| In Stamp-Charging coke making, the material coal bulk is compacted tightly by periodically impacting, which makes the constitutive relationship of the briquette more complex, as well as the distribution of the stress. Therefore, no mature method is used to analyze the process.To solve the constitutive problem during stamping, a relatively mature soil constitutive model, Duncan-Chang, is brought into the calculation. Firstly, Duncan-Chang parameters of the briquette at different states are obtained through a sampling experiment. Then the five more sensitive parameters in stamping are found out. During calculating, the strain invariants (ε1+ε2+ε3) are extracted to represent the change of the density, based on which the five parameters are fitted linearly to provide reaction to the change of the bulk density at different time increments. Thus a constitutive model capable of stamping has been built up. Meantime, based on the original Duncan-Chang model, a new corresponding user material subroutine(UMAT) is developed and verified.The finite element model of briquette is established on ABAQUS for dynamic analysis of stamping process with the revised Duncan-Chang constitutive model. Besides, more details about the initial state of the briquette has also been studied in this paper. Via the import function and the method of data transferring, the simulation of consecutive multi-impaction is fulfilled. And in this way, the speed of calculation can be improved effectively.In this paper, the initial stage during stamping, the preloaded coal stamping, in which the state of the briquette changes most radically, is calculated. Through the calculation, the impact time and pressure on the bottom plate are acquired. Compared with the results of experiment, the feasibility and accuracy of the new model subroutine are verified, for the results of calculation act in accord with field test data. It means the proposed method can be used for the calculation and analysis of similar problems. |
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