Determination of mechanical properties from sharp dynamic indentation

2021 ◽  
pp. 030932472110592
Author(s):  
Bowen Si ◽  
Zhiqiang Li ◽  
Gesheng Xiao ◽  
Xuefeng Shu
Keyword(s):  
Mechanical Properties ◽  
Power Law ◽  
Split Hopkinson Pressure Bar ◽  
Indentation Test ◽  
Hopkinson Pressure Bar ◽  
Dynamic Indentation ◽  
Material Parameters ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Indentation Response

In this study, a dynamic indentation test method based on the split Hopkinson pressure bar is proposed to obtain the dynamic parameters of Ludwik power law constitutive, namely, Young’s modulus E, strength coefficient K, and strain hardening index n by analyzing dynamic indentation load-indentation depth curve obtained from the theories relating to the Hopkinson pressure bar. The important parameters, namely, loading curvature C and transformation factor [Formula: see text], are invoked to examine the dynamic indentation response results in a wide range of target material parameters. Finite element calculation results are processed through simulation of dynamic indentation response with broad material parameters. Furthermore, the analytical method is used to fit simulation results to obtain the analytical equations for elastic–plastic parameters and curvature parameters for the subsequent analysis. The analytical equation of forward model to predict dynamic indentation response parameter–loading curvature C of a known material is proposed. Then, the elastic–plastic parameters of unknown materials (according to Ludwik power law) are obtained by substituting the dynamic indentation response parameters into an inverse analytical equation under the two types of half-cone angle indenters. The method is verified by other typical materials, which shows that the dynamic indentation test based on the split Hopkinson pressure bar can obtain sufficient conditions to obtain dynamic mechanical properties of target materials.

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.

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.

Dynamic Behavior of Monolithic and Composite Materials by Split Hopkinson Pressure Bar Testing

2002 ◽  
Author(s):  
Marco Costanzi ◽  
Gautam Sayal ◽  
Golam Newaz
Keyword(s):  
Mechanical Properties ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
Glass Fiber Reinforced ◽  
Experimental Apparatus ◽  
Different Types ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
Long Cylinder

A Split Hopkinson Pressure Bar (SHPB), an experimental apparatus for testing of solid materials at high strain rates, was in-house designed and realized by the Mechanical Engineering Dept. of WSU: it can test different types of materials and provide their dynamic mechanical properties (e.g. Young’s modulus, hardening or plasticization coefficients, yield strength). This SHPB works at strain rate levels between 1000 and 3000 s-1 and impact speeds between 6 and 9 m/s. The specimen is simply a 6 mm dia. 3 mm long cylinder. The apparatus and its software were benchmarked by means of tests on Aluminum and Titanium, whose mechanical properties are well known, and later successfully applied to non-metallic materials like Nylon, Epoxy, Carbon fiber and glass fiber reinforced composites.

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.

Effect of Strain Rate on Mechanical Properties of Pure Iron

2013 ◽  
Vol 705 ◽  
pp. 21-25 ◽  
Author(s):  
Wei Ping Bao ◽  
Zhi Ping Xiong ◽  
Xue Ping Ren ◽  
Fu Ming Wang
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Work Hardening ◽  
Pure Iron ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Hopkinson Pressure Bar ◽  
Hardening Effect ◽  
Split Hopkinson ◽  
Pressure Bar

Effect of strain rate on mechanical properties of pure iron was studied by compression experiments using Gleebe-1500D thermal simulation testing machine and Split-Hopkinson Pressure Bar, indicating that pure iron only has strain rate hardening effect. Adiabatic temperature rise tends to increase with increasing the strain rate. Work hardening effect is also analyzed. It found that there are only two work hardening regions in static stage (10-3 to 1 s-1) while there are three work hardening regions in dynamic stage (650 to 8500 s-1). It is on account of onset of twining at high strain rates.

Mechanical and ballistic analysis of aramid/vinyl ester composites

2017 ◽  
Vol 52 (3) ◽  
pp. 289-299 ◽  
Author(s):  
Marlova Pagnoncelli ◽  
Vanessa Piroli ◽  
Daiane Romanzini ◽  
Iaci M Pereira ◽  
Rafael Rodrigues Dias ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Vinyl Ester ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Mechanical Properties ◽  
Fiber Content ◽  
Hopkinson Pressure Bar ◽  
Ballistic Protection ◽  
Split Hopkinson ◽  
Level I ◽  
Pressure Bar

This study focused on evaluating mechanical and dynamic-mechanical properties of polyaramid/vinyl ester composites, as a function of the fiber content. Furthermore, split Hopkinson pressure bar technique and V50 Ballistic limit tests were performed. Composites were prepared by resin transfer molding (RTM) with different fiber content, samples being identified as AD4, AD5 and AD6 (with 4, 5 and 6 polyaramid layers, respectively). Initially, fiber, void and matrix contents were calculated and statistically analyzed, in different regions of the composites. Mechanical and dynamical mechanical properties of the composites were improved by using higher fiber content. For example, impact strength of AD6 composite was 35% higher than AD4. Moreover, increase in the fiber content promoted an increase in tenacity and stress of the composites, in the same strain rate. Velocity limit in AD6 sample was estimated in ballistics tests and it was concluded that the composite obtained could accomplish the level I requisites of ballistic protection with V50 of 304 m.s−1.

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