Probabilistic Control Volume Method for Evaluating the Effects of Notch Size and Loading Type on Fatigue Life

The probabilistic control volume method has great prospects in correlating the effects of specimen size,notch and loading type on fatigue life or fatigue strength.In this work,the effects of notch size and loading type on fatigue life are investigated by using the probabilistic control volume method.Rotating bending and axial loading fatigue te«t«are at first performed on the hourglass specimen,circumferential V-notch specimen and V-notch plate specimen of 30CrMnSiA steel.Experimental results indicate that the notch reduces the fatigue strength of specimens in terms of nominal stress amplitude while in terms of local stress amplitude,the notch specimen could endure higher fatigue strength.Then,the probabilistic control volume method is used to evaluate the effects of notch size and loading type on fatigue life.It is shown that the probabilistic control volume method correlates well the effects of notch size and loading type on fatigue life,even for the local stress of the notch root exceeding the yield stress of the material.

Research on Controlled Volume Operation Method of Large-scale Water Transfer Canal

The controlled volume method of operation is especially suitable for large-scale water delivery canal system with complex operation requirements. An operating simulation model based on the storage volume control method for multi-reach canal system in series was established. In allusion to the deficiency of existing controlled volume algorithm, the improved controlled volume algorithm of the whole canal pools was proposed, and the simulation results indicated that the storage volume and water level of each canal pool could be accurately controlled after the improved algorithm had been adopted. However, for some typical discharge demand operating conditions, if the previously mentioned algorithm was adopted, then it certainly would cause some unnecessary gate adjustments, and consequently the disturbed canal pools would be increased. Therefore, the idea of controlled volume operation method of continuous canal pools was proposed, and corresponding algorithm was designed. Through simulating practical project, the results indicated that the new controlled volume algorithm proposed for typical operating conditions could comparatively and obviously reduce the number of regulated check gates and disturb canal pools for some typical discharge demand operating conditions, thus the control efficiency of canal system could be improved.

A New Method to Track Resin Flow Fronts in Mold Filling Simulation of RTM Process

A new method to track resin flow fronts, referred to as the topological interpolated method (TIM), which is based onfilling states and topological relations of adjacent nodes was proposed. An experiment on the mould filling process wasconducted. It was compared with exact solutions and the experimental results, and good agreements were observed.Numerical and experimental comparisons with the conventional contour mathod were also carried out, and it showedthat TIM could enhance the local accuracy of flow front solutions with respect to the contour method when mergingflow fronts and resin approaching the mold wall were involved.

A simple analytical method for deflation prediction of inflatable structures

The static performance of inflatable structures has been well studied and the dynamic deployment simulation has received much attention. However, very few studies focus on its deflation behavior. Although there are several dynamic finite element algorithms that can be applied to the deflation simulation, their computation costs are expensive, especially for large scale structures. In this work, a simple method based on classic thermodynamics and the analytical relationship between air and membrane was proposed to efficiently analyze the air state variables under the condition of ventilation. Combined with failure analysis of static bearing capacity, a fast incremental analytical method was presented to predict both elastic and post wrinkling deflation process of inflatable structures. Comparisons between simplified analysis, dynamic finite element simulation, and a full-scale experimental test are presented and the suitability of this simple method for solving the air state and predicting the deflation behavior of inflatable structures is proved.

Pressure distribution of combining center cavity slipper for axial piston pump

In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.

General Governing Equations and Numerical Solution Method in Electromagnetics and Fluid Mechanism

Based on an analogy among the governing equations among the electrostatic field,static magnetic field and fluid flow,all these equations can be expressed by a general differential equation,and the control volume method,which has been widely used in computational fluid dynamics,was developed to solve all these equations.Numerical results showed that control volume method is a successful numerical in the computational fluid dynamics and the electromagnetics,and the upwind(or downwind)scheme have the clear mathematical meaning and can be applied to calculate the charges' movement in the electrostatic field.

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Research on the extrusion of natural polymers(food,feed,etc.)is relatively new due to the complex physicochemical transformations of raw materials,although plastics melt conveying and transport have been well studied.The structure and composition,rheological behavior as well as extrusion processing of natural polymer are much more complicated.In this study,a quasi-three-dimensional(3D)fluid flow model for non-Newtonian,non-isothermal and undeveloped temperature was developed,the model prediction being in reasonably good agreement with the experiment.Results show that the influence of moisture content,among other process variables,is the most significant,followed by screw speed.Some interaction exists between these two variables and the screw speed effect becomes marginal at high moisture contents.In addition,viscosity change in the channel was studied.