147 Measurement of Tensile Strength and Strain Rates of Concretes by Impact Method of Reflected Tensile Stress Waves

The Hopkinson Bar has been widely used by many researchers for the analysis of dynamic properties of different brittle materials and, due to its great interest, for the study of concrete. In concrete structures subjected to high velocity impacts, initial compression pulses travel through the material leading to tensile stresses when they reach a free surface. These tensile efforts are the main cause of concrete fracture due to its low tensile strength compared to the compressive one. This is the reason why dynamic tests in concrete are becoming of great interest and are mostly focused in obtaining tensile fracture properties. Apart form the dynamic tensile strength, which has been widely studied by many authors in the last decades, the dynamic fracture energy presents an increased difficulty and so not too much experimental information can be found in literature. Moreover, up to date there is not a clear methodology proposed in order to obtain this parameter in an accurate way. In this work a new methodology for measuring the dynamic fracture energy is proposed by using the Hopkinson Bar technique. Initial tests for a conventional concrete have been carried out and the results for the dynamic fracture energy of concrete at different strain rates are presented.

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Tensile Stress-Strain Curves Modeling of Four Kinds of Solders with Temperature and Rate Dependence

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.297-300.905 ◽

2005 ◽

Vol 297-300 ◽

pp. 905-911 ◽

Cited By ~ 2

Author(s):

Xu Chen ◽

Li Zhang ◽

Masao Sakane ◽

Haruo Nose

Keyword(s):

Tensile Stress ◽

Constitutive Model ◽

Strain Rate ◽

Constant Strain Rate ◽

Tensile Tests ◽

Strain Rate Range ◽

Rate Dependence ◽

Strain Rates ◽

Stress Strain ◽

Rate Range

A series of tensile tests at constant strain rate were conducted on tin-lead based solders with different Sn content under wide ranges of temperatures and strain rates. It was shown that the stress-strain relationships had strong temperature- and strain rate- dependence. The parameters of Anand model for four solders were determined. The four solders were 60Sn-40Pb, 40Sn-60Pb, 10Sn-90Pb and 5Sn-95Pb. Anand constitutive model was employed to simulate the stress-strain behaviors of the solders for the temperature range from 313K to 398K and the strain rate range from 0.001%sP -1 P to 2%sP -1 P. The results showed that Anand model can adequately predict the rate- and temperature- related constitutive behaviors at all test temperatures and strain rates.

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Mechanical behaviour and structure of snow under uniaxial tensile stress

Journal of Glaciology ◽

10.1017/s0022143000010819 ◽

1980 ◽

Vol 26 (94) ◽

pp. 275-282 ◽

Cited By ~ 62

Author(s):

Hidek Narita

Keyword(s):

Tensile Stress ◽

Strain Rate ◽

Mechanical Behaviour ◽

Maximum Strength ◽

Ductile Deformation ◽

Uniaxial Tensile ◽

Strain Rates ◽

Thin Sections ◽

Uniaxial Tensile Stress ◽

Small Cracks

AbstractThe mechanical behaviour of snow was studied at — 10°C under uniaxial tensile stress in a range of cross-head speed 6.8 × 10–8to 3.1 × 10–4ms–1and snow density 240-470 kg m–3.It was found from the resisting force-deformation curves that the snow was deformed in two different ways: namely, brittle and ductile deformation at high and low strain-rates, respectively. The critical strain-rate dividing the two deformation modes was found to depend on the density of snow. In ductile deformation, many small cracks appeared throughout the entire specimen. Their features were observed by making thin sections and they were compared with small cracks formed in natural snow on a mountain slope.The maximum strength of snow was found to depend on strain-rate: at strain-rates above about 10–5s–1, the maximum strength increased with decreasing strain-rate but below 10–5s–1it decreased with decreasing strain-rate.

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Mechanical behaviour and structure of snow under uniaxial tensile stress

Journal of Glaciology ◽

10.3189/s0022143000010819 ◽

1980 ◽

Vol 26 (94) ◽

pp. 275-282 ◽

Cited By ~ 3

Author(s):

Hidek Narita

Keyword(s):

Tensile Stress ◽

Strain Rate ◽

Mechanical Behaviour ◽

Maximum Strength ◽

Ductile Deformation ◽

Uniaxial Tensile ◽

Strain Rates ◽

Thin Sections ◽

Uniaxial Tensile Stress ◽

Small Cracks

AbstractThe mechanical behaviour of snow was studied at — 10°C under uniaxial tensile stress in a range of cross-head speed 6.8 × 10–8 to 3.1 × 10–4 ms–1 and snow density 240-470 kg m–3.It was found from the resisting force-deformation curves that the snow was deformed in two different ways: namely, brittle and ductile deformation at high and low strain-rates, respectively. The critical strain-rate dividing the two deformation modes was found to depend on the density of snow. In ductile deformation, many small cracks appeared throughout the entire specimen. Their features were observed by making thin sections and they were compared with small cracks formed in natural snow on a mountain slope.The maximum strength of snow was found to depend on strain-rate: at strain-rates above about 10–5 s –1, the maximum strength increased with decreasing strain-rate but below 10–5 s–1 it decreased with decreasing strain-rate.

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Mechanical Behaviour of Silicone Membranes Saturated with Short Strand, Loose Polyester Fibres for Prosthetic and Rehabilitative Surrogate Skin Applications

Materials ◽

10.3390/ma12223647 ◽

2019 ◽

Vol 12 (22) ◽

pp. 3647 ◽

Cited By ~ 1

Author(s):

Richard Arm ◽

Arash Shahidi ◽

Tilak Dias

Keyword(s):

Plastic Deformation ◽

Tensile Strength ◽

High Strain ◽

Mechanical Tests ◽

Fibre Content ◽

Strain Rates ◽

Linear Coefficient ◽

The Aesthetic ◽

Silicone Membranes ◽

Hardness Values

Silicone-based elastomers saturated with embedded, short-strand fibres are used for their ability to mimic the aesthetic qualities of skin in clinical and theatrical maxillofacial appliance design. Well-known to prostheses fabricators and technicians, the mechanical impact of fibre addition on elastomeric behaviour endures as tacit, embodied knowledge of the craft, almost unknown in the literature. To examine mechanical changes caused by fibre addition, 100 modified polydimethylsiloxane (PDMS) elastomeric compounds containing incremental amounts of loose polyester fibres were prepared and examined in a variety of mechanical tests. It was found that elasticity and strain percentage at breaking point was reduced by increasing fibre content, but Young’s modulus and ultimate tensile strength (UTS) increased. As fibre content was increased, strain hardening was seen at low strain rates, but exaggerated plastic deformation at high strain rates. PDMS hardness increased by 5 degrees of hardness (Shore-00 scale) for every additional percentage of fibres added and a strong positive linear coefficient (0.993 and 0.995) was identified to reach the hardness values given in the literature for living human skin. The apparent reorienting of loose fibres in the PDMS interrupts and absorbs stress during the loading process similar to the organic response to soft tissue loading, except in extension.

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

EPJ Web of Conferences ◽

10.1051/epjconf/201818302042 ◽

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.

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Master Curve for Tensile Stress—Strain Behavior of Amorphous Elastomers at Small and Large Deformations

Rubber Chemistry and Technology ◽

10.5254/1.3540442 ◽

1974 ◽

Vol 47 (2) ◽

pp. 318-332 ◽

Cited By ~ 4

Author(s):

N. Nakajima ◽

E. A. Collins ◽

H. H. Bowerman

Keyword(s):

Tensile Stress ◽

Master Curve ◽

Large Deformations ◽

Strain Rates ◽

Stress Strain ◽

Strain Behavior

Abstract A master curve scheme for small and large deformations was developed for tensile stress-strain behavior of butadiene—acrylonitrile uncrosslinked elastomers. Measurements were carried out at strain rates of 267 to 26,700 per cent/sec at temperatures of 25 to 97° C.

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Residual Stress Distribution in Pure Bending Beam Subjected to Tensile Failure on One Side

Materials Science Forum ◽

10.4028/www.scientific.net/msf.524-525.253 ◽

2006 ◽

Vol 524-525 ◽

pp. 253-258

Author(s):

X.B. Wang

Keyword(s):

Residual Stress ◽

Tensile Strength ◽

Stress Distribution ◽

Tensile Stress ◽

Strain Localization ◽

Tensile Strain ◽

Residual Stress Distribution ◽

Neutral Axis ◽

Residual Tensile Stress ◽

Pure Bending

The stress distribution on the midsection of a pure bending beam where tensile strain localization band initiates on the tensile side of the beam and propagates within the beam is analyzed. Using the static equilibrium condition on the section of the midspan of the beam and the assumption of plane section as well as the linear softening constitutive relation beyond the tensile strength, the expressions for the length of tensile strain localization band and the distance from the tip of the band to the neutral axis are derived. After superimposing a linear unloading stress distribution over the initial stress distribution, the residual stress distribution on the midsection of the beam is investigated. In the process of strain localization band’s propagation, strain-softening behavior of the band occurs and neutral axis will shift. When the unloading moment is lower, the length of tensile strain localization band remains a constant since the stress on the base side of the beam is tensile stress. While, for larger unloading moment, with an increase of unloading moment, the length of tensile strain localization band decreases and the distance from the initial neutral axis to the unloading neutral axis increases. The neutral axis of midsection of the beam will shift in the unloading process. The present analysis is applicable to some metal materials and many quasi-brittle geomaterials (rocks and concrete, etc) in which tensile strength is lower than compressive strength. The present investigation is limited to the case of no real crack. Moreover, the present investigation is limited to the case that the length of strain localization band before unloading is less than half of depth of the beam. Otherwise, the residual tensile stress above the elastic neutral axis will be greater than the tensile strength, leading to the further development of tensile strain localization band in the unloading process.

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