Mode I delamination behaviour of carbon/epoxy composite at different displacement rates

Low, Kean Ong; Teng, ShuHui; Johar, Mahzan; Israr, Haris Ahmad; Wong, KokSheik

doi:10.1016/j.compositesb.2019.107293

Cited by 33 publications

(41 citation statements)

References 39 publications

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“…The unidirectional carbon/epoxy prepreg has a nominal thickness of 0.15 mm with an average fiber volume fraction of 65.7% ± 6.3% [ 15 ]. All specimens were supplied by X Plas Singapore (Kallang Way, Singapore).…”

Section: Methodsmentioning

confidence: 99%

“…Composite arms are modeled using continuum shell elements (SC8R), while the mid-plane interface is modeled using cohesive elements (COH3D8). The entire composite is meshed by four elements in the thickness direction, which has shown to be enough to simulate the bending behavior of the composite [ 15 ]. To avoid interpenetration between the upper and lower arms, contact surfaces are defined at the adjacent surfaces of the interface using frictionless contact.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…To avoid interpenetration between the upper and lower arms, contact surfaces are defined at the adjacent surfaces of the interface using frictionless contact. An element thickness of 10 µm is used for the cohesive elements [ 15 , 23 ], which is also in the same order of the resin-rich region [ 24 ] and the Teflon thickness. The delamination zone is meshed with 0.1 mm element size, while the region outside the delamination zone is meshed with mesh size of 2 mm.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…Good repeatability is found, with a maximum C.V of less than 8%. The E 11 value estimated at dry condition is the same as reported in a previous study [ 15 ], where the same carbon/epoxy composite was used. Therefore, the same lamina properties reported in reference [ 15 ] are used for dry condition.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…The E 11 value estimated at dry condition is the same as reported in a previous study [ 15 ], where the same carbon/epoxy composite was used. Therefore, the same lamina properties reported in reference [ 15 ] are used for dry condition. As for the other lamina properties (transverse modulus E 22 , in-plane shear modulus G 12 , out-of-plane shear modulus G 13 , and G 23 ) at wet conditions, they are estimated using the same ratio of the corresponding E 11 with respect to its dry value.…”

Section: Numerical Simulationmentioning

confidence: 99%

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Moisture Absorption Effects on Mode II Delamination of Carbon/Epoxy Composites

et al. 2020

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It is necessary to consider the influence of moisture damage on the interlaminar fracture toughness for composite structures that are used for outdoor applications. However, the studies on the progressive variation of the fracture toughness as a function of moisture content M (%) is rather limited. In this regard, this study focuses on the characterization of mode II delamination of carbon/epoxy composites conditioned at 70 °C/85% relative humidity (RH). End-notched flexure test is conducted for specimens aged at various moisture absorption levels. Experimental results reveal that mode II fracture toughness degrades with the moisture content, with a maximum of 23% decrement. A residual property model is used to predict the variation of the fracture toughness with the moisture content. Through numerical simulations, it is found that the approaches used to estimate the lamina and cohesive properties are suitable to obtain reliable simulation results. In addition, the damage initiation is noticed during the early loading stage; however, the complete damage is only observed when the numerical peak load is achieved. Results from the present research could serve as guidelines to predict the residual properties and simulate the mode II delamination behavior under moisture attack.

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Section: Methodsmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

Section: Numerical Simulationmentioning

confidence: 99%

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Moisture Absorption Effects on Mode II Delamination of Carbon/Epoxy Composites

et al. 2020

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Fiber bridging mechanism in moisture‐induced mode I delamination in carbon/epoxy composites: Finite element analysis and experimental investigation

2022

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Prolonged exposure of fiber reinforced composite structures to high moisture and temperature in outdoor environment could lead to the degradation of mechanical properties of the materials. To provides reliable prediction of the delamination behavior as the moisture progressively ingresses into the composites, we proposed a Bilinear-Exponential Traction-Separation (BETS) lawwhich can account for the fiber bridging mechanism-for investigating the mode I delamination of unidirectional carbon fiber reinforced epoxy composite laminates in wet states. Finite element analysis (FEA) of the delamination model was conducted to evaluate the effects of moisture content on the global force-displacement curves. A cohesive zone model (CZM) was used to describe the delamination behavior at the interface. With regard to the forcedisplacement curves, the BETS law agrees well with results from experimental study (using the double cantilever beam testing on the wet specimens) at both the elastic and failure regions. The delamination model governed by the BETS law also showed good agreement with the crack length versus the crosshead displacement. The FE model that considered the inputs from the BETS law yielded prediction about the evolution of the damage parameter and crack growth profile. In particular, the predicted crack extension increases linearly with increasing crosshead displacement. The proposed BETS law has the advantage of not requiring crack growth monitoring during experiment, and only one fitting parameter was needed to describe the bridging law at different moisture content levels.Abbreviations: a o , initial crack length; BETS, bilinear-exponential traction-separation; BTS, bilinear traction-separation; COD, crack opening displacement; COH3D8, cohesive elements; CT, compact tension; CZL, cohesive zone length; CZM, cohesive zone model; d, crosshead displacement; D, damage parameter; da, crack extension (or incremental crack length); da ss , crack extension when steady-state fracture toughness is attained; DCB, double cantilever beam; E 11 , longitudinal modulus of the composite; E 22 , transverse modulus of the composite; E m , young's modulus of the epoxy resin; FML, fiber-metal laminates; G, fracture energy; G Ib , fracture energy due to fiber bridging effect; G IC , fracture toughness; G ss , steady-state fracture toughness; h ce , thickness of the cohesive element; K nn , mode I penalty stiffness; m, fracture toughness ratio; M, moisture content levels; n, strength ratio; SC8R, continuum shell elements; t b,n , bridging initiation traction; t n , normal traction; TTS, trilinear Traction-Separation; t u,n , mode I interface strength; VCCT, virtual crack closure technique; V f , fiber volume fraction; Y T , transverse tensile strength; α, cohesive zone model parameter; γ, fitting parameter in the damage parameter equation; δ b,n , bridging initiation separation; δ f,n , separation at ultimate failure; δ n -δ o,n , relative separation between normal and at damage initiation; δ n , normal separation; δ o,n , separatio...

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