scholarly journals An axisymmetric model for Taylor impact test and estimation of metal plasticity

Author(s):  
Sukanta Chakraborty ◽  
Amit Shaw ◽  
Biswanath Banerjee

The impact of a flat-ended cylindrical rod onto a rigid stationary anvil, often known as the Taylor impact test, is studied. An axisymmetric model is developed to capture the deformation behaviour of the rod after impact. The most distinctive feature of the proposed model is that it takes into account the spatial and temporal variation of both longitudinal and radial deformation and consequently the strains and strain rates. The final deformed shapes and time histories of different field variables, as obtained from the model, are found to be in good agreement with corresponding experimental and numerical results reported in the literature. The proposed model is then used to formulate an inverse framework to estimate the Johnson–Cook constitutive parameters. In the inverse formulation, the objective function is constructed using the final deformed length and diameter at the impact end of the retrieved rod. Finally, the potential of the proposed model in estimating material parameters is illustrated through some examples.

2021 ◽  
Vol 8 ◽  
Author(s):  
Li Juncheng ◽  
Chen Gang ◽  
Lu Yonggang ◽  
Huang Fenglei

Taylor impact test is characterized by high impact energy, low cost, and good repeatability, giving it the technical foundation and development potential for application in high-g loading. In this paper, the feasibility of performing high-g load impact testing to a missile-borne recorder by conducting Taylor impact test was studied by combining simulation analyses with experimental verification. Acccording to the actual dimensions of the missile-borne recorder, an experimental piece was designed based on the Taylor impact principle. The impact loading characteristics of the missile-borne recorder were then simulated and analyzed at different impact velocities. In addition, the peak acceleration function and the pulse duration function of the load were fitted to guide the experimental design. A Taylor-Hopkinson impact experiment was also conducted to measure the impact load that was actually experienced by the missile-borne recorder and the results were compared with the results of strain measurements on the Hopkinson incident bar. The results showed that the peak value of impact load, the pulse duration and the waveform of the actual experimental results were in good agreement with the results predicted by the simulations. Additionally, the strain data measured on the incident bar could be used to verify or replace the acceleration testing of the specimen to simplify the experimental process required. Based on the impact velocity, high-g loading impact was achieved with peak values in the 7,000–30,000 g range and durations of 1.3–1 ms, and the waveform generated was a sawtooth wave. The research results provide a new approach for high amplitude and long pulse duration impact loading to large-mass components, and broaden the application field of Taylor impact test.


Author(s):  
N. K. Bourne ◽  
S. C. Garcea ◽  
D. S. Eastwood ◽  
S. Parry ◽  
C. Rau ◽  
...  

The well-known Taylor cylinder impact test, which follows the impact of a flat-ended cylindrical rod onto a rigid stationary anvil, is conducted over a range of impact speeds for two polymers, polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK). In previous work, experiments and a model were developed to capture the deformation behaviour of the cylinder after impact. These works showed a region in which spatial and temporal variation of both longitudinal and radial deformation provided evidence of changes in phase within the material. In this further series of experiments, this region is imaged in a range of impacted targets at the Diamond synchrotron. Further techniques were fielded to resolve compressed regions within the recovered polymer cylinders that showed a fracture zone in the impact region. The combination of macroscopic high-speed photography and three-dimensional X-ray imaging has identified the development of failure with these polymers and shown that there is no abrupt transition in behaviours but rather a continuous range of responses to competing operating mechanisms. The behaviours noted in PEEK in these polymers show critical gaps in understanding of polymer high strain-rate response.


Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 713
Author(s):  
Jun-Cheng Li ◽  
Gang Chen ◽  
Feng-Lei Huang ◽  
Yong-Gang Lu

This study focused on the impact load produced by a projectile and its potential application in the Taylor impact test. Taylor impact tests were designed and carried out for projectiles with four types of nose shapes, and the impact deformation characteristics and variation of the impact load as a function of the nose shape and impact velocity were studied. The overall high g loading experienced by the projectile body during the impact was discussed, and based on classical Taylor impact theory, impact analysis models for the various nose-shape projectiles were established and the causes of the different impact load pulse shapes were analyzed. This study reveals that the nose shape has a significant effect on the impact load waveform and pulse duration characteristics, while the impact velocity primarily affects the peak value of the impact load. Thus, the loading of specific impact environments could be regulated by the projectile nose shape design and impact velocity control, and the impact load could be simulated. Research results support the assumption that the Taylor impact test can be applied to high g loading test.


2021 ◽  
Vol 250 ◽  
pp. 01028
Author(s):  
Chong Gao ◽  
Takeshi Iwamoto

It is a challenge to apply the infrared detector to a test at higher strain rate because lots of articles report that the detector has an extremelyhigh responsiveness. However, all the research works about the measurement of temperature is focused on 103 s-1 of the strain rate achieved by the split Hopkinson pressure bar test. To evaluate the thermo-mechanical behaviour of materials in higher strain rate range, a method for measuring the temperature in Taylor impact test is required to establish. Additionally, a use of the fiber should be considered to protect the detector from any damages by the impact of the specimen and realize the measurement in the point-like area. In this study, an optically-measuring system of temperature with the infrared detector and PIR fiber is designed. Then, the designed system is introduced into the apparatus based on the instrumented Taylor impact test proposed recently. The temperature rise at a local point on the surface of pure aluminium is measured during the test. Then, a calculation for distribution of temperature from a heat conduction equation is proposed.


2012 ◽  
Vol 525-526 ◽  
pp. 377-380
Author(s):  
F. Xu ◽  
Wei Guo Guo ◽  
Q.J. Wang ◽  
Zhi Yin Zeng

In this paper, to determine the dynamic strength model for steels, a new approach which does not rely on the Hopkinson bar test has been proposed. As the DH36 steel for example, using the results of Taylor impact test and the quasi-static compression test, the initial parameters of Johnson-Cook plastic strength model have been fitted out, then the initial strength parameters have been optimized using the optimization techniques of the sparse Taylor impact cylinder. It has been shown that the optimized results in numerical simulation are consistent with results of Taylor impact test, and the optimized Johnson-Cook model can also well describe flow stress curve fitted from the Hopkinson bar test.


2012 ◽  
Vol 26 ◽  
pp. 01062 ◽  
Author(s):  
L. Kruszka ◽  
Ł. Anaszewicz ◽  
J. Janiszewski ◽  
M. Grązka

2011 ◽  
Vol 673 ◽  
pp. 83-88 ◽  
Author(s):  
Hyung Seop Shin ◽  
Sung Su Park ◽  
Joon Hong Choi

The understanding of the deformation behavior of rubber materials under high strain-rate or high loading-rate conditions will be important in their impact applications adopting significant viscoelastic behavior. Taylor impact test has originally used to determine the average dynamic yield strength of metallic materials at high strain rates, but it also can be used to examine the overall deformation behavior of rubbers representing large elastic deformation by using a high-speed photography technique. Taylor impact tests of rubber materials were carried out in the velocity range between 100~250 m/s using a 20 mm air gun. In order to investigate the overall dynamic deformation behavior of rubber projectiles during Taylor impact test, a 8-Ch high-speed photography system which provides a series of images at each elapsed time was incorporated. Three kinds of rubber materials with different Tg (glass transition temperature) were supplied. The bulging behavior of rubber projectile could be evaluated quantitatively by digitizing images taken. Taylor impact tests at various temperature levels were conducted to predict the bulging behavior of rubbers at high strain rate.


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