DiBenedetto Glass Transition Modeling in Diffusion Controlled Resins
DiBenedetto modeling governs vitrification prediction, preventing unreacted resin pockets and internal residual stress during structural composite cure cycles.
Interlaminar Shear Strength
Meaning
Mechanical property quantifying the resistance of a layered material to internal sliding forces parallel to the laminate planes. Measuring interlaminar shear strength is necessary to evaluate the bond quality between individual plies in a composite structure.
Structural Limit
Loading conditions that induce bending often create high shear stress at the mid-plane of a beam. A low interlaminar shear strength value indicates a high probability of internal delamination under service loads.
Adhesion Audit
Testing typically involves the short-beam shear method, where a small specimen is subjected to three-point bending. If the interlaminar shear strength is below the design requirement, the manufacturing process likely suffered from contaminated fibers or insufficient resin flow. Environmental factors like moisture absorption or heat exposure degrade the matrix and reduce the bond integrity over time.
Failure Morphology
Observations of the fracture surface reveal whether the resin cracked or the fiber-matrix interface failed. Increasing the interlaminar shear strength often involves toughening the resin system or adding z-axis reinforcement such as stitching. The use of these values sets the safety margins for critical components in wings, hulls, fuselages and pressure vessels.
This property determines the maximum thickness of a part that can be safely loaded in flexure.