Modeling With Aggregate Expansion Method And Performance Simulation Of Polymer-Mineral Composite

The polymer-mineral composite is a new type of multiphase composite formed by curing with granite as aggregate,using modified epoxy resin as cementing material,and adding an appropriate amount of quartz sand and other fillers.Polymer-mineral composite is widely used in the field of machine tool bed manufacturing due to their high mechanical properties,low thermal resistance,excellent resistance to damping and corrosion resistance.With the rapid development of computer technology and computational material science,more and more researchers study the physical properties of polymer-mineral composite through finite element simulation technology,which can reduce the period and cost of material development.The microscopic numerical model of polymer-mineral composite can be regarded as a kind of multiphase composite formed by aggregates,matrix and interfacial transition zone.The computer modeling technology can be used to establish a numerical model which is close to the real material structure,and to study the influence of different components on the physical properties of the polymer-mineral composite,so as to provide some reference for the structural optimization design of polymer-mineral composite.By studying the numerical modeling method of polymer-mineral composite,this paper aims at the shortcomings of the existing modeling methods of polymer-mineral composite,such as the low modeling efficiency and the low volume fraction of aggregate in the models.The high density model is modeled by a method of expanding the shrunken aggregate.By using aggregate expansion method,the high volume model can be generated efficiently,which makes the generated meso model closer to the real material structure and ensures the accuracy of the simulation process.The mechanical properties,thermal expansion rate and thermal conductivity of five different aggregate gradation models are analyzed,and the optimal aggregate gradation is studied,which can provide some guidance for the performance prediction and structural optimization design of polymer-mineral composite.The main work and conclusions of this paper are as follows:(1)A method for modeling high volume fraction of polymer-mineral composite is presented.Firstly,the aggregate within each particle size range is reduced by a certain proportion and put into the sample model space,and then the reduced aggregate model is imported into the finite element software.By applying a certain temperature load,the reduced aggregate expands to a predetermined particle size,which can generate a high density microscopic numerical model of polymer mineral composite.This modeling method can not only efficiently generate a numerical model with aggregate volume fraction of more than 50%,but also save more than 20%of modeling time compared with the existing modeling method of random placement of aggregate,which indicates that the aggregate expansion method is more efficient in establishing a high volume fraction model of aggregate and has prominent modeling advantages.(2)Based on the statistical data of real aggregate shape parameters,an algorithm for generating convex and concave aggregate models is proposed.The modeling time of the expansion method is further optimized by analyzing the time of the expansion modeling when the aggregate reduced different proportions.In order to prove that the randomness of the aggregate in space is not affected during the expansion process.Through statistical study on the spatial position of aggregate before and after expansion in two models with different aggregate distribution,it is found that the spatial distribution of aggregate before and after expansion remains random.Through statistical study on the spatial position of aggregate before and after expansion in two models with different aggregate distribution,it is found that the spatial distribution of aggregate before and after expansion remains random.(3)Numerical models of five different aggregate gradation are generated by expansion method,and the models are imported into the finite element software ABAQUS to analyze the elastic modulus of the models of five different aggregate gradation.The results show that the elastic modulus of shaker grading model is the largest and the elastic model of polymer-mineral composite is proportional to the aggregate content.At the same time,the influence of different porosity on the elastic modulus of the model is studied,it is found that the elastic modulus of the model is inversely proportional to the porosity.In order to study the tensile strength of the models with different gradation,a cohesive force unit is inserted between aggregate and matrix and between the two parts of matrix respectively.The simulation results show that the cracks in the model first appear at the interface between aggregate and matrix,and the cracks first appear between aggregate and matrix.If the interface fracture strength between the aggregate and the matrix is close to or greater than the fracture strength of the aggregate,the crack will first appear in the aggregate.(4)The influence law of thermal expansion rate and thermal conductivity of different aggregate gradation models is analyzed by ABAQUS.In order to study the thermal properties of polymer-mineral composite,the thermal expansion and temperature transfer models of five different aggregate gradation are studied using the temperature-displacement coupling simulation method in the finite element software ABAQUS.The results show that the thermal expansion rate of shaker gradation model is the smallest,mainly because the aggregate volume fraction in shaker gradation model is the highest,the temperature transfer is slow,and the model deformation is small.(5)MATLAB is used to fit the influence law of different physical properties of aggregate and matrix on the physical properties of polymer-mineral composite,and the corresponding optimized response surface is given.It can guide the design of polymer-mineral composite with the best comprehensive performance,so as to provide certain guiding value for the production,processing and structural optimization design of polymer-mineral composite.