On determining the dynamic modulus of elasticity of metal alloys
Comparative experimental and computational research have been carried out to identify the most reliable method of determining the dynamic modulus of elasticity of metal alloys: by the speed of propagation of ultrasonic waves in the material, by the frequency of resonant and decaying vibrations in a cantilevered specimen, and by the frequency of vibrations in a specimen suspended on threads after pulsed impact. Calculations have been carried out analytically and using 3D finite element models of specimens by the inverse method of successive approximations, varying the values of the elastic modulus until calculated and experimental vibration frequencies coincide. It is demonstrated that the vibration excitation conditions, specimen fastening methods, and manufacturing tolerances have a significant effect on accuracy of the dynamic modulus of elasticity determining. At normal temperature, the determination error can reach 10%. The method of determining the dynamic modulus of elasticity using a vibration spectrum of a specimen suspended on threads turned out to be the most accurate one. A comparison of elastic modulus obtained by dynamic and static test methods has been performed due to the appearance of contradicting publications. It is confirmed that the dynamic modulus of elasticity at normal temperature is slightly higher than the static one for the studied alloys based on titanium (VT6L) and aluminum (D16).