scholarly journals Experimental Investigation of Delamination in Composite Continuous Fiber-Reinforced Plastic Laminates with Elastic Couplings

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5146
Author(s):  
Jakub Rzeczkowski ◽  
Sylwester Samborski ◽  
Marcelo de Moura
Keyword(s):  
Composite Laminates ◽  
Beam Theory ◽  
Strain Energy Release ◽  
Experimental Tests ◽  
Sem Analysis ◽  
Mode I ◽  
Initiation And Propagation ◽  
Energy Release Rates ◽  
American Society ◽  
Elastic Couplings

This paper presents an experimental evaluation of influence of the elastic couplings on the fracture toughness as well as on delamination initiation and propagation in carbon/epoxy composite laminates. For this purpose the mode I double cantilever beam (DCB) tests according to the American Society for Testing and Materials (ASTM) D5528 Standard were performed on specimens with different delamination interfaces and specific lay-ups composition exhibiting the bending-twisting (BT) and the bending-extension (BE) couplings. The critical strain energy release rates (mode I c-SERR, GIC) were calculated by using the classical methods, namely: the modified beam theory (MBT), the compliance calibration (CCM) and the modified compliance calibration (MCC). In order to evaluate an accuracy of the different methods, the values of c-SERR obtained by using standardized data reduction schemes were compared with values calculated by using the compliance based beam method (CBBM). All the methods give rise to comparable values of the GIC, which makes the CBBM an appealing choice, since it does not depend on crack length monitoring during the test. Initiation and propagation of delamination were investigated by using the acoustic emission (AE) technique. Moreover, the scanning electron microscope (SEM) analysis were performed after the experimental tests in order to investigate a fracture surface at delamination plane.

scholarly journals Mode I Interlaminar Fracture of Glass/Epoxy Unidirectional Laminates. Part I: Experimental Studies

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1607 ◽  
Author(s):  
Sylwester Samborski ◽  
Adrian Gliszczynski ◽  
Jakub Rzeczkowski ◽  
Nina Wiacek
Keyword(s):  
Failure Process ◽  
Experimental Studies ◽  
Beam Theory ◽  
Strain Energy Release ◽  
Experimental Tests ◽  
Calibration Method ◽  
Fast Fourier Transformation ◽  
Mode I ◽  
Frequency Spectra ◽  
Average Value

The paper presents experimental tests of unidirectional double cantilever beams made of a glass fiber reinforced (GFRP) laminate. The critical value of the strain energy release rate (c-SERR or GIC), i.e., the mode I fracture toughness of the considered material was determined with three different methods: the compliance calibration method (CC), the modified compliance calibration method (MCC), and the corrected beam theory (CBT). Due to the common difficulties in precise definition of delamination initiation force, the Acoustic Emission (AE) technique was applied as an auxiliary source of data. The failure process was monitored, as well, in order to detect and identify different damage phenomena. This was achieved through a detailed analysis of the raw AE signal subjected to fast Fourier transformation (FFT). The frequency spectra revealed three dominating frequency bands with the basic one described by the average value of 63.1 kHz, revealing intensive delamination processes. This way, not only precise values of the critical SERR, but also the information on damage evolution during propagation of delamination, was obtained.

Mode I Fracture in Nanocomposite Laminates within Multistage Traction-Separation Law

2021 ◽  
Author(s):  
pouyan ghabezi ◽  
Mohammad Reza Farahani
Keyword(s):  
Composite Laminates ◽  
Fracture Process ◽  
Double Cantilever Beam ◽  
Process Zone ◽  
Beam Theory ◽  
Mode I ◽  
Release Rates ◽  
Mode I Fracture ◽  
Cohesive Laws ◽  
Energy Release Rates

The main focus of this work is to investigate and compare the effect of adding nanoparticles to composite laminates on fracture process zone characterization including bridging and cohesive laws according to a multistage traction-separation law. To do this, three different methods have been utilized (Corrected Beam Theory, Experimental Compliance Method and Modified Compliance Calibration) to calculate the energy release rates in Mode I fracture. The numerical investigation of mode I fracture in nanocomposite laminates was done based on the multistage traction-separation law derived from double cantilever beam tests.

Delamination in Thickness Tapered Composite Laminates

1993 ◽  
Vol 115 (2) ◽  
pp. 193-199 ◽  
Author(s):  
B. R. Trethewey ◽  
J. W. Gillespie ◽  
D. J. Wilkins
Keyword(s):  
Energy Release ◽  
Composite Laminates ◽  
Strain Energy ◽  
Plate Theory ◽  
Strain Energy Release ◽  
Pure Mode ◽  
Element Analysis ◽  
Growth Criterion ◽  
Energy Release Rates ◽  
Failure Loads

The structural performance of thickness-tapered laminates has been investigated using an energy-based damage tolerance methodology. The geometry studied is a thin laminate with discontinuous internal plies and a through-width delamination embedded at the interface between continuous and discontinuous sublaminates. An analytic model, based on shear deformation plate theory and linear-elastic fracture mechanics is employed to determine the Mode I and Mode II components of strain energy release rate. A two-dimensional plane strain finite element analysis is conducted to confirm the accuracy of the analytic predictions. The resulting pure mode strain energy release rates are combined with a mixed-mode growth criterion to predict the axial load required to induce delamination growth. Finally, the analytic and numerical model were used to predict failure in a delamination critical test specimen. Reasonable agreement of the actual and predicted failure loads was observed.

Strain energy release rates and the fatigue growth of matrix cracks in model arrays in composite laminates

1991 ◽  
Vol 432 (1886) ◽  
pp. 427-444 ◽  
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Composite Laminates ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Matrix Cracks ◽  
Energy Release Rates

Crack growth in the transverse plies of cross-ply composite laminates has been investigated both experimentally and theoretically. Expressions for the strain energy release rate associated with the growth of cracks in model arrays have been obtained using both the compliance approach and the energy method. Measurements of compliance change with crack length were obtained using glass-epoxy laminates and compared with various predictions. Correlations between the crack growth rate and the strain energy release rate range indicate that a Paris law is applicable.

Deviant Crack Path Behaviour of Aluminium-Lithium Alloy AA8090 Plate

1996 ◽  
Vol 210 (2) ◽  
pp. 117-121
Author(s):  
P J Gregson ◽  
I Sinclair
Keyword(s):  
Crack Growth ◽  
Mixed Mode ◽  
Fatigue Testing ◽  
Fatigue Cracks ◽  
Elastic Strain Energy ◽  
Strain Energy Release ◽  
Mode I ◽  
Mixed Mode Crack ◽  
Energy Release Rates ◽  
Strain Energy Release Rates

The unusual susceptibility of the Al-Li alloy AA8090 to sustained macroscopic deviation of fatigue cracks from a nominal mode I path during conventional fatigue testing is discussed. It is demonstrated that the mixed mode crack growth associated with macroscopic deviation may be characterized in terms of elastic strain energy release rates for a range of mixed mode loading conditions. It is specifically shown that this form of mixed mode crack growth may lead to non-conservative crack growth predictions when these materials are subjected to conventional, mode I based structure lifing techniques.

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