scholarly journals Determination of dynamic delamination toughness of a graphite-fiber/epoxy composite using Hopkinson pressure bar

2005 ◽  
Vol 26 (2) ◽  
pp. 165-180 ◽  
Author(s):  
Xiang-Fa Wu ◽  
Yuris A. Dzenis
Keyword(s):  
Epoxy Composite ◽  
Graphite Fiber ◽  
Hopkinson Pressure Bar ◽  
Delamination Toughness ◽  
Pressure Bar

scholarly journals Generation of R-Curve from 4ENF Specimens: An Experimental Study

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
V. Alfred Franklin ◽  
T. Christopher
Keyword(s):  
Composite Materials ◽  
Fracture Energy ◽  
Epoxy Composite ◽  
Beam Theory ◽  
Fiber Direction ◽  
Crack Growth Resistance Curve ◽  
Aerospace Applications ◽  
Delamination Toughness ◽  
Theory Solution

The experimental determination of the resistance to delamination is very important in aerospace applications as composite materials have superior properties only in the fiber direction. To measure the interlaminar fracture toughness of composite materials, different kinds of specimens and experimental methods are available. This article examines the fracture energy of four-point end-notched flexure (4ENF) composite specimens made of carbon/epoxy and glass/epoxy. Experiments were conducted on these laminates and the mode II fracture energy, GIIC, was evaluated using compliance method and was compared with beam theory solution. The crack growth resistance curve (R-curve) for these specimens was generated and the found glass/epoxy shows higher toughness values than carbon/epoxy composite. From this study, it was observed that R-curve effect in 4ENF specimens is quite mild, which means that the measured delamination toughness, GIIC, is more accurate.

Determination of the Temperature Dependent Dynamic Response of Elastomeric Materials Using the Split Hopkinson Pressure Bar

2006 ◽  
Author(s):  
Glenn E. Vallee ◽  
Steven D. Army
Keyword(s):  
Dynamic Modulus ◽  
Split Hopkinson Pressure Bar ◽  
Low Cost ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Temperature Dependent ◽  
Elastomeric Materials ◽  
Split Hopkinson ◽  
Pressure Bar

An effective, low cost method of determining the temperature dependent dynamic response of elastomeric materials at high strain rates using the Split Hopkinson Pressure Bar (SHPB) is developed. The test system allows the determination of the dynamic modulus at temperatures up to 150°C with control of specimen temperature within ± 3°C without the use of specialized equipment or cumbersome heating and positioning fixtures often required for temperature dependent testing. The test specimen is heated using a low cost electric resistance tape, which heats the transmitter and incident bars adjacent to the specimen. A finite element analysis is performed to predict the temperature vs. time response of the test specimen, which is verified using a simple thermocouple arrangement. The dynamic stress-strain response of a nitrile elastomer, commonly used as an impact absorber, is investigated over temperatures ranging from 20°C to 110°C at strain rates between 3000/s and 3500/s. The effect of strain rate on the dynamic modulus is not significant, but the effect of temperature is dramatic. The dynamic modulus of the nitrile is reduced by more than 60% at 110°C.

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