All components of the piezo-optic coefficient matrix of calcium tungstate crystals, belonging to the 4/ m symmetry class, are determined. The reliability of the piezo-optic effect measurements in CaWO

The paper presents the research results on assessment of in-service degradation of the 0.17 C-Mn-Si steel of gas transit pipeline operated for 36 years. High degradation degree of the operated steel was manifested in a significant decrease in plasticity characteristics, impact toughness and resistance to stress corrosion cracking and hydrogen embrittlement compared to the as-delivered steel. The tests carried out using the low stress method revealed significant changes in elastic hysteresis, elasticity modulus and relative residual deformation of the steel depending on its state (as-delivered and post-operated ones), demonstrated to be highly sensitive to assess in-service degradation degree of pipeline steels.

The piezo-optic effect (POE) in cubic GaP crystals (symmetry class [equation]3 m) is studied in detail by interferometry. The relations for determining the absolute piezo-optic coefficients (POCs) π...

Specific features of constructing indicatory surfaces of the electro-optic effect (EOE) are described. The generalized case for the symmetry class 3 mand all three possible indicatory surfaces under...

All possible experimental geometries of the piezo-optic effect in crystals of trigonal symmetry are studied in detail through the interferometric technique, and the corresponding expressions for the calculation of piezo-optic coefficients (POCs) π_im and some sums of π_im based on experimental data obtained from the samples of direct and X/45°-cuts are given. The reliability of the values of POCs is proven by the convergence of π_im obtained from different experimental geometries as well as by the convergence of some sums of POCs. Because both the signs and the absolute values of POCs π₁₄ and π₄₁ are defined by the choice of the right crystal-physics coordinate system, we here use the system whereby the condition S₁₄ > 0 is fulfilled (S₁₄ is an elastic compliance coefficient). The absolute value and the sign of S₁₄ are determined by piezo-optic interferometric method from two experimental geometries. The errors of POCs are calculated as mean square values of the errors of the half-wave stresses and the elastic term. All components of the matrix of elasto-optic coefficients p_in are calculated based on POCs and elastic stiffness coefficients. The technique is tested on LiTaO₃ crystal. The obtained results are compared with the corresponding data for trigonal LiNbO₃ and Ca₃TaGa₃Si₂O₁₄ crystals.