Abstract:The hardness variation and the behaviour of precipitation during the process of three stage ageing of three Al-Cu-Mg alloys were investigated using micro-hardness and differential scanning calorimetry (DSC). To facilitate the determination of the optimised heat treatment condition, a uniform design method was employed by which the influences of three stages interrupted ageing on the hardness and precipitation can be elucidated with a limited number of experiments. It is found that optimised heat treatment with… Show more
“…Similar results on AA7050 were reported [13]. For AA2024 strength improvements were obtained, but toughness values were not reported [14]. In AA6061 interrupt treatment has been claimed to simultaneously enhance strength and toughness [2,4,5,7,9,15].…”
“…Similar results on AA7050 were reported [13]. For AA2024 strength improvements were obtained, but toughness values were not reported [14]. In AA6061 interrupt treatment has been claimed to simultaneously enhance strength and toughness [2,4,5,7,9,15].…”
“…This uniform design is widely used in many design applications. 22–24 Figure 10.The (a) maximum principal stress and (b) von Mises stress at the discontinuous cross-section of the handle-stem model under the fatigue testing simulation.Figure 11.Control factors for the handlebar stem model.…”
Section: Optimal Design For the Handlebar Stemmentioning
An integrating optimization procedure is presented to improve the von Mises stress and fatigue safety factor for a handlebar stem system in a bicycle system. The optimization procedure involves uniform design of experiment, Kriging interpolation, genetic algorithm, and nonlinear programming method. Using ANSYS/Workbench software and the ISO 4210 bicycle handlebar stem testing standard, the von Mises stress for the lateral bending test simulation and the fatigue safety factor for the fatigue test simulation is calculated. The von Mises stress and fatigue safety factor are combined into a single and integrated objective function, and Kriging interpolation is then used to create the surrogate model of the integrated objective function. When the integrating optimization procedure is used, the integrated objective function demonstrates that the von Mises stress for the optimized handlebar stem is reduced to 225 MPa and the fatigue safety factor increases to 1.796. This shows that the optimized design increases the strength of the handlebar stem. The proposed technique yields a handlebar stem with an optimized shape.
“…As a duralumin, Al-Cu-Mg aluminum alloy has a good molding ability and mechanical processing properties. Al-Cu-Mg aluminum alloy products mainly consist of plates, wires, and bars, which are mainly developed for the aircraft skin, bulkheads, wing ribs, engine components, and automobile industries [2,3].…”
Deformation scheme and preheat treatment of Al-4.1%Cu-1.4%Mg aluminum alloy are chosen, homogenizing annealing at 430°C for 1.5 h, cooling to 250°C in furnace at a cooling rate of less than 30°C/h and then cooling to room temperature to make Al-4.1%Cu-1.4%Mg aluminum alloy annealed fully. Heat treatment tests of Al-4.1%Cu-1.4%Mg aluminum alloy mainly consisting of rolling and aging were conducted, and the optimum peak of aging mechanism is 190°C/12 h. Through comparison of microstructure and mechanical properties with different deformation rates and aging mechanisms, effect of deformation rates and aging mechanism on properties of Al-4.1%Cu-1.4%Mg aluminum alloy was analyzed, and the optimum double peak of aging mechanism is 135°C/7 h + 185°C/14 h. Orthogonal experiments were carried out to analyze mechanical and electrical properties of tested materials before and after deformation, and the effect of aging mechanism on Al-4.1%Cu-1.4%Mg Al alloy was analyzed, and the optimum regression of aging mechanism is 190°C/12 h + 240°C/40 min + 190°C/12 h. Aging scheme is closely related to corrosion resistance of Al-4.1%Cu-1.4%Mg aluminum alloy, and three different aging schemes can improve the corrosion resistance. The exfoliation corrosion evaluation results show that the aging effect on exfoliation corrosion ability order is RRA > two-step aging > peak aging.
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