How is Hashin damage used to model composite material failure?

The Hashin damage model in Abaqus is a widely used failure theory designed to predict damage initiation and evolution in fiber-reinforced composite materials. It provides a detailed breakdown of failure mechanisms by distinguishing between fiber and matrix failures under different loading conditions. This makes it particularly suitable for accurately simulating the complex behavior of composites.

Key Features of the Hashin Damage Model:

1. Damage initiation criteria:
   Based on Hashin’s theory, the model identifies four primary failure modes:
   • HSNFTCRT (fiber tension): rupture of fibers under tensile stress.
   • HSNFCCRT (fiber compression): Buckling or kinking of fibers under compressive stress.
   • HSNMTCRT (matrix tension): cracking in the matrix due to transverse tensile stress and shear.
   • HSNMCCRT (matrix compression): crushing of the matrix under transverse compressive stress and shear.
   • These criteria are implemented using plane stress elements like shell, continuum shell, and membrane elements. For 3D solid elements, alternative models like LaRC05 or custom VUMAT subroutines are required.
2. Damage evolution:
   • After damage initiation, Abaqus uses an energy-based approach to model progressive material degradation. The fracture energy (Gf) for each failure mode governs the rate at which stiffness is reduced, ensuring realistic simulation of post-damage behavior.
3. Element deletion:
   • Abaqus allows for element removal once all material points within an element are fully degraded, simulating complete material failure. This feature is particularly useful for analyzing large-scale failures like delamination or bolt-bearing damage in composite joints.
4. Applications in composite analysis:
   • The Hashin damage model is commonly used to simulate ply-level failures in laminated composites, such as CFRPs (carbon fiber-reinforced polymers). It can predict localized damage near stress concentrations (e.g., bolt holes) and assess overall structural integrity under complex loading conditions.
   • In bolted composite joints, it enables accurate modeling of interlaminar stresses and ply failures, providing insights into factors like clamping force effects and joint strength degradation.
5. Limitations and recommendations:
   • The Hashin model is limited to plane stress formulations and cannot directly handle 3D stress states. For applications requiring through-thickness stress analysis (e.g., pressure vessels), users should consider LaRC05 or custom subroutines like VUMAT.
   • Accurate results require detailed input parameters, including tensile/compressive strengths and shear properties for both fibers and the matrix. A mesh convergence study is also recommended to ensure reliability.