This master thesis aims to study hybrid joints of polyetherimide (PEI) and aluminum 6082-T6 produced by Friction-based Injection Clinching Joining (FICJ). The influences of the process parameters in the frictional heat and polymer degradation were analyzed through a half factorial design. The degradation of PEI was evaluated by size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR). The effect of degradation in the joint microstructure and mechanical properties was also analyzed. The macro and microstructural characteristics were evaluated by optical microscopy and Vickers hardness. The static mechanical properties were determined by lap shear testing and cross tensile testing. It has been shown that the F-ICJ causes degradation through multiple chains scissions. Additionally, a thermomechanically affected zone, with lower hardness, and defects such as pores and weld lines are formed. The mechanical performance, mainly in cross tensile testing, is negatively affected by degradation and presence of defects. These results contribute to the optimization and application of F-ICJ to join hybrid structures. Key-words: Friction joining, injection-based clinching joining, F-ICJ, hybrid joints, polyetherimide, PEI, degradation

Universidade federal de são carlos centro de ciências exatas e de tecnologia programa de pós-graduação em ciência e

http://www.ysxbcn.com/down/upfile/soft/2008617/200861716192729.pdf

Effect of processing way and aging treatment on properties and microstructures of 7B04 aluminum alloy

During the immersion quenching process, severe temperature changes and significant temperature differences between the core and superficial area can give rise to high residual stresses within the aluminum alloy thick plate to cause subsequent machining distortion of the thin-walled part. Reducing the residual stress within the thick plate can effectively minimize the distortion in part. In this research, ABAQUS software was adopted to simulate the internal temperature and stress fields of thick plates of Al7055 alloy during the quenching and pre-stretching processes, sequentially and respectively. In addition, the x-ray residual stress measurement method was used to measure and characterize the surface residual stress of the plates. The results indicate that the medium temperature affects residual stress inside the thick plate significantly during the immersion quenching process. The level of which inside the plate gradually increases as the medium temperature decreases. Further, the pre-stretching treatment can effectively reduce residual stresses within the thick plate, and the residual stress level gradually decreases with the pre-stretching ratio increasing. The experimental results verify the feasibility of numerical simulation to predict the status of quenching stress in thick plates. Subsequently, a simulation study for material removal processes was carried out based on the above studies. The results reveal that the thin-walled part’s machining distortion degree improves as the raw thick plate’s initial quench residual stress level decreases.

Finite element simulation on residual stress during immersion quenching and pre-stretching of Al7055 thick plates

https://link.springer.com/content/pdf/10.1007/s12204-021-2389-y.pdf

Numerical Simulation on the Effect of Conveyor Velocity of the Roller Table on Stress Distribution and Evolution in Large Aluminum Alloy Thick Plates

The aircraft industry is constantly striving for improved materials which enables higher performance at reduced cost. The development of high speed milling machines and improvements in thick plate properties regarding distortion during machining have led to the conclusion that large machined structures can replace forged components and significantly reduce the cost by reducing the number of components and joints. For this reason, Hoogovens Aluminium Rolled Products together with Hoogovens Research and Development, has continued to improve the property balance required for AA7xxx high strength thick plates in aerospace applications. This paper will focus on investigations performed to optimise the process for high strength thick plates. This work contains a careful analysis of the process steps including the measurement of quench rate within thick plates, quench factor analysis, simulation of the effect of changes in quench practice on final properties and modelling work of residual stress to gain the best property balance required for thick plates in aerospace applications. Finally, the improved mechanical properties and the low level of distortion during machining for high strength thick plates will be discussed.

J. van der Lugt

Papers

Recent Improvement in High Strength Thick AA7050-Plate