Delamination Modeling of Double Cantilever Beam of Unidirectional Composite Laminates
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TECHNICAL ARTICLE—PEER-REVIEWED
Delamination Modeling of Double Cantilever Beam of Unidirectional Composite Laminates Mohammed Y. Abdellah
Submitted: 23 November 2016 / in revised form: 31 January 2017 Ó ASM International 2017
Abstract Delamination crack growth in a double cantilever beam laminated composites is modeled by using simple stress analysis beam theory combined with simple linear elastic fracture mechanics and consideration of the theory of elastic failure in mechanics of material. Furthermore, advanced finite element (FE) model is built up. The FE approach employs surface cohesive zone model that is used to simulate the debonding and crack propagation. The analytical modeling, moreover, cracks growth and strain measurements, which are obtained from FE models, are compared with the available published experimental work. The predicted results give good agreement with interlaminar fracture toughness and maximum load which correspond to crack initiation point. The FE models results agree well with the available experimental data for both crack initiation and propagation.
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Keywords Fracture toughness Delamination DCB Cohesive surface Crack propagation
df tn ts tt GIC, GIIC, and GIIIC
List of symbols rco GIC
Introduction
F E I b h v
Cohesive stress Mode I surface release energy or fracture toughness The load at the end of arm The Young’s modulus The second moment of area Beam width Beam thickness Total vertical displacement
M. Y. Abdellah (&) Mechanical Engineering Department, Faculty of Engineering, South Valley University, Qena 83523, Egypt e-mail: [email protected]
Half displacement Compliance Crack extension area Bending stress Distance from point load at crack tip Stored elastic energy Bending moment in x axis plane Surface release energy Un-notch tensile strength Transverse tensile strength Effective Young’s modulus Effective stiffness Critical initiation traction– separation displacement Critical crack opening Normal contact stress Shear contact stress Traction contact stress Mode I, II, and III surface release energy
Layered composites are commonly failed with the delamination mode through the thickness. These types of failure modes are generally measured using Mode I or Mode II and Mode III fracture toughness in a unidirectional layered composite. Delamination is considered one of the main serious forms of failure and damage in laminated composites. This type of damage is generated due to many reasons like stress concentration near geometric discontinuity, defects in manufacturing technology [1, 2]. A brief survey about delamination and its effects are given in [3, 4].
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J Fail. Anal. and Preven.
La Saponara et al. [2] investigated delamination crack growth in laminated composites using experimental procedures and finite element (FE) models. Their tests were performed on cross-ply graphite/epoxy specimens under static conditions. While the FE model is used a cohesive element method which was used to simulate the debonding and
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