scholarly journals Numerical Modeling of Concrete Spallation at Medium Strain-rate

2021 ◽  
Vol 9 (1) ◽  
pp. 112-120
Author(s):  
Ammar Babiker ◽  
Ulrich Häussler-Combe ◽  
Aamir Dean ◽  
Salih E. M. Ahmmed ◽  
Elsadig Mahdi
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Material Model ◽  
Dynamic Tensile Strength ◽  
Split Hopkinson ◽  
Laboratory Investigations ◽  
Medium Strain Rate ◽  
Direct Tensile ◽  
Brazilian Splitting

Dynamic tensile strength of brittle materials such as concrete is usually obtained by performing laboratory investigations such as direct tensile, Brazilian splitting, and spall tests. This research presents a study aimed to investigate numerically the dynamic behavior of concrete exposed to tensile loading at medium strain-rate. The dynamic tensile behavior of concrete is investigated using the Modified Split Hopkinson Bar (MSHB) at strain-rate ranges from 33 to 80 s-1. The commercial finite element explicit code LS-DYNA is used to perform the numerical simulations of the MSHB tests. Karagozian & Case Concrete Model (K&C) is adopted to define the mechanical properties of the investigated specimens. The employed K&C material model is verified by using the experimental results obtained in [1]. The validation of the K&C material model is carried out with the comparison of the computed and experimental pull-back velocities of the specimens free end. The results of the analysis are used to enhance the understanding of strain-rate sensitivity of the concrete tensile strength.  

Comparative study of tensile tests based on Hopkinson bar for recycled aggregate concrete

2018 ◽  
Vol 10 (1) ◽  
pp. 26-53
Author(s):  
Junzhou Duan ◽  
Yubin Lu ◽  
Shu Zhang ◽  
Xiquan Jiang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Coarse Aggregate ◽  
Tensile Tests ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Dynamic Tensile Strength ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Direct Tensile

To comparatively study the tensile properties and fracture patterns of recycled aggregate concrete with various replacement percentages (i.e. 0%, 25%, 50%, 75%, and 100%) of recycled coarse aggregate, the dynamic direct tensile tests, splitting tests, and spalling tests of recycled aggregate concrete in the strain-rate range of 100–102 s−1 were carried out using large diameter (75 mm) split Hopkinson tensile bar and pressure bar. Test results show that for recycled aggregate concrete, the quasi-static direct tensile strength is more marvelous than its quasi-static splitting strength. When recycled coarse aggregate replacement percentage is 0%–75%, the replacement percentage impact minimally on the quasi-static tensile strength of recycled aggregate concrete. In dynamic tensile tests, there exists apparent difference between the dynamic direct tensile strength and dynamic splitting. The dynamic tensile strength of recycled aggregate concrete increases with the increase of average strain-rate in all three kinds of tests. The average strain-rate affects the damage form of recycled aggregate concrete, which indicates that the recycled aggregate concrete has obvious rate sensitivity. There shows no obvious regularity between the dynamic tensile strength and the recycled coarse aggregate replacement percentage. And the indirect tensile strength calculation method used in this article offers the theoretical basis for the engineering application of recycled aggregate concrete.

Tensile Strength of Concrete at Different Strain Rates

1985 ◽  
Vol 64 ◽  
Author(s):  
Parviz Soroushian ◽  
Ki-Bong Choi ◽  
Gung Fu
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Moisture Content ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Direct Tension ◽  
Dynamic Tensile Strength ◽  
Strength Tests ◽  
Compressive Strength Of Concrete

ABSTRACTResults of dynamic tensile strength tests of concrete, produced by the authors and other investigators, were used to study the effects of strain rate on the tensile strength of concrete. The influence of moisture content and compressive strength of concrete, and type of test (splitting tension, flexure, or direct tension) on the strain rate-sensitivity of the tensile strength were evaluated. An empirically developed expression is presented for the dynamic-to-static ratio of concrete tensile strength in terms of the rate of straining.

scholarly journals Study on the dynamic properties of AM-SLM AlSi10Mg alloy using the Split Hopkinson Pressure Bar (SHPB) technique

2018 ◽  
Vol 183 ◽  
pp. 04005 ◽  
Author(s):  
Bar Nurel ◽  
Moshe Nahmany ◽  
Adin Stern ◽  
Nahum Frage ◽  
Oren Sadot
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Properties ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Static Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Additive manufacturing by Selective Laser Melting of metals is attracting substantial attention, due to its advantages, such as short-time production of customized structures. This technique is useful for building complex components using a metallic pre-alloyed powder. One of the most used materials in AMSLM is AlSi10Mg powder. Additively manufactured AlSi10Mg may be used as a structural material and it static mechanical properties were widely investigated. Properties in the strain rates of 5×102–1.6×103 s-1 and at higher strain rates of 5×103 –105 s-1 have been also reported. The aim of this study is investigation of dynamic properties in the 7×102–8×103 s-1 strain rate range, using the split Hopkinson pressure bar technique. It was found that the dynamic properties at strain-rates of 1×103–3×103 s-1 depend on a build direction and affected by heat treatment. At higher and lower strain-rates the effect of build direction is limited. The anisotropic nature of the material was determined by the ellipticity of samples after the SHPB test. No strain rate sensitivity was observed.

Strain rate sensitivity and strain hardening response of DP1000 dual phase steel

2018 ◽  
Vol 115 (5) ◽  
pp. 507
Author(s):  
Onur Çavusoglu ◽  
Hakan Gürün ◽  
Serkan Toros ◽  
Ahmet Güral
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Dual Phase Steel ◽  
Rate Sensitivity ◽  
Dual Phase ◽  
Significant Difference ◽  
Load Carrying ◽  
Hardening Coefficient

In this study, strain hardening and strain rate sensitivity behavior of commercial DP1000 dual phase steel have been examined in detail at temperatures of 25 °C, 100 °C, 200 °C and 300 °C, at strain rates of 0.0016 s−1 and 0.16 s−1. As the strain rate has increased, the yield strength has increased but no significant change in tensile strength and strain hardening coefficient has been observed. As the temperature has increased, the yield and tensile strength has decreased in between 25 and 200 °C but it has showed an increase at 300 °C. The strain hardening coefficient has increased in parallel with temperature increase. It has been seen that the strain rate sensitivity has not been affected by temperature. No significant difference in the hardening rate has appeared in between 25 and 200 °C, but the highest value has been calculated at 300 °C. It has been determined that the fracture behavior has occurred earlier and load carrying capacity on necking has reduced with the increase of strain rate and not significantly affected by temperature.

Effect of the Strain Rate and Water Saturation for the Dynamic Tensile Strength of Rocks

2004 ◽  
Vol 465-466 ◽  
pp. 361-366 ◽  
Author(s):  
Yuji Ogata ◽  
Woo-jin Jung ◽  
Shiro Kubota ◽  
Yuji Wada
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Water Saturation ◽  
Dynamic Tensile Strength

scholarly journals Experimental and Numerical Study on Tensile Strength of Concrete under Different Strain Rates

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Fanlu Min ◽  
Zhanhu Yao ◽  
Teng Jiang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Numerical Study ◽  
Material Behavior ◽  
Constitutive Law ◽  
Test Machine ◽  
Strain Rates ◽  
Dynamic Tensile Strength ◽  
Dynamic Increase Factor ◽  
Versus Strain

The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10−7 s−1to 10−4 s−1in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates.

Dependence of the tensile strength of pitch-based carbon and para-aramid fibres on the rate of strain

1990 ◽  
Vol 428 (1875) ◽  
pp. 493-510 ◽  
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Scale Parameter ◽  
Hybrid Composites ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Carbon Fibres ◽  
Rule Model ◽  
Aramid Fibres ◽  
Rate Behaviour

Understanding the rate dependencies of the tensile strength of reinforcing fibres is a key for the understanding of the rate dependencies of the properties of the corresponding composite materials. Hence, in this study it is attempted to clarify the mechanical responses of aramid and carbon fibres at different rates of strain in the light of our previous observations of strain rate dependence of the corresponding hybrid composites under both static and fatigue flexural conditions. In addition, it is attempted to correlate the rate sensitivity with the degree of structural order in the fibres. The study is carried out with low-, medium- and high-modulus pitch based carbon fibres and with Kevlar 29, 49 and 149 para-aramid fibres, whose strengths were tested at strain rates ranging between 0.004 to 2.0% s -1 . It is shown that the strength results of the two fibre families follow the Weibull distribution at all strain rates studied. In the case of the carbon fibres two different régimes are observed for the scale parameter as a function of strain rate. At low strain rates the scale parameter increases slowly with the rate, whereas a strong decrease is observed at higher strain rates. This trend becomes more evident as the crystallinity of the fibre increases. The low strain rate behaviour is governed by the power law breakdown rule model, whereas the high strain rate behaviour is accounted for by the rate of growth of a sharp inter-crystallite flaw. In the case of the aramid fibres the scale parameter is insensitive to the strain rate, which supposedly results from a situation where fracture in these fibres does not necessarily involve an activation volume controlled mechanism.

Effect of Surface Modification on Strain Rate Sensitivity of Polypropylene/Muscovite Layered Silicate Composites

2014 ◽  
Vol 803 ◽  
pp. 343-347
Author(s):  
M.F. Omar ◽  
Nur Suhaili Abd Wahab ◽  
Hazizan Md Akil ◽  
Zainal Arifin Ahmad ◽  
Mohd Fadli Ahmad Rasyid ◽  
...  
Keyword(s):  
Surface Modification ◽  
Ion Exchange ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Split Hopkinson Pressure Bar ◽  
Layered Silicate ◽  
Rate Sensitivity ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

Surface modification is one of the treatment methods that can be implemented to improve the strain rate sensitivity of composite materials. In this study, both untreated and treated polypropylene/muscovite layered silicate composites were tested under static and dynamic loading up to 1100 s-1 using the universal testing machine and the split Hopkinson pressure bar apparatus, respectively. Muscovite particles were treated with lithium nitrate and cetyltrimethylammonium bromide as a surfactant through ion exchange treatment. Results show that the treated polypropylene/muscovite specimens with fine state of dispersion level shows better rate of sensitivity as compared to untreated polypropylene/muscovite specimens under a wide range of strain rate investigated. Apart from that, the rate of sensitivity of both tested polypropylene/muscovite layered silicate composites also show great dependency on the strain rate sensitivity was steadily increased with increasing strain rate. Unfortunately, the thermal activation values show contrary trend. Key words: Ion exchange treatment; Strain rate sensitivity; Muscovite particles; Split Hopkinson pressure bar apparatus; Strain rates

scholarly journals Dynamic Tensile Properties of CFRP Manufactured by PCM and WCM: Effect of Strain Rate and Configurations

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1491
Author(s):  
Yujin Yang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Tensile Properties ◽  
Strain Rate Sensitivity ◽  
Failure Strain ◽  
Dynamic Performance ◽  
Rate Sensitivity ◽  
Fracture Mechanisms ◽  
Reinforced Plastic ◽  
Dynamic Tensile Properties

Carbon fiber-reinforced plastic (CFRP) is a promising material to achieve lightweight automotive components. The effects of the strain rate and configurations of CFRP on dynamic tensile properties have not yet been fully explored; thus, its lightweight benefits cannot be maximized. In this paper, the dynamic tensile properties of CFRPs, tested using two different processes with two different resins and four different configurations, were studied with a strain rate from 0.001 to 500 s−1. The tensile strength, modulus, failure strain, and fracture mechanism were analyzed. It was found that the dynamic performance enhances the strength and modulus, whereas it decreases the failure strain. The two processes demonstrated the same level of tensile strength but via different fracture mechanisms. Fiber orientation also significantly affects the fracture mode of CFRP. Resins and configurations both have an influence on strain rate sensitivity. An analytic model was proposed to examine the strain rate sensitivity of CFRPs with different processes and configurations. The proposed model agreed well with the experimental data, and it can be used in simulations to maximize the lightweight properties of CFRP.

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