Abstract
This article presents the results of an experimental and numerical analysis of the fracture resistance of cast aluminum alloys subjected to variable loads over time based on the fracture mechanics method. The subjects of the analysis were the AlSi9 and AlZn6MgCu alloys (usually used for plastic processing) in which the presence of porosities in the form of separate or dispersed voids was revealed experimentally. The material for the experimental procedures was obtained directly from a casting or from casting samples. Depending on the type of the defect detected, different numerical models were proposed. The results of the numerical calculations were verified experimentally. Static tensile tests, fatigue low-cycle tests, fracture mechanics tests, fatigue crack propagation tests, a microscopic examination of the sample fracture area, and an x-ray tomographic analysis were all performed. A correlation of the results between the numerical analysis and the experimental work has been found. On the basis of the proposed calculation models, the fatigue life of castings of the analyzed alloys can be predicted in the case of concentrated and dispersed defects.
Highlights
When defects are detected in the casting part, three possible paths can mainly be taken: and issues related to material fatigue
The examples presented below are the application of the calculation models discussed above and used in the analysis of the fatigue life or cracking resistance of the two analyzed alloys
The boundary conditions assumed in calculation are as follows: a rotor speed of 2000 RPM and the aerodynamic coefficients according to Ref 20
Summary
When defects are detected in the casting part, three possible paths can mainly be taken: and issues related to material fatigue (adequately determined by the specific properties of the materials obtained by the casting methods). A casting qualified as a scrap is associated with economic losses and entails a series of actions aimed at eliminating the causes or consequences of the defect. The priority action is to determine the causes of the defect and its elimination. This applies in particular to the mass production of low-weight castings. Repair is a good practice, especially when the price of a single cast is relatively high and the size of the series is small. In the case of the repair decision, it seems important to determine the impact of the ‘‘unresolved’’ defect in the casting (including its durability) and understand the exploitation conditions of the casting
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