Search

Tool wear can affect surface quality of the work-piece and frequent tool changing leads to low machining efficiency. Tool life of milling ultrahigh strength steel is thus an important indicator in manufacturing. In this study, we compare Diffuse Approximation (DA) and Kriging method for predicting tool life of milling ultrahigh strength steel. Latin hypercube method is employed as design of experiments after comparing three different designs of experiments (full factorial design, Latin Hypercube Sampling (LHS) and random design). An example with LHS is taken to investigate accuracy of approximation of DA and Kriging method. The results show that the DA provides significant improvement in accuracy of prediction compared with Kriging method. Tool life of milling ultrahigh strength steel predicted by DA is almost close to ‘exact’ values, especial for big mutation of adjacent measured values. The most errors with DA are less than ones with Kriging method.

The water droplet erosion protection of the rotor blades has been an important issue for a long time, regardless of the design. The aim of this paper is to present a aerodynamic design method for decrease risk of water droplet erosion in wet steam turbine, as well as to present the comparison between then five diffrent bow stator blades. This paper also presents numerical investigation of three dimensional wet steam flows in a stage. This stage has long transonic blades designed using recent aerodynamic and mechanical design methods. The results show that, the one of the five diffrent bow stator blades decrease rist of water droplet erosion of rotaional blades, and the change of the efficiency is small.

A large number of weakly rigid parts are used in the progress of aircraft assembly, while it’s deviation will affect the quality of the product finally. The assembly variation model of aircraft weakly rigid parts based on influence coefficient method are constructed for controlling assembly accuracy effectively. Based on the linear elastic hypothesis of small deformation, the model carry out the mechanical analysis of aircraft weakly rigid parts in the typical process of positioning, clamping, jointing and spring-back. Influence coefficient matrix of the key features affected by parts manufacturing variation and fixture variation is calculated through the Finite Element method and Monte Carlo simulation, then the assembly variation model is constructed. Finally, based on the above model, an engineering example of assembly variation prediction of aircraft panels was given.

The riveting joint is the main connection method in aircraft assembly. There are some kind of rivets, such as slug rivet and protruding rivet, that riveting quality will be impacted while rivets axis are not coincident with the plate holes axis. By using the finite element method with ABAQUS software, this paper built the 3D riveting joint structure of finite element, and analyzed the axis deviation effect on the deformation, stress and strain of riveting. Through statistical data, the relationship among axis deviation value, deformation, stress and strain of rivet are built.

In the process of automated riveting, the position between the riveting head and the holes distributed on the stringer and wing skin to be riveted will go beyond the design requirements currently. Using the edge distance determination technology to measure and compensate the deviation in time is one effective method to solve this problem. In the dissertation, after the characteristic of the edge distance determination technology is introduced, the working principle of the edge distance tracer apparatus is developed. Based on the mechanical design solution, a pressure sensor is selected to measure the position relationship between the riveting head and the stringer. Then an edge distance tracer apparatus is struck out to detect the deviation, which is an automatic positioning feedback device that can be fit for many kinds of stringers. And the riveting head is operated to meet the design deviation requirements. By using this technology, the drilling precision of the automated riveting system can be effectively improved.

In this paper, we introduce the study on fuzzy neural network control used in wastewater treatment. An effective fuzzy neural network controller is proposed. The simulation result shows that the system gives strong robustness and good dynamic characteristics. It is used to control dissolved oxygen and forecast water quality. The result indicates that the concentration of dissolved oxygen can reach expectation fleetly and effectively. The model has better precision of forecasting and faster speed of convergence.

An efficient flexible iterative algorithm with a general approach is presented for calculations of surface form errors in peripheral milling of thin-walled workpiece. An efficient finite-element model for tool/workpiece is presented to analyze the surface dimensional errors in peripheral milling of aerospace thin-walled workpieces. The efficient flexible iterative algorithm is proposed to calculate the deflections and the maximum surface form errors as contrasted with the rigid iterative algorithm used in the literatures. Meanwhile, some key techniques such as the finite-element modeling of the tool-workpiece system; the determinant algorithm to judge instantaneous immersion boundaries between a cutter element and the workpiece; iterative scheme for the calculations of tool-workpiece deflections considering the former convergence cutting position are developed and the method for calculating the position and magnitude of the maximum surface form errors are developed and presented in detail. The proposed approach is validated and proved to be efficient through comparing the obtained numerical results with the test results.