Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Sellitto, Andrea; Saputo, Salvatore; Caprio, Francesco Di; Riccio, Aniello; Russo, Angela; Acanfora, Valerio

doi:10.3390/app9112372

Cited by 36 publications

(23 citation statements)

References 36 publications

(53 reference statements)

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“…The FRP composites are essentially brittle with no plastic deformation, thus adequately described using a bilinear stress-strain curves with elastic and softening responses. The softening response represents the permanent deformation of the material, described through the continuous degradation of stiffness and strength to complete fracture [10][11][12][13]. The general loading on composite structures, including axial, flexural, and torsional loads, generates a complex stress state in the material.…”

Section: Introductionmentioning

confidence: 99%

An Energy-Based Concept for Yielding of Multidirectional FRP Composite Structures Using a Mesoscale Lamina Damage Model

et al. 2020

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Composite structures are made of multidirectional (MD) fiber-reinforced polymer (FRP) composite laminates, which fail due to multiple damages in matrix, interface, and fiber constituents at different scales. The yield point of a unidirectional FRP composite is assumed as the lamina strength limit representing the damage initiation phenomena, while yielding of MD composites in structural applications are not quantified due to the complexity of the sequence of damage evolutions in different laminas dependent on their angle and specification. This paper proposes a new method to identify the yield point of MD composite structures based on the evolution of the damage dissipation energy (DDE). Such a characteristic evolution curve is computed using a validated finite element model with a mesoscale damage-based constitutive model that accounts for different matrix and fiber failure modes in angle lamina. The yield point of composite structures is identified to correspond to a 5% increase in the initial slope of the DDE evolution curve. The yield points of three antisymmetric MD FRP composite structures under flexural loading conditions are established based on Hashin unidirectional (UD) criteria and the energy-based criterion. It is shown that the new energy concept provides a significantly larger safe limit of yield for MD composite structures compared to UD criteria, in which the accumulation of energy dissipated due to all damage modes is less than 5% of the fracture energy required for the structural rupture.

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Section: Introductionmentioning

confidence: 99%

An Energy-Based Concept for Yielding of Multidirectional FRP Composite Structures Using a Mesoscale Lamina Damage Model

et al. 2020

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“…They concluded that it is possible to predict the Mode II interlaminar fracture toughness by using the formula

where B is a coefficient that takes into account the additional shear stress contribution. Considering the loading conditions found in impact events, the main cause of failure within the composite structure can be related to the shear stress [ 41 , 42 , 43 ] localised within a structure during the dynamic loading. Consequently, it is possible to assume that Mode II failure is dominant and high dependency from the ply angle is expected for the G c value in this loading condition.…”

Section: Functionally Graded Pitch (Fgp) Laminatesmentioning

confidence: 99%

Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

et al. 2021

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Composite laminated materials have been largely implemented in advanced applications due to the high tailorability of their mechanical performance and low weight. However, due to their low resistance against out-of-plane loading, they are prone to generate damage as a consequence of an impact event, leading to the loss of mechanical properties and eventually to the catastrophic failure of the entire structure. In order to overcome this issue, the high tailorability can be exploited to replicate complex biological structures that are naturally optimised to withstand extreme impact loading. Bioinspired helicoidal laminates have been already studied in-depth with good results; however, they have been manufactured by applying a constant pitch rotation between each consecutive ply. This is in contrast to that observed in biological structures where the pitch rotation is not constant along the thickness, but gradually increases from the outer shell to the inner core in order to optimise energy absorption and stress distribution. Based on this concept, Functionally Graded Pitch (FGP) laminated composites were designed and manufactured in order to improve the impact resistance relative to a benchmark laminate, exploiting the tough nature of helicoidal structures with variable rotation angles. To the authors’ knowledge, this is one of the first attempts to fully reproduce the helicoidal arrangement found in nature using a mathematically scaled form of the triangular sequence to define the lamination layup. Samples were subject to three-point bending and tested under Low Velocity Impact (LVI) conditions at 15 J and 25 J impact energies and ultrasonic testing was used to evaluate the damaged area. Flexural After Impact (FAI) tests were used to evaluate the post-impact residual energy to confirm the superior impact resistance offered by these bioinspired structures. Vast improvements in impact behaviour were observed in the FGP laminates over the benchmark, with an average reduction of 41% of the damaged area and an increase in post-impact residual energy of 111%. The absorbed energy was similarly reduced (−44%), and greater mechanical strength (+21%) and elastic energy capacity (+78%) were demonstrated in the three-point bending test.

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“…Concrete material is also investigated in relation to impact resistance [18] and self-healing properties [19]. Impact behavior is studied with reference to laminate composites [20,21]. Other papers devoted to rocks concern their cutting resistance [22] and their multiaxial response under dry and saturated conditions [23].…”

Section: Fracturementioning

confidence: 99%

Special Issue on Fatigue and Fracture of Non-Metallic Materials and Structures

Spagnoli

2020

Applied Sciences

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This Special Issue covers the broad topic of structural integrity of non-metallic materials, and it is concerned with the modelling, assessment and reliability of structural elements of any scale. In particular, the articles being contained in this issue concentrate on the mechanics of fracture and fatigue in relation to applications to a variety of non-metallic materials, including concrete and cementitious composites, rocks, glass, ceramics, bituminous mixtures, composites, polymers, rubber and soft matters, bones and biological materials, advanced and multifunctional materials.

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Numerical–Experimental Correlation of Impact-Induced Damages in CFRP Laminates

Cited by 36 publications

References 36 publications

An Energy-Based Concept for Yielding of Multidirectional FRP Composite Structures Using a Mesoscale Lamina Damage Model

An Energy-Based Concept for Yielding of Multidirectional FRP Composite Structures Using a Mesoscale Lamina Damage Model

Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

Special Issue on Fatigue and Fracture of Non-Metallic Materials and Structures

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