scholarly journals Mechanical Characterization of Cement Composites Reinforced with Fiberglass, Carbon Nanotubes or Glass Reinforced Plastic (GRP) at High Strain Rates

2011 ◽  
Vol 82 ◽  
pp. 190-195 ◽  
Author(s):  
Luigi Coppola ◽  
Ezio Cadoni ◽  
Daniele Forni ◽  
Alessandra Buoso
Keyword(s):  
Carbon Nanotubes ◽  
Tensile Strength ◽  
Strain Rate ◽  
Fracture Energy ◽  
High Strain ◽  
Glass Fibers ◽  
Cement Matrix ◽  
Impact Loads ◽  
Natural Sand ◽  
Reinforced Plastics

Advanced researches on concrete are directed toward investigating the behavior of reinforced concrete structures in severe conditions such as those promoted by impact loads. Some particular structures (protective shelters, nuclear reactor containment, offshore structures, military structures, chemical or Energy production plant) may be subjected to loading at very high rate of stress or strain caused by impact of missiles or flying objects, also by vehicle collisions or impulses due to explosions and earthquakes. Resistance to impact loads is guaranteed by using cementitious materials having both high strength and ductility. In order to improve ductility cementitious mortars with Glass Reinforced Plastics (GRP) replacing partially the natural sand were manufactured. Moreover, glass fiber (GF) reinforced mortars were produced to enhance toughness. For this scope two types of glass fibers were used different in length and diameter. Since the use of GRP and GF don’t produce any increase in strength of the mortars Carbon Nanotubes were added in the cement matrix to enhance tensile strength of the cementitious composite. Flexural, compressive and Hopkinson bar tests were carried out to evaluate the role of the different materials used. Replacing partially the natural sand with Glass Reinforced Plastics (GRP), compressive and flexural strength decrease (about 20%) with respect those of the reference mortar both on static and dynamic condition as a consequence of an anomalous air entrapment. Adding glass fibers (GF), GRP or/and Carbon Nanotubes (CNTs) no substantial improvement in terms of mechanical properties under static condition was occurred. The Dynamic Increase Factor of the reference mortar was higher than that of the reinforced mixtures, but fracture energy was lower. In particular, combined addition of carbon nanotubes and GRP determines an increase in the energy fracture. The higher the carbon nanotubes content, the higher both fracture energy and tensile strength because nanoparticles oppose to wave and crack propagation, increasing the high strain rate strength. GRP and CNTs reinforced mortars need more fracture energy to failure at 150 s-1 strain rate.

scholarly journals An Image-Based Impact Test for the High Strain Rate Tensile Properties of Brittle Materials

2018 ◽  
Vol 183 ◽  
pp. 02042
Author(s):  
Lloyd Fletcher ◽  
Fabrice Pierron
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
High Strain ◽  
Brittle Materials ◽  
Test Method ◽  
Strain Rates ◽  
High Strain Rates

Testing ceramics at high strain rates presents many experimental diffsiculties due to the brittle nature of the material being tested. When using a split Hopkinson pressure bar (SHPB) for high strain rate testing, adequate time is required for stress wave effects to dampen out. For brittle materials, with small strains to failure, it is difficult to satisfy this constraint. Because of this limitation, there are minimal data (if any) available on the stiffness and tensile strength of ceramics at high strain rates. Recently, a new image-based inertial impact (IBII) test method has shown promise for analysing the high strain rate behaviour of brittle materials. This test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Throughout the propagation of the stress wave, full-field displacement measurements are taken, from which strain and acceleration fields are derived. The acceleration fields are then used to reconstruct stress information and identify the material properties. The aim of this study is to apply the IBII test methodology to analyse the stiffness and strength of ceramics at high strain rates. The results show that it is possible to identify the elastic modulus and tensile strength of tungsten carbide at strain rates on the order of 1000 s-1. For a tungsten carbide with 13% cobalt binder the elastic modulus was identified as 516 GPa and the strength was 1400 MPa. Future applications concern boron carbide and sapphire, for which limited data exist in high rate tension.

Tensile strength of aluminum-epoxy resin composite structure under high strain rate conditions

2012 ◽  
Author(s):  
Damien Laporte ◽  
Frederic Malaise ◽  
Michel Boustie ◽  
Jean-Marc Chevalier ◽  
Eric Buzaud
Keyword(s):  
Tensile Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
Epoxy Resin ◽  
Composite Structure ◽  
High Strain ◽  
Resin Composite ◽  
Epoxy Resin Composite

High strain rate fracture and C-chain unraveling in carbon nanotubes

1997 ◽  
Vol 8 (4) ◽  
pp. 341-348 ◽  
Author(s):  
B.I. Yakobson ◽  
M.P. Campbell ◽  
C.J. Brabec ◽  
J. Bernholc
Keyword(s):  
Carbon Nanotubes ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain

scholarly journals Energy dissipation and high-strain rate dynamic response of E-glass fiber composites with anchored carbon nanotubes

2016 ◽  
Vol 88 ◽  
pp. 44-54 ◽  
Author(s):  
Veera M. Boddu ◽  
Matthew W. Brenner ◽  
Jignesh S. Patel ◽  
Ashok Kumar ◽  
P. Raju Mantena ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Energy Dissipation ◽  
Dynamic Response ◽  
High Strain Rate ◽  
Strain Rate ◽  
Glass Fiber ◽  
High Strain ◽  
Fiber Composites ◽  
Glass Fiber Composites ◽  
Rate Dynamic

scholarly journals Effect of Fiber Blending Ratio on the Tensile Properties of Steel Fiber Hybrid Reinforced Cementitious Composites under Different Strain Rates

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4504
Author(s):  
Minjae Son ◽  
Gyuyong Kim ◽  
Hongseop Kim ◽  
Sangkyu Lee ◽  
Yaechan Lee ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Synergistic Effect ◽  
Strain Rate ◽  
Tensile Properties ◽  
High Performance ◽  
Steel Fiber ◽  
High Strain ◽  
Strain Rates ◽  
Cementitious Composite ◽  
Hybrid Fiber

In this study, a high-performance hybrid fiber-reinforced cementitious composite (HP-HFRCC) was prepared, by mixing hooked steel fiber (HSF) and smooth steel fiber (SSF) at different blending ratios, to evaluate the synergistic effect of the blending ratio between HSF and SSF and the strain rate on the tensile properties of HP-HFRCC. The experimental results showed that the micro- and macrocrack control capacities of HP-HFRCC varied depending on the blending ratio and strain rate, and the requirement for deriving the appropriate blending ratio was confirmed. Among the HP-HFRCC specimens, the specimen mixed with HSF 1.0 vol.% and SSF 1.0 vol.% (H1.0S1.0) exhibited a significant increase in the synergistic effect on the tensile properties at the high strain rate, as SSF controlled the microcracks and HSF controlled the macrocracks. Consequently, it exhibited the highest strain rate sensitivities of tensile strength, strain capacity, and peak toughness among the specimens evaluated in this study.

Dynamic Fracture of Natural Rubber3

2007 ◽  
Vol 35 (4) ◽  
pp. 252-275 ◽  
Author(s):  
Ali A. Al-Quraishi ◽  
Michelle S. Hoo Fatt
Keyword(s):  
Finite Element ◽  
Carbon Black ◽  
Natural Rubber ◽  
Strain Rate ◽  
Fracture Energy ◽  
Dynamic Fracture ◽  
High Strain ◽  
Field Strain ◽  
Far Field ◽  
Strain Rates

Abstract This paper illustrates how the fracture energy of a tensile strip made of unfilled and 25 phr carbon black-filled natural rubber varies with far-field strain rate in the range 0.01–71 s−1. Quasistatic and dynamic fracture tests were performed at room temperature with an electromechanical INSTRON machine, a servo-hydraulic MTS machine, and Charpy tensile apparatus, respectively. It was found that the fracture energy of the unfilled natural rubber did not vary significantly over the range of sample strain rate, but there was significant variation in the fracture energy of the 25 phr carbon black-filled natural rubber from 0.01 to 71 s−1 sample strain rate. The fracture energy of the 25 phr carbon black-filled natural rubber at a sample strain rate of 0.1 s−1 was about three times greater than it was at the 10 s−1 sample strain rate. While the carbon black fillers increased the fracture energy of natural rubber by about 200% at quasistatic sample strain rates (0.01–0.1 s−1) and at 71 s−1, the carbon black fillers did nothing to improve the fracture energy of natural rubber at sample strain rates between 5 and 29 s−1. In this strain rate range, the fracture energy of 25 phr carbon black-filled natural rubber was almost the same as that in the unfilled natural rubber. The variation in the fracture energy with far-field strain rate was due to changes in the material behavior of natural rubber at high strain rates. Finite element analysis using a high-strain-rate constitutive equation for the 25 phr carbon black rubber specimen was used to calculate the fracture energy of the specimen at a sample strain rate of 55 s−1, and good agreement was found between the test and finite element results.

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