Microscopical observations of inter-fibre failure under tension

2018 ◽  
Vol 155 ◽  
pp. 213-220 ◽  
Author(s):  
Elena Correa ◽  
María Inmaculada Valverde ◽  
María Luisa Velasco ◽  
Federico París
Keyword(s):  
Fibre Failure

scholarly journals Characterisation of Impact Damage of Composite Structures Using Wavelet-Based Fusion of Ultrasonic and Optical Images

2014 ◽  
Vol 23 (5) ◽  
pp. 096369351402300
Author(s):  
Andrzej Katunin ◽  
Pawel Kostka
Keyword(s):  
Composite Structures ◽  
Damage Identification ◽  
Impact Damage ◽  
Human Perception ◽  
Laminated Plates ◽  
Low Velocity ◽  
Fusion Algorithm ◽  
Fibre Failure ◽  
Optical Images ◽  
The Impact

This paper presents the novel approach for the impact damage characterisation of composite structures, which is based on fusion of ultrasonic scans and optical images. Both internal (inter-fibre failure, fibre failure, delaminations) and external (scratches and surface cracks) damages occurred in the composite structures during their operation need to be analysed due to their occurrence on both of these levels, especially in the case of impact damages. The presented approach allows for the improvement of the characterisation quality, i.e. the whole damaged area could be detected and localized. In order to assure the proper damage identification the wavelet-based fusion with application of appropriate wavelets and parameters of a fusion algorithm was used, which allows for distinction of different types of damages and overall improvement of the resulted image with respect to the human perception capability. The approach was validated experimentally on the glass-epoxy laminated plates after the low-velocity impacts. Representative cases of damaged structure were presented and analysed.

scholarly journals Time and Cycle Dependence in High Temperature Fatigue of Ceramic Matrix Composites

1996 ◽  
Author(s):  
Marc Steen ◽  
José-Lorenzo Vallés
Keyword(s):  
High Temperature ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Behaviour ◽  
Time Dependent ◽  
Matrix Composites ◽  
Fibre Failure ◽  
High Temperature Fatigue ◽  
Stress Ratios ◽  
Cyclic Damage

The high temperature fatigue behaviour of two 2D reinforced ceramic matrix composites (CMCs) Is studied under high vacuum conditions. The mechanical loads imposed result in matrix cracking upon first loading, so that continued cyclic loading results in progressive interfacial debonding and/or matrix crack multiplication, as well as fibre failure. In order to investigate whether the fatigue life is mainly governed by time-dependent creep or by cyclically induced fatigue damage, a range of frequencies and two stress ratios are explored in stress controlled fatigue tests. The results obtained indicate that under pulsating fatigue (positive stress ratios or tension-tension) the material response is affected by both creep and fatigue mechanisms. The cyclic damage component gains in relative importance with increasing test frequency. Under reversed loading conditions (negative stress ratios), and depending on the creep strength mismatch between the fibres and the matrix, the time-dependent damage component can be largely suppressed, and the composite fatigue behaviour can become close to purely cycle-dependent. In both cases and for both composites fatigue failure is triggered by fibre failure.

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