A higher-order theory is developed to model the behavior of composite laminates with delamination and transverse matrix cracking. The higher-order displacement field is used in the sublaminates for accurate representation of the effects of transverse shear. This also allows description of the independent displacement fields above and below the delamination. A refined displacement field is obtained through the satisfaction of stress-free boundary conditions at all free surfaces, including delaminated interfaces. The effect of matrix cracking is determined using a separate finite element model of a representative crack and implemented into the structural model by means of reduced laminate stiffnesses. Matrix crack closure creates a bimodularity where stiffness under compression is greater than stiffness under tension. This bimodularity is addressed using an iterative process. The effect of this bimodularity on mode shapes is shown to be small, and a method is presented for determining natural frequencies in the presence of matrix cracks. Results show that this model provides a consistent level of accuracy for a variety of laminate materials and configurations, with various combinations of delaminations and matrix cracks.
ASJC Scopus subject areas
- Aerospace Engineering