Structural integrity of composite laminates with interlaced actuators

Abstract

A three-dimensional finite-element model is developed to analyze the interlaminar stress state surrounding an interlaced. active actuator embedded within a unidirectional composite laminate. Interlacing increases the strength of composite structures with embedded actuators by redistributing t h e load around the inclusion and softening the material discontinuity between the actuator and the composite structure. The analysis shows that interlacing results in as much as a 42% reduction in the magnitude of the maximum interlaminar tensile normal stress and a 22% reduction in the magnitude of the maximum interlaminar shear stress in the laminate. Moreover, the critical location of delamination initiation can be relocated from the interface between the actuator and the host material to a location away from the embedded actuator, thus maintaining the authority of the actuator even after the onset of delamination.

Design of an embedded sensor, for improved structural performance

“…The simulated and experimentally observed load deflection gradients of the flexural specimens (groups D and E, Table 2) are shown in Table 7 interlaminar stresses [6,10,11,13]. The finite element results in this section ( Figures 8a and 8b), identify the interlaminar stress concentrations created by embedding the inductively coupled sensors within the flexural strength specimens, aiding with the interpretation of the results of the flexural strength testing (Table 5).…”

Analysis of ultrasonic waveforms from smart sandwich composite structures under creep bending at elevated temperature

“…On the other hand, transducers embedded inside a composite structure may or may not act as stress raisers and accelerate life to failure (e.g. Mall, 2002;Qing et al, 2007;Schaaf et al, 2006;Singh and Vizzini, 1994;Tang et al, 2011).…”

Onset of Resin Micro-cracks in Unidirectional Glass Fiber Laminates with Integrated SHM Sensors: Numerical Analysis

“…Their results indicate that the interlaminar stresses are an order of magnitude lower than the stress representing the applied far-field load and the stress concentration factor is dependent on the stacking sequence of the laminates. Singh and Vizzini [12] have analyzed the interlaminar stress state surrounding an interlaced, active piezoceramic actuator embedded within a unidirectional composite laminate. Their finite element model appears to be insensitive to the transition resin layer thickness and the resin-pocket length when the length is greater than seven times the ply thickness.…”