超音波伝ぱ速度の応力依存性に関する実験的研究

概要

論文の詳細を見る
Ultrasonic velocities in elastic materials vary with stress applied to them and this phenomenon has been used to determine the third order elastic constants of materials. On the other hand, a new experimental method of stress analysis, named "Acoustoelasticity", has been developed which utilizes polarized ultrasonic shear waves similar to photoelasticity. This technique, however, has not been put into practice for commercial materials, because of the influences of some uncontrollable factors such as the rate of pre-worked plastic deformation to them. To study a possibility of practical application of this method, the ultrasonic velocities of longi-tudinal waves propagating perpendicularly to the stress axis of specimens stressed uniaxially were measured precisely in the present work. The materials used were carbon steel "S45C", aluminum "A3B2" (92%), copper "CuB1-H" (99.9%) and 6-nylon. Furthermore, the modulus deviation calcu-lated from the relation between strains and travelling time deviations was discussed. Using the sing-around method, the ultrasonic velocities were obtained from the travelling time of ultrasonic wave (5MHZ) in the 10mm thick specimens. The experimental procedure was as follows: The stress was applied on the specimen and then released abruptly, and the change in travelling time responding to the instantaneous change in stress was measured. The results are summarized as follows : (1) In every material used, the travelling time deviation ΔT/T_0 and the modulus deviation ΔM/ M_0 under a given stress are of the same order of the strain caused by the stress. (2) In copper, the relation between the modulus deviation and the strain is representable by a parabolic curve with little scattering. The results can be expressed by the equation ΔM/M_0 =Aε-Bε^2, where A is a constant relating to the third order elastic constants, and B a constant relating to the density and the pinnig length of dislocation. (3) In annealed aluminum, the modulus deviation measured was in accordance with that expected from the third order elastic constants, but not in steel. The former was explained from that, because of a lot of impurity atoms, the mobility of dislocation would be reduced, and the later seemed to be due to pre-existent structures which would still remain after annealing at a relatively 10w temperature (250℃). (4) In 6-nylon, the relation between the modulus deviation and the strain shows almost a straigtht line with little scattering.
社団法人日本材料学会の論文
1977-10-15

超音波伝ぱ速度の応力依存性に関する実験的研究

スポンサーリンク

概要

著者

関連論文

スポンサーリンク