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Investigating the dynamic behavior of AA7075-T651
AlDaour, Ibrahim Motasim
AlDaour, Ibrahim Motasim
Date
2025-08
Author
Advisor
Type
Thesis
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35.232-2025.71a Ibrahim Motasim AlDaour.pdf
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Description
A Master of Science thesis in Mechanical Engineering by Ibrahim Motasim AlDaour entitled, “Investigating the dynamic behavior of AA7075-T651”, submitted in August 2025. Thesis advisor is Dr. Maen Abdelqader Alkhader and thesis co-advisor is Dr. Wael Abuzaid. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
In the last five decades, aluminum alloy 7075 (AA7075) has garnered tremendous attention in materials science literature owing to its lightweight and superior strength compared to aluminum alloys. However, the dynamic behavior of this material at extremely high strain rates and temperatures has not been fully explored and characterized. Accordingly, this thesis investigates the behavior of AA7075-T651 across a wide range of strain rates and temperatures, spanning from quasi-static and room-temperature conditions to extreme strain-rate and high-temperature environments. In particular, experiments were carried out under quasi-static conditions using a universal testing machine and dynamic loading conditions using a Split Hopkinson Pressure Bar system over a temperature range of 25 °C to 250 °C. The quasi-static tests were performed at strain rates of 0.001 s⁻¹ and 0.1 s⁻¹, while the dynamic tests covered variable strain rates of up to 10,000 s⁻¹. The response of the material was modeled using a Johnson-Cook model. Results showed a complex interaction between strain hardening, temperature, and strain rate, with negative work hardening manifesting at very high strain rates due to adiabatic heating and thermal softening. The findings indicate that the Johnson–Cook model cannot fully describe the material response across the examined strain-rate range because of the intricate coupling between strain rate, strain hardening, and temperature. Alternatively, employing two separate models, each calibrated for quasi-static and high strain-rate conditions, resulted in a significantly improved representation of the response.