Abstract
Adhesive layer plays a critical role in the strength restoration of the scarf repaired carbon fibre-reinforced plastic (CFRP) laminates. In this work, Araldite 2015 is used. Hence, it is crucial to model the behaviour of adhesive layer accurately in case of numerical model. Modelling of adhesive layer by cohesive zone law characterises the fracture behaviour of the bonded joint accurately. In this paper, cohesive zone law parameters for mode I and mode II are determined by comparing numerical predictions to experimental observations of a double cantilever beam (DCB) for mode I and end notched flexure (ENF) for mode II fracture test. In this work, Araldite 2015 (supplied by Huntsman) is used for repair work. Strain energy release rate for both mode I and mode II is determined by performing DCB and ENF test, respectively. Traction–separation law for mode I is generated by direct method which involves differentiation of the relation between the strain energy release rate and crack tip opening displacement which is measured using digital image correlation (DIC) technique. Traction–separation law for mode II is generated by inverse method which involves fitting the numerical and experimental load–displacement curves. The obtained cohesive law is used to model the adhesive layer in numerical analysis of double-sided stepped lap joint repair of CFRP laminate subjected to tensile loading. The numerical predictions are validated by comparing the load–displacement curve obtained from the experimental study. A good agreement exists between numerical and experimental results confirming that the proposed cohesive law for mode I and mode II can be applied to model adhesive layer with CFRP as adherend.
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Abbreviations
- a :
-
Crack length
- a e :
-
Equivalent crack length
- a 0 :
-
Initial crack length
- B :
-
Width of the specimen
- C :
-
Compliance of the specimen
- C 0 :
-
Initial compliance
- E f :
-
Flexural modulus
- G I :
-
Mode I strain energy release rate
- G IC :
-
Mode I fracture toughness
- G II :
-
Mode II strain energy release rate
- G IIC :
-
Mode II fracture toughness
- h :
-
Height of single adherend
- L :
-
Total specimen length
- P :
-
Applied load on the specimen
- w :
-
Crack tip opening displacement (CTOD)
- δ :
-
Displacement of the specimen
- δ 0 :
-
Damage initiation relative displacement
- δ c :
-
Ultimate relative displacement
- Δ:
-
Correction factor for root rotation effect
- t a :
-
Adhesive thickness
- σ :
-
Normal traction
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Acknowledgements
The first author thank Dr. Viswanath R Chintapenta, Assistant Professor, Indian Institute of Technology Hyderabad for his guidance, lab mates in engineering optics lab and central workshop staff at Indian Institute of Technology Hyderabad.
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Seshadri, M., Ramji, M. (2018). Numerical and Experimental Analysis of Double-Sided Stepped Lap-Repaired CFRP Laminates Under Tensile Loading. In: Prakash, R., Jayaram, V., Saxena, A. (eds) Advances in Structural Integrity. Springer, Singapore. https://doi.org/10.1007/978-981-10-7197-3_21
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