Based Eso Method With Cracks Structural Shape Optimization Study

In aerospace industry, a lot of aircrafts which doesn't complete their design life have been destroyed. So, for increasing these aircrafts' airworthiness and availability, many researchers have paid attention to the way of eliminating the crack and retarding the crack propagation.This paper's presents an optimization technique that considers the stress intensity factor associated with the crack as design objective. When optimizing the cracked structure, the aim is to determine the optimal shape that would minimize the maximum stress intensity factor along the design boundary. This research provides the theoretical foundation for ageing aircrafts' rework repair and reducing expenditures, which has the important theoretical and practical value.First, based on the theory of fracture mechanics, this paper analyzes the cracked structure, and deduces the formulation of peak stress intensity factor associated with the cracks; according to the evolutionary structural optimization algorithm, the formulation for Von mises stress is deduced for 2D structure.Second, the present paper researches an advanced optimization algorithm—evolutionary structural optimization (ESO). According to the evolutionary structural optimization algorithm, the formulation for Von mises stress is deduced for 2D structure.Then, this paper uses the ANSYS soft to develop the geometric and the initial finite element model, which includes the cracks in the specified design boundary, and analyze the value and distribution of the intensity factor associated with the cracks.Fourthly, combined the theory of fracture mechanics and the ESO algorithm, the optimization algorithm is programmed using the Ansys Parameter Design Language (APDL) and optimizes the FE model using the program.Lastly, this paper smoothes the irregular optimization boundary using two methods, including B-spline and ellipse fitting, and contrasts the stress intensity factor distributions along three different boundaries.So, two examples prove that this method is feasible and effective and can improve efficiently the whole structural fatigue life.