On the Statistical Size Effect of Cast Aluminium.

Area of Science:

• Materials Science
• Mechanical Engineering
• Fatigue Analysis

Background:

• Manufacturing imperfections act as microcracks, reducing fatigue strength.
• Defect size distribution is influenced by the highly-stressed volume, known as the statistical size effect.

Purpose of the Study:

• To develop a fatigue assessment model accounting for the statistical size effect.
• To improve the accuracy of fatigue design for lightweight aluminium cast alloys.

Main Methods:

• Assessed statistical distribution of defect sizes in reference (V0) and enlarged (Vα) volumes.
• Implemented crack resistance curves within the Kitagawa-Takahashi diagram.
• Developed a multidimensional fatigue assessment map based on volume-dependent defect probability.

Main Results:

• Current methods for statistical size effect evaluation can cause ~10% over-sizing in fatigue design.
• The new approach links defect distribution to a crack-resistant Kitagawa-Takahashi diagram.
• Achieved a more accurate fatigue design with a maximal conservative deviation of 5% from experimental data.

Conclusions:

• The developed fatigue assessment map enhances fatigue design by accurately considering the statistical size effect.
• This methodology offers improved precision compared to state-of-the-art approaches.
• Optimizes fatigue design for lightweight aluminium cast alloys by minimizing conservative over-sizing.