Crack length correction and root rotation angle in a sandwich single cantilever beam (SCB) fracture specimen

Saseendran, Vishnu; Carlsson, Leif A.; Berggreen, Christian; Seneviratne, Waruna

doi:10.1016/j.ijlmm.2020.06.005

Cited by 2 publications

(15 citation statements)

References 19 publications

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“…The analytical bounds have been verified using the crack length corrections derived experimentally in Ref. [20] for two CRFP/honeycomb core sandwiches for aerospace applications, 5320e1/T650 Plain Weave/Nomex ® HRH-10 (carbon fiber reinforced polymer (CFRP)). Sandwich #1 has a core density 96 Kg/m 3 , cell size 3.2 mm, and h c /h f = 8.64; Sandwich #2 has a core density 48 Kg/ m 3 , cell size 9.5 mm, and h c /h f = 17.16.…”

Section: Experimental Verificationmentioning

confidence: 77%

“…The crack length correction has been derived using the compliance 1/3 versus crack length technique in Refs. [20,22] and matching the 2D energy release rate in Ref. [21].…”

Section: Numerical Validationmentioning

confidence: 99%

“…The homogenized elastic constants for face sheets and core have been derived in Ref. [20], E f = 67300 MPa and E c = 414 MPa (Sand. #1) and E c = 117 MPa (Sand.…”

Section: Experimental Verificationmentioning

confidence: 99%

“…The Winkler foundation model has been applied to double (DCB) and single (SCB) cantilever beam sandwich specimens in Refs. [9][10][11][19][20][21][22][23]. In the SCB sandwich specimen, the crack is placed at the upper core/face interface and a force or a moment is applied to the debonded face sheet while the lower part of the sandwich is secured to a rigid base, as shown in Figs.…”

Section: Introductionmentioning

confidence: 99%

“…Different foundation moduli have been used in the analysis of DCB and SCB sandwich fracture specimens, e.g., [9][10][11]29,32], [19,20], and k SCB,DCB = bE cm /h c [21,23], based mainly on simple extensions of Kanninen's modulus or by fitting the energy release rate of the approximate models to casespecific finite element results; E c , h c , h f , b are core transverse modulus, core, and face-sheet thicknesses and specimen width; E cm is a parameter depending on the elastic constants of the core, which has been derived through an elasticity-based approach in Refs. [23,34].…”

Section: Introductionmentioning

confidence: 99%

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Upper and Lower Bounds for the Parameters of One-Dimensional Theories for Sandwich Fracture Specimens

Massabò

2020

Journal of Applied Mechanics

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Upper and lower bounds for the parameters of one-dimensional theories used in the analysis of sandwich fracture specimens are derived by matching the energy release rate with 2D elasticity solutions. The theory of a beam on an elastic foundation and modified beam theory are considered. Bounds are derived analytically for foundation modulus and crack length correction in single cantilever beam sandwich specimens and verified using accurate finite element results and experimental data from the literature. Foundation modulus and crack length correction depend on the elastic mismatch between face-sheets and core and are independent of the core thickness if this is above a limit value, which also depends on the elastic mismatch. The results in this paper clarify conflicting results in the literature, explain the approximate solutions and highlight their limitations. The bounds of the model parameters can be applied directly to specimens satisfying specific geometrical/material ratios, which are given in the paper, or used to support and validate numerical calculations and define asymptotic limits.

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Section: Experimental Verificationmentioning

confidence: 77%

“…The crack length correction has been derived using the compliance 1/3 versus crack length technique in Refs. [20,22] and matching the 2D energy release rate in Ref. [21].…”

Section: Numerical Validationmentioning

confidence: 99%

“…The homogenized elastic constants for face sheets and core have been derived in Ref. [20], E f = 67300 MPa and E c = 414 MPa (Sand. #1) and E c = 117 MPa (Sand.…”

Section: Experimental Verificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Upper and Lower Bounds for the Parameters of One-Dimensional Theories for Sandwich Fracture Specimens

Massabò

2020

Journal of Applied Mechanics

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The effective crack extension and its implications on the single cantilever beam test for sandwich composites

Massabò

2023

Jnl of Sandwich Structures & Materials

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The response of Single Cantilever Beam sandwich specimens may be analyzed effectively through one-dimensional theories accounting for the actual deformation of the core and its effects on fracture parameters and compliance. The model of a beam on an elastic Winkler foundation describes the detaching facesheet as an Euler–Bernoulli beam resting, in the bonded region, on an elastic foundation which generates oscillating deflections with characteristic length [Formula: see text]. Modified beam theory (MBT) describes the debonded part of the face sheet as a cantilever beam, built-in at the debond tip, with an effective length which is longer than the actual detached length, by a quantity [Formula: see text]. If [Formula: see text] the two models predict the same energy release rate and similar load-point displacements. Effective crack extension and characteristic length depend on the thicknesses and elastic constants of facesheets and core and may be derived through experimental measurements of the specimen compliance at various increments of crack growth, as prescribed by experimental protocols. In the theoretical analyses, [Formula: see text] is typically assumed, either by directly using formulas proposed for other specimens or by calibrating their parameters to case specific finite element results. In this paper, we investigate the applicability of such formulas to a wide selection of sandwich composites for naval and aeronautical applications having thicknesses or materials other than those used for the original fitting; we then highlight their limitations and effects on the design of experimental protocols for material characterization. The applicability of a recent isotropic-elasticity based formula for [Formula: see text] is then verified using extensive data from the literature and novel finite element (FE) results for typical sandwich composites. Finally, a novel elasticity solution for the load-point displacement of a layer on a half plane is derived which supports the test data reduction procedure for [Formula: see text].

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Crack length correction and root rotation angle in a sandwich single cantilever beam (SCB) fracture specimen

Cited by 2 publications

References 19 publications

Upper and Lower Bounds for the Parameters of One-Dimensional Theories for Sandwich Fracture Specimens

Upper and Lower Bounds for the Parameters of One-Dimensional Theories for Sandwich Fracture Specimens

The effective crack extension and its implications on the single cantilever beam test for sandwich composites

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