Advanced Materials Research Vols. 433-440

Abstract: A two-step interpolation algorithms for a newly developed parallel kinematic machine is investigated. In the rough interpolation stage, a point-vector blending method is implemented to solve the problem that the position and pose is coupling; in the fine interpolation stage, two different spline curves is compared for the choice of appropriate fine interpolation algorithm.. Nonlinear mapping between real and virtual space is analyzed and the nonlinear error is estimated. The calculation results show that PVT spline curve can satisfy the accuracy requirement of the A3 head in high-speed machining.

Abstract: Aero Thin-Walled Structure (ATWS) is tending to deformed in automated riveting. Fixture plays an important role in enhancing riveting quality of the ATWS assembly process, and an appropriate layout of locating points can decrease the assembly variation substantially. This paper focused on the layout of locating points for ATWS automated riveting, using Genetic Algorithm and Ants Algorithm (GAAA) to minimize the locating points to decrease riveting variation. Firstly, the scheme of locating points is analyzed, and all potential locating points are represented by leveled matrixes. Secondly, on base of the locating point scheme, information of potential locating points is coded as gene, and the configuration of splint is defined as chromosome; the fitness is also defined according to the Key Characteristic Points (KCPs)’ riveting variation. Thirdly, the genetic and ants manipulations are discussed individually, and the two parts are connected by threshold value of the probability for chromosome in the genetic manipulation. Lastly, a case of aircraft wing panel is studied, and the finite element analysis result proves that the purposed optimizing method can solve the layout of locating point for ATWS automated riveting well.

Abstract: Industrial occupations such as metal stamping workers, electronics parts assembly operators, automotive industry welders, and lathe operators perform their jobs in standing position for a long period of time. Prolonged standing can contribute to discomfort, and muscle fatigue particularly in the back and legs. This study developed prolonged standing strain index (PSSI) to quantify risk levels due to standing jobs and propose recommendations to minimize the risk levels. Risk factors associated with standing jobs such as working posture, muscles activity, standing duration, holding time, whole-body vibration, and indoor air quality were considered as basis to develop the PSSI. All risk factors are assigned with multipliers, and the PSSI is the product of these multipliers. Based on PSSI, recommendations were proposed, however, extensive studies are required to validate their effectiveness.

Abstract: In this paper, intelligent control system in the intersection was designed by use of the control principles of green light length. The green light time from four groups were controlled by actual traffic flow, which could be detected by use of inductive sensors to auto-adjust the length of time. Secondly, combined with the traffic scale, road, time and seasonal changes situation, turn-left controller was tried to add in the traffic lights system by use of fuzzy control method at the crossroads. The feasibility of control principles from green light length were verified by debug in the PLC program.

Abstract: By filament winding technology, a pin hole can be formed in the process of composite manufacturing through wrapped fiber tow around pin, so fiber tows around the pin hole are continued. The paper presents the failure analysis for this kind of pin hole. The experimental results and numerical results show that the pin hole has a good tensile bearing ability. According to Hashin criteria, numerical results show that main failure modes are fiber tensile failure and matrix tensile failure which are agreed with the experimental results.

Abstract: A manual-controlled injection barium-strontium titanate based on glass fiber filter enricher(MIBSTE) was prepared, and its application in speciation of Cr(III) and Cr(VI) from water was studied. The optimum experimental parameters for preconcentration and separation of the Cr(III) and Cr(VI) have been investigated. The results showed that the BBST had adsorption capacity towards the Cr(III) and Cr(VI) at the different conditions. And two forms of chromium show different adsorption capacities at different pH values, Cr (III) could be adsorbed at pH ≥ 10, but Cr(VI) can’t be adsorbed. Whereas Cr (VI) retained at pH ≤ 2, but Cr(III) can’t be adsorbed. Therefore, it is possible that the two forms of chromium are complete separated. The Cr(III) and Cr(VI) could be completely eluted with 1 mol•L⁻¹ HCl and 1 mol•L⁻¹ NaOH, respectively. The chromium concentration was measured by atomic absorption spectroscopy. A new method for determination of the speciation of chromium in environmental water samples based on the manual-controlled injection enricher and atomic absorption spectroscopy determination was proposed. The method was successfully applied for the determination of Cr(III) and Cr(VI) in environmental waters with satisfactory results.

Abstract: With constant development of machine tools toward the direction of high speed, high precision, high efficiency and high compound rapidly. The performance of high-speed machine tools is affected by the dynamic characteristic of machine tools in the very great degree. More and more attention is played to them and higher and higher demands are proposed. Finite element method is a kind of fast and efficient auxiliary tools in modern engineering analysis and design. Three-dimensional finite element model of spindle box is established in this paper based on large finite element analysis software ANSYS. Through modal analysis, the first five order natural frequency, vibration mode and various order vibrating modal characteristics are obtained. These results are verified by using the method of experimental modal. Harmonic response analysis is carried after doing modal analysis on spindle box. Response and stress under different frequency are obtained. Continuous dynamic characteristics are forecasted.

Abstract: Machining-induced distortion of large monolithic parts with thin walled structures creates problems in aircraft manufacturing industry. Typical monolithic beams of airframe are machined by NC machine and machining distortions are recorded. Thin walled structures are prone to distortions and dimensional instabilities due to internal stresses; therefore, stress-relieved vibration method is applied to reduce the internal stresses in blank material and results in better machining performance and dimension stability. But vibration stress-relief method doesn’t work always due to unknown reasons. Machining simulations in ANSYS are performed to predict the residual stress-induced machining distortion and simulation result is compared with the machining measurements to validate the simulation process. Cutting simulations have been executed by the element deactivation technique after developing the initial residual stresses via sequential coupled field analysis. The possibility of residual stress being relieved more reasonably and less distortion by optimized machining sequence through simulation is discussed.

Abstract: A numerical method to determine the shoulder height in the angular contact ball bearing using 3D contact analysis is proposed. The load analysis of a ball bearing was performed to calculate the distributions of internal loads and contact angles of each rolling element. From the results of bearing load analysis and the contact geometry between ball and inner/outer raceway, 3D contact analyses are conducted. The developed algorithm is applied to an angular contact ball bearing for the automotive wheel. The critical axial loads which are not affected by edge in the present shoulder height are calculated. The critical shoulder heights are also determined when the bearing is subjected to a practical load.

Abstract: In this study, liquid film perturbed pressure equation is derived firstly using a Taylor Series expanding pressure formula. By linear film assumption, the axial stiffness and damping coefficients of the mechanical seal are derived. Then kinematical equation of the rotating shaft-mechanical seal system is established. The research focus on solving response of the rotating shaft-mechanical seal system and leakage of the mechanical seal when the rotating shaft is under different frequencies excitatied or under frequency disturbed in different form excitatied in this paper. The analytical results show that response of the rotating shaft-mechanical seal system can finally be close to the stable state, when excitatied frequency of the rotating shaft is disturbed in different form. But for amplitude of the displace between the stationary ring, rotating ring and rotating shaft occurs mutation point at the time when the excitatied frequency is disturbed, meanwhile the excitatied frequency of the rotating shaft is disturbed in rectangular pulse form or in instant maximum pulse form. It will cause liquid film thickness to happen mutation until the leakage increases and mechanical seal fails at last. The study results show that the sealing performance of mechanical seal and excitatied frequency of the rotating shaft has closely positive correlation. The rotating shaft-mechanical seal system can be optimization design and performance prediction based on the study of this paper.