Furthermore, the strains in kinase inhibitor Baricitinib the zero-thickness element are computed from��=1h��u��v��wT,(10)where ��u, ��v, and ��w are the relative displacements and h is the virtual element thickness. Also, note that ��u = utop ? ubot, ��v = vtop ? vbot, and ��w = wtop ? wbot.In the present study, we only focus on the localized imperfection with a uniform degeneration in Gxz, Gyz, and Ez although different degradation can be imposed on one or more of these properties by using different values of R in [Dint ]. From (5) and (10), the strains in the zero-thickness element are related to its nodal displacements via��=[Bint?]d��,(11)where[Bint?]=1h[?NN],d��=dbot��dtop��T,(12)and [Bint ]3��24 and d��24��1 are the element strain-displacement matrix and nodal displacements of the zero-thickness element, respectively.
Consequently, the element stiffness matrix of the zero-thickness interface element can be computed usingKint?=?RnBint?TDint?Bint?|J|d��?d��,(13)whereJ=[?x?��?y?��?x?��?y?��](14)is the Jacobian matrix.The stiffness matrix of the zero-thickness interface element is assembled accordingly into the local stiffness matrix of the laminate element (Figures 1(b) and 1(c)). The DOF (u, v, and w) of the nodes located at the top surface of the interface element are merged with the DOF (u, v, and w) of the nodes of top lamina. The same is performed for the DOF of the bottom surface of the interface element and those of bottom lamina.The complete local stiffness matrix of the laminate element will be then arranged accordingly to form the global stiffness matrix of the laminate.
By discretely manipulating the properties of the zero-thickness interface element, any intensity of interfacial imperfection can be prescribed at any location of the laminate. We shall next consider the effects of various perturbations of interfacial properties on the transverse deformation of a [90/0] laminated plate using such concept.3. Performance of Degenerated Laminated Composite3.1. VerificationA two-layer cross-ply composite laminate with a perfect bonding and the same laminae thickness, as shown in Figure 1(a), is modeled for verification of the present model. The fiber and the matrix of the lamina are E-Glass and Epoxy (3501-6), respectively, the composite material properties of which are shown in Table 1. In addition, the material properties of the interface layer are set similar to those of the matrix since it is customarily used in practice as the bonding component for laminates. It should be noted that the thickness of the interface layer is prescribed as one-tenth of the lamina thickness in accordance with the study conducted by Sheikh and Chakrabarti Drug_discovery .