Chapter Four - Identification of Material Models and Boundary Conditions

Abstract

As mentioned, searching for a balance between accuracy of modeling and efficiency of metals processing simulations is the overall objective of this book. Majority of the content deals with various aspects and possibilities of increasing the accuracy and at the same time decreasing the computing costs. However, it has to be pointed out that modeling of materials processing requires not only solutions of the family of differential and/or algebraic equations as presented in Chapter 3 but also proper definition of boundary and initial conditions. Boundary conditions in metal forming usually describe friction or the transfer of heat and forces at the contact zone. Initial conditions define the behavior of the workpiece before and during formation. Identification of material models and boundary conditions is usually performed using inverse analysis of experimental tests and also requires long computing times but is of importance from computational accuracy point of view. Possibilities of making inverse analysis more efficient are discussed in the present chapter. Tests performed to identify material models are briefly described in the first part. Testing techniques are discussed with their advantages and disadvantages. Examples of application of inverse analysis to interpretation of these tests are presented in the second part. The results of the tests are examined and empirical and mathematical models presented in Chapter 3 are identified, which allows further use of the data. The particular emphasis is put on presenting possibilities to decrease the computing costs.