Determination of the Constants of Material Models Using Inverse Taylor Test

Abstract

The constants of the Johnson-Cook and Zerilli-Armstrong material models are determined using an inverse Taylor test. In this technique, the target (specimen) and the projectile (striker) swap their positions as usually considered in the conventional Taylor test. This type of test configuration eliminates the difficulties that are normally associated with in situ heating up the specimen. The experiments are conducted at ambient and elevated temperatures under high impact velocities. The constants of the models correspond to the case when the difference between the experimental and numerical mushroomed profiles of the specimen after impact is optimized. The results indicate that Z-A model is superior to J-C model in prediction of the copper alloy deformation in the inverse Taylor test. The reason is believed to the fact that the effects of strain, strain rate, and temperature are coupled in Z-A model, but have separate effects in J-C model.

A constitutive model for hardness considering the effects of strain, strain rate and temperature

“…The temperature term in equation (22) then becomes Now, substituting the relations for the strain (equation (24)), strain rate (equations (26) and (27)) and temperature (equation (30)) into equation (22) …”

“…25 The parameters of the model were identified by minimizing the difference between experimentally and numerically final shape profiles of specimens (see Figure 8) obtained from Taylor test and its Finite Element Method (FEM) simulation. 26 The results are given in Table 3.…”

“…In Compression 655 100 1 200 2 300 2 400 1 875 100 1 200 2 300 1 400 1 Tensile 600 100 1 200 1 300 2 400 1 750 100 1 200 2 300 1 400 3 Compression 600 28 1 900 28 1 985 28 2 1100 28 2 Tensile 350 28 1 500 28 1 610 28 1 710 28 1 800 28 1 900 28 1 1200 28 1 this case, the strain rate and temperature terms (denoted by N( _ e) and Q(T * ), respectively) in equation (22) tend to unity. The reason is that for T = T room , Q(T * ) tends to unity and for quasi-static conditions, N( _ e) approaches one as D in equations (26) and (27) is nearly one. Therefore, only the effect of the strain remains to be determined.…”

“…Having considered the variation of the hardness versus temperature typically shown in Figure 22 for more strains and strain rates, the mean value for the coefficient m can be computed as 0.789. The temperature term in equation (22) then becomes Now, substituting the relations for the strain (equation (24)), strain rate (equations (26) and (27)) and temperature (equation (30)) into equation (22), the hardness model for the compression and tension then becomes Validation of the hardness models…”

Performance of a Two-stages Gas Gun: Experimental, Analytical and Numerical Analysis

“…Two stages gas gun is widely used for mechanical characterization of materials. Taylor [1], flying plate [2], powder compaction [3] and ballistic [4] tests are among the material characterizing and production tests which are accomplished using gas gun. The schematic view of a two-stages gas gun is shown in Figure 1.…”