Numerical modeling of adhesively bonded composite patch repair of cracked aluminum panels with concept of CZM and XFEM

Abstract

Application of composite patches in repair of damaged/aged aircraft structures is one of the most popular repairing methods in aerospace engineering. Since running experiments are difficult, time consuming, expensive, and also require high level of expertise, simulation of the behavior of the patch and also the faulty components after repair can assist designers and engineers in optimization of their designs. In this article, full-scale simulation of a damaged panel that is experimentally repaired with a composite patch will be considered using ABAQUS, a commercial finite element code. The crack growth process is modeled with the extended finite element method and the cohesive zone model (CZM) is used to model the progressive damage in the adhesive of the composite patch repair. Also, sensitivity analysis is performed on the CZM parameters and it is shown that the three parameters i.e. the shear toughness, maximum first shear traction, and penalty parameter for the elastic stiffness are important in the simulation of adhesively bonded composite patch repairs. The calibrated cohesive properties are successfully used to predict the response of the composite patch to the strengthened in damaged structure with considering the linear and nonlinear stage of failure process. The simulation results obtained in different stages have been verified with the existing experimental results.

Optimization of composite patch repair for maximum stability of crack growth in an aluminum plate

“…For this purpose, the genetic algorithm tool of MATLAB software is used. 5 The results of the crack growth simulation and the progression of damage in CZM are shown in Figure 3. In this figure (i.e.…”

“…In this FE modeling, damage initiation is determined using the maximum nominal stress criterion which is described by equation (2) 5,10 where subscripts n, s, and t indicate the normal, first, and second shear directions, respectively.…”

“…Here, damage evolution is described as the material stiffness degradation. The stress components during damage evolution are affected by the damage variable (Dc) as in equation (3) 5,10

where tntrue¯, tstrue¯ and tttrue¯ are the stress components predicted by the elastic traction–separation behavior without damage. D c is the scalar damage variable of the cohesive element.…”

“…But, a prerequisite for this is the simulation of crack growth to the point of instability. Therefore, optimization of a composite patch that has previously been designed by the current team 5 and Okafor et al. 6 is performed in this study.…”

Optimal sensors layout design based on reference‐free damage localization with lamb wave propagation

“…In other words, these two analyses (implicit–dynamic and explicit–dynamic) should be coupled to obtain acceptable results. By considering a cosimulation model, different solvers can be allowed to do the calculations for the piezoelectric transducers and the host structure . As a result, a standard–explicit cosimulation interface is defined for each transducer to link its elements to the plate elements, as shown in Figure .…”