CHABOCHE VISCOPLASTICITY MODELING TOOL

The Chaboche viscoplasticity model is a widely used constitutive model in continuum mechanics, particularly for describing the rate-dependent inelastic behavior of metals and alloys at high temperatures, especially under cyclic loading. It's an unified viscoplasticity model, meaning it doesn't distinguish between plastic and creep strains, treating them as a single inelastic measure that is rate-dependent.

It accounts for the time-dependent nature of deformation. This means that the material's response (deformation) depends not only on the applied stress but also on the rate at which the stress is applied. This is crucial for modeling phenomena like creep (deformation under constant stress over time) and stress relaxation (decrease in stress over time at constant strain).

The Chaboche model contains two types of hardening to capture material behavior: isotropic and kinematic. Isotropic hardening describes the expansion or contraction of the yield surface (the boundary in stress space beyond which plastic deformation occurs). It typically represents the overall strengthening or softening of the material due to accumulated plastic strain. Kinematic hardening describes the translation (shifting) of the yield surface in stress space. It's essential for capturing directional-dependent effects like the Bauschinger effect (where yielding in compression occurs at a lower stress after tensile yielding) and ratcheting (progressive accumulation of plastic strain under cyclic loading with a non-zero mean stress). The Chaboche model typically uses a sum of several Armstrong-Frederick type terms to represent this nonlinear kinematic hardening, allowing for a more accurate description of complex cyclic behaviors.

The unified Chaboche constitutive model has received much attention due to its simplicity to comprehend and use. he model involves a set of material parameters that need to be determined from experimental data, typically obtained from uniaxial monotonic and cyclic tests (like low-cycle fatigue and stress relaxation tests).

Fatigue analysis, especially for components operating at elevated temperatures or under complex cyclic loading conditions, requires accurate material models that can capture the sophisticated stress-strain response.

The Chaboche model is widely implemented in commercial finite element software (e.g., ABAQUS, COMSOL). This enables engineers to perform advanced simulations of complex structures under various loading conditions, allowing for a more accurate assessment of fatigue life in critical components. It is implemented as a tool on this site to support basic calculations.

Math model developed by Noah Al-Shaer alongside Florida Poly