Kaifu Zhang

Optimization method of fixture layout for aeronautical thin‐walled structures with automated riveting

Purpose – An appropriate fixture layout can decrease the assembly variation of Aeronautical Thin‐Walled Structure (ATWS) substantially. The purpose of this paper is to develop a fixture layout method to minimize variation.Design/methodology/approach – The paper uses genetic algorithm and ants algorithm (GAAA) to optimize the fixture layout by first, analyzing the “N‐2‐1” positioning principle of ATWS riveting, and then developing a hierarchical fixture layout model to represent the base points and locating points of ATWS. Second, information of base points and locating points is coded as gene and chromosome, according to a special coding rule and the fixture layout model. The fitness is also defined by the assembly variation of key characteristic points (KCPs). Third, 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.Findings – The method can solve the fixture layout problem of ATW...

An analytical method for predicting the fluctuation of thrust force during drilling of unidirectional carbon fiber reinforced plastics

This paper devotes to predicting and analyzing the fluctuation of the thrust force during drilling of unidirectional carbon fiber reinforced plastics (UD-CFRPs). The fluctuation properties could be evaluated by the average value, maximum value, minimum value, change frequency and the amplitude of thrust force. Firstly, an orthogonal cutting model is introduced, and the model is modified in order to reveal how the drilling parameters affect the fluctuation. Secondly, the cutting lips are assumed to conduct orthogonal cutting, and the thrust force generated on cutting lips is calculated by using the orthogonal cutting model. Thirdly, the variable parameter, which leads to the fluctuation of thrust force, involved in the analytical model is analyzed separately. Lastly, experiments were conducted to determine the coefficients and testify the model. The comparison between the theoretical values and the experimental results prove that the analytical model can predict the fluctuation of thrust force well.

Tribological Behavior and Microstructure of Carbon Fiber–Reinforced Polymer against Ti6Al4V Alloy in Fretting Contact

ABSTRACT This article investigates the tribological behavior of carbon fiber–reinforced polymer (CFRP) against Ti6Al4V alloy for fretting contacts. Tests were conducted for CFRP against Ti6Al4V in a ball-on-flat configuration. The fretting coefficient of friction (COF) was measured and worn surfaces were characterized. Three-dimensional topographies and surface roughness of fretting scars with different fretting amplitudes were examined. The relationships between COF and various fretting amplitudes, normal force, frequency, fibers orientation, and temperature are presented. The results shows that these factors influence the fretting friction coefficient as follows: fretting amplitude applied load fiber orientation frequency, and temperature and fretting mode have a combined action on the evolution of COF. The surface properties of fretting scars under various fretting amplitudes were demonstrated. In addition, fibrous polishing and shear fracture and fatigue cracking of the matrix are the main fretting wear mechanisms under low fretting amplitude.