Determination of length to diameter ratio of the bars in torsional Split Hopkinson bar

Majzoobi, G.H.; Rahmani, Kaveh; Lahmi, S.

doi:10.1016/j.measurement.2019.04.054

Cited by 7 publications

(3 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The conventional SHPB measuring system is based on the theory of one-dimensional wave propagation, which is why the design of the Hopkinson device uses bars of small diameter and long length to minimize measurement error. 1,19 Moreover, in order to extract the reflected signal correctly from the signal recorded by strain gauges of the input bar, strain gauges should be mounted at the middle of the bars. According to the wave propagation analysis, the incident pulse duration ( Δ t ) is a linear function of striker bar length ( L )…”

Section: Resultsmentioning

confidence: 99%

Determination of dynamic material properties using laser measurement technique in split Hopkinson pressure bar

Mirshafiee

Ashrafi

Mousavi

2023

The Journal of Strain Analysis for Engineering Design

View full text Add to dashboard Cite

The split Hopkinson pressure bar (SHPB) is a commonly used technique to measure the stress-strain of materials at high strain rate. Using the strain records in the input and output bars, the average stress-strain and strain rate in the sample can be calculated by SHPB formulas based on the one-dimensional wave propagation theory. The accuracy of a SHPB test is based on this assumption. In this paper, first a laser measuring system is designed, implemented, and calibrated in order to obtain the dynamic properties of different materials using split Hopkinson pressure bar test. In this method which is a non-contact one, the displacements of bar/sample interfaces are measured directly using a laser extensometer technique, by using the provided equations, in addition to the strain, the stress of the tested sample can be calculated. Moreover, the operation of the method is evaluated using numerical simulation. Aluminum 7075 and copper C10200 samples were studied to evaluate the implemented measurement method. The comparison with other measurement methods shows good agreement of numerical and experimental results. Moreover, since the one-dimensional wave propagation is not used directly in this method, we show the proposed method can be used even with shorter pressure bars which can reduce the cost of manufacturing and maintenance of the SHPB apparatus.

show abstract

Section: Resultsmentioning

confidence: 99%

Determination of dynamic material properties using laser measurement technique in split Hopkinson pressure bar

Mirshafiee

Ashrafi

Mousavi

2023

The Journal of Strain Analysis for Engineering Design

View full text Add to dashboard Cite

show abstract

“…Various experimental systems, including the Torsional split-Hopkinson bar (TSHB) [34], Charpy pendulum, drop weight, hydraulic servo machine, and plane impact testing, have been employed by researchers to characterize materials across different loading rates [35,36]. To explore the impact of powder compaction speed on final density of Mg samples, the compaction process was conducted at three different compaction speeds, i.e., 15.5 m s −1 (using a Hopkinson bar), 8 m s −1 (using a drop weight), and 1 mm min −1 (using an Instron machine).…”

Section: Influence Of Compaction Speed (Strain Rate) On Properties Of...mentioning

confidence: 99%

Determining the Drucker-Prager Cap model constants using experimental, numerical and optimization for compacted Mg powders at different strain rates

Rahmani,

Bakhtiari,

Malekmohammadi

et al. 2024

Phys. Scr.

View full text Add to dashboard Cite

This article investigates an inverse approach to determine the coefficients of the Drucker-Prager model for magnesium powder. The approach involves conducting finite element simulations of the powder compression process within LS-DYNA software, employing the Drucker-Prager material model. The goal is to minimize the disparity between force-displacement outcomes derived from simulations and experimental data using a surrogate optimization method. Experimental data were obtained through a uniaxial compression test and served as a basis for adjusting the Cap model coefficients. A random selection of coefficients was made using the Latin cube method and simulations were performed based on the initial coefficients. The optimization was then performed using the particle swarm algorithm over 20 iterations. The optimized coefficients were validated against experimental data, demonstrating close agreement. By utilizing the extracted coefficients, the relative density of the samples was calculated at three different compaction speeds, i.e., 15.5 m/s (using a Hopkinson bar), 8 m/s (using a drop weight), and 1 mm/min (using an Instron machine). The analysis revealed the highest relative density and stress in the densified sample via the Hopkinson bar method, reaching 99.83% and 1.1 GPa, respectively.

show abstract

“…Needles to say that in this test, the specimen experienced uniform and pure shear stress. Equations for calculating shear stress and shear strain rates from the transmitted, reflected, and incident waves are provided as follows (Majzoobi et al, 2019)…”

Section: High Strain Rate Torsion Testmentioning

confidence: 99%

High strain rate torsional response of maraging steel parts produced by laser powder bed fusion techniques: Deformation behavior and constitutive model

Dehgahi

Pirgazi

Sanjari

et al. 2022

Mechanics of Materials

View full text Add to dashboard Cite

Determination of length to diameter ratio of the bars in torsional Split Hopkinson bar

Cited by 7 publications

References 12 publications

Determination of dynamic material properties using laser measurement technique in split Hopkinson pressure bar

Determination of dynamic material properties using laser measurement technique in split Hopkinson pressure bar

Determining the Drucker-Prager Cap model constants using experimental, numerical and optimization for compacted Mg powders at different strain rates

High strain rate torsional response of maraging steel parts produced by laser powder bed fusion techniques: Deformation behavior and constitutive model

Contact Info

Product

Resources

About