NUMERICAL SIMULATIONS OF THE INFLUENCE OF STRIKER BAR LENGTH ON SHPB MEASUREMENTS

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5813-5818 ◽  
Author(s):  
DONG WEI SHU ◽  
CHUN QI LUO ◽  
GUO XING LU
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Strain Response ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Simulation And Experiment ◽  
Strain Relationship ◽  
Axial Compressive Stress ◽  
Pressure Bar ◽  
Relationship Of

Split Hopkinson Pressure Bar (SHPB) has become a frequently used technique for measuring uni-axial compressive stress-strain relationship of various engineering materials under high strain rates. The pulse shape generated in the incident bar is sensitive to the length of the striker bar. In this paper, a finite element simulation of a Split Hopkinson Pressure Bar is performed to estimate the effect of varying length of striker bar on the stress-strain relationship of a material. A series of striker bars with different lengths, from 200mm to 350mm, are employed to obtain the stress-strain response of AL6061-T6 in both simulation and experiment. A comparison is made between the experimental and the computed stress-strain curves. Finally the influence of variation of striker bar length on the sample's stress-strain response is presented.

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.

An improved method for compressive stress-strain measurements at very high strain rates

1992 ◽  
Vol 438 (1902) ◽  
pp. 153-170 ◽  
Keyword(s):  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Pure Copper ◽  
High Strength ◽  
Tungsten Alloy ◽  
High Speed Photography ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

This paper describes a modification of the split Hopkinson pressure bar, to allow compression testing of high strength metals at a strain rate of up to about 10 5 s –1 . All dimensions are minimized to reduce effects of dispersion and inertia, with specimens of the order of 1 mm diameter. Strain is calculated from the stress record and calibrated with high-speed photography. Particular attention has been paid to the accuracy of the technique, and errors arising from nonlinearity in the instrumentation, dispersion, frictional restraint and inertia have all been quantitatively assessed. Stress–strain results are presented of Ti 6A14V alloy, a high strength tungsten alloy, and pure copper.

Dynamic Compression Test of CFRP Laminates Using SHPB Technique

2014 ◽  
Vol 566 ◽  
pp. 122-127
Author(s):  
Takayuki Kusaka ◽  
Takanori Kono ◽  
Yasutoshi Nomura ◽  
Hiroki Wakabayashi
Keyword(s):  
Compressive Strength ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Failure Process ◽  
Compression Tests ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Cfrp Laminates ◽  
Split Hopkinson ◽  
Pressure Bar

A novel experimental method was proposed for characterizing the compressive properties of composite materials under impact loading. Split Hopkinson pressure bar system was employed to carry out the dynamic compression tests. The dynamic stress-strain relations could be precisely estimated by the proposed method, where the ramped input, generated by the plastic deformation of a zinc buffer, was effective to reduce the oscillation of the stress field in the specimen. The longitudinal strain of gage area could be estimated from the nominal deformation of gage area, and consequently the failure process could be grasped in detail from the stress-strain relation. The dynamic compressive strength of the material was slightly higher than the static compressive strength. In addition, the validity of the proposed method was confirmed by the computational and experimental results.

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.

scholarly journals Effects of annealing and specimen geometry on dynamic compression of a Zr-based bulk metallic glass

2007 ◽  
Vol 22 (2) ◽  
pp. 389-401 ◽  
Author(s):  
George Sunny ◽  
John Lewandowski ◽  
Vikas Prakash
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Split Hopkinson Pressure Bar ◽  
Peak Stress ◽  
Specimen Geometry ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Split Hopkinson ◽  
Pressure Bar

High strain-rate compression experiments were performed with a split-Hopkinson pressure bar (SHPB) at 500–4000/s on cylindrical samples of a Zr-based bulk metallic glass (LM-1) in both the fully amorphous and annealed conditions. The effects of changes to the specimen geometry (i.e., L/D ratio) and the material heat treatment [i.e., annealing versus amorphous (as-received)], on the peak stress, strain-to-failure, and failure behavior were determined with the aid of an in situ video obtained by using a high-speed digital camera in conjunction with the split-Hopkinson pressure bar (SHPB). Examination of the in situ video recordings and light optical microscopy showed that the failed samples revealed preferential failure initiating at the sample ends due to stress concentration at the sample-insert interface. A new insert design was developed using transient, elastic-plastic finite-element simulations to reduce the effects of these stress concentrations. SHPB testing, combined with in situ video, subsequently revealed that this new experimental configuration promoted failure within the gage length and away from the sample ends in the samples tested. Significant effects of specimen geometry, insert design, and annealing on the apparent values of the peak stress, strain-to-failure, and fracture behavior were exhibited.

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.

Study on Constitutive Relationship of Fe-36Ni Invar Alloy

2011 ◽  
Vol 291-294 ◽  
pp. 1131-1135
Author(s):  
Guo He Li ◽  
Yu Jun Cai ◽  
Hou Jun Qi
Keyword(s):  
Strain Rate ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Constitutive Relationship ◽  
Invar Alloy ◽  
Hopkinson Pressure Bar ◽  
Universal Testing ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Relationship Of

By electronic universal testing machine and Split Hopkinson Pressure Bar, the mechanical properties data of Fe-36Ni invar alloy are gained at a range of temperature from 20°C to 800°C and strain rate from 10-3 /s to 104/s. An improved Johnson-Cook model is presented to describe the mechanical behavior of Fe-36Ni invar alloy at high temperature and high strain rate, and verified by experimental results.

Numerical Simulation of Double Specimens in Split Hopkinson Pressure Bar Testing

2010 ◽  
Vol 654-656 ◽  
pp. 2483-2486
Author(s):  
Muhammad Agus Kariem ◽  
John H. Beynon ◽  
Dong Ruan
Keyword(s):  
Dynamic Behaviour ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Performance ◽  
Strain Curve ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Element Analysis ◽  
Specimen Test ◽  
Split Hopkinson ◽  
Pressure Bar

The split Hopkinson pressure bar (SHPB) is the most commonly used technique to characterize the dynamic behaviour of materials at very high strain rates. However, a classic single specimen test only generates a single stress-strain curve at the average strain rate of the test. This paper proposes three arrangements on the use of double specimens in SHPB compression testing. All waves propagating along the bars have been used to analyse the dynamic behaviour of the specimens. To simulate the test and predict its dynamic performance, an axisymmetric finite element analysis using LS-DYNA was conducted for the experiment using 13 mm bar diameter. The validity of the simulations was checked with experimental data from normal SHPB testing. Based on the simulations, the modified techniques are achievable and at least two stress-strain curves of materials can be extracted without violating the requirement of a valid SHPB test.

Sign in / Sign up

Export Citation Format

Share Document