Numerical–experimental analysis of metal bars undergoing intermediate strain rate impacts

Gobbi, Massimiliano; Mastinu, Giampiero; Muñoz, Luis; Pandolfi, Anna

doi:10.1007/s00466-008-0279-x

Cited by 2 publications

(2 citation statements)

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“…This system of deceleration is also known as the Bar Bending Braking System (BBBS) (Gobbi et al 2009). The plastic dissipation in a single bar occurs through two mobile hinges at the interior pins and one stationary hinge at the center of the bar (Gobbi et al 2009). Figure 1(b) shows the diagram with the three plastic hinges after the bar has been impacted by the sled.…”

Section: Introductionmentioning

confidence: 99%

“…The sled system is decelerated, as required, by suitable placement of the bending bars made of St 37-2 steel. This system of deceleration is also known as the Bar Bending Braking System (BBBS) (Gobbi et al 2009). The plastic dissipation in a single bar occurs through two mobile hinges at the interior pins and one stationary hinge at the center of the bar (Gobbi et al 2009).…”

Section: Introductionmentioning

confidence: 99%

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Determining the Intermediate and High Strain Rate Properties of Bar Bending Braking System Material in a Forward Velocity Sled

Sriniva,

Vorkady

et al. 2023

Preprint

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The Bar Bending Braking System (BBBS) in a forward velocity sled utilizes the plastic deformation of the metallic bars to dissipate the Kinetic energy of impact and generate the required deceleration pulse. The National Aerospace Laboratories forward velocity sled’s BBBS material, Mild steel St37-2, is characterized in compression at room temperature, using the quasi-static tests and the Split Hopkinson Pressure Bar (SHPB) at strain rates ranging from 10− 3/s − 2500/s. Very high strain rate dependence of yield and flow stress was observed from these tests as there was nearly a 100% increase in the yield stress between the highest and lowest strain rates. Thinner samples (L/D < 0.5) were used for the SHPB tests apart from the usual ratio (L/D = 0.5) samples and it was observed that the stress strain curves of these thinner samples were consistent with those of the samples with L/D = 0.5 showing that there was no significant effect of the three-dimensional state of stress on the curves. The Compression stress-strain data for the steel, which has over 12 stress strain curves at different strain rates, is analysed to determine the Viscoplastic Johnson-Cook (JC) model and the Cowper-Symonds (CS) Model. The JC Model was developed over a limited strain rate range (0.001-300/s), as linear dependence of the log(strainrate) to the yield or flow stress was only possible in this range. The CS model was developed for the entire range and effectively models the stress strain curves throughout the range of strain rate. The values of the JC and CS constants are compared with existing literature for St 37 steel and are found similar for strain rate sensitivity though there is considerable difference in the static plasticity constants.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%