Translated Abstract
In this thesis, thermal stress during the quenching of Hadfield Steelcontaining alumina particles was investigated by numerical simulationmethod. The influence of raised angles and size of particles on the aluminaparticles and the Hadfield Steel matrix was investigated, and at the sametime, the influence of size and preheating temperature on the stress ofalumina particles during the thermal shock of casting was also investigated.In addition, the simulating result was validated by the validation testdesigned. The numerical simulation was performed via finite elementanalysis software-ANSYS. A hole-drilling technique was used to determinethe residual stress in the sample. Finally, a process program calculating thestress was programmed by visual programming tool.On the basis of thermal-elastic-plastic finite element method andproper finite element geometry model, a series of simulation analysis hasbeen made considering that attribute parameter of material is correlated totemperature. The result indicates that material model of matrix can not besimulated with the elastic model and the plasticity of the matrix must betaken into account due to the sharp change of temperature field during thequenching. The raised angle of alumina particle greatly affects the stressconcentration of matrix and particle, especially, when the raised angle isless than 60°. The size of alumina particle greatly affects the value and thedistribution of the stress too. When equivalent diameter of particle is in therange of 0.2~1.0mm, the influence is not obvious. When the equivalentdiameter of particle exceeds 1.0mm, the stress increases with an increase inthe equivalent diameter. During the simulation on the interference of doubleparticles, it shows that the stress increases in the interference area when thevolume fraction of the particles is larger, that is, when the distance amongthe particle decreases to the certain extent. In addition, the thermal shockivstress of alumina particle, poured into the high temperature Hadfield Steelliquid, decreases with the decrease of equivalent diameter of aluminaparticle and with the increase of preheating temperature. Usingsmaller-sized alumina particles and increasing the preheating temperature isproved to be an effective way to reduce the thermal shock stress, therebyavoid breaking.Validation result shows that the results of simulation are consistentwith the measured value on the trend. This proves that the finite elementgeometry and thermal-elastic-plasticity material model are correctcompletely in analyzing the Hadfield Steel containing alumina particles.Adopting the parameterized programming and OOD and dealing withdifferent matrixes properties and different diameter of the hole, theuniversal program is programmed to deal with measured data. The stress canbe conveniently calculated through three static strains measured at the spot.The difference between this paper and other similar thesis lies in somefacets as follows: the influence of the raised angle of the reinforcementparticles on the stress during the quenching of Hadfield steel wasemphatically investigated according to the actual form of the particles,instead of ball model, ellipsoid model and cylinder model particles withoutraised angle. A series of simulation conclusions about the influence ofraised angle and size effect of the reinforcement particles have goodguidance significance to design and synthesize particles reinforcedcomposite.
Translated Keyword
[Numerical simulation Residual stress]
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