Prediction of forming characteristics of titanium alloy self-locking nuts

Titanium alloy is an important class of aerospace material due to its high specific strength, excellent anti-corrosion and anti-oxidation. In this paper, a three-dimensional thermo-mechanical coupled simulation was carried out to predict the formation characteristics of TC4 titanium alloy self-locking nut during the upset forging process. The stability of the upset forging was analyzed, and the influences of initial temperature and deformation velocity on the formation quality were investigated. The results show that if length-diameter ratio of the sample less than 3.27, the upset forging formation tends to be stable, and here, the length-diameter ratio of 2.89 was selected. Additionally, the forming quality of TC4 self-locking nut improves with the increase of initial temperature and decreases with the increase of the velocity of the upper die. The analysis results can provide a theoretical guidance for the upset forging formation of TC4 titanium alloy nuts.

Impact of cutting parameters on machining of Ti-6Al-4V alloy: an experimental and FEM approach

Titanium alloys are used as an aerospace material due to their inherent properties such as high strength to weight ratio, corrosion, and fracture resistance. However, the low conductivity and reactivity towards plastic deformation causes these materials to be difficult to cut category. The prediction of various parameters like chip formation and actual cutting forces are important factors for better machinability which involves lot of resources. To overcome such issues, this work proposes three-dimensional FE approach to simulate the machinability behavior of Ti-6Al-4V especially on conventional turning. The impact of cutting speed and feed rate on the cutting force, thrust force, feed force and surface roughness were analyzed experimentally for various conditions. The predicted machining forces showed strong correlation with the experimental results and the effective von mises stress were examined.

Dynamics Modeling and Theoretical Study of the Two-Axis Four-Gimbal Coarse–Fine Composite UAV Electro-Optical Pod

In the UAV electro-optical pod of the two-axis four-gimbal, the characteristics of a coarse–fine composite structure and the complexity of dynamics modeling affect the entire system’s high precision control performance. The core goal of this paper is to solve the high precision control of a two-axis four-gimbal electro-optical pod through dynamic modeling and theoretical study. In response to this problem, we used finite element analysis (FEA) and stress study of the key component to design the structure. The gimbals adopt the aerospace material 7075-t3510 aluminum alloy in order to meet the requirements of an ultralight weight of less than 1 kg. According to the Euler rigid body dynamics model, the transmission path and kinematics coupling compensation matrix between the two-axis four-gimbal structures are obtained. The coarse–fine composite self-correction drive equation in the Cartesian system is derived to solve the pre-selection and check problem of the mechatronic under high-precision control. Finally, the modeling method is substituted into the disturbance observer (DOB) disturbance suppression experiment, which can monitor and compensate for the motion coupling between gimbal structures in real time. Results show that the disturbance suppression impact of the DOB method with dynamics model is increased by up to 90% compared to PID (Proportion Integration Differentiation method) and is 25% better than the traditional DOB method.