Nondestructive Characterization of Fiber-Matrix Adhesion in Composites by Vibration Damping

1995 ◽  
Vol 385 ◽  
Author(s):  
Weiqun Gu ◽  
Guo-Quan Lu ◽  
H. Felix Wu ◽  
Stephen L. Kampe ◽  
P. Ross Lichtenstein ◽  
...  

ABSTRACTAdhesion at fiber-matrix interface in fiber-reinforced composites plays an important role in controlling the mechanical properties and overall performance of composites. Among the many available tests applicable to the composite interfaces, vibration damping technique has the advantages of being nondestructive as well as highly sensitive. We set up an optical system to measure the damping tangent delta of a cantilever beam, and correlated the damping data in glass-fiber reinforced epoxy-resin composites with transverse tensile strength which is also a qualitative measurement of adhesion at fiber-matrix interface. Four different composite systems containing three different glass-fiber surface treatments were tested and compared. Our experimental results showed an inverse relationship between damping contributed by the interface and composite transverse tensile strength.

Scanning ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Enze Jin ◽  
Denghao Ma ◽  
Zeshuai Yuan ◽  
Wenting Sun ◽  
Hao Wang ◽  
...  

Here, we show that when the oxidation treatment temperature exceeded 600°C, the tensile strength of SiC/SiC begins to decrease. Oxidation leads to the damages on the PyC fiber/matrix interface, which is replaced by SiO2 at higher temperature. The fracture mode converts from fiber pull-out to fiber-break as the fiber/matrix interface is filled with SiO2. Oxidation time also plays an important role in affecting the tensile strength of SiC/SiC. The tensile modulus decreases with temperature from RT to 800°C, then increases above 800°C due to the decomposition of remaining CSi x O y and crystallization of the SiC matrix. A special surface densification treatment performed in this study is confirmed to be an effective approach to reduce the oxidation damages and improve the tensile strength of SiC/SiC after oxidation.


PAMM ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Benedikt Rohrmüller ◽  
Michael Schober ◽  
Kerstin Dittmann ◽  
Peter Gumbsch ◽  
Jörg Hohe

Author(s):  
Kulwinder Singh Chani ◽  
JS Saini ◽  
H Bhunia

This work deals with the accelerated aging of the bolted joints prepared from glass fiber-reinforced nanocomposite laminates. ASTM D5961 was used to design the bolted joint, and the geometric parameters, i.e. width-to hole-diameter ( W/ D) ratio and edge distance-to-hole diameter ( E/ D) ratio were fixed to 6 and 5, respectively. ASTM D1544 was used for accelerated aging, and a maximum of 500 h cyclical ultraviolet exposure, 8 h of ultraviolet radiation at 60 ℃ followed by 4 h of condensation at 50 ℃, was given to the specimens. A full factorial design of experiment was conducted on important control factors, i.e. aging time, bolt torque, and material variation, using response surface methodology. To investigate the effect of nanoclay content, a range of 0–5 wt% was investigated. Specimens with 3 wt% of nanoclay demonstrated optimum tensile strength and were selected to manufacture the bolted joint. Nanoplatelets having high aspect ratio increased the specific surface area and thus the tensile strength of the nanocomposite. It was found that the strength of the joints prepared with and without the nanoclay content decreased with the increase in the duration of aging. However, the joints with the nanoclay content had higher failure loads. The strength retention in the joints with nanoclay content was more in comparison to the joints made with neat epoxy. Nanoclay acted as a mechanical interlock at the fiber–matrix interface and improved the interfacial bond strength. A good dispersion of nanoclay also acts as a barrier to the moisture, which eventually reduces the degradation of the composite material due to the lesser fiber–matrix de-bonding under accelerated aging conditions.


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