Effects of Temperature on Mode II Fracture Toughness of Multidirectional CFRP Laminates

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1717-1723 ◽  
Author(s):  
Hyoung Soo Kim ◽  
Wen Xue Wang ◽  
Yoshihiro Takao ◽  
Goichi Ben
Keyword(s):  
Fracture Toughness ◽  
Fiber Orientation ◽  
Fracture Behavior ◽  
Sem Analysis ◽  
Mode Ii ◽  
Interlaminar Fracture ◽  
Cfrp Laminates ◽  
Mode Ii Fracture Toughness ◽  
Matrix Property ◽  
Effects Of Temperature

End notched flexure (ENF) tests were performed to investigate the effects of temperature and fiber orientation on Mode II interlaminar fracture behavior, GIIC (GII at the crack initiation), of carbon fiber-reinforced epoxy composites, T800H/#3631. The values of GIIC for three kinds of laminates, [012//012], [22.5/-22.5/08/-22.5/22.5//-22.5/22.5/08/22.5/-22.5] and [45/-45/08/-45/45//-45/45/08/45/-45], with a pre-cracked interface, that is // in each laminate, were obtained at three temperatures, i.e. -100°C, 25°C and 150°C. It is shown that GIIC is obviously affected by the temperature and fiber orientation. The scanning electron microscope (SEM) observation was also carried out to investigate the fracture surface. SEM analysis suggested that the decreased Mode II interlaminar fracture toughness for all kinds of specimens at high temperature could be attributed to temperature-induced matrix property change or fiber-matrix interfacial weakening.

Interlaminar Fracture Toughness of Composite Laminate with Splicing Plies

2011 ◽  
Vol 194-196 ◽  
pp. 1697-1702
Author(s):  
Li Liang ◽  
Pu Rong Jia ◽  
Gui Qiong Jiao
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Tensile Testing ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Fiber Reinforced ◽  
Interlaminar Fracture ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness ◽  
Delamination Failure

Delamination is one of the important damage modes in the fiber-reinforced composite laminates. The interlaminar fracture toughness is the key parameter in delamination failure analysis of composites. The stress analysis by a finite element modeling has shown that the shear stress is very large near the ply splicing area. So the delamination failure is mainly dependent on the mode II fracture toughness. A new way of loading in tensile testing is proposed for the measurement of mode II fracture toughness. Specific specimen with splicing plies has been designed and used for the experiment. Testing study on the carbon-fiber-reinforced laminate with ply splicing was performed. Steady crack propagation has been seen by the tensile testing of the specimen. Mode II fracture toughness GIIC of the laminate has been determined by the experiment data analysis. The experiment and numerical analysis shows that the tensile testing for the measurement of mode II interlaminar fracture toughness is feasible.

Interlaminar and Intralaminar Fracture Behavior of Carbon Fiber Reinforced Polymer Composites

2016 ◽  
Vol 713 ◽  
pp. 325-328 ◽  
Author(s):  
Sandip Haldar ◽  
Claudio S. Lopes ◽  
Carlos Gonzalez
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Fracture Behavior ◽  
Compact Tension ◽  
Mode Ii ◽  
Fiber Reinforced ◽  
Fiber Reinforced Polymer Composites ◽  
Mode Ii Fracture Toughness ◽  
Carbon Fiber Reinforced ◽  
Woven Reinforcement

Interlaminar and intralaminar fracture behavior of carbon fiber reinforced composites have been experimentally studied. Unidirectional, woven reinforcement and thermoplastic and thermoset polymer matrix laminates have been characterized using double cantilever beam (DCB) and end notch flexure (ENF) specimens for Mode-I and Mode-II fracture toughness, respectively and compact tension (CT) specimens for intralaminar fracture. AS4/PEEK, AS4/8552 and AGP193PW/8552 laminates have been characterized in this study. The fracture toughness determined from the experimental data could be related to the constituents and reinforcements. It has been observed between the two UD laminates, AS4/PEEK exhibit higher fracture resistance under both interlaminar and intralaminar fracture. Woven reinforcement is found to show higher mode-II interlaminar fracture toughness.

Mode II Interlaminar Fracture Toughness of CNF-CFRP Hybrid Composite

2006 ◽  
Author(s):  
Masahiro Arai ◽  
Koh-Ichi Sugimoto ◽  
Morinobu Endo
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Hybrid Composites ◽  
Beam Theory ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Cfrp Laminates ◽  
Nano Fiber ◽  
Hybrid Laminates

Interlaminar fracture toughness for mode II deformation were investigated for carbon fiber (CF)/epoxy laminates toughened by carbon-nano-fiber/epoxy interlayer. Vapor grown carbon fiber (VGCF) and vapor grown carbon ‘nano’ fiber (VGNF) were chosen as the stiffeners for the interlayer. In order to illustrate the effect of the interlayer on the model II fracture toughness of the laminates, several types of CFRP/CNF hybrid laminates were fabricated, which are composed of unidirectional prepregs and carbon nano fiber varying the thickness of the interlayer. Mode II interlaminar fracture toughnesses of the hybrid composites were evaluated by end notched flexure (ENF) test using short-type beam specimens. The fracture toughnesses were calculated by traditional beam theory using the energy release rate of the crack. From the experimental results, it is confirmed that the mode II interlaminar fracture toughnesses for hybrid laminates are from 2.0 to 3.0 times higher than that of original CFRP laminates, and the optimal thickness (area density) of the CNF interlayer exists. The difference in the effect of the interlayer fracture properties under mode II deformation was discussed on the bases of fractographic observations derived from scanning electric microscope.

Experimental Investigation on Mode II Fracture Toughness KIIC of Concrete and Fracture Behavior

2006 ◽  
Vol 324-325 ◽  
pp. 1149-1152 ◽  
Author(s):  
Shi Lang Xu ◽  
Hong Bo Gao ◽  
Xiu Fang Zhang
Keyword(s):  
Fracture Toughness ◽  
Crack Length ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Discontinuity Point ◽  
Fracture Load ◽  
Mode Ii ◽  
Mode Ii Fracture ◽  
Double Edge ◽  
Mode Ii Fracture Toughness

Using the double-edge notched geometry proposed by Xu and Reinhardt recently, the dimension of 200 mm×200 mm×100mm concrete cube specimens, of which the crack length are 10 mm, 20 mm, 30mm, 40mm, 50mm respectively, are designed to experimentally measure mode II fracture toughness KIIC of concrete. For almost all specimens, typical shear fracture features i.e. approximately 0º initial cracking angle as well the following crack forwards propagation along the direction of ligament is phenomenally observed. This fact strongly confirms that this double-edge notched geometry is validly and capable of being utilized as a mode II fracture geometry to evaluate mode II fracture behavior. Then, from the discontinuity point of the measured load-displacement plot, the critical shear fracture load Pc is determined and the corresponding mode II fracture toughness KIIC is also calculated using the formula developed by Xu and Reinhardt. The computed results show that KIIC has no dependency on initial crack length, about 3.36MPa·m1/2 for the tested specimens.

Improvement of Vibration Damping Capacity and Fracture Toughness in Composite Laminates by the Use of Polymeric Interleaves

1999 ◽  
Author(s):  
Ronald F. Gibson ◽  
Hui Zhao
Keyword(s):  
Fracture Toughness ◽  
Composite Laminates ◽  
Critical Thickness ◽  
Vibration Damping ◽  
Thickness Effect ◽  
Damping Capacity ◽  
Mode Ii ◽  
Interlaminar Fracture Toughness ◽  
Interlaminar Fracture ◽  
Mode Ii Fracture Toughness

Abstract It is shown that simultaneous improvement of vibration damping capacity and interlaminar fracture toughness in composite laminates can be achieved by using polymeric interleaves between the composite laminae. The specific case of Mode II interlaminar fracture toughness and flexural damping capacity of interleaved composite laminates is studied. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping capacity. The Mode II energy release rate GIIc for all three composites increased linearly with increasing interleaf thickness up to a critical thickness, then dropped off with further increases in thickness. The damping loss factor η for all three composites increased linearly with increasing interleaf thickness up to the maximum thickness. Analytical models for predicting the influence of interleaves on GIIc and η are developed, along with a hypothesis for the critical thickness effect with regard to fracture toughness.

Sign in / Sign up

Export Citation Format

Share Document