Research On The Application Of Smooth Finite Element In Secondary Development Of ABAQUS

As an important numerical calculation method,the finite element method has wide application prospects in the engineering field,which benefits from the widespread use of commercial finite element software.However,when the finite element analysis software is used to analyze the engineering practical problems such as complex structures or large mechanical deformation,the performance of these software is not satisfactory.The main reasons are as follows: the calculation precision of the common unstructured grid is low,and the preprocessing of the structured grid is difficult and the calculation cost is high.A series of new numerical algorithms represented by smooth finite element(FEM)have been developed in recent years.However,these new numerical algorithms only exist as independent code and have not been applied to finite element analysis software.Fortunately,the commonly used finite element analysis software ABAQUS,ANSYS,MSC and so on have the function of secondary development.Based on this,this paper uses the user element subroutine(implicit/UEL,explicit/VUEL)provided by ABAQUS,and puts forward the method of embedding smooth finite element method into ABAQUS around statics,metal forming and large-scale deformation of incompressible materials.The main work can be summarized as follows:(1)A smooth finite element method in ABAQUS user subroutine(UEL)is proposed and used to analyze linear elastic problems.The edge based smooth finite element method(ES-FEM)and node based smooth finite element method(NS-FEM)are used.With the help of user-defined element subroutine(UEL)of ABAQUS,the high-efficiency and high-precision analysis of linear elastic problems based on unstructured meshes is realized.In this paper,the pre-processing,calling subroutine and post-processing in the implementation of UEL are described in detail.It solves the problem that cross element calculation can't be carried out in UEL,and provides an idea for the implementation of similar numerical algorithms in UEL.The results show that this method not only retains the advantages of good adaptability and easy division of unstructured meshes,but also achieves high efficiency and high precision analysis.(2)The implementation framework of user element subroutine(implicit/UEL,explicit/VUEL)based on the smooth finite element for metal forming analysis is constructed.In this paper,the basic formulas of constructing geometrical and material nonlinearity in es-fem are derived.By using explicit and implicit algorithm,standard and explicit solver and contact module of ABAQUS,the analysis of metal forming problem by using UEL and VUEL is realized.This method solves the problem of smooth finite element in the application of UEL and VUEL.The results show that the method is feasible and effective.This method is also suitable for large deformation analysis of other material constitutive models.(3)The ES/NS-FEM joint analysis model is built in the user cell subroutine(UEL)to analyze the large deformation of incompressible materials.By using high-precision ES-FEM to calculate the deflection part of material strain energy and NS-FEM to calculate the volume part of strain energy,the volume self-locking phenomenon of incompressible material in finite element analysis is solved and the high accuracy is retained.The method is then integrated into ABAQUS using UEL.Numerical examples show the effectiveness of the method.