SAM

Effect of projectile nose shape on ballistic resistance of interstitial-free steel sheets

KPENYIGBA, K. M. — Thu, 01 Jan 2015 00:00:00 GMT

Effect of projectile nose shape on ballistic resistance of interstitial-free steel sheets KPENYIGBA, K. M.; JANKOWIAK, Tomasz; RUSINEK, Alexis; WANG, Bin; PESCI, Raphaël In this paper an experimental and numerical work is reported concerning the process of perforation of thin steel plates using different projectile nose shapes. The main goal is to analyze how the projectile shape may change the ballistic properties of materials. A wide range of impact velocities from 35 to 180 m/s has been covered during the tests. All the projectiles were 13 mm in diameter and the targets were 1 mm thick, as such the projectile can be regarded as rigid and the target sheets were of interstitial free (IF) steel. The mass ratio (projectile mass/steel sheet mass) and the ratio between the span of the steel sheet and the diameter of the projectile were kept constant, equal to 0.38 and 3.85 respectively. To define the thermoviscoplastic behavior of the target material, the Rusinek-Klepaczko (RK) constitutive model [1] was used. The complete identification of the material constants was done based on a rigorous material characterization. Numerical simulations of some experimental tests were carried out using a non-linear finite element code ABAQUS/Explicit. It was found that the numerical models are able to describe the physical mechanisms in the perforation process with a good accuracy.

Mechanical charecterization and analytical modeling of the thermo-viscoplastic behaviour AISI 304 steel under wide ranges of strain rates at room temperature

RODRIGUEZ-MARTINEZ, José A. — Fri, 01 Jan 2010 00:00:00 GMT

Mechanical charecterization and analytical modeling of the thermo-viscoplastic behaviour AISI 304 steel under wide ranges of strain rates at room temperature RODRIGUEZ-MARTINEZ, José A.; RUSINEK, Alexis; ARIAS, Angel; PESCI, Raphaël In this investigation, the thermo-viscoplastic behaviour of the steel AISI 304 has been examined. The experimental characterization of the material has been conducted in tension under wide ranges of strain rates.An analytical description of the macroscopic behaviour of this metal is reported. For such goal, the extended Rusinek-Klepaczko model to viscous drag effects is applied.It allows for proper description of the material behaviour within the whole range of loading conditions considered.In addition, the analytical formulation proposed gathers limited number of material constants and simple calibration procedure.

A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates

ZAERA, Ramon — Sun, 01 Jan 2012 00:00:00 GMT

A constitutive model for analyzing martensite formation in austenitic steels deforming at high strain rates ZAERA, Ramon; RODRIGUEZ-MARTINEZ, J. A.; CASADO, Ana Maria; FERNANDEZ-SAEZ, José; RUSINEK, Alexis; PESCI, Raphaël This study presents a constitutive model for steels exhibiting SIMT, based on previous seminal works, and the corresponding methodology to estimate their parameters. The model includes temperature effects in the phase transformation kinetics, and in the softening of each solid phase through the use of a homogenization technique. The model was validated with experimental results of dynamic tensile tests on AISI 304 sheet steel specimens, and their predictions correlate well with the experimental evidence in terms of macroscopic stress–strain curves and martensite volume fraction formed at high strain rates. The work shows the value of considering temperature effects in the modeling of metastable austenitic steels submitted to impact conditions. Regarding most of the works reported in the literature on SIMT, modeling of the martensitic transformation at high strain rates is the distinctive feature of the present paper.

Perforation Behavior of 304 Stainless Steel Plates at Various Temperatures

JIA, Binsdu — Tue, 01 Jan 2019 00:00:00 GMT

Perforation Behavior of 304 Stainless Steel Plates at Various Temperatures JIA, Binsdu; RUSINEK, Alexis; BAHI, Slim; BERNIER, Richard; BENDARMA, Amine; PESCI, Raphaël The effect of temperature on perforation behavior of 304 austenitic stainless steel plates was investigated experimentally. Perforation tests have been conducted at velocities from 80 to 180 m/s and temperatures between − 163 and 200 °C. Low temperatures were obtained using a specific designed cooling device and the temperature distribution on the specimens was verified to be uniform. Based on the experimental results, the failure mode, the initial-residual velocity curves, the ballistic limit velocities and the energy absorption capacity under different temperatures were analyzed. It was found that petalling was the main failure mode during the perforation process. The average number of petals was three at 20 °C or 200 °C and was increasing continuously to five at − 163 °C. The ballistic limit velocity Vbl was also affected by the initial temperature. It increased slightly from 93 m/s at 200 °C to 103 m/s at − 20 °C and then remained constant at lower temperatures. The material showed better energy absorption capacity at low temperatures and this came not only from the temperature sensitivity of the material but also from the strain-induced martensitic transformation effect. According to martensite measurement by X-ray diffraction technique, the martensite fractions along the fracture surface of petals were 87.1%, 66.2%, 52.8% and 32.4% respectively for initial temperatures of − 163 °C, − 60 °C, − 20 °C and 20 °C.

A novel technique for dynamic shear testing of bulk metals with application to 304 austenitic stainless steel

JIA, Bin — Wed, 01 Jan 2020 00:00:00 GMT

A novel technique for dynamic shear testing of bulk metals with application to 304 austenitic stainless steel JIA, Bin; RUSINEK, Alexis; BERNIER, Richard; BAHI, Slim; WOOD, Paul; PESCI, Raphaël This paper describes a new single-shear specimen (SSS) and method to characterize the dynamic shear behavior of bulk metals using a traditional Split Hopkinson Pressure Bar (SHPB). By this method, the shear behavior of materials can be tested conveniently over a wide range of strain rates within 105 s−1. This technique was applied to a 304 austenitic stainless steel (ASS) under shear strain rates from 0.001 s−1 to 38700 s−1 at room temperature. Based on finite element (FE) simulations, it was found that the deformation of the specimen shear zone was dominated by shear stress/strain components. Stress state parameters represented by stress triaxiality η and Lode angle parameter θ- were found very close to zero, indicating a deformation mode of simple shear. Besides, an obvious gap existed between the local deformation behavior in the specimen shear zone and the macroscopic stress-strain relations measured by the strain gauges on the SHPB bars. A correction coefficient method was adopted to extract the real shear behavior from the experimentally obtained force-displacement data. Through comparisons between the tested and simulated stress-strain curves, a good agreement was obtained.

Simple shear behavior and constitutive modeling of 304 stainless steel over a wide range of strain rates and temperatures

JIA, Bin — Fri, 01 Jan 2021 00:00:00 GMT

Simple shear behavior and constitutive modeling of 304 stainless steel over a wide range of strain rates and temperatures JIA, Bin; RUSINEK, Alexis; BERNIER, Richard; BAHI, Slim; BENDARMA, Amine; WOOD, Paul; PESCI, Raphaël A novel single shear specimen (SSS) together with a correction coefficient method is used to study the deformation behavior of a 304 stainless steel under shear loadings. Shear stress-shear strain relations over a wide range of shear strain rates (0.001 to 39000 s−1) at three initial temperatures (77 to 473 K) are obtained experimentally. The effects of strain rate and temperature on the flow stress curves are determined. With increasing strain rate or temperature, the strain hardening rate decreases continuously. At the maximum strain rate of 39000 s−1, negative strain hardening rates are observed. At very high strain rates above 13000 s−1, a sharp increase in flow stress is observed, indicating a rapid rise in strain rate sensitivity. The fracture morphology of post-mortem specimens is analyzed and no well-developed adiabatic shear bands are observed. This may be due to the shear-tension stress state without hydrostatic pressure in the fracture process. Based on the experimentally obtained shear stress-shear strain curves, parameters of a modified Johnson-Cook (MJC) model are determined. A good agreement between experiments and model predictions is found, with an average error of 3.9%. Using finite element analysis, distributions of stress and strain components in the specimen shear zone is analyzed. It is found that the shear stress and shear strain play dominant roles, and a simple shear stress state with low stress triaxiality (0.015) and Lode angle parameter (0.014) is obtained.

Thermo-viscoplastic behavior of 304 austenitic stainless steel at various strain rates and temperatures: Testing, modeling and validation

JIA, Bin — Wed, 01 Jan 2020 00:00:00 GMT

Thermo-viscoplastic behavior of 304 austenitic stainless steel at various strain rates and temperatures: Testing, modeling and validation JIA, Bin; RUSINEK, Alexis; BAHI, Slim; BERNIER, Richard; PESCI, Raphaël This paper presents a systematic study of the thermo-viscoplastic behavior of a 304 austenitic stainless steel (ASS). The experiments were conducted over a wide range of strain rates (10 − 3 s − 1 to 3270 s − 1 ) and temperatures (-163°C to 172°C), for which the deformation behavior of 304 ASS becomes more complex due to the strain- induced martensitic transformation (SIMT) effect. Dynamic tests at low/elevated temperatures were conducted using the Hopkinson technique coupled with a cooling device/heating furnace, and temperature distribution within the specimen was verified to be uniform. Experimental results showed that the strain hardening rate of 304 ASS was strongly affected by SIMT effect. For quasi-static tests (10 − 3 s − 1 to 1 s − 1 ) at low temperatures (-163°C to -20°C), the stress-strain relations exhibited an S-shape and a second strain hardening phenomenon. The strain rate sensitivity and temperature sensitivity of 304 ASS were also different from metallic materials deformed by dislocation glide. Several unexpected phenomena including the negative strain rate sensitivity and the changing temperature sensitivity from quasi-static to dynamic tests were observed. Based on experimental results, an extension of the Rusinek-Klepaczko (RK) model considering SIMT effect was used to simulate the deformation behavior of 304 ASS: it predicted flow stress curves of 304 ASS above -60°C correctly. In addition, to validate the extended RK model and the identified model parameters, numerical simulations of ballistic impact tests of 304 ASS plates at various temperatures were carried out, showing a good agreement with experiments.

Experimental survey on the behaviour of AISI 304 steel sheets subjected to perforation

RODRIGUEZ-MARTINEZ, J. A. — Fri, 01 Jan 2010 00:00:00 GMT

Experimental survey on the behaviour of AISI 304 steel sheets subjected to perforation RODRIGUEZ-MARTINEZ, J. A.; RUSINEK, Alexis; PESCI, Raphaël This paper presents and analyzes the behaviour of AISI 304 steel sheets subjected to perforation under a wide range of impact velocities. The relevance of this steel resides in the potential transformation of austenite into martensite during mechanical loading. This process leads to an increase in strength and ductility of the material. It makes the AISI 304 attractive for many engineering applications, especially for building structural elements responsible for absorbing energy under fast loading. However, this transformation takes place only under determined loading conditions strongly dependent on initial temperature and deformation rate. In order to study the material behaviour under impact loading, perforation tests have been performed at room temperature using both, a drop weight tower and a pneumatic gas gun within the range of impact velocities 2.5 m/s≤V0≤85 m/s. The results are compared with those reported in [18] and [21] for ES steel and TRIP 1000 steel. The comparison highlights the good performance of the AISI 304 under high loading rates. Martensitic transformation taking place in this steel during perforation is identified responsible for such behaviour.

Experimental and numerical analysis on the martensitic transformation in AISI 304 steel sheets subjected to perforation by conical and hemispherical projectiles

RODRIGUEZ MARTINEZ, José Antonio — Tue, 01 Jan 2013 00:00:00 GMT

Experimental and numerical analysis on the martensitic transformation in AISI 304 steel sheets subjected to perforation by conical and hemispherical projectiles RODRIGUEZ MARTINEZ, José Antonio; RUSINEK, Alexis; ZAERA, Ramon; PESCI, Raphaël In this work, an experimental and numerical analysis of the martensitic transformation in AISI 304 steel sheets subjected to perforation by conical and hemispherical projectiles is conducted. Experiments are performed using a pneumatic gas gun for with the impact velocities in the range of 35 m=s < V0 < 200 m=s. Two target thicknesses are examined, t1 ¼ 0:5 mm and t2 ¼ 1:0 mm. The experimental setup enabled the determination of the impact velocity, the residual velocity and the failure mode of the steel sheets. The effect of the projectile nose shape on the target’s capacity for energy absorption is evaluated. Moreover, martensite is detected in all the impacted samples, and the role played by the projectile nose shape on the transformation is highlighted. A three-dimensional model is developed in ABAQUS/Explicit to simulate the perforation tests. The material is defined via the constitutive model developed by Zaera et al. (2012) to describe the strain-induced martensitic transformation occurring in metastable austenitic steels at high strain rates. The finite element results are compared with the experimental evidence, and satisfactory matching is observed over the entire range of impact velocities tested and for both projectile configurations and target thicknesses considered. The numerical model succeeds in describing the perforation mechanisms associated with each projectile-target configuration analyzed. The roles played by impact velocity, target thickness and projectile nose shape on the martensitic transformation are properly captured. Lien vers la version éditeur: http://www.sciencedirect.com/science/article/pii/S0020768312004039

Ballistic behavior of steel sheet subjected to impact and perforation

JANKOWIAK, Tomasz — Wed, 01 Jan 2014 00:00:00 GMT

Ballistic behavior of steel sheet subjected to impact and perforation JANKOWIAK, Tomasz; RUSINEK, Alexis; KPENYIGBA, K. M.; PESCI, Raphaël The paper is reporting some comparisons between experimental and numerical results in terms of failure mode, failure time and ballistic properties of mild steel sheet. Several projectile shapes have been considered to take into account the stress triaxiality effect on the failure mode during impact, penetration and perforation. The initial and residual velocities as well as the failure time have been measured during the tests to estimate more physical quantities. It has to be noticed that the failure time was defined using a High Speed Camera (HSC). Thanks to it, the impact forces (average and maximum level), were analyzed using numerical simulations together with an analytical description coupled to experimental observations. The key point of the model is the consideration of a shape function to define the pulse loading during perforation.