Fracture characteristics and topology optimization of unlocking devices with magnesium alloy strip under thermal shock environment

DOI:	10.11809/bqzbgcxb2023.11.006
Keywords:	unlocking device with magnesium alloy strip; thermal shock; fracture; Johnson Cook failure model; topology optimization
Abstract:	Fracture characteristics of unlocking devices with magnesium alloy strip under actions of high temperature and high pressure exhaust jet flow of engines are analyzed and then a topology optimization design is carred out. Firstly,a two dimensional, compressible and unsteady flow field analysis model of an engine nozzle tail blocked by a magnesium alloy strip is constructed. Pressure curves and temperature curves at characteristic points of the magnesium alloy strip at different time points are obtained. Then, based on the finite element method, responses of the magnesium alloy strip with initial configuration under wake jet pressure and temperature calculated. Thus effects of different factors on the fracture characteristics of the magnesium alloy strip can be analyzed. Next, five kinds of magnesium alloy strips with different configurations are designed based on the “weak link” idea. Fracture times under thermal shock environment are obtained based on the Johnson Cook failure mode and transient analysis process. Finally, topology optimization of the thermal shock zone in the middle of the magnesium strips based on the developed variable density method with double nesting feature is conducted to obtain the optimal topology configuration by taking the residual volume fractions of material as optimization variables and the specified fracture times as objectives. It is verified based on geometric reconstruction that the optimized magnesium alloy strip can meet the design requirements.
Issue:	Vol. 44 No. 11 (2023)
Published:	2023-11-28
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