In the previous report, the load distribution was analyzed assuming that the load-carrying belt teeth which are wound on the pulley mesh completely with pulley teeth. But in practice, the toothed belt drives have some incomplete meshing teeth at the beginning and the end of meshing. In this paper, the load distribution under consideration of incomplete meshing teeth is discussed, and the analytical result on load distribution is found to almost exactly agree with the experimental one.
It is theoretically shown that the reflection coefficient of an elastic wave in layers of plates depends on the frequency of the incident wave, the width and the number of layers. Then the spectral change of ultrasonic waves reflected in layers composed of aluminum and steel is measured and compared with the theoretical results. It is found that both results agree well if the bond between the materials is taken into account as one of the elastic layers.
This paper analyzes the effects of acoustoelasticity and damages on propagation of ultrasonic waves in fiber-reinforced plastics. Acoustoelasticity is used for nondestructive evaluation of the internal stress of materials. The technique utilizes the speed shift of ultrasonic waves due to nonlinearity of the elastic characteristics. When a fiber-reinforced plastic is subjected to a strong load, microdamage may be caused, for example, fiber failure, matrix cracking, and matrix yielding. Thus, propagation of ultrasonic waves in such composite materials depends not only on the stress but also on the microdamage in the materials. This paper presents the constitutive equation of fiber-reinforced viscoelastic materials with damage based on damage mechanics. The effects of microdamage and stress on the speeds of ultrasonic longitudinal waves are examined in the acoustoelastic test for high-polymer composite material, PBT, reinforced with glass fiber
The effects of stress ratio, ratio of number of cycles and magnitude of applied stress on the fatigue strength of notched medium steel were studied under many-fold multiple rotating bending load in two stress levels. A few other investigators have reported that on the notched specimen the fatigue life is nearly equal to the calculated life by the linear damage law, i.e, Nth=n0/(nA/NA+na/Na). According to the test results the fatigue life on the notched specimen shows the same tendency to change with the stress ratio, the ratio of number of cycles and the magnitude of the applied stress as on the smooth specimen all over the stress range. But the value of N/Nth on the notched specimen seems to be larger than that on the smooth specimen. In the last part of this paper we state the way to modify the linear damage law with the stress correction factors which are the functions of stress ratio, the ratio of number of cycles and magnitude of applied stress. The method makes it possible to deduce the fatigue life under manyfold multiple load with the help of a few experimental data.
The pitch difference between toothed belt and pulley exerts great influence on the fatigue strength of toothed belt. We reseached experimentally the relationship between pitch difference and fatigue strength for L-belt section of polychloroprene rubber and polyurethane toothed belts. From this study, the following results have been obtained. There are several features of fracture which relate to pitch difference and belt tension. A high fatigue strength can be expected if the pitch difference is selected to equalize the load distribution.
Indentation problems for an elastic half-space may possess similarity solutions when the local shape of the contacting body is expressed by a homogeneous function. In this situation, the desired solution for curved punches can be obtained by the integration, namely, cumulative superposition, of the solution to a single auxiliary problem which amounts to indentation by a flat-ended punch. This procedure avoids treating the moving and unknown contact boundary explicitly, so that the contact region can be determined in an accurate manner. In this study, the advantage of this procedure is explored from analytical and numerical points of view. Although the theoretical basis is laid down for frictionless indentation of an elastic half-space by a rigid punch, the method is shown to be applicable to the contact between two elastic bodies and for more general frictional behavior. To demonstrate the use of this superposition principle, the three-dimensional indentation by a punch with elliptic cross sections, as well as the plane strain indentation by an asymmetric punch are solved by this method. Numerical accuracy of the present procedure is verified employing some examples of plane-strain problems. The use of the boundary element method for the reduced flatpunch problem is shown to be effective and promising for more complicated three-dimensional indentation problems.
Recently, adaptive structures have been the focus of much attention because they change their shapes or characteristics to the optimum according to the mission or the design requirements. As a basic study on such adaptive structures, this paper attempts to control the deflection curve of a beam to the desired one using actuators. We obtain, by symbolic manipulation, the optimum solution for the moments which are applied to each part of a divided cantilever beam in order to obtain the desired deflection curve. The theoretical result is compared with the experimental one where the beam is deformed by the actuators using shape memory alloy wires.
In this paper, the interference between belt tooth and pulley tooth at the incomplete meshing region of toothed belt drives is numerically calculated by using the analytical method mentioned in the 4th report, and the influence of the radius of the tip corner rounding and the pressure angle of belt and pulley tooth on the interference is discussed. Also, the authors discuss experimentally on the effect of the radius of the tip corner rounding of pulley tooth on the fatigue strength of L type polyurethane and polychloroprene rubber belt, and the displacement of the belt pitch line depending on the load and the frictional force acting on belt tooth at the incomplete meshing region. Further, the sliding velocity of the contacting point of belt tooth and pulley tooth is calculated and the total nominal stress at the bottom land corner of belt tooth is discussed.
