An Energy-Based interpretation of Interfacial Adhesion from Single Fibre Composite Fragmentation Testing

1993 ◽  
Vol 2 (5) ◽  
pp. 096369359300200 ◽  
Author(s):  
H.D. Wagner ◽  
S. Ling
Keyword(s):  
Interfacial Adhesion ◽  
Mechanical Characteristics ◽  
Interfacial Shear Strength ◽  
Fibre Composite ◽  
Stress Transfer ◽  
Single Fibre ◽  
Transfer Length ◽  
Fragmentation Test ◽  
Energy Balance Approach ◽  
Fibre Matrix

An energy balance approach is proposed for the single fibre composite (or fragmentation) test, by which the degree of fibre-matrix bonding is quantified by means of the interfacial energy, rather than the interfacial shear strength, as a function of the fibre geometrical and mechanical characteristics, the stress transfer length, and the debonding length. The validity of the approach is discussed using E-glass fibres embedded in epoxy, both in the dry state and in the presence of hot distilled water.

scholarly journals Micromechanical Tests on Natural Fibre Composites with Enzymatically Enhanced Fibre–Matrix Adhesion

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Hanna M. Brodowsky ◽  
Anne Hennig
Keyword(s):  
Shear Strength ◽  
Single Fibre ◽  
Natural Fibre ◽  
Interfacial Shear ◽  
Frictional Stress ◽  
Reinforced Composites ◽  
Fragmentation Test ◽  
Fibre Pullout ◽  
Fibre Matrix ◽  
Fibre Reinforced Composites

Abstract Natural fibre–reinforced composites are more sustainable than other composites with respect to the raw materials. Their properties are attractive due to high specific properties, and especially so wherever high damping is valued. As the interphase between fibre and matrix is the region of highest stresses, a strong bond between fibre and matrix is essential for any composites’ properties. The present study compares two methods of determining the interfacial shear stress in natural fibre–reinforced composites: the single fibre fragmentation test and the single fibre pullout test. The studied composites are flax fibre reinforced epoxy. For a variety of fibre–matrix interaction, the fibres are treated with a laccase enzyme and dopamine, which is known to improve the fibre–matrix shear strength. In the observed samples, single fibre fragmentation test data, i.e. of fracture mode and fragment length, scatter when compared to pullout data. In single fibre pullout tests, the local interfacial shear strength showed a 30% increase in the laccase-treated samples, compared to the control samples. The method also permitted an evaluation of the frictional stress occurring after surface failure.

scholarly journals Clarifying the application of Weibull Statistics for Determining the Stress state of A Fibre from Fragmentation Tests

1993 ◽  
Vol 2 (5) ◽  
pp. 096369359300200 ◽  
Author(s):  
H. D. Wagner ◽  
J. R. Wood ◽  
G. Marom
Keyword(s):  
Compressive Strength ◽  
Stress State ◽  
Fibre Composite ◽  
Single Fibre ◽  
Weibull Statistics ◽  
Novel Technique ◽  
Fragmentation Test ◽  
Single Fibres ◽  
First Time ◽  
Manufacturing Stage

A novel technique was recently introduced in our laboratories for the measurement of the compressive strength of single fibres, based on a modified configuration of the single fibre composite fragmentation test. In particular, the effect of the length of the embedded fibre on its compressive strength was assessed for the first time, based on Weibull statistics considerations. Moreover, during the sample manufacturing stage, a fibre can break in compression due to induced cooling stresses, rather than mechanical stresses, which can be determined from the fragmentation phenomenon. In this note, improved analyses of such compressive fragmentation effects are presented and discussed.

Poisson's stresses in fibre composites. I: Analysis

1984 ◽  
Vol 19 (1) ◽  
pp. 43-49 ◽  
Author(s):  
J Ostrowski ◽  
G T Will ◽  
M R Piggott
Keyword(s):  
Finite Element ◽  
Fibre Composite ◽  
Single Fibre ◽  
Fibre Volume ◽  
Matrix Interface ◽  
Fibre Direction ◽  
Element Analysis ◽  
Infinite Array ◽  
Transverse Stresses ◽  
Fibre Matrix

Two methods have been used to evaluate the transverse stresses when an aligned fibre composite is stressed in the fibre direction. A single fibre model is shown to overestimate the stresses at the fibre-matrix interface by about 20 per cent compared with a finite element solution for an infinite array of fibres. Using relatively few fibres in the finite element analysis, however, only gives very approximate stress distributions. With fibre volume fractions in the range 0-0.50 the average radial stresses across the fibre-matrix interface are always compressive, and can be represented by a relatively simple formula with an accuracy which is normally with in a few percent of the finite element value.

Interfacial studies of carbon fibre / polycarbonate composites using dynamic mechanical analysis

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Maria C. Paiva ◽  
João F. Mano
Keyword(s):  
Shear Strength ◽  
Carbon Fibre ◽  
Dynamic Mechanical Analysis ◽  
Interfacial Shear Strength ◽  
Mechanical Analysis ◽  
Interfacial Shear ◽  
Carbon Fibres ◽  
Matrix Interaction ◽  
Fragmentation Test ◽  
Fibre Matrix

AbstractUnidirectional composite material samples with ultrahigh modulus carbon fibres, treated and untreated by oxygen plasma, and a polycarbonate matrix were prepared and tested. Dynamic mechanical analysis (DMA) was used to study interfacial fibre/matrix interaction and the fragmentation test method was applied to determine interfacial shear strength. For the composite samples with treated carbon fibres, analyzed by DMA, a consistent shift of the loss modulus peak toward higher temperature was observed. The damping ratio was highly affected by residual stresses along the carbon fibre direction due to the large difference of thermal expansion coefficients of matrix and fibres. Critical fibre length and interfacial shear strength, obtained from the fragmentation test, showed substantial improvement for treated fibres as compared to the untreated ones. Plasma oxidation of the fibre surface improved considerably the fibre-matrix interaction. Care must be taken interpreting the DMA results, due to specific characteristics of the system studied.

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