Etsujiro Imanishi

Experimental study on acoustical birefringence in stressed and slightly anisotropic materials

The acoustoelastic effect in rolled metals is examined experimentally by the ultrasonic method. The first experiment is concerned with the birefringence due only to the texture‐induced anisotropy. In the second experiment, the uni‐axial tensile stress is applied to five specimens which are differently inclined from the common rolling direction, and the birefringence due to both the slight orthotropy and stress is examined. Though the experimental results are a little complicated, they are well explained by those theoretical acoustoelastic relations which one of the authors previously proposed for slightly orthotropic materials. This means that, in general, the polarization directions are fairly rotated by the stress, which is explicitly reaffirmed by the third experiment. It is the main conclusion of the present paper that the acoustoelastic relations referred to above are essential for rolled metals. In previous experimental works, slight anisotropies of polycrystalline metals were hardly taken into acco...

A time integration method for analysis of dynamic systems using domain decomposition technique

This paper presents a precise and stable time integration method for dynamic analysis of vibration or multibody systems A total system is divided into several subsystems and then responses are calculated separately, while the coupling effect is treated equivalently as constant force during time steps By using iterative procedure to improve equivalent coupling forces, a precise and stable solution is obtained Some examples such as a seismic response and multibody analyses were carried out to demonstrate its usefulness

Fast simulation of flexible multibody dynamics with electric-hydraulic drive system

Hardware in the loop simulation (HILS) has been investigated in the field of the multibody dynamics (MBD), which combined the MBD simulation with the actual mechanical system. The fast simulation is necessary for the HILS system in order to require the real time simulation. This paper presents a fast simulation technique using the domain decomposition method with the iteration in the flexible multibody system in which flexible linkage system and electro-hydraulic drive system are coupled with each other.

Multibody Dynamics and Competitiveness on the Company

This paper presents how the multibody dynamics is utilized in the company. In recent years, the advance evaluations considering the dynamics of the products become to be the mainstream on the design state in new product development. Moreover, the multibody dynamics is utilized to develop the advanced technology of the new products. As it becomes to be possible that the dynamics of the products is examined even in the design stage at the good accuracy by the progress of the multibody dynamics, the essential solutions and the quantitative evaluations can be carried out in the development of the new products. In the development of the completely new concept machine, the multibody dynamics is necessary to carry out the system optimization of the machine. In this paper, the activities using the multibody dynamics are introduced through the cases of the evaluation on the disorder winding of the wire rope in the tower crane, and the evaluation of the power consumption in the hydraulic excavator.Copyright

An experimental study of the acousto-elastic effect in a rolled plate of steel

The acousto-elastic effect in rolled steel is studied experimentally by transmitting ultrasonic transverse waves and measuring amplitudes of reflected echoes. A Y-cut quartz transducer with a frequency 4.8 MHz and ultrasonic flaw detection equipment are used for generation and detection of waves, and three tensile specimens with different orientations are prepared from a rolled plate so as to ascertain an important role of its slight orthotropy. At first the variation of amplitude with the transducer direction is examined in the unstressed state, and the slight orthotropy of each specimen is determined quantitatively. Then the variation of amplitude with the tensile stress is examined in the elastic range. The results depend clearly on the orientation of each specimen, and rotation of polarization direction is affirmed in the specimen with an inclination 45° against the rolling direction. Quantitative discussions about the whole experimental results give the conclusion that the acousto elastic effect in this rolled plate obeys the relations which were proposed theoretically by one of the authors.