Structural adhesives play a crucial role in various industries, with particular challenges in wind energy applications. In rotor blades, separate components are bonded with adhesives, and cracks, particularly in the bonding line of the trailing edge, often lead to costly repairs and operational failures. These failures highlight existing knowledge gaps in the analysis and design of adhesive joints. To meet the demanding loading conditions experienced over the lifespan of rotor blades, new adhesives have been developed for the wind energy sector, primarily composed of epoxy polymers reinforced with short fibers. The mechanical performance of these Short Fiber-Reinforced Polymeric (SFRP) adhesives is significantly influenced by the orientation and distribution of the fibers. This contribution presents a phase-field modeling framework to simulate ductile fracture in SFRP adhesives under both quasi-static and fatigue loading conditions. An invariant-based anisotropic elasto-plastic material model is utilized to describe the macroscopic behavior of the adhesives, incorporating pressure-sensitive characteristics. Non-associative plasticity is introduced to capture realistic deformation behavior. The model is further extended to account for fatigue effects by modifying the energy functional in accordance with thermodynamic principles, leading to a degradation of fracture toughness over time. The theoretical formulation and its numerical implementation are discussed, and the approach is validated through a series of simulations, demonstrating its robustness and applicability in predicting fracture behavior in SFRP adhesives.

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Phase-Field Fracture Modeling of Short Fiber-Reinforced Polymeric Adhesives

  • Aamir Dean,
  • Maryam Hematipour,
  • Pavan K. A. V. Kumar,
  • Raimund Rolfes

摘要

Structural adhesives play a crucial role in various industries, with particular challenges in wind energy applications. In rotor blades, separate components are bonded with adhesives, and cracks, particularly in the bonding line of the trailing edge, often lead to costly repairs and operational failures. These failures highlight existing knowledge gaps in the analysis and design of adhesive joints. To meet the demanding loading conditions experienced over the lifespan of rotor blades, new adhesives have been developed for the wind energy sector, primarily composed of epoxy polymers reinforced with short fibers. The mechanical performance of these Short Fiber-Reinforced Polymeric (SFRP) adhesives is significantly influenced by the orientation and distribution of the fibers. This contribution presents a phase-field modeling framework to simulate ductile fracture in SFRP adhesives under both quasi-static and fatigue loading conditions. An invariant-based anisotropic elasto-plastic material model is utilized to describe the macroscopic behavior of the adhesives, incorporating pressure-sensitive characteristics. Non-associative plasticity is introduced to capture realistic deformation behavior. The model is further extended to account for fatigue effects by modifying the energy functional in accordance with thermodynamic principles, leading to a degradation of fracture toughness over time. The theoretical formulation and its numerical implementation are discussed, and the approach is validated through a series of simulations, demonstrating its robustness and applicability in predicting fracture behavior in SFRP adhesives.