The study is concerned with the investigation of metal flow and strain distribution in steady and non-steady state bulk deformation processes by using an improved visioplasticity method. By comparing various smoothing schemes the five-point least square smoothing method is employed to reduce the measurement errors.
As a steady-state forming process experiments are carried out for axisymmetric forward extrusion through conical and curved dies of various area reductions using Aluminum and steel billets. Axisymmetric backward extrusion is chosen for a non-steady process.
In axisymmetric forward extrusion the results from visioplasticity shows that the curved die of fourth-order polynomial renders more uniform distribution of strain rate and strain. Higher reduction leads to greater strain at the outer side of the billet.
The visioplastic observation for axisymmetric backward extrusion shows the concentration of higher strain at the inner wall of the extruded product.
The visioplastic results in forward and backward extrusion are in agreement with the computed results by the finite element method.
It is thus shown that the visioplasticity method combined with a smoothing technique is an effective method to determine flow pattern and the distribution of strain rate and strain.
