Advanced Multi-Scale Composites Material Characterization for Fracture Toughness and Impact Resistance Applications

2010 ◽  
Author(s):  
Mohit Garg ◽  
Galib Abumeri ◽  
Frank Abdi
Keyword(s):  
Fracture Toughness ◽  
Material Characterization ◽  
Impact Resistance ◽  
Multi Scale

Concrete and Fiber Reinforced Concrete Subjected to Impact Loading

1985 ◽  
Vol 64 ◽  
Author(s):  
Surendra P. Shah
Keyword(s):  
Fracture Toughness ◽  
Tensile Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Basic Material ◽  
Strain History ◽  
Moderate Increase ◽  
Fiber Reinforced ◽  
The Impact

ABSTRACTDespite its extensive use, low tensile strength has been recognized as one of the major drawbacks of concrete. Although one has learned to avoid exposing concrete structures to adverse static tensile load, these cannot be shielded from short duration dynamic tensile stresses. Such loads originate from sources such as impact from missiles and projectiles, wind gusts, earthquakes and machine vibrations. The need to accurately predict the structural response and reserve capacity under such loading has led to an interest in the mechanical properties of the component materials at high rates of straining.One method to improve the resistance of concrete when subjected to impact and/or impulsive loading is by the incorporation of randomly distributed short fibers. Concrete (or Mortar) so reinforced is termed fiber reinforced concrete (FRC). Moderate increase in tensile strength and significant increases in energy absorption (toughness or impact-resistance) have been reported by several investigators in static tests on concrete reinforced with randomly distributed short steel fibers. A theoretical model to predict fracture toughness of FRC is proposed. This model is based on the concept of nonlinear elastic fracture mechanics.As yet no standard test methods are available to quantify the impact resistance of such composites, although several investigators have employed a variety of tests including drop weight, swinging pendulums and the detonation of explosives. These tests though useful in ascertaining the relative merits of different composites do not yield basic material characteristics which can be used for design.The author has recently developed an instrumented Charpy type of impact test to obtain basic information such as load-deflection relationship, fracture toughness, crack velocity and load-strain history during an impact event. From this information, a damage based constitutive model was proposed. Relative improvements in performance due to the addition of fibers as observed in the instrumented tests are also compared with other conventional methods.

Microstructure and Mechanical Properties of Multi-Scale Titanium Diboride Matrix Nanocomposite Ceramic Tool Materials

2010 ◽  
Vol 431-432 ◽  
pp. 523-526
Author(s):  
Han Lian Liu ◽  
Chuan Zhen Huang ◽  
Shou Rong Xiao ◽  
Hui Wang ◽  
Ming Hong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Transgranular Fracture ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Micro Scale ◽  
Multi Scale ◽  
Nano Scale ◽  
Matrix Nanocomposite

Under the liquid-phase hot-pressing technique, the multi-scale titanium diboride matrix nanocomposite ceramic tool materials were fabricated by adding both micro-scale and nano-scale TiN particles into TiB2 with Ni and Mo as sintering aids. The effect of content of nano-scale TiN and sintering temperature on the microstructure and mechanical properties was studied. The result showed that flexural strength and fracture toughness of the composites increased first, and then decreased with an increase of the content of nano-scale TiN, while the Vickers hardness decreased with an increase of the content of nano-scale TiN. The optimal mechanical properties were flexural strength 742 MPa, fracture toughness 6.5 MPa•m1/2 and Vickers hardness 17GPa respectively. The intergranular and transgranular fracture mode were observed in the composites. The metal phase can cause ductility toughening and crack bridging, while crack deflection and transgranular fracture mode could be brought by micro-scale TiN and nano-scale TiN respectively.

Mechanical Properties of Tank Car Steels Retired From the Fleet

2009 ◽  
Author(s):  
Peter C. McKeighan ◽  
David Y. Jeong ◽  
Joseph W. Cardinal
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Material Characterization ◽  
Laboratory Testing ◽  
Structural Integrity ◽  
Hazardous Materials ◽  
High Rate ◽  
Test Program ◽  
Testing Program ◽  
Toughness Testing

As a consequence of recent accidents involving the release of hazardous materials (hazmat), the structural integrity and crashworthiness of railroad tank cars have come under scrutiny. Particular attention has been given to the older portion of the fleet that was built prior to steel normalization requirements instituted in 1989. This paper describes a laboratory testing program to examine the mechanical properties of steel samples obtained from tank cars that were retired from the fleet. The test program consisted of two parts: (1) material characterization comprised of chemical, tensile and Charpy V-notch (CVN) impact energy and (2) high-rate fracture toughness testing. In total, steel samples from 34 tank cars were received and tested. These 34 tank cars yielded 61 different pre-1989 TC128-B conditions (40 shell and 21 head samples), three tank cars yielded seven different post-1989 TC128-B conditions (four shell and three head samples), and six tank cars yielded other material (A212, A515, and A285 steel) conditions (six shell and five head samples). The vast majority of the TC128-B samples extracted from retired tank cars met current TC128-B material specifications. Elemental composition requirements were satisfied in 97 percent of the population whereas the required tensile properties were satisfied in 82 percent of the population. Interpretation of the high-rate fracture toughness tests required dividing the pre-1989 fleet into quartiles that depended on year of manufacture or age, and testing three tank cars per quartile. Considering the high-rate fracture toughness results at 0°F for the pre-1989 fleet, 100 percent of the oldest two quartiles, 58 percent of the second youngest quartile, and 83 percent of the youngest quartile exhibited adequate or better fracture toughness (defined as toughness greater than 50 ksi√in). High-rate fracture toughness at –50°F was adequate for 83 percent of two quartiles (the youngest and second oldest), but the other two quartiles exhibited lower toughness with only 33 (2nd youngest) to 50 percent (oldest) exhibiting adequate properties.

Effect of Graphene Oxide on Interfacial Interactions and Fracture Toughness of Basalt Fiber-Reinforced Epoxy Composites

2020 ◽  
Vol 20 (11) ◽  
pp. 6760-6767
Author(s):  
Seong Hwang Kim ◽  
Soo-Jin Park
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Graphene Oxide ◽  
High Performance ◽  
Basalt Fiber ◽  
Superior Performance ◽  
Microstructured Fibers ◽  
Multi Scale ◽  
Fundamental Understanding ◽  
Interlaminar Shear

Multiscale hierarchy is a promising chemical approach that provides superior performance in syner-gistically integrated microstructured fibers and nanostructured materials in composite applications. The main purpose of this work was to introduce graphene oxide (GO) between an epoxy matrix and basalt fibers to improve mechanical properties by enhancing interfacial adhesion. The composites were reinforced with various concentrations of GO. For all of the fabricated composites, the optimum GO content was found to be 0.5 wt%, which improved the interlaminar shear strength and fracture toughness by 66.2% and 86.1%, respectively, compared with those of neat composites. We observed a direct linear relationship between fracture toughness and certain surface free energy. In addition, the fracture toughness mechanisms were illustrated using a crack theory based on morphology analyses of fracture surfaces. Such an effort could accelerate the conversion of multi-scale composites into high-performance materials and provide rational guidance and fundamental understanding toward realizing the theoretical limits of mechanical properties.

Comparison between Commercial and Synthesized Hyperbranched Polyesters Regarding Fracture Toughness of Epoxy Matrix

2015 ◽  
Vol 719-720 ◽  
pp. 110-113
Author(s):  
Thatiane Brocks ◽  
Veronica Ambrogi ◽  
Maria Odila Hilário Cioffi
Keyword(s):  
Fracture Toughness ◽  
Epoxy Matrix ◽  
Impact Resistance ◽  
Thermomechanical Properties ◽  
Weight Percentage ◽  
Hyperbranched Polyesters ◽  
Hyperbranched Poly ◽  
Sem Morphology ◽  
Toughness Improvement ◽  
Toughening Agent

A hyperbranched poly (butylene adipate) (HPBA) polymer was compared with a commercial dendritic polyol (Boltorn H311) as toughening agent for a commercial one-part epoxy resin, Cycom 890 RTM. Both modifiers were added in a weight percentage 1, 3, 5 and 10 %. Blends obtained were characterized through DMA and impact resistance (KIC). SEM morphology were also evaluated. The toughness improvement was achieved without substantial impairment on thermomechanical properties. Fractography analysis has evidenced the fracture standard changing from brittle to ductile by modifiers addition.

The Mechanical Characterization of Al2O3 Reinforced AL6061 Metal Matrix Composite

2015 ◽  
Vol 766-767 ◽  
pp. 257-262
Author(s):  
P. Mohan ◽  
M. Kathirvel ◽  
N. Azhagesan ◽  
M. Sivapragash
Keyword(s):  
Fracture Toughness ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Material Characterization ◽  
Metal Matrix ◽  
Treatment Process ◽  
Mechanical Characterization ◽  
Casting Process ◽  
Stir Casting

The aluminium based composites are increasingly being used in the transport, aerospace, marine, automobile and mineral processing industries. The widely used reinforcing materials for these composites are silicon carbide, aluminium oxide and graphite in the form of particles or whiskers. In this study Al6061-6 & 4wt% Al2O3 based metal matrix composite were produced by mechanical stir casting process. The obtained cast metal matrix composite is carefully machined to prepare the test specimens for hardness, tensile as well as fracture toughness studies as per ASTM standards. The hardness, tensile strength and fracture toughness properties of Al6061-Al2O3 composites are explored experimentally. Finally compare the material characterization with heat treatment process sample and compare the fracture toughness of sample with mathematical approach, experimental and finite element method.

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