Finite element analysis and optimization of multi-layer combined ultrahigh pressure cylinder
The finite element model was established by the finite element method of Workbench. The prestressed state and the working state of the multi-layer composite cylinder was used to calculate by the finite element method. The general distribution law of the stress of the multi-layer cylinder is obtained, and the equivalent stress distribution is not uniform. At the same time theoretically based on the elastic limit of multilayer composite cylinder unified solution, and the optimization condition is determined. The design of multi-layer ultrahigh pressure cylinder is optimized. The results show that the nonuniformity of the stress distribution of the cylinder can be improved greatly. The study can provide technical support for the structural design and optimization of the multi-layer ultrahigh pressure cylinder.
Application of Edge Elements to 3-D Electromagnetic Field Analysis Accounting for Both Inductive and Capacitive Effects
The traditional low-frequency eddy-current solvers do not include displacement current effect, while high-frequency solvers do not consider the nonlinearity of material properties. A novel solver for electromagnetic field analysis that addresses both the inductive and capacitive effects is, thus, highly valuable. A stable time-domain magnetic vector potential (MVP) formulation, which includes both the inductive and capacitive effects, is proposed and numerical examples are solved using the proposed formulation. The proposed MVP formulation is very promising in further engineering applications.
On the Effect of Triaxial State of Stress on Ductility Using Nonlinear CDM Model
Ductility takes into account the material capability to plastically deform. This parameter is not only modified by temperature but it is strongly affected by the stress triaxiality that, in the case of positive hydrostatic stress, reduces the material strain to failure. Due to the importance of this parameter in engineering design many attempts to predict the evolution of ductility with stress triaxiality have been done. Here, a nonlinear continuum damage model, as proposed by the author, is used to obtain the evolution of material ductility with stress triaxiality. The expression found relates the strain to failure in multi-axial state of stress regime only to the uniaxial strain to failure, to the damage strain threshold, to the material Poisson's ratio, and, of course, to stress triaxiality. The proposed model was successfully verified comparing the predicted evolution of material ductility with the experimental data relative to several metals. The procedure for the damage parameters identification is also discussed in details.