Determination of Johnson cook material and failure model constants and numerical modelling of Charpy impact test of armour steel

Banerjee, Arnab; Dhar, S.; Acharyya, S. K.; Datta, Debasis; Nayak, N.U.

doi:10.1016/j.msea.2015.05.073

Cited by 195 publications

(111 citation statements)

References 11 publications

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“…The Johnson-Cook strength model is commonly used in simulations of impact and penetration problems (Banerjee et al, 2015). It takes into account strain rate dependence of the stress where the strain rate is between ε0 = 10 -2 /s and ε0 = 10 6 /s (Shrot, 2012).…”

Section: Strength Modelmentioning

confidence: 99%

Explicit finite element analysis of high speed piston impacts

Yusuf¹

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The University of Queensland operates three large scale free-piston drivers which consists of the T4, X2 and X3 facilities. These facilities are designed for the worst case scenarios based on conservative analytical impact mechanics, in terms of avoiding catastrophic piston impacts. However, these do not accurately predict the mechanical response for complex real geometry in the event of a piston impact.In 2009, there was a high speed impact of a heavy piston that rendered the facility inoperable for two months. Repeated attempts were made to relieve enough stress in the plastically deformed piston to dislodge it from the compression tube. This impact reiterated the potential damage that can be caused by incorrect operation of the free-piston drivers and revealed that there was no structured methodology to estimate the condition of the facility to inform the repair procedure.In this study, the AUTODYN solver was used to investigate three main explicit structural analysis problems including recreating the 2009 T4 high speed piston impact, perfoming a transient stress analysis of the peak pressure loadings acting on X2's lightweight piston using high strain rate material data and analysing the buffer for the X3 facility.The approach to this study involved testing the solver's ability to capture the physical mechanisms involved during a high speed piston impact. An axisymmetric analysis of T4 shot 10509 was later developed where the numerical results were compared to observational comments of the facility made by the technician following the repair job. This approach to using an axisymmetric model was also used to analyse the peak pressure loadings acting on the X2 piston and the results from this were validated against a static structural analysis. An axisymmetric model of the X3 buffer was developed and this was validated against a 3D model. This study has shown that the AUTODYN solver can be used to model high speed piston impacts with relative confidence. Furthermore, there was enough evidence to show that the numerical recreation of T4 shot 10509 did agree with the technician's observations following T4 shot 10509. This allowed for the response of the facility at higher impact speeds and with varying material properties to be investigated. The transient analysis conducted for the X2 lightweight piston agreed closely with the static structural analysis conducted prior. Since the X3 lightweight piston was made out of similar materials to the X2 piston, this validated the material data used for the X3 piston. It was also discovered that the nylon studs in the X3 facility would not likely fracture from an impact speed of 30 m/s by the X3 lightweight piston. This quantification of safe impact speeds for the X3 buffer was deemed important following the development of new driver operating conditons for the X3 facility.ii Acknowledgements Foremost, I would like to thank my supervisor Dr Gildfind for his continued support throughout the year, and faith in my ability to overcome all obstacles that got in my way....

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Section: Strength Modelmentioning

confidence: 99%

Explicit finite element analysis of high speed piston impacts

Yusuf¹

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“…The procedure for experimentally determining the Johnson-Cook equation constants will follow the procedure shown by Banerjee et al that uses tensile testing only [18]. In their study, two machines were used to capture a full range of strain rates.…”

Section: Procedures For Determining Jc Equation Constants From Experimmentioning

confidence: 99%

“…Here, the constant is the yield stress of the material and and are found by curve fitting to the true stress vs plastic strain curve that follows the yield point [18].…”

Section: Cook Equation To That Shown In Equation 31mentioning

confidence: 99%

“…Banerjee et al plots the true stress value at a constant point of plastic strain ( = 0.05) for tests performed at multiple strain rates (̇ * ) [18], making the strain dependent term constant. Further manipulation produces Equation 38, showing a linear relation between stress and effective strain rate …”

Section: Cook Equation To That Shown In Equation 31mentioning

confidence: 99%

“…These points are then plotted and a linear fit is calculated, with the temperature dependence given as the slope. It should be noted that Banerjee et al used cylindrical tensile specimens for temperature dependence tests [18]. Figure 3.16: Plot from banerjee et al's study showing how the strain hardening constant C is taken as the slope between points that compare strain rate and resulting stress at 5% plastic strain…”

Section: Cook Equation To That Shown In Equation 31mentioning

confidence: 99%

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Development of material strength and failure models for structural simulation of metallic shock tube diaphragms

Lacey¹

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Rupture dynamics of thin metallic diaphragms significantly influence the development of radially uniform planar shocks in hypersonic impulse facilities and consequently have a significant influence on the operating conditions of such facilities. Little literature exists for predicting the rupture pressure and opening times of diaphragms in impulse facilities and therefore there is interest among researchers in this field to develop characteristic models that describe mechanical properties of diaphragms during deformation and rupture. This thesis investigates a novel procedure for developing material models that describe plastic yielding and ductile rupture of thin metallic diaphragms using tensile testing equipment. Johnson-Cook strength and damage model constants have been determined from raw tensile data produced from tensile specimens of notched and un-notched geometries tested at a range of strain rates. The validity of the model constants produced was shown by comparing simulated load-displacement plots of tensile tests to data taken directly from such experiments. It was found that the models produced accurate predictions for specimens with geometries that introduced high stress concentrations at quasi-static speeds. Simulations of specimens without stress concentrations had over-predicted extensions at failure, and high strain rate simulations were impeded by experimental uncertainty in the strain rate dependent constants. To continue previous work in this field at the University of Queensland, a finite element model of 1/8 th of the diaphragm region of the X3 impulse facility was created and simulations performed. Mesh convergent simulations predicted a rupture pressure of 11.88 which was similar to the experimentally determined rupture pressure of 15 − 18 . Disagreement in results was attributed to uncertainty in damage constants due to measurement techniques, uncertainty in strain rate dependent constants due to experimental variation and an uncertainty in the exact rupture pressure at the diaphragm location in the X3 impulse facility.

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Finite element based model for predicting induced residual stresses and cutting forces in AISI 1020 steel alloy

Bosire

Muvengei

Mutua

et al. 2023

Materialwissenschaft Werkst

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The application of finite element models is a promising method for ensuring part quality during machining to accurately predict induced residual stresses and cutting forces. The present study applied Analysis System software to formulate a 3D model to predict induced residual stress and forces for AISI 1020 alloy. Taguchi method was applied in the design of the experiment with three levels and three factors selected: Cutting speed, feed rate and depth of cut. For validation, stresses are measured using an x-ray diffractometer from the surface to a depth of 0.6 mm in steps of 0.2 mm. The cutting forces are determined using a force dynamometer. Simulation results showed that cutting speed, feed rate and depth of cut contributed 94.76 %, 0.048 %, and 0.11 % respectively. The predictive model equations were statistically significant with a p-value of < 0.005. The average induced residual stress on the superficial layer from the experiment and simulation were À 367.7 MPa and À 365.6 MPa respectively. The average residual stresses obtained at depths of 0.2 mm, 0.4 mm, and 0.6 mm were À 260 MPa, À 233 MPa, and À 211 MPa, respectively. The proposed model offers a potential solution to reducing the costs of experimental methods.

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Determination of Johnson cook material and failure model constants and numerical modelling of Charpy impact test of armour steel

Cited by 195 publications

References 11 publications

Explicit finite element analysis of high speed piston impacts

Explicit finite element analysis of high speed piston impacts

Development of material strength and failure models for structural simulation of metallic shock tube diaphragms

Finite element based model for predicting induced residual stresses and cutting forces in AISI 1020 steel alloy

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