Characterization of composite materials damage under quasi-static three-point bending test using wavelet and fuzzy C-means clustering

2012 ◽  
Vol 46 (15) ◽  
pp. 1795-1808 ◽  
Author(s):  
Mohamad Fotouhi ◽  
Hossein Heidary ◽  
Mehdi Ahmadi ◽  
Farzad Pashmforoush
1995 ◽  
Vol 117 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Robert Greif ◽  
Benjamin Hebert

This research combines theoretical and experimental approaches for dynamic material characterization of composite materials. The samples studied include continuous fiber graphite/epoxy beams with various symmetric lay-up configurations. Included are laminated beams with the following lay-ups: [08/908]s, [908/08]s, [(45/0/−45)5]s and [(0/45/0/−45)3/90/0/01/2]s. The resonant dwell technique is used to determine the material damping and the real part of the dynamic flexural modulus of double cantilever beam specimens in the first mode of vibration over the frequency range 25 Hz to 300 Hz. The dynamic properties are determined as a function of the frequency of oscillation at room temperature. In addition, the Metravib Viscoanalyzer, based on off-resonance tests, is also used to provide another source of experimental data for comparison. Although the Viscoanalyzer was originally intended for testing viscoelastic polymers, the present research establishes the limits of applicability for composite materials, with particular emphasis on the three point bending test. Comparisons and limitations of both techniques are critically discussed.


2011 ◽  
Vol 110-116 ◽  
pp. 1221-1228
Author(s):  
Fotouhi Mohamad ◽  
Heidary Hossein ◽  
Pashmforoush Farzad ◽  
Mehdi Ahmadi Najaf Abadi

In this study, acoustic emission (AE) monitoring with a Fuzzy C-Means (FCM) clustering is developed to detect the delamination process during quasi-static 3-point bending test on glass/epoxy composite materials. The main fracture mode that should be emphasized and has an effect on the residual strength of composite materials is delamination. The 3-point bending test simulates thrust force due to drilling process without backup plate. In this work, two types of specimen at different layups, woven [0,90] s and unidirectional [0] s, leading to different levels of damage evolution, were studied. Using acoustic emission monitoring can help to detect these fracture mechanisms. The obtained AE signals were classified using FCM. Dependency percentage of damages in each class is different in two specimens. Three parameters (Peak Amplitude, Count, and Average Frequency) were used to validate the FCM based classification. The results show that there is a good agreement with the FCM classification and microscopic observation by SEM.


2006 ◽  
Vol 321-323 ◽  
pp. 913-916
Author(s):  
Sang Ll Lee ◽  
Yun Seok Shin ◽  
Jin Kyung Lee ◽  
Jong Baek Lee ◽  
Jun Young Park

The microstructure and the mechanical property of liquid phase sintered (LPS) SiC materials with oxide secondary phases have been investigated. The strength variation of LPS-SiC materials exposed at the elevated temperatures has been also examined. LPS-SiC materials were sintered at the different temperatures using two types of Al2O3/Y2O3 compositional ratio. The characterization of LPS-SiC materials was investigated by means of SEM with EDS, three point bending test and indentation test. The LPS-SiC material with a density of about 3.2 Mg/m3 represented a flexural strength of about 800 MPa and a fracture toughness of about 9.0 MPa⋅√m.


2018 ◽  
Vol 11 (4) ◽  
pp. 339-344 ◽  
Author(s):  
Yucheng Huang ◽  
Yanhua Guan ◽  
Linbing Wang ◽  
Jian Zhou ◽  
Zhi Ge ◽  
...  

2014 ◽  
Vol 580-583 ◽  
pp. 2213-2219 ◽  
Author(s):  
Lin Liao ◽  
Sergio Cavalaro ◽  
Albert de la Fuente ◽  
Antonio Aguado

Many researches have been conducted in past decades for promoting the application of steel fibre reinforced concrete (SFRC), either conventional or self-compacting. However, the differences of post-crack behaviour and the properties of these two types of concrete remains unclear. The objective of this paper is to analyse such differences in terms of flexural behaviour, fibre orientation and contribution as well as the fibre content. For that, an extensive experimental campaign was carried out. In total 3 mixes of self-compacting and 3 mixes with traditional concrete were produced with the nominal fibre contents of 30kg/m3, 45kg/m3 and 60kg/m3. In each series, specimens were produces and characterized by three point bending test (code EN 14651) and inductive test. The results illustrate how fibre orientation and distribution justify the differences in the mechanical behaviour of the materials and the scatter of the bending test results.


2017 ◽  
Vol 891 ◽  
pp. 542-546 ◽  
Author(s):  
Ladislav Fojtl ◽  
Soňa Rusnáková ◽  
Milan Žaludek ◽  
Alexander Čapka ◽  
Lukáš Maňas

Jute fabric is well-known reinforcing material in composite science, however, there is a necessity to treat these fabrics to reduce moisture uptake and improve properties. Nevertheless, every modification increases the cost and reduces the possible applications. Presented research deals with an investigation of possibility to use untreated jute in various fabric weight as a reinforcing material in sandwich structures facings. Untreated jute reinforcements and two types of cork cores were saturated in one step during vacuum infusion creating a lightweight sandwich composite. All samples were mechanically tested in three-point bending test. Experimental results showed the most appropriate material combination and produced sandwich structure are proposed for design applications.


2004 ◽  
Vol 261-263 ◽  
pp. 1481-1486 ◽  
Author(s):  
Sang Ll Lee ◽  
J.O. Jin ◽  
J.S. Park ◽  
Jong K. Lee ◽  
Byeong Hyeon Min ◽  
...  

This study dealt with the characterization of MoSi2 based composites containing three types of additive materials such as SiC, NbSi2 and ZrO2 particles have been investigated, based on the detailed examination of their microstructures and fracture surfaces. The effects of reinforcing materials on the high temperature strength of MoSi2 based composites have been also examined. MoSi2 based composites were fabricated by the hot press process under the vacuum atmosphere. The volume fraction of reinforcing materials in the composite system was fixed as 20 %. The microstructures and the mechanical properties of MoSi2 based composites were investigated by means of SEM, EDS, XRD and three point bending test.


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