Strain rate effects on the deformation behaviour and fracture mode of recycled aluminium alloys reinforced alumina oxide

• Main Author: Ma’at, Norzarina
• Format: Thesis
• Language: English; English; English
• Published: 2023
• Subjects: T Technology (General)
• Online Access: http://eprints.uthm.edu.my/11049/1/24p%20NORZARINA%20MA%E2%80%99AT.pdf; http://eprints.uthm.edu.my/11049/2/NORZARINA%20MA%E2%80%99AT%20COPYRIGHT%20DECLARATION.pdf; http://eprints.uthm.edu.my/11049/3/NORZARINA%20MA%E2%80%99AT%20WATERMARK.pdf; http://eprints.uthm.edu.my/11049/

In recent years, reinforcement with alumina oxide (Al2O3) has been considered to enhance the mechanical characteristics of recycled aluminium alloys. However, there is no established information on the deformation behaviour of such recycled material when subjected to various loading conditions, including damage progression. In addition, minimal efforts were conducted to develop numerical modeling to predict the deformation behaviour. Based on this motivation, a hybrid experimental-numerical approach is used in this research project. A hot press forging method is used to produce the specimen. The deformation behaviour, including damage progression of recycled AA6061 reinforced alumina oxide was investigated using the uniaxial tensile test at different strain rates (6×10-3 – 6×10-1 s-1) and the Taylor cylinder impact test at impact velocity ranging from 190 m/s – 370 m/s. The recycled AA6061 reinforced alumina oxide exhibits a strain-rate dependence behaviour and ductile-brittle elastoplastic from the experimental work. The mechanical properties of the recycled AA6061 reinforced alumina oxide are degraded due to the behaviour of alumina oxide (brittle) and damage progression under loading deformation. The Taylor cylinder impact tests showed three fracture modes (mushrooming, tensile splitting, and petalling) with a critical impact velocity of 280 m/s and also exhibits plastic anisotropic behaviour and antideformation solid capability. The increasing impact velocity increases the severity of damage progression of the recycled AA6061 reinforced alumina oxide. Metallurgical analysis showed that micro-voids were initiated in the pre-test specimen, and damage evolved due to the nucleation, growth, and coalescence of micro-voids when loading was applied. The numerical approach was performed in the finite element analysis using LS-DYNA to predict the deformation behaviour of recycled AA6061 reinforced alumina oxide. The Simplified Johnson-Cook model was chosen and the input parameters characterize based on uniaxial tensile test data. The simulation result was then validated against both tests' experimental data and showed a satisfactory agreement