This work is part of the FractAl project, which is carried on by the department of structural engineering CASA of the Norwegian University of Science and Technology in Trondheim. The project deals with microstructure-based modelling of ductile fracture in aluminium alloys. In the design of aluminium structures against failure, the material’s strength and ductility are important factors. To design lightweight structures it is often necessary to use high strength aluminium alloys, while taking advantage of ductility in full. For aluminium alloys, increased strength often comes at the expense of ductility of the material, increasing the risk of structural failure. Therefore, it is important to have good models for ductility of aluminium alloys under different load situations. The modelling framework enables designers and engineers to select the most suitable aluminum alloy for a given structure with less time-consuming and costly mechanical tests. The framework can also be used to tailor alloys with ideal strength and ductility of a given structure. This could introduce to a new way of designing aluminium structures. In this work, the focus is on low-velocity impact events; in particular, the response of three different tempers, T4, T6 and T7, of the same 6016 aluminum alloys, subjected to the drop weight impact test, is studied. A tensile test is performed in order to compute the material parameters, exploiting both 2D-DIC as well as finite element analysis, using the software Abaqus. After that, experimental tests with the drop weight impact machine are carried on on plates with and without slits. Finite element analyses representing the experiments were carried on and the results were analyzed to check if the predictions were correct. Other models were studied to verify the influence of boundary condition and friction.
Questo lavoro fa parte del progetto FractAl, portato avanti dal dipartimento di ingegneria strutturale CASA presso l’università norvegese NTNU. Il progetto si occupa della modellazione microstrutturale della frattura duttile nelle leghe di alluminio. Durante la fase di design, resistenza e duttilità sono fattori importanti. Nella progettazione di strutture leggere, è necessario usare leghe con un’alta resistenza, sfruttando la duttilità: nelle leghe di alluminio, l’aumento nella resistenza significa una diminuzione della duttilità del materiale, aumentando il rischio di cedimento strutturale. Quindi, è importante avere dei modelli per la duttilità delle leghe di alluminio sottoposte a diverse condizioni. La modellazione permette di selezionare il materiale più adatto per una data struttura, evitando test meccanici che possono essere lunghi e costosi. Questo elaborato si concentra su impatti a basa velocità, studiando la risposta di una lega di alluminio 6016, soggetta a tre diversi rinvenimenti, T4, T6 e T7, sottoposta a drop weight impact test. Una prova di trazione è stata necessario per determinare i parametri del materiale, sfruttando sia la 2D-DIC che l’analisi agli elementi finiti, usando il software Abaqus. Prove sperimentali tipo drop weight impact sono state effettuate su delle lastre quadrate, con e senza intagli. Sono state effettuate simulazioni agli elementi finiti e i risultati sono stati comparati con quelli sperimentali. Altri modelli per il drop weight impact test sono stati sviluppati per capire l’infuenza delle condizioni al contorno e dell’attrito tra l’impattatore e la lastra.
Experimental testing and numerical modelling of low-velocity impacts on heat-treated aluminum plates
CANALI, JASMINE
2019/2020
Abstract
This work is part of the FractAl project, which is carried on by the department of structural engineering CASA of the Norwegian University of Science and Technology in Trondheim. The project deals with microstructure-based modelling of ductile fracture in aluminium alloys. In the design of aluminium structures against failure, the material’s strength and ductility are important factors. To design lightweight structures it is often necessary to use high strength aluminium alloys, while taking advantage of ductility in full. For aluminium alloys, increased strength often comes at the expense of ductility of the material, increasing the risk of structural failure. Therefore, it is important to have good models for ductility of aluminium alloys under different load situations. The modelling framework enables designers and engineers to select the most suitable aluminum alloy for a given structure with less time-consuming and costly mechanical tests. The framework can also be used to tailor alloys with ideal strength and ductility of a given structure. This could introduce to a new way of designing aluminium structures. In this work, the focus is on low-velocity impact events; in particular, the response of three different tempers, T4, T6 and T7, of the same 6016 aluminum alloys, subjected to the drop weight impact test, is studied. A tensile test is performed in order to compute the material parameters, exploiting both 2D-DIC as well as finite element analysis, using the software Abaqus. After that, experimental tests with the drop weight impact machine are carried on on plates with and without slits. Finite element analyses representing the experiments were carried on and the results were analyzed to check if the predictions were correct. Other models were studied to verify the influence of boundary condition and friction.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/154561