Abstract

Fatigue cracks have been traced in 1050A aluminum alloy; All the studies and research that have been examined study cracks as short and long cracks, that is, two phases, but through the study it became clear that cracks grow and progress in three phases, the first phase through the microscopic granule, the second phase through the granule to the extent of approximately one millimeter, and the third and final phase to the point of fracture. by phase The first is through the grain size and is called (microscopic short cracks MSC), the second stage is across the grain up to one millimeter is called (the physical short cracks PSC) and the third stage is to the extent of the fracture is called (the long cracks LC). The case of different vibration stresses and factors affecting crack growth in each phase was also studied, and a mathematical model was built that consisted of three equations, each equation representing the cracks’ behavior in each phase. The proposed model was also evaluated and compared with a previous proposed model for the same material with practical results. More safety compared to the practical results and the previous model, and this is what is required in the parts from which aircraft fuel tanks are made, as well as in the manufacture of pipelines that carry fuel inside aircraft and for the designer to be in a state of safety when designing aircraft parts. Two MATLAB programs are designed to perform calculations to collect results. The first program to calculate the practical constants and the second to make the calculations required to complete the work schedules.