scholarly journals An Experimental Analysis of Fracture Mechanisms by Acoustic Emission of Woven Composite Bolted Assembly = Analyse Expérimentale des Mécanismes de Rupture par Émission Acoustique des Assemblages Boulonnés en Composite Tissé

Author(s):  
Mostefa Baccouche ◽  
Youcef Faci
Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 208
Author(s):  
O.F. Pacheco-Salazar ◽  
Shuichi Wakayama ◽  
L.A. Can-Herrera ◽  
M.A.A. Dzul-Cervantes ◽  
C.R. Ríos-Soberanis ◽  
...  

In this research, damage in bone cements that were prepared with core-shell nanoparticles was monitored during four-point bending tests through an analysis of acoustic emission (AE) signals. The core-shell structure consisted of poly(butyl acrylate) (PBA) as rubbery core and methyl methacrylate/styrene copolymer (P(MMA-co-St)) as a glassy shell. Furthermore, different core-shell ratios 20/80, 30/70, 40/60, and 50/50 were prepared and incorporated into the solid phase of the bone cement formulation at 5, 10, and 15 wt %, respectively. The incorporation of a rubbery phase into the bone cement formulation decreased the bending strength and bending modulus. The AE technique revealed that the nanoparticles play an important role on the fracture mechanism of the bone cement, since a higher amount of AE signals (higher amplitude and energy) were obtained from bone cements that were prepared with the nanoparticles in comparison with those without nanoparticles (the reference bone cement). The SEM examination of the fracture surfaces revealed that all of the bone cement formulations exhibited stress whitening, which arises from the development of crazes before the crack propagation. Finally, the use of the AE technique and the fracture surface analysis by SEM enabled insight into the fracture mechanisms that are presented during four-point bending test of the bone cement containing nanoparticles.


2018 ◽  
Vol 176 (1) ◽  
pp. 265-277 ◽  
Author(s):  
Deyi Jiang ◽  
Kainan Xie ◽  
Jie Chen ◽  
Shuilin Zhang ◽  
William Ngaha Tiedeu ◽  
...  

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3775
Author(s):  
Chiara Bertolin ◽  
Lavinia de Ferri ◽  
Filippo Berto

The main issue of wood is its sensitivity to Relative Humidity (RH) variations, affecting its dimensional stability, and thus leading to crack formations and propagations. In situ structural health monitoring campaigns imply the use of portable noninvasive techniques such as acoustic emission, used for real-time detection of energy released when cracks form and grow. This paper proposes a calibration method, i.e., acoustic emission, as an early warning tool for estimating the length of new formed cracks. The predictability of ductile and brittle fracture mechanisms based on acoustic emission features was investigated, as well as climate-induced damage effect, leading to a strain-hardening mechanism. Tensile tests were performed on specimens submitted to a 50% RH variation and coated with chemicals to limit moisture penetration through the radial surfaces. Samples were monitored for acoustic emission using a digital camera to individuate calibration curves that correlated the total emitted energy with the crack propagation, specifically during brittle fracture mechanism, since equations provide the energy to create a new surface as the crack propagates. The dynamic surface energy value was also evaluated and used to define a Locus of Equilibrium of the energy surface rate for crack initiation and arrest, as well as to experimentally demonstrate the proven fluctuation concept.


2020 ◽  
Vol 20 (11) ◽  
pp. 6064-6074 ◽  
Author(s):  
Mengchuan Li ◽  
Yunze He ◽  
Zhiqiang Meng ◽  
Jun Wang ◽  
Xiang Zou ◽  
...  

2010 ◽  
Vol 434-435 ◽  
pp. 57-60 ◽  
Author(s):  
Figen Kaya

In this work damage micro-mechanisms of two different types of fibre reinforced composites are investigated by acoustic emission, AE. Ceramic based oxide fibre reinforced mullite matrix composite and metallic based SiC fibre reinforced titanium matrix composites exhibit different fracture mechanisms during loading and AE technique could pinpoint these damage mechanisms based on the AE responses detected simultaneously. The results show that in a ceramic matrix composite, the identification of fibre fracture and matrix cracking requires careful analysis of the AE data as both fibres and matrix break in brittle manner. Whereas the separation of fibre fracture from the ductile tearing of matrix ligaments could be easier in metallic based composites, such as titanium matrix composites.


2017 ◽  
Vol 51 (4) ◽  
pp. 1047-1062 ◽  
Author(s):  
Li Ning ◽  
Zhang Shicheng ◽  
Zou Yushi ◽  
Ma Xinfang ◽  
Wu Shan ◽  
...  

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