young`s modulus and Poisson`s ratio in situ. A Cantilever Beam Method to evaluate the Young`s modulus and Poisson`s ratio of thermal spray coatings is presented. The method requires only inexpensive materials and instruments and makes use of laminated plate theory to computer Young`s modulus and Poisson`s ratio from data on deformations of the cantilever beam under static loads. A sensitivity analysis of the method has shown the method to be accurate over a wide range of coatings and substrate materials. The method is verified by comparing predicted values of Young`s modulus and Poisson`s ratio with reference values from a three-dimensional finite element analysis of the thermal spray coated cantilever beam. The method was applied to evaluate the Young`s modulus and Poisson`s ratio of four thermal spray coatings of industrial importance.