The Dynamic Mechanical Behavior and Microstructural Evolution of Commercial Pure Titanium

2014 ◽  
Vol 968 ◽  
pp. 7-11
Author(s):  
Tong Bo Wang ◽  
Bo Long Li ◽  
Mian Li ◽  
Ying Chao Li ◽  
Zuo Ren Nie
Keyword(s):  
Microstructural Evolution ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
Pure Titanium ◽  
Adiabatic Shear ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Cold Rolled ◽  
Average Size ◽  
Pressure Bar

The high strain rate deformation behavior of as-annealed and as-cold rolled pure titanium was inspected by Split Hopkinson Pressure Bar (SHPB). The effect of deformation structure on adiabatic shear behavior in pure titanium was analyzed from the aspect of dynamic mechanical response and microstructural evolution. It was found that the strong {0001} basal texture was formed in as-cold rolled pure titanium. There were Geometrically Necessary Boundaries (GNBs) with spacing of 0.6μm and Incidental Dislocation Boundaries (IDBs) with size of 80nm in one grain. The enhancement of adiabatic shear sensitivity in as-cold rolled titanium was attributed to the deformation induced dislocation boundaries. The core of adiabatic shear band (ASB) was full of fine equiaxed grains with average size of 0.4μm, which was induced by dynamic recrystallization.

Effect of High Strain Rate on Adiabatic Shear Sensitivity and Microstructures in Pure Titanium

2014 ◽  
Vol 915-916 ◽  
pp. 567-571
Author(s):  
Tong Bo Wang ◽  
Bo Long Li ◽  
Mian Li ◽  
Zuo Ren Nie
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
Pure Titanium ◽  
Model Material ◽  
Adiabatic Shear ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Shear Sensitivity ◽  
Cold Rolled

As a model material, commercial pure titanium was rolled to plates with different dislocation boundaries. The dynamic mechanical response of Ti specimen was analyzed during impacted with Split Hopkinson Pressure Bar (SHPB) at different strain rates, and microstructure evolution was investigated using optical microscopy and transmission electron microscopy. It was found that adiabatic shear sensitivity was decreased with increasing strain rates for all as-annealed, 25% and 50% cold rolled states. To the contrary, for 70% cold rolled state the adiabatic shear sensitivity was increased with increasing strain rates. The microstructure of adiabatic shear bands (ASBs) were developed from elongation morphology to fine equiaxed grains in the specimens of 25% cold rolled state, and ASBs became broader with increasing strain rate.

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.

A comparative study on dynamic mechanical performance of concrete and rock

2015 ◽  
Author(s):  
Xia Zhengbing ◽  
Zhang Kefeng ◽  
Deng Yanfeng ◽  
Ge Fuwen
Keyword(s):  
Mechanical Performance ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Peak Strain ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Strain And Strain Rate ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Relationship Of

Recently, engineering blasting is widely applied in projects such as rock mineral mining, construction of underground cavities and field-leveling excavation. Dynamic mechanical performance of rocks has been gradually attached importance both in China and abroad. Concrete and rock are two kinds of the most frequently used engineering materials and also frequently used as experimental objects currently. To compare dynamic mechanical performance of these two materials, this study performed dynamic compression test with five different strain rates on concrete and rock using Split Hopkinson Pressure Bar (SHPB) to obtain basic dynamic mechanical parameters of them and then summarized the relationship of dynamic compressive strength, peak strain and strain rate of two materials. Moreover, specific energy absorption is introduced to confirm dynamic damage mechanisms of concrete and rock materials. This work can not only help to improve working efficiency to the largest extent but also ensure the smooth development of engineering, providing rich theoretical guidance for development of related engineering in the future.

Simultaneous effects of strain rate and temperature on mechanical response of fabricated Mg–SiC nanocomposite

2019 ◽  
Vol 54 (5) ◽  
pp. 659-668 ◽  
Author(s):  
K Rahmani ◽  
GH Majzoobi ◽  
A Atrian
Keyword(s):  
Strain Rate ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
High Rate ◽  
Dynamic Tests ◽  
Hopkinson Pressure Bar ◽  
Compaction Temperature ◽  
Static Tests ◽  
Split Hopkinson ◽  
Pressure Bar

Mg–SiC nanocomposite samples were fabricated using split Hopkinson pressure bar for different SiC volume fractions and under different temperature conditions. The microstructures and mechanical properties of the samples including microhardness and stress–strain curves were captured from quasi-static and dynamic tests carried out using Instron and split Hopkinson pressure bar, respectively. Nanocomposites were produced by hot and high-rate compaction method using split Hopkinson pressure bar. Temperature also significantly affects relative density and can lead to 2.5% increase in density. Adding SiC-reinforcing particles to samples increased their Vickers microhardness from 46 VH to 68 VH (45% increase) depending on the compaction temperature. X-ray diffraction analysis showed that by increasing temperature from 25℃ to 450℃, the Mg crystallite size increases from 37 nm to 72 nm and decreases the lattice strain from 45% to 30%. In quasi-static tests, the ultimate compressive strength for the compaction temperature of 450℃ was improved from 123% for Mg–0 vol.% SiC to 200% for the Mg–10 vol.% SiC samples compared with those of the compaction at room temperature. In dynamic tests, the ultimate strength for Mg–10 vol.% SiC sample compacted at high strain rate increased remarkably by 110% compared with that for Mg–0 vol.% SiC sample compacted at low strain rate.

Dynamic mechanical experiments and microstructure constitutive model of frozen soil with different particle sizes

2017 ◽  
Vol 27 (5) ◽  
pp. 686-706 ◽  
Author(s):  
Zhiwu Zhu ◽  
Zhijie Liu ◽  
Qijun Xie ◽  
Yesen Lu ◽  
Dingyun Li
Keyword(s):  
Constitutive Model ◽  
Evolution Equations ◽  
Split Hopkinson Pressure Bar ◽  
Frozen Soil ◽  
Particle Sizes ◽  
Hopkinson Pressure Bar ◽  
Dynamic Mechanical ◽  
Micro Cracks ◽  
Split Hopkinson ◽  
Pressure Bar

To reveal the influences of soil particle size on the dynamic impact mechanical properties of frozen soil, four groups of frozen soil specimens composed of different particle sizes are tested using a split-Hopkinson pressure bar. Based on the Druger–Prager failure criterion and coupled damage-plasticity, a dynamic micro-constitutive model is established for describing the dynamic mechanical behavior of the frozen soil. Macroscopically, frozen soil is assumed to be homogeneous and continuous, although a large number of micro-cracks and micro-voids are distributed randomly throughout the volume. When a frozen soil specimen is subjected to a substantial shock, the propagation of micro-cracks and the collapse of micro-voids can induce damage. The evolution equations of the two damage mechanisms are proposed. Finally, through a comparison, it was shown that simulation results agreed well with the experimental results, thus validating the suitability of the developed model.

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.

INFLUENCE OF THE BONE MORPHOLOGY ON MECHANICAL BEHAVIOR OF HUMAN SKULL FOR TWO STRAIN RATE CASES

2018 ◽  
Vol 18 (04) ◽  
pp. 1850046
Author(s):  
MANAF KARKAR ◽  
CHRISTOPHE MARECHAL ◽  
REMI DELILLE ◽  
GREGORY HAUGOU ◽  
FRANCOIS BRESSON ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
Parietal Bone ◽  
Hopkinson Pressure Bar ◽  
Bone Morphology ◽  
Split Hopkinson ◽  
Micro Tomography ◽  
Human Skulls ◽  
Pressure Bar

Modeling the mechanical behavior of bone is very complex due to substantial variability of the mechanical response of bone. The objective of this study is to investigate the link between morphology of the human parietal bone and its mechanical behavior in compression with two different strain rates. Five formalin-preserved human skulls were used, and 10 specimens were taken from the parietal bone of each subject. The internal geometry of the osseous material was studied with a micro-tomography device. For mechanical testing, quasi-static (0.02 s–1) tests on a conventional compression machine and dynamic tests (1500 s–1) on a split Hopkinson pressure bar (SHPB) were conducted on 9 mm diameter samples. The results were used to examine relationships between the morphological parameters to find morphological correlations. Linkages between mechanical behavior and morphology of the human parietal bone were also analyzed to develop a behavior model based on micro-structure parameters as determined by micro-scanning.

Predeformation Effects on Shear Response and Microstructure in Pure Titanium-TA2

2007 ◽  
Vol 546-549 ◽  
pp. 1409-1412
Author(s):  
Shu Hua Li ◽  
Fu Chi Wang ◽  
Cheng Wen Tan ◽  
Zhi Yong Chen ◽  
Zhi Sun
Keyword(s):  
Shear Bands ◽  
Pure Titanium ◽  
Adiabatic Shear ◽  
Transmission Electron Micrograph ◽  
Adiabatic Shear Bands ◽  
Hopkinson Pressure Bar ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Pressure Bar

Adiabatic shear properties of pure titanium-TA2 have been investigated using specially designed specimen in a Hopkinson pressure bar at high strain rate of 103s- 1. Microstructural characteristics was investigated using scanning electrion microscopy as well as transmission and high resolution transmission electrion microscopy .The results showed that the shear stress and adiabatic sensitivity for rolled 45% TA2 are higher than forged TA2. Comparing the adiabatic shear bands (ASB) both in the forged and rolled TA2, no evidence in morphology alteration was found except to shear band widths. The transmission electron micrograph of the ASB in forged and rolled TA2 showed the grain size reduction from ~20μm to 200nm. No deformation twins have been observed in ASB. The selected area electron diffraction patterns of the ASB showed reflections of multiple grains, forming discontinuous rings which can be indexed as h.c.p. structure of α-Ti. This indicates that the ASB consists of fine grains of α-Ti and the α-Ti→ β-Ti transformation did not occur.

Thermo-Mechanical Aspects of Adiabatic Shear Failure of AM50 and Ti6Al4V Alloys

2008 ◽  
Author(s):  
D. Rittel ◽  
Z. G. Wang
Keyword(s):  
High Speed ◽  
Shear Failure ◽  
Split Hopkinson Pressure Bar ◽  
Adiabatic Shear ◽  
Maximum Temperature ◽  
Hopkinson Pressure Bar ◽  
Gauge Section ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Deformation Patterns

The thermo-mechanical aspects of adiabatic shear band (ASB) formation are studied for two commercial alloys: Mg AM50 and Ti6Al4V. Tests are carried out on shear compression specimens (SCS). The evolution of the temperature in the deforming gauge section is monitored in real time, using an array of high speed infrared detectors synchronized with a Kolsky apparatus (split Hopkinson pressure bar). The evolution of the gage temperature is found to comprise 3 basic stages, in agreement with Marchand and Duffy’s simultaneous observations of mechanical data and gauge deformation patterns (1988). The onset and full formation stages of ASB are identified by combining the collected thermal and mechanical data. Full development of the ASB is identified as the point at which the measured and calculated temperature curves intersect and diverge thereon. At that stage, the homogeneous strain assumption used in calculating the maximum temperature rise is no longer valid.

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