Civil Engineering Reference
In-Depth Information
Chapter 5
Compressive Electrically Assisted
Forming Model
5.1 Analytical Modeling of Compression Forming Processes
The overall goal of this chapter is to develop a model for an electrically assisted
forging process and then use this model to highlight specific sensitivities and rela-
tionships within the EAF process. A modeling strategy will be defined, based on
existing conventional forging equations. These equations will then be modified to
account for the electroplastic effect in an EAF process.
5.1.1 Definition of an EAF Modeling Strategy
The first task in creating a thermo-mechanical model is to define how EAF could
be modeled, with the optimization of current metal forming equations by creating
new coefficients to capture electricity's effects. As is explained below, an
electroplas-
tic effect coefficient
(EEC) is created to help account for the direct electrical effects
on the forming process [
1
]. The objective of this chapter is to establish a closed-
form solution describing the flow stress of a material, which is plastically deformed
under a compressive load while direct electric current is applied through the dies.
Equations predicting the effective stresses are derived from balancing the input and
output energies of the system. These energy-based equations are aimed at predicting
the effective stresses and strains of the system, and the forming loads for different
parameters of the applied current. It is expected that this model may be beneficial in
the preliminary determination of the feasibility of electrically assisted forging a part
based on formability improvement. In particular, the model would determine process
input requirements for given formability improvements, in order to support process
design decisions by the user. An analytical model brings a better understanding of the
electroplastic deformation mechanism and opens new avenues for derivation of solu-
tions for more complicated manufacturing processes.
