The Dynamic Mechanical Constitutive Equation of Concrete under High Temperture

2011 ◽  
Vol 99-100 ◽  
pp. 782-785 ◽  
Author(s):  
Bin Jia ◽  
Zheng Liang Li ◽  
Jun Lin Tao ◽  
Chun Tao Zhang
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dynamic Mechanical ◽  
Whole Process ◽  
Pressure Bar

Based on the test by the split Hopkinson Pressure Bar (SHPB), in this papaer the research on the dynamic mechanical properties of concrete under high temperture has been conducted, the influence law of temperature and strain rate on the mechanical peoperties has been analyzed, and the dynamic stress-strain curves of concrete under high temperature have been obtained. Analysis indicate that the concrete strain rate hardening effect is coupled with the high temperature weakening effect. Therefore, on the basis of classical damage theoretical model, in accordance with the concrete high-temperature dynamic mechanical characteristics, a unified equation is established to describe the whole process of concrete dynamic stress-strain relationship under high temperature, which is well coincided with the test results.

Dynamic Mechanical Properties of Float Glass

2013 ◽  
Vol 631-632 ◽  
pp. 383-387
Author(s):  
Lei Li ◽  
Jian Hua Liu ◽  
Yao Feng Ji
Keyword(s):  
Mechanical Properties ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Mechanical Properties ◽  
Float Glass ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Nonlinear Elastic

In order to study dynamic mechanical properties of float glass under blast and ballistic/fragmentation impacts, the curves of stress- strain are obtained in higher ranges by using the modified Split Hopkinson Pressure Bar (SHPB) techniques. Experimental results indicate that float glass is nonlinear elastic-brittle materials, and its dynamic curves of stress-strain are nonlinear and can be divided into three stages: elastic, nonlinear strengthening and stress drop. The dynamic Young’s modulus and the dynamic compressive strength of float glass increase with the increasing of strain rate. Finally, an explanation was given according to principle of energy equilibrium of Griffith.

Dynamic Stress-Strain Behavior of AZ91 Alloy at High-Strain Rate

2007 ◽  
Vol 546-549 ◽  
pp. 89-92 ◽  
Author(s):  
Gui Ying Sha ◽  
En Hou Han ◽  
Yong Bo Xu ◽  
Lu Liu
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Az91 Alloy ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Strain Rate Effects ◽  
Strain Behavior ◽  
Pressure Bar

The dynamic stress-strain behavior of the AZ91 alloys in different treatment conditions (as-cast, T4 and T6) was investigated by means of split Hopkinson pressure bar. It was found that the flow stress increased at first, and then declined with the strain rate increasing at the range of 102~103s-1 for the alloys in these three conditions. And the alloys exhibited both positive and negative strain rate effects. The former was caused by strain rate strengthening and the latter was caused by strain rate weakening. However the flow stress for the alloy in aged condition at the same strain rate was higher than both of the alloys in as-cast and solution conditions. The study also showed that the maximum strains of the alloys in different conditions increased with the strain rate increasing, and the strain rate to fracture for the alloy in solution condition was higher than those of other two alloys. The work-hardening of α–Mg matrix and the reinforcement of β-Mg17Al12 phases led to the strengthening of the alloy, while thermal softening of matrix, the fracture of β phases and initiation and propagation of the cracks were responsible for the weakening of the alloy.

scholarly journals Development of a True-Biaxial Split Hopkinson Pressure Bar Device and Its Application

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7298
Author(s):  
Shumeng Pang ◽  
Weijun Tao ◽  
Yingjing Liang ◽  
Shi Huan ◽  
Yijie Liu ◽  
...  
Keyword(s):  
Stress Wave ◽  
Impact Loading ◽  
Split Hopkinson Pressure Bar ◽  
Axial Stress ◽  
Dynamic Mechanical Properties ◽  
Stress Waves ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Although highly desirable, the experimental technology of the dynamic mechanical properties of materials under multiaxial impact loading is rarely explored. In this study, a true-biaxial split Hopkinson pressure bar device is developed to achieve the biaxial synchronous impact loading of a specimen. A symmetrical wedge-shaped, dual-wave bar is designed to decompose a single stress wave into two independent and symmetric stress waves that eventually form an orthogonal system and load the specimen synchronously. Furthermore, a combination of ground gaskets and lubricant is employed to eliminate the shear stress wave and separate the coupling of the shear and axial stress waves propagating in bars. Some confirmatory and applied tests are carried out, and the results show not only the feasibility of this modified device but also the dynamic mechanical characteristics of specimens under biaxial impact loading. This novel technique is readily implementable and also has good application potential in material mechanics testing.

One-Dimensional Dynamic Compressive Behavior of EPDM Rubber

2003 ◽  
Vol 125 (3) ◽  
pp. 294-301 ◽  
Author(s):  
B. Song ◽  
W. Chen
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Constant Strain Rate ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Epdm Rubber ◽  
One Dimensional

Dynamic compressive stress-strain curves at various strain rates of an Ethylene-Propylene-Diene Monomer Copolymer (EPDM) rubber have been determined with a modified split Hopkinson pressure bar (SHPB). The use of a pulse-shaping technique ensures that the specimen deforms at a nearly constant strain rate under dynamically equilibrated stress. The validity of the experiments was monitored by a high-speed digital camera for specimen edge deformation, and by piezoelectric force transducers for dynamic stress equilibrium. The resulting dynamic stress-strain curves for the EPDM indicate that the material is sensitive to strain rates and that the strain-rate sensitivity depends on the value of strain. Based on a strain energy function theory, a one-dimensional dynamic constitutive equation for this rubber was modified to describe the high strain-rate experimental results within the ranges of strain and strain rates presented in this paper.

The Effects of Water Saturation on Dynamic Mechanical Properties in Red and Buff Sandstones Having Different Porosities Studied with Split Hopkinson Pressure Bar (SHPB)

2015 ◽  
Vol 752-753 ◽  
pp. 784-789 ◽  
Author(s):  
Eun Hye Kim ◽  
Davi Bastos Martins de Oliveira
Keyword(s):  
Mechanical Properties ◽  
Dynamic Loading ◽  
Oil And Gas ◽  
Split Hopkinson Pressure Bar ◽  
Water Saturation ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Split Hopkinson ◽  
Pressure Bar

Dynamic mechanical behavior of geomaterials has been widely observed in tunneling, oil and gas extraction, and blasting in civil and mining applications. It is important to understand how much energy is necessary to break or fail geomaterials to optimize the design of blasting patterns, oil and gas extractions, demolition, military defense, etc. However, there is little understanding for quantifying the required energy to break geomaterials under dynamic loading. More importantly, as typical geomaterials tend to hydrate, it is necessary to understand how much energy will be needed to break the structures under water saturation. Thus, in this study, we analyzed the consumed energy used to deform geomaterials using a split Hopkinson pressure bar (SHPB), enabling to measure stress and strain responses of geomaterials under dynamic loading condition of high strain rate (102–104/sec). Two different saturation levels (dry vs. fully saturation) in two sandstone samples having different pore sizes were tested under dynamic loading conditions. Our results demonstrate that dynamic mechanical strength (maximum stress) is greater in the dry geomaterials when compared with the saturated samples, and Young’s modulus (or maximum strain) can be a useful parameter to examine porosity effects between dry and saturated geomaterials on dynamic mechanical properties.

Deformation of Ceramics at High Strain Rate and High Temperature Using Split Hopkinson Pressure Bar Method

2003 ◽  
Vol 2003.11 (0) ◽  
pp. 47-48
Author(s):  
Toshifumi KAKIUCHI ◽  
Chikatomo HOSOKAWA ◽  
Masanao SEKINE ◽  
Katsuhiko SATOH ◽  
Koji FUJIMOTO ◽  
...  
Keyword(s):  
High Temperature ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Split Hopkinson ◽  
Pressure Bar

Measurement of Mechanical Properties of St 37 Material at High Strain Rates Using a Split Hopkinson Pressure Bar

2014 ◽  
Vol 660 ◽  
pp. 562-566 ◽  
Author(s):  
Akbar Afdhal ◽  
Leonardo Gunawan ◽  
Sigit P. Santosa ◽  
Ichsan Setya Putra ◽  
Hoon Huh
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Test Specimen ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

The dynamic mechanical properties of a material are important keys to investigate the impact characteristic of a structure such as a crash box. For some materials, the stress-strain relationships at high strain rate loadings are different than that at the static condition. These mechanical properties depend on the strain rate of the loadings, and hence an appropriate testing technique is required to measure them. To measure the mechanical properties of a material at high strain rates, ranging from 500 s-1 to 10000 s-1, a Split Hopkinson Pressure Bar is commonly used. In the measurements, strain pulses are generated in the bars system, and pulses being reflected and transmitted by a test specimen in the bar system are measured. The stress-strain curves as the material properties of the test specimen are obtained by processing the measured reflected and transmitted pulses. This paper presents the measurements of the mechanical properties of St 37 mild steel at several strain rates using a Split Hopkinson Pressure Bar. The stress-strain curves obtained in the measurement were curve fitted using the Power Law. The results show that the strength of St 37 material increases as the strain rate increases.

SHPB Test on Dynamical Mechanical Behavior of Concrete with High Temperature

2011 ◽  
Vol 71-78 ◽  
pp. 760-763 ◽  
Author(s):  
Bin Jia ◽  
Zheng Liang Li ◽  
Hua Chuan Yao ◽  
Jun Lin Tao
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Split Hopkinson Pressure Bar ◽  
Experimental System ◽  
Wave Theory ◽  
Hopkinson Pressure Bar ◽  
Temperature Changes ◽  
Split Hopkinson ◽  
Pressure Bar

An experimental system is designed by combining the split Hopkinson pressure bar (SHPB) with microwave heating device, based on stress wave theory, availability of the experiment technique is analyzed. Tests of concrete whose temperature changes from room temperature to 650°C and impact velocity from 5m/s to 12m/s are completed and for the first time high-temperature dynamical damaging phenomena of concrete are obtained. Based on data analysis, the dynamical mechanical behavior of concrete with high temperature is affected by not only the strain rate effect whose influence keeps on decreasing with temperature increasing, but also the high temperature weakening effect. And the strain rate hardening effect is coupled with high temperature weakening effect, but the latter has greater influence.

scholarly journals Dynamic Mechanical Properties and Constitutive Relation of an Aluminized Polymer Bonded Explosive at Low Temperatures

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Yuliang Lin ◽  
Binbin Xu ◽  
Rong Chen ◽  
Jingui Qin ◽  
Fangyun Lu
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Extreme Environments ◽  
Dynamic Mechanical Properties ◽  
Experimental Results ◽  
Effect Of Temperature ◽  
Hopkinson Pressure Bar ◽  
Polymer Bonded Explosives ◽  
Split Hopkinson ◽  
Pressure Bar

Polymer bonded explosives (PBXs) are widely used as energetic fillings in various warheads, which maybe are utilized under extreme environments, such as low or high temperatures. In this paper, the dynamic response of an aluminized polymer bonded explosive was tested at a range of temperatures from −55°C to −2°C and a fixed loading strain rate (~700 s−1) with the split Hopkinson pressure bar (SHPB). The PBX tested is aluminized, which contains 76 wt% RDX, 20 wt% aluminum powder, and 4 wt% polymer binder, respectively. The results show that the effect of temperature on the strength of the PBX is obvious at the tested strain rates. Based on the experimental results and prophase studies, a constitutive model was obtained, in which the effect of temperature and strain rate were considered. The modeling curves fit well with the experimental results, not only at low temperature under 0°C, but also at room temperature (20°C). The model may be used to predict the dynamic performances of the PBXs in various environments.

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