Crack face sliding effect on stiffness of laminates with ply cracks

Physical interpretation of parameters in synergistic continuum damage mechanics model for laminates

“…The analysis was performed for symmetric case where the support layer S1 has equal properties, u , see [13] for details, also follows a power law It has to be mentioned that the use of solutions for a periodic system of cracks in homogeneous isotropic material [15] to calculate COD and CSD leads to significant overestimation and in result the stiffness reduction is also overestimated. …”

“…An exact expression for stiffness of a general symmetric laminate with intralaminar cracks in plies was derived in [12,13] […”

“…A theoretical framework establishing unique link between the damaged laminate thermo-elastic properties and the microdamage parameters COD and CSD was developed in [12,13]. It was shown that the details of the relative displacement profile along the crack surface are not important: only the average values of these quantities enter the stiffness expressions.…”

“…The normalized COD dependence on geometrical parameters of the laminate and on the material properties was studied experimentally using optical microscopy of loaded damaged specimens in [10,11]. FE studies were performed to understand which material and geometry parameters affect the COD and CSD [12,13]. Based on this analysis simple empirical relationships (power laws) were suggested.…”

“…The objective of the presented paper is to use the general framework for analysis of damaged laminates developed in [12,13] to identify the physical meaning of material constants in the CDM model [2] and to give exact expressions for their calculation. We will present transformation expressions for these constants when the layer orientation angle changes.…”