Modeling the Dynamic Effects of Delamination in Adaptive Composite Laminate

Modeling delamination in composite structures by incorporating the Fermi–Dirac distribution function and hybrid damage indicators

“…Conventional finite element approaches for modeling delaminations in laminated composite structures use sub laminates technique [15][16][17] or the Heaviside unit step function [11][12][13][14]18] to model possible jumps in the displacement field due to delamination allowing slipping and separation at the delaminated interface. Normally, sub laminates technique or Heaviside unit step function are not easy to model smooth transition in the displacement and the strain field of the delaminated interfaces.…”

Vibration of beams with delaminations and embedded piezoelectric sensors and actuators

“…Similarly, for short delamination and lower vibration modes, the nonlinearity due to the contact/impact between the delaminated layers was shown to be less significant and becomes significant for long delamination at higher vibration modes (Luo and Hanagud, 1997;Thornburg and Chattopadhyay, 2002). (Lestari and Hanagud, 1999).…”

“…TSDT-based 'free mode' model for composite plates with piezoelectric actuators were presented Chattopadhyay et al (1999bChattopadhyay et al ( , 2000b and Nam et al (2000). Thornburg and Chattopadhyay (2002) FE model for composite plates with piezoelectric patches and internal delaminations. They further investigated the contact between the delaminated layers by using fictitious springs, which was assumed to have zero stiffness under tension and stiffness proportional to the transverse modulus of the plate when subjected to compression.…”

“…Studies showed that delamination locations also affect the natural frequencies of the laminate. It was observed that a delamination located at midplane and near the fixed end of the laminate decreases the natural frequency most (Mujumdar and Suryanarayan, 1988;Krawczuk et al, 1996aKrawczuk et al, , b, 1997Kim et al, 2003a;Thornburg and Chattopadhyay, 2002).…”

“…In the experiments by Shen and Grady (1992) and Lestari and Hanagud (1999), the 'delamination breathing' was shown to cause nonlinearity in the mode shapes ( Figure 2.10). However, the 'delamination breathing' has been shown to have little effect on the natural frequencies of low vibration modes when the delamination is small (Luo and Hanagud, 1997a, b;Thornburg and Chattopadhyay, 2002). Further investigations by Lestari et al (2000) and Lu et al (2001) showed that for long delaminations and thin delaminated layers, the nonlinearity of the vibration mode shapes is significant.…”