Tensile Strain Measurement in Recycled Paperboard Grades
Recycled paperboard strain measurement requires direct optical extensometry under ISO 1924-3 to isolate true sheet elongation from clamp slippage.
Optical DIC Strain
Measurement Boundary
Surface deformation tracking evaluates displacement fields across printed paperboard during mechanical loading events. Optical DIC strain captures full field surface kinematics by correlating digital images acquired through stereo lenses during tensile or compressive tests. High resolution charge coupled device sensors record speckle patterns applied to coated folding boxboard specimens prior to testing.
Commercial packaging converters utilize this optical method to quantify localized shear deformation near crease lines and die cut edges. Substrate anisotropy governs displacement vectors under multi axial stress states. Spatial resolution depends directly upon speckle size and facet grid dimensions configured within the evaluation software.
Deformation Matrix
Localized displacement gradients reveal structural integrity limits within corrugated board fluting mediums under stacking loads. High strain concentrations develop adjacent to glued carton flaps during compression cycles. Speckle pattern degradation invalidates correlation algorithms when surface delamination occurs prematurely during bending.
Print quality inspectors monitor how ink coverage influences speckle adhesion during high speed converting operations. Caliper variations across recycled linerboard coils alter surface response predictability under identical mechanical constraints.
Failure Criterion
Maximum principal strain values establish functional thresholds for structural carton designs. Tensile rupture limits dictate maximum tolerable deformation before structural compromise occurs in folding cartons. Shear stress thresholds prevent delamination in laminated paperboard laminates subjected to creasing forces.
Numerical simulations rely upon empirically derived displacement fields to calibrate finite element models for packaging optimization. Accurate deformation mapping prevents costly field failures during transit and warehouse storage.