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Strength Evaluation Model Of Composite Wing Structure After Adhesive Repair

Posted on:2019-01-23Degree:MasterType:Thesis
Country:ChinaCandidate:X R WangFull Text:PDF
GTID:2322330569988307Subject:Aeronautical Engineering
Abstract/Summary:PDF Full Text Request
Composite materials have been widely used in the aviation field and have played an increasingly important role.At the same time,the problem of repairing composite materials has also become important.Adhesive repair technology has the advantage that mechanical connections do not have,making it a research hotspot.The specific work is as follows:First of all,for orthotropic composite laminates in repair structure,the advantages and disadvantages of the damage criteria have been analyzed,the stiffness matrix,damage criteria and degradation program have been determined.The Hashin-Puck criterion was used as the initial damage criterion,determine the nonlinear function for the degradation program.The UMAT subroutine was used to develop the ABAQUS software.The validity of the method was verified by calculation examples.Then,based on the cohesive zone model(CZM),the stiffness matrix,initial damage criterion and damage propagation criterion of the adhesive layer are determined,and a new nonlinear degradation scheme is proposed.UMAT was also written into the finite element solution process.A three-dimensional finite element model of the double-sided affixed structure was established.The damage process was analyzed and the ultimate strength was compared to verify the accuracy of the model.The trend of the effect of repair parameters on the results was studied.At last,combining the characteristics of the wing's stress and the characteristics of repairing the damaged area,the wing structure is reasonably simplified as the damage repair problem on the reinforced skin thin wall.References to determine the repair tolerance of the reinforced wing.Design the repair plan,determine the repair parameters,and analyze the repaired structure's damage pattern and load limit recovery.For the reinforced skin panel with damage,the single-sided patching scheme proposed in this paper restores the residual strength of the structure to 93.2% of non-damage,verifying the effectiveness of the repair scheme.The glue repair strength model in this paper can distinguish different degree of damage patterns,predict structural strength,and have certain application value in engineering.
Keywords/Search Tags:composites, UMAT, glue repair, residual strength, repair tolerance
PDF Full Text Request
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