Flexoelectric Sensing of Laminated Composite Structures Considering Bonding Compliance

  • Kumar Rout, Suraj (Indian Institute of Technology Delhi)
  • Kapuria, Santosh (Indian Institute of Technology Delhi)

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Fibre-reinforced composite materials, owing to their high specific strength and stiffness, and resistance to fatigue and corrosion, are increasingly integrated with electromechanical transducers for applications such as energy harvesting, active vibration control, and structural health monitoring (SHM). Among the available electromechanical transducers, piezoelectric transducers are the most widely used due to their low cost, compact size, wide linear operating range, and unobtrusive nature. However, in recent years, a relatively novel electromechanical phenomenon known as flexoelectricity has attracted significant attention as a potential alternative to piezoelectric materials for actuation, sensing, and energy harvesting applications. The flexoelectric effect refers to the generation of electric polarization due to non-uniform strain fields (direct flexoelectric effect) and the mechanical strain under an applied electric field gradient (converse flexoelectric effect). Despite the growing interest in flexoelectricity over the past decade, analytical models for sensing the response of composite structures using flexoelectric transducers remain unexplored. To address this gap, a one-dimensional analytical model is developed for sensing in composite laminates bonded with flexoelectric transducers through a physically modelled adhesive layer. The formulation incorporates both interfacial shear (τ) and peel ($σ) stresses governing stress transfer between the host laminate and the sensor. The host laminate and transducer are modelled as small-width beams under plane stress conditions and as infinite-width panels under plane strain conditions using first-order shear deformation theory. The resulting formulation yields a seventh-order differential equation governing the interfacial shear stress, which is solved in closed form by satisfying appropriate mechanical boundary conditions, while the corresponding peel stress is obtained from its differential relation with the shear stress.