Integration of a new data acquisition/processing scheme in SHPB test and characterization of the dynamic material properties of high-strength steels using the optional form of Johnson-Cook model

Abstract

In this study, high strain rate conditions were obtained using a compressive split-Hopkinson pressure bar test apparatus that adopted a new data acquisition and processing scheme utilizing a LabVIEW system. Quasi-static strain rate conditions were obtained using a universal testing machine. The material responses of three high-strength steels under high strain rate and quasi-static conditions were investigated. They were characterized using the Johnson-Cook constitutive model. Two other optional strain rate forms were substituted for the constitutive model to predict material flow stress, especially at high strain rates exceeding 10 4 s −1 . The considered optional strain rate forms were the modified Johnson-Cook and Huh-Kang models, which both showed a non-linear relation between flow stress and logarithm strain rate. The material parameters in the constitutive equations of the three high-strength steels were evaluated by fitting and comparing the data over a wide range of strain rates.

Constitutive Equations of Yield Stress Sensitivity to Strain Rate of Metals: A Comparative Study

“…Huh and Kang [15] proposed a quadratic for the strain rate sensitivity. Tuazon et al [16] expressed the dependence on the logarithm of strain rate as a power-law. Couque [17] proposed a modified Johnson-Cook equation where the strain rate sensitivity is written in terms of a four-constant equation.…”

A Modified Eyring Equation for Modeling Yield and Flow Stresses of Metals at Strain Rates Ranging from 10−5to 5 × 104 s−1

“…Nevertheless, this assumption is mostly valid up to a threshold strain rate. The strain rate sensitivity highly increases at high strain rates [23,24], indeed. Several modifications have then been proposed to extend the validity of the Johnson-Cook model up to the very high strain rate range [24][25][26][27].…”

Energy-based numerical modeling of the strain rate effect on fracture toughness of SA508 Gr. 1a

“…The values for g and _ Equation 4with equation 5or (6) is compared to the experimental true stress-strain curves in Figure 2. The values estimated using equation 4with equation (5) or (6) for the yield, tensile strengths, and strainhardening coefficient are compared to the experimental data obtained from experimental stress-strain curves in Figure 3. Note that the basic assumption in equation 4is that the strain-hardening exponent does not depend on the strain rate, but the experimental data show that it decreases slightly with increasing strain rate.…”

“…Symmetric conditions were fully utilized, and the first-order solid elements (C3D8 within ABAQUS 25 ) were used with a 0.1-mm element size. The true stress-strain curves given by equation 4with equation (5) or (6) were used, and the large (nonlinear) geometry change option was chosen with the J 2 flow theory. The simulated results of the simulation for the notched bars are compared to the experimental data in Figure 4, showing overall good agreements.…”

“…The size of the elements in the crack propagation region was fixed to L e = 0.2 mm with 31,503 elements and 35,088 nodes in the FE mesh. The true stress-strain curves given by equation 4with equation (5) or (6) were used with the J 2 flow theory, and to incorporate the large deformation in the simulation, the large (nonlinear) geometry change option was chosen. The incremental damage was calculated using equation 11with the multi-axial fracture strain from equation 1or with the multi-axial fracture strain energy from equation 3.…”