Stress and failure analyses of scarf repaired CFRP laminates using a cohesive damage model

Abstract

This study describes stress and failure analyses of tensile loaded repaired Carbon Fibre Reinforced Composite (CFRP) laminates, using scarf configuration. A numerical model including interface finite elements was used to obtain peel and shear-stress distributions in the directions tangent and normal to the scarf. These stresses were evaluated at several locations in the repair, namely in the middle of the adhesive, at interfaces between adhesive and patch, and between adhesive and parent material. Several scarf angle values were considered in the analysis. A cohesive mixed-mode damage model was also used to carry out the failure analysis, in order to assess the efficiency of the repairs, for different stacking sequences. A study was performed to evaluate the influence of the mechanical properties of the adhesive and parent laminate/adhesive and adhesive/patch interfaces on the strength and failure modes of the joint. It was concluded that the strengths of the adhesive and interfaces are more important than the fracture properties in the failure process of the repair. It was also verified that the strength of the repair increased exponentially with the scarf angle reduction.

Strength prediction of single- and double-lap joints by standard and extended finite element modelling

“…n s stress gradients, thus allowing to accurately capture these phenomena [2,18]. The joints were modelled as two-dimensional, with plane-strain solid elements (referenced as CPE8 from the ABAQUS s library).…”

“…The limitations of the reported approaches are surpassed by CZMs, combining elements of strength and fracture approaches to derive the fracture loads [17,18]. The use of CZMs in fracture problems has become frequent in recent years.…”

Scarf Repair of Composite Laminates

“…For the smaller values of D, normal stresses, V n , diminish in relative magnitude to W avg . Under these conditions, shear stresses, W tn , govern the repairs behavior [10]. …”

Experimental and numerical evaluation of composite repairs on wood beams damaged by cross-graining

“…In the beams length, the mesh is moderately refined along the extent of the crack, since this region is not expected to be severely loaded. The bonded regions at both sides of the crack were simulated with forty elements, with bias effects for an accurate characterization of the expected peak stresses near the patch edges [39,40]. The patch was modelled with four solid elements through thickness.…”