Blade Shaft Research Articles

Dynamic Characteristics of Blade-Disk-Rotor System with Structural Mistuned Features

The finite element method is adopted to establish the dynamical models of blade, bladed disk and blades-diskshaft assemblies. Based on the analysis of mistuned structure and the dynamic characteristics of model in different levels, it gives the vibration mode distribution of different models. The research shows that the characteristics of the bladed disk and shaft have a huge difference, where some modes are caused by the strongly split and coupled vibration. The mistuned effects are likely to cause different coupled vibrations of blades between the blades-disk model and the blades-disk-shaft model. Meanwhile, it shows the frequency separation and concentration, and misses the system mode and the local vibration, which bring some difficulties for designing the blade-rotor system. In this paper, the results may provide a certain reference for blade-rotor system design and diagnosis.

Design of Sweet Potato Vine Chopping and Returning Machine

Based on sweet potato vine creeping stems features and northern cropping patterns, this paper developed a sweet potato vine chopping and returning machine. It consists of pick-up mechanism, cut-off device, crushing device, ground wheel assembly and main frame etc.. The machine is attached directly to the tractor´s three-point linkage. It can complete vine picking up, cut-off, crushing and returning in one operation. The gear box which is made for turning and increasing speed is driven by PTO, and then drives cut-off system and crushing device individually. With the tractor forward, the vines was first picked up by the pick-up mechanism and cut off by the rotating disc of the cut-off device, and crushed by the crushing shaft with the help of the negative pressure caused by the high speed rotation of the crushing blade shaft.

Strength and stiffness analysis of Z-shape bladed shaft of a dual-shaft mixer

A procedure for analysis of the strength and stiffness of a dual-bladed Z-shape mixer shaft, which is a three-dimensional structure with curvilinear rods, is proposed; the structure is uniformly loaded along one of the helical rods. An example is cited for analysis of a plant version of the bladed Z-shape shaft of a mixer.

A NEW ACTIVE CONTROL STRATEGY FOR WIND-TURBINE BLADES UNDER OFF-DESIGN CONDITIONS

A new active control strategy for wind-turbine blades under off-design conditions has been investigated in this paper. According to our previous work, in comparison with the traditional straight leading-edge blade, a new kind of bionic blades with a sinusoidal leading edge can significantly enhance the turbine's power output at high speed inflows. However, the wavy leading-edge shape is unfavorable under the design operating conditions since an early boundary-layer separation is inevitable for a wind-turbine blade because of the geometric disturbances of the leading-edge tubercles. But for the present active control, the deflect in wavy leading-edge blades can be eliminated by introducing a series of small flat delta wings as the control units, since delta wings can also generate powerful leading-edge vortices. As a preliminary test, our numerical results show that, the shaft-torque fluctuation in the turbine's stall region can be improved from 27.8% for a straight leading-edge blade (no control) to 8.9% for the present active control; and by adjusting the control parameters, the control units nearly have not any negative effect on the blade's shaft torque under the design conditions. We believe that, as an auxiliary tool of the conventional control strategies, the present active control approach may be favorable to generate a more stable and more controllable power output for wind turbines under all operating conditions (even in the yawed inflows).

Screw Conveyor Design and Processing in Rubber Production

Powder was fed to improving or increasing rubber performance in rubber production. Due to the variety of powder, different feeding quantity and material liquidity and high precision needed, often choose screw conveyor to convey and weigh all kinds of powder. This paper mainly introduce the structure of the screw conveyor for rubber production, analyses the impact of the main parameters of screw conveyor on its performance and conveying capacity. A method of chosen and confirmed the mainly design parameters of screw conveyor was illustrated, and introduced the helical blade and screw shaft of the screw conveyor processing method combining with actual production.

Engineering and Construction Torsional Responses of Glass-Fiber/Epoxy Composite Blade Shaft for A small Wind Turbine

Recently, composites made of thermosetting epoxy matrix reinforced by glass fibers have been widely used for advanced engineering and aerospace applications. This study newly proposes a developed methodology to manufacture a glass-fiber/epoxy resin composite blade of a small 1kW wind generator system. The improved mechanical properties of the composite blade are verified in a series of systematic experiments. The study focuses on the responses of applying a torsional loading to a long straight member such as the root of the composite blade. The core aluminum shaft was wrapped in glass-fiber/epoxy to form the root of the composite blade and a composite shaft. The composite shaft is a sandwich structure combining glass-fiber/epoxy and an aluminum shaft. The composite shaft was placed in a torsional testing machine and a strain gage monitored the strain on the composite shaft. We considered the composite blade to have a circular cross section and determined both stress distribution within the member and the angle of twist. Finally, mechanical properties were obtained in torsional testing, including the relationship between applied torque and the angle of twist on the composite shaft. The torsional loading and failure locations of the blade root were measured experimentally. The experiments showed that the weakest location of the blade root is at the interface of the aluminum shaft and glass-fiber/epoxy lay-ups in the composite blade root. It is found that the quality of the aluminum shaft, the glass-fiber/epoxy layers around the shaft and the bonding at the interface between the shaft and the layers should be increased to improve the torsional strength of the composite blade. These results can provide a reference for analysts and designers of small wind turbine systems.

Effect of Support Stiffness on the Stability of a Rotor System with Blade Flexibility

A simple mathematical model describing the motion of a rotating flexible blade, rigid-disk, and flexible shaft assembly is derived. The model provides a fast parametric study for the dynamic behaviour of the proposed rotor system. The Lagrangian approach combined with the assumed mode method is used to derive the governing equations of motion for this system. The model consists of asymmetrical continuous shaft mounted on two isotropic supports; an end support, represented by two rotational and two translational springs, and an intermediate support, represented by two translational springs only. A rigid disk, with a number of flexible blades of uniformly distributed stiffness and mass, cantilevered to the disk, is attached to the free end of the shaft. The effect of support flexibility on the stability of the system is studied. Instability regions are presented for different system parameters. Coupling between flexible blades and shaft coordinates showed very little effect on the instability regions. The mathematical model results are similar to those found in the literature.

Stabilizing collar for a concrete saw blade

A stabilizing collar for a concrete saw blade provides a rigid blade structure for smoother cutting operations, particularly in partially cured concrete. A pair of the present collars are secured to the blade shaft on each side of the blade, clamping the blade securely therebetween. Each collar has a slightly recessed central area and a raised toroidal rim therearound. Clamping the blade and collar assembly tightly on the shaft, compresses the recessed areas and clamps the rim portions of the collars tightly against the blade at some distance outward from the shaft, thereby providing a rigid assembly and essentially eliminating lateral vibration and flexing of the blade. This enables an otherwise conventional concrete saw to be used for cutting “green” concrete, i.e., relatively soft concrete which has only partially cured, without risk of spalling and breaking up of the edges of the cut due to blade vibration thereagainst.

Enhanced accuracy is necessary for refractive surgery instrumentation

New optical zone markers, diamond knives, and gauge blocks were ordered from a random selection of manufacturers and inspected by an independent metallurgical engineer. This study revealed workmanship flaws and poor instrument accuracy. None of the 26 optical zone markers examined came with instructions as to whether the incisions were to be carried to or from the inside diameter or the outside diameter of the corneal impression made by the marker. Two markers had a 100 μm or greater error in their centering devices and one had a centering device off center by 210 μm. Two of the seven diamond micrometer knives had broken blade tips and uneven footplates; two knives had misaligned blades and uneven footplates, one knife had extremely roughly finished footplates, and one knife had a 100 μm error in its micrometer. All the knives had a wobble in the blade shaft upon advancement and had rounded footplates, making blade extension verification difficult. Five of seven blade gauges were accurate to within 10 μm; two had errors of more than 60 μm which could lead to incisions too deep or too shallow and micro- or macroperforations of the cornea during refractive surgery. It is recommended that all refractive surgery instruments be carefully inspected under a high power micron-level microscope at the time of purchase and routinely thereafter.