Some observations on the nature of fibre reinforced plastics and the implications for structural design

1980 ◽  
Vol 294 (1411) ◽  
pp. 507-517 ◽  
Keyword(s):  
Structural Design ◽  
Marked Effect ◽  
Construction Materials ◽  
Resin Composites ◽  
Matrix Interface ◽  
Reinforced Plastics ◽  
Transverse Cracking ◽  
Wide Range ◽  
The Matrix ◽  
Fibre Matrix

Fibre reinforced plastics exhibit many phenomena not found in conventional construction materials and these can have a marked effect both on the performance of structures made from them and, by implication, on the way in which such structures are designed. This paper considers three of the more interesting phenomena, namely compressive behaviour, tensile notch sensitivity and transverse cracking in multidirectional laminates. The latter two phenomena both involve failure of the matrix or fibre/matrix interface which, perhaps paradoxically, has a beneficial effect in one case but is detrimental in the other. Although the paper refers primarily to carbon fibre-epoxy resin composites, the conclusions and design implications relate to a wide range of fibre reinforced materials.

Fibre-Matrix Interface Development during High Temperature Exposition of Long Fibre Reinforced SiOC Matrix

2013 ◽  
Vol 592-593 ◽  
pp. 401-404
Author(s):  
Zdeněk Chlup ◽  
Martin Černý ◽  
Adam Strachota ◽  
Martina Halasova ◽  
Ivo Dlouhý
Keyword(s):  
High Temperature ◽  
Crack Formation ◽  
Fracture Behaviour ◽  
Point Of View ◽  
Reinforced Composites ◽  
Matrix Interface ◽  
Significant Damage ◽  
The Matrix ◽  
Fibre Matrix ◽  
Fibre Reinforced Composites

The fracture behaviour of long fibre reinforced composites is predetermined mainly by properties of fibre-matrix interface. The matrix prepared by pyrolysis of polysiloxane resin possesses ability to resist high temperatures without significant damage under oxidising atmosphere. The application is therefore limited by fibres and possible changes in the fibre matrix interface. The study of development of interface during high temperature exposition is the main aim of this contribution. Application of various techniques as FIB, GIS, TEM, XRD allowed to monitor microstructural changes in the interface of selected places without additional damage caused by preparation. Additionally, it was possible to obtain information about damage, the crack formation, caused by the heat treatment from the fracture mechanics point of view.

Numerical Study of the Progression of the Micromechanical Debonding Damage in Composites

2018 ◽  
Vol 774 ◽  
pp. 644-649
Author(s):  
M.L. Velasco ◽  
Federico París ◽  
E. Correa
Keyword(s):  
Scale Effect ◽  
Release Rate ◽  
Transverse Crack ◽  
Numerical Study ◽  
Multiscale Model ◽  
Second Phase ◽  
Matrix Interface ◽  
Kinked Crack ◽  
The Matrix ◽  
Fibre Matrix

This paper deals with the study of the actual progression of the damage in the 90 degrees lamina of a composite. It has been proved and observed that isolated debondings between fibres and matrix are the first manifestation of damage in the weakest lamina, the 90 degrees lamina in a [0,90]S laminate. It was also numerically supported that this first phase was independent of the thickness of the 90 degrees lamina, not being then affected by the “scale effect”. The continuation of this first phase of damage is the objective of the present paper. To this end, a multiscale model is created involving the debonding between fibre and matrix and studying the kink of this crack, abandoning the fibre-matrix interface and entering into the matrix to produce a meso-transverse crack in the 90 degrees ply. The study is based on the application of Fracture Mechanics to an incipient kinked crack that starts from a debonding between fibre and matrix. It is concluded that this second phase of damage, playing with the thickness of the 90 degrees lamina, is not affected by the scale effect, as the variation of the energy release rate of the kinked crack is not significantly influenced by the variation of the thickness of the lamina.

On the mechanism of tensile fracture in notched fibre reinforced plastics

1978 ◽  
Vol 361 (1706) ◽  
pp. 325-341 ◽  
Keyword(s):  
Fracture Stress ◽  
Transverse Crack ◽  
Fracture Criterion ◽  
Experimental Results ◽  
Tensile Fracture ◽  
Structural Factors ◽  
Matrix Interface ◽  
Reinforced Plastics ◽  
Fibre Matrix ◽  
Fracture Processes

By observation of the tensile fracture processes occurring in continuous fibre reinforced plastics, the micro-structural factors which govern the unstable propagation of a transverse crack have been identified. A tensile fracture criterion is thereby developed in which the notch sensitivity is related to the properties of the fibre, matrix and fibre/ matrix interface. The fracture criterion is applied to elliptically notched laminates, whence predictions of the effect of notch size on tensile fracture stress are compared with experimental results for circular notches of various diameters.

scholarly journals Routine evaluation of Interfacial Adhesion in Fibre Reinforced Plastics

1994 ◽  
Vol 3 (6) ◽  
pp. 096369359400300
Author(s):  
E.U. Okoroafor ◽  
A–M. Priston ◽  
R. Hill
Keyword(s):  
Interfacial Adhesion ◽  
Strain Range ◽  
Relative Number ◽  
Stress And Strain ◽  
Matrix Interface ◽  
Interfacial Failure ◽  
Reinforced Plastics ◽  
Transverse Tension ◽  
Damage Process ◽  
Fibre Matrix

The predominant damage process occurring, when unidirectional composites are subjected to transverse tension, is interfacial failure events which are detected as acoustic emission(AE) by a transducer in contact with the test piece. The stress and strain range over which these AE events occur determine the strength of the fibre—matrix interface, while the relative number of recorded events give indication as to the interfacial failure mode.

scholarly journals Exploration of Nano Fillers (Multi Walled Carbon Nano Tubes and Graphene Powders) in the Reinforcement of Epoxy/Glass Fibre Polymers (GFRP)

2019 ◽  
Vol 8 (12) ◽  
pp. 2718-2722
Keyword(s):  
Mechanical Properties ◽  
Glass Fibre ◽  
Experimental Investigations ◽  
Matrix Interface ◽  
Gfrp Composites ◽  
Reinforced Polymers ◽  
The Matrix ◽  
Glass Fibre Reinforced ◽  
Carbon Nano Tubes ◽  
Fibre Matrix

Variations in the mechanical properties of the glass fibre reinforced polymers were seen when exploring nano fillers such as Multi Walled Carbon Nano Tubes (MWCNTs) and graphene powders for reinforcement. GFRP composites when fabricated with increase in percentage weights of MWCNTs and graphene get better interfacial bonding with the matrix. Nano fillers improve the performance of the composites. This paper deals with the examination and experimental investigations carried out for the prediction of the enhancement of mechanical properties on GFRP reinforced with MWCNTs and graphene powders. GFRP composites were fabricated with variations in the amount of nano fillers in percentage weights of 2%, 4%, 6%, 8% and 10% wt. MWCNTs and graphene powders. The method used for reinforcement of resin with nano fillers was ultrasonication method meant for avoiding voids. A tendency for the mechanical properties to deteriorate was observed when nano fillers added were beyond certain weights of MWCNTs and graphene powders. This could be due to the agglomeration of nano fillers that change the fibre/matrix interface. Graphene nano fillers opts to be better compared to MWCNTs since the fabricated graphene reinforced glass fibre specimens have a better performance than GFRP specimens reinforced with MWCNTs.

Dynamic fibre sliding along debonded, frictional interfaces

2006 ◽  
Vol 462 (2068) ◽  
pp. 1081-1106 ◽  
Author(s):  
Q.D Yang ◽  
A Rosakis ◽  
B.N Cox
Keyword(s):  
Wave Speed ◽  
Constitutive Law ◽  
Inertial Effects ◽  
Matrix Interface ◽  
Complete Understanding ◽  
Displacement Fields ◽  
Loading Rates ◽  
The Matrix ◽  
Loading Problem ◽  
Fibre Matrix

The problem is considered of a fibre that is driven dynamically, by compression at one end, into a matrix. The fibre is not initially bonded to the matrix, so that its motion is resisted solely by friction. Prior work based on simplified models has shown that the combination of inertial effects and friction acting over long domains of the fibre–matrix interface gives rise to behaviour that is far more complex than in the well-known static loading problem. The front velocity may depart significantly from the bar wave speed and regimes of slip, slip/stick and reverse slip can exist for different material choices and loading rates. Here more realistic numerical simulations and detailed observations of dynamic displacement fields in a model push-in experiment are used to seek more complete understanding of the problem. The prior results are at least partly confirmed, especially the ability of simple shear-lag theory to predict front velocities and gross features of the deformation. Some other fundamental aspects are newly revealed, including oscillations in the interface stresses during loading; and suggestions of unstable, possibly chaotic interface conditions during unloading. Consideration of the experiments and two different orders of model suggest that the tentatively characterized chaotic phenomena may arise because of the essential nonlinearity of friction, that the shear traction changes discontinuously with the sense of the motion, rather than being associated with the details of the constitutive law that is assumed for the friction. This contrasts with recent understanding of instability and ill-posedness at interfaces loaded uniformly in time, where the nature of the assumed friction law dominates the outcome.

scholarly journals The Influence of Mixing Methods of Epoxy Composition Ingredients on Selected Mechanical Properties of Modified Epoxy Construction Materials

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 411
Author(s):  
Izabela Miturska ◽  
Anna Rudawska ◽  
Miroslav Müller ◽  
Monika Hromasová
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Construction Materials ◽  
Preliminary Heating ◽  
Epoxy Composition ◽  
Mixing Speed ◽  
Adhesive Composition ◽  
Adhesive Compositions ◽  
The Matrix ◽  
Level Of Significance

The proper process of preparing an adhesive composition has a significant impact on the degree of dispersion of the composition ingredients in the matrix, as well as on the degree of aeration of the resulting composition, which in turn directly affects the strength and functional properties of the obtained adhesive compositions. The paper presents the results of tensile strength tests and SEM microphotographs of the adhesive composition of Epidian 57 epoxy resin with Z-1 curing agent, which was modified using three fillers NanoBent ZR2 montmorillonite, CaCO3 calcium carbonate and CWZ-22 active carbon. For comparison purposes, samples made of unmodified composition were also tested. The compositions were prepared with the use of six mixing methods, with variable parameters such as type of mixer arm, deaeration and epoxy resin temperature. Then, three mixing speeds were applied: 460, 1170 and 2500 rpm. The analyses of the obtained results showed that the most effective tensile results were obtained in the case of mixing with the use of a dispersing disc mixer with preliminary heating of the epoxy resin to 50 °C and deaeration of the composition during mixing. The highest tensile strength of adhesive compositions was obtained at the highest mixing speed; however, the best repeatability of the results was observed at 1170 rpm mixing speed. Based on a comparison test of average values, it was observed that, in case of modified compositions, the values of average tensile strength obtained at mixing speeds at 1170 and 2500 rpm do not differ significantly with the assumed level of significance α = 0.05.

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