Characterization of Steels Using a Revised Kinematic Hardening Model Incorporating Bauschinger Effect

Abstract

A new variant of the nonlinear kinematic hardening model is proposed which accommodates both nonlinear and linear strain hardening during initial tensile loading and reduced elastic modulus during initial load reversal. It also incorporates the Bauschinger effect, as a function of prior tensile plastic strain, during the nonlinear compressive loading phase. The model is shown to fit experimental data from a total of five candidate gun steels. The numerical fits will be employed in subsequent work to predict residual stresses and fatigue lifetimes for autofrettaged tubes manufactured from the candidate steels.

Fatigue life prediction of autofrettage tubes using actual material behaviour

“…A cylinder of inner and outer radii of r i ¼ 78.4 mm and, r o ¼ 147.4 mm, with operating pressure of P APP ¼ 385 MPa and autofrettage level of 50% (50% of the wall thickness is overstrained in the autofrettage process), with initial crack length of a i ¼ .1 mm, typical for field fired tubes [11,18], is considered. Calculation for reference displacement field is performed using FEA software package ANSYS [19].…”

“…This method is designed for use with FEM commercial packages and considers the dependency of BEF on plastic overstrains. More recently, other material models have appeared for easy incorporation in FEM packages [10,11]. Megahed and Abbas [10] attempted to follow a full nonlinear unloading profile, which is a function of plastic strain, but the analysis requires an empirical equation describing BEF dependence on plastic strain.…”

A Re-Autofrettage Procedure for Mitigation of Bauschinger Effect in Thick Cylinders

“…At some point after load reversal behavior becomes non-linear moving asymptotically towards a bound. The value of stress at point E, the onset of non-linearity, is -βσ Y where β is the Bauschinger effect factor [3]. Both β and the shape of the curve E-F are a strong function of the maximum initial plastic strain e pl L1* .…”

“…A less significant cause of reduced residual stress is the reduction in elastic modulus, i.e. E U1 is less than E L1 ; again the relationship between E U1 and E L1 may be expressed as a function of initial plastic strain [3].…”

Residual stress analysis of swage autofrettaged gun barrel via finite element method

“…Lee et al [4] evaluated residual stresses in autofrettage pressure vessels. Parker et al [5] represented the material model for gun barrels using the A723 gun steel material, explained the nonlinear behavior of this material, and examined three different armament gun tubes and investigated the material behavior of these tubes. Parker and Toriono [6] conducted experiments on the uniaxial Bauschinger effect, which has been evaluated in several high-strength steels adopted for armaments.…”