Secondary Development Of Damage Constitutive Model For White Sandstone Based On ABAQUS

White sandstone is almost ubiquitous in geological engineering.In the process of experiments,white sandstone materials are generally identified as homogeneous isotropic materials.In different natural and engineering environments,white sandstone will have various damages.And the damage of white sandstone is not achieved overnight,but caused by the baptism of nature for a long time.Therefore,it requires a long experimental process to simulate the damage process of white sandstone in the laboratory,which will consume a lot of manpower and material resources.Therefore,this paper uses the function of ABAQUS secondary development to simulate the damage process.ABAQUS finite element analysis software has very powerful functions in geotechnical mechanics,but the material library of ABAQUS software does not have the constitutive model of white sandstone under different dry and wet cycles under acidic conditions.In this paper,the constitutive model of this damaged material is embedded In the ABAQUS software,the model is compiled into a UMAT subroutine to simulate the damage characteristics of the material and verify the simulation process.Therefore,the research in this paper has certain significance for the subsequent research on secondary development.The main research contents of this paper are as follows:(1)The functional modules of the ABAQUS software,the design language of the secondary development of the ABAQUS software,the script interface of the ABAQUS software,the object model and the GUI program development process are studied in detail.According to the different function modules of ABAQUS/CAE,the process of finite element analysis of white sandstone damage model is developed.The process is to create parts,create material properties,assemble parts,create analysis steps,define loads,define boundary conditions,and mesh.According to the above process,with the advantages of ABAQUS software,the script program of all processes is recorded through the abaqus.rpy file.With this file,it saves a lot of time for future operations.You only need to open this script program to get the already set Model.(2)According to the basic theory of damage,the constitutive model of white sandstone after dry-wet cycle treatment under acidic condition is deduced,which provides sufficient theoretical basis for the realization of subsequent subroutines.The damage mechanics and the research methods of damage mechanics are introduced,and the parameters of the white sandstone model are determined by the derived constitutive equation.The uniaxial compression test and triaxial compression test procedures are described.(3)Developed the UMAT subroutine corresponding to the damage constitutive model of white sandstone.The characteristics of implicit integral calculation and explicit integral calculation are expounded.Based on the method of choosing the implicit integral according to the constitutive model,the specific steps of the UMAT subroutine are briefly explained.And according to the process of embedding subprograms for ABAQUA,how to debug the compiled UMAT subprocesses is explained,which lays a foundation for the second developed UMAT subprocesses to run successfully on the ABAQUS software.Provides a solid foundation for the same researchers developing user subroutines.(4)Compare the simulation results obtained by the subprogram of UMAT secondary development with the actual test data.It can reflect the influence of the two on the mechanical properties of white sandstone materials,and the simulation results are basically consistent with the actual experimental results.This verifies that the subroutine developed in this paper can simulate the actual experiment.Therefore,this article can be of great help to those who develop UMAT subroutines.