A method for analytical model modification of a structure is proposed. Corrected mass and stiffness matrices are obtained by minimizing the weighted Euclidean norm subject to specified constraints. This method generates a mass matrix that is exactly fitted to the given mass property test data and mass and stiffness matrices to force eigensolutions that agree with the vibration test data. An example is presented to demonstrate the validity of this method.
It is common practice to measure the velocity profile of the wake using Pitot tubes and a hot-wire anemometer. The velocity profile is obtained from the traverse in the wake of the measurement equipment. This measurement procedure can be time-consuming and a more efficient technique would be most welcome. The author tried using a long hot-wire anemometer to measure the wake in a single measurement. The length of the hot-wire is greater than the width of the wake and the wire covers the entire flow field of the wake. The characteristics of the long hot-wire can be predicted using a heat conduction/transfer equation for the wire based on the heat transfer formulae for a cylinder. The wake of a cylinder was investigated using this long hot-wire anemometry. It was found that the output voltage of the hot-wire is correlated to the drag of the cylinder. Other 2-D and 3-D bodies were investigated and the hot-wire output correlated well to the drag.
It is well known that the Taylor-Goertler vortex arises when a two-dimensional jet flows on the concave surface of circular cylinder of y0.5/R≥0.17-0.27 (y0.5: half width of jet, R: radius of cylinder). Many researches have done to clarify the condition to arise the Taylor-Goertler vortex, the profile and the stability of the vortex and so on. But, the analysis for the decay of the maximum velocity and the pressure distribution in the flow field have not been clarified yet. This study shows the equation of velocity profile and clarifies the flow characteristics (decay of the maximum velocity, pressure distribution in the flow field and so on) under that the Taylor-Goertler vortex does not arise (y0.5/R≤0.17-0.27) using the momentum integral equation and its validity is confirmed by the experimental results.
This paper presents four-point bending tests to examine pure bending deformation of rectangular symmetric crossplies of fiber reinforced composites. The bending deformation is visualized and measured by holographic interferometry. Test results show that the pure bending deformation is realized, at least in a central portion of a specimen, provided that the aspect ratios of the specimen between the supporting and the loading points fall into certain ranges depending on the laminate composition. The higher the ratio of the axial to the transverse bending rigidity is, the greater the aspect ratios are required. These confirm the theoretical predictions made by a numerical analysis in a preceding paper of the authors'. Specific values of the aspect ratios are recommended for various laminate compositions.
The behavior of the outer flow around a three dimensional ACV was simulated by the discrete vortex method, which was almost similar to that proposed by Shirayama. In the present numerical method, the Kelvin's theorem was used. The shape of ACV is semispherical and impulsively started flow is investigated in this paper. It was confirmed, from the comparison of the present numerical results with the flow visualization of earlier works, that the present numerical method might simulate the feature of the outer flow around a three dimensional ACV. Especially we simulated a horseshoe-shaped vortex. It is seen that the feature of the outer flow around this shape of ACV changes according to the air supply flux to the cushion chamber and we may classify roughly into two groups: (1) In the large amount of the air supply flux, the fluid is issued from the overall edge of the cushion chamber to the exterior and the horseshoe-shaped vortex is generated around the body of ACV. (2) In the small amount of the air supply flux, the outer fluid inflows into the cushion chamber from the front part of the cushion chamber and the concentration of vortices does not develop near this part.
Longitudinal vibration characteristics of a liquid launch vehicle are reported. A bar-type longitudinal vibration mode was detected experimentally as a first mode. It was also found that the resonant frequencies of a tank filled with a liquid depend on the signal type of the excitation force.