Dynamic Mechanical Behavior of Reinforced Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 139-142
Author(s):  
Hai Feng Liu ◽  
Wei Wu Yang ◽  
Jian Guo Ning
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Behavior ◽  
Dynamic Compression ◽  
Strain Rates ◽  
Analysis Method ◽  
Lagrangian Analysis ◽  
Linear Rate ◽  
Gas Gun ◽  
Dynamic Mechanical Behavior ◽  
Confining Pressures

The dynamic compression experiments of reinforced concrete are carried out by one-stage light gas gun apparatus which subjects the reinforced concrete to deformation at strain rates of the order of 104/s with confining pressures of 1~1.5GPa. The stress-strain curves of reinforced concrete with different impact velocities are obtained using Lagrangian analysis method. Experimental results indicate that reinforced concrete is non-linear, rate-sensitive and pressure-dependent.

Microstructural and Dynamic Mechanical Characterization of Biodegradable Magnesium-Calcium Alloy for Orthopedic Implants

2014 ◽  
Author(s):  
V. S. Brooks ◽  
Y. B. Guo
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Orthopedic Implants ◽  
Strain Rates ◽  
High Strain Rates ◽  
Static Compression ◽  
Metallic Biomaterial

Magnesium-Calcium (Mg-Ca) alloy is an emerging metallic biomaterial for manufacturing biodegradable orthopedic implants. However, very few studies have been conducted on mechanical properties of the bi-phase Mg-Ca alloy, especially at the high strain rates often encountered in manufacturing processes. The mechanical properties are critical to design and manufacturing of Mg-Ca implants. The objective of this study is to study the microstructural and mechanical properties of Mg-Ca0.8 (wt %) alloy. Both elastic and plastic behaviors of the Mg-Ca0.8 alloy were characterized at different strains and strain rates in quasi-static tension and compression testing as well as dynamic split-Hopkinson pressure bar (SHPB) testing. It has been shown that Young’s modulus of Mg-Ca0.8 alloy in quasi-static compression is much higher than those at high strain rates. Yield strength and ultimate strength of the material are very sensitive to strain rates and increase with strain rate in compression. Strain softening also occurs at large strains in dynamic compression. Furthermore, quasi-static mechanical behavior of the material in tension is very different from that in compression. The stress-strain data was repeatable with reasonable accuracy in both deformation modes. In addition, a set of material constants for the internal state variable plasticity model has been obtained to model the dynamical mechanical behavior of the novel metallic biomaterial.

Dynamic Mechanical Behavior of Titanium Ti-6Al-4V at Transient Large Deformation Manufacturing Processes

2007 ◽  
Author(s):  
J. Sun ◽  
Y. B. Guo
Keyword(s):  
Flow Stress ◽  
Mechanical Behavior ◽  
Large Deformation ◽  
Large Deformations ◽  
Model Parameters ◽  
Manufacturing Processes ◽  
Strain Rates ◽  
Dynamic Mechanical ◽  
Dynamic Mechanical Behavior ◽  
Jc Model

Titanium Ti-6Al-4V alloy has been widely used in the aerospace, biomedical, automobile and petroleum industries. However, Ti-6Al-4V is a typical difficult-to-process material owning to its unique physical and mechanical properties which are characterized by low thermal conductivity, low modulus of elasticity, and high yield strength at elevated temperatures. The rapidly rising demand for titanium components demands more efficient manufacturing processes. Material property of Ti-6Al-4V plays an important role in process design and optimization especially for transient large deformations processes such as forming and machining. However, the dynamic mechanical behavior is poorly understood and accurate predictive models have yet to be developed. To obtain meaningful results which reflect the physical mechanisms of large deformation processes, it is essential to study the dynamic mechanical behavior of Ti-6Al-4V. The Johnson-Cook (JC) model has shown to be effective for modeling strain-hardening behavior of metals and it is numerically robust and can easily be used in finite element simulation models. However, the determination of JC model parameters is determined mostly based on split Hopkinson bar pressure (SHPB) test at isothermal conditions, which is very different from those of transient large deformations characterized by quick and high temperature changes. This study focuses on the dynamic mechanical behavior of titanium in transient manufacturing processes. The mechanical behavior of Ti-6Al-4V at large strains and strain rates beyond the isothermal conditions has been studied using the JC model coupled with the adiabatic condition. Heat fraction coefficient and temperature parameter have great effect on Flow stress-strain relationship. A significant drop of the flow stress occurs at large deformations with high strain rates. The flow stress sensitivity to JC strength model parameters was also investigated. The effect of pressure-stress ratio on material failure strain has shown the material may exhibit super plasticity before failure at hydro compression mode.

scholarly journals Mechanical Behaviors of Flax Fiber-Reinforced Composites at Different Strain Rates and Rate-Dependent Constitutive Model

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 854 ◽  
Author(s):  
Dayong Hu ◽  
Linwei Dang ◽  
Chong Zhang ◽  
Zhiqiang Zhang
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Flax Fiber ◽  
Fiber Reinforced Composites ◽  
Strain Rates ◽  
Reinforced Composites ◽  
Dynamic Mechanical ◽  
Rate Dependent ◽  
Dynamic Mechanical Behavior

Flax fiber-reinforced composites (FFRCs) exhibit excellent environmentally friendly qualities, such as light weight, low cost, recyclability, and excellent mechanical properties. Understanding the dynamic mechanical behavior of FFRCs could broaden their potential applications in lightweight, crashworthy, and impact-critical structures. This study presents a study on the fabrication of FFRCs by vacuum-assisted resin infusion. The dynamic stress–strain responses of the fabricated specimens at strain rates ranging from 0.006 s-1 to 2200 s-1 were evaluated using quasi-static tests and the Split–Hopkinson pressure bar (SHPB). The results indicated that the FFRC exhibited superior strain rate sensitivity. Final deformation photographs and scanning electron micrographs clearly revealed the damage evolution of the FFRC specimens, as well as various failure mechanisms, including fiber–matrix debonding, fiber pull-out, and fiber fracture at different strain rates. On the basis of the experimental results, a simplified Johnson–Cook model was established to describe the strain-rate dependent constitutive model of FFRC. The validation of the suggested constitutive model was embedded in the finite element simulations and could well repeat the strain wave observed from the experiment results. Finally, the quasi-static compression and drop-hammer impact of pyramidal lattice structures with FFRC cores were investigated both numerically and experimentally, proving the effectiveness of the simplified Johnson–Cook model. This study could potentially contribute to a deeper understanding of the dynamic mechanical behavior of FFRCs and provide fundamental experimental data for future engineering applications.

Study of the Longitudinal Pedestal Layout during Beam Prefabrication on Bridge Floor

2012 ◽  
Vol 178-181 ◽  
pp. 2062-2065
Author(s):  
Shui Xing Zhou ◽  
Ling Ling Li ◽  
Wei Zhou ◽  
Chang Long Yang
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Mechanical Behavior ◽  
Analysis Method ◽  
Finite Element Software ◽  
Orthogonal Analysis ◽  
Internal Forces ◽  
Difficult Terrain ◽  
Concrete Deck

A method of prefabricating beam on bridge floor is sometimes employed in mountain difficult terrain. Four forms of longitudinal pedestal layout and three analysis cases obtained by orthogonal analysis method were drawn up, the mechanical behavior of the tool girder were studied by the finite element software and the role of deck pavement for tool girder was discussed. The results show that when the end of pedestal was situated in mid-span, the tool girder will reach the most disadvantageous status. Moreover, reinforced concrete deck pavement not only can improve the stiffness and integrity of the tool girder, but also can effectively decrease internal forces and deformations of the tool girder.

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