Numerical study of the critical impact velocity in shear

The influence of radial and axial boundary effect on penetration effect are calculated, numerical simulation are executed to compute the kinetic projectile against deep hard target by finite element code, the boundary effects were achieved for different velocity range. Result shows that the minimal Dt/Dp (diameter ratio of target to projectile) for impact velocity 600m/s is 17.5, while the minimal Dt/Dp for impact velocity 900m/s is 20. Furthermore, the depth of equivalent target to substitute semi-infinite target is twice of penetration depth limit for impact velocity 300m/s, and 1.6 times respectively, for impact velocity 600m/s, 900m/s.

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Numerical study of dynamic behavior of foams subjected to high- to hyper-velocity impact

2019 15th Hypervelocity Impact Symposium ◽

10.1115/hvis2019-071 ◽

2019 ◽

Author(s):

Xiaotian Zhang ◽

Ruiqing Wang ◽

Q.M. Li

Keyword(s):

Dynamic Behavior ◽

Impact Velocity ◽

Foam Cell ◽

Numerical Study ◽

Failure Process ◽

Failure Mechanisms ◽

Hypervelocity Impact ◽

Deformation And Failure ◽

Set Up ◽

The Impact

Abstract Hypervelocity tests and numerical studies have been reported in the literature for aluminum foam to show its potential applications in spacecraft shielding against space debris based on “shielding set-up”. Meanwhile the “forward impact” set-up has been widely reported in the literature to study the dynamic behavior of the foam materials in the range of low to intermediate impact velocities. This paper extends the forward impact to high- and hyper-velocity impacts to understand the dynamic deformation and failure mechanisms based on numerical simulation. The focused impact velocity range is from about 1km/s to 6km/s. The cell-based numerical model of the foam material is used along with the Smoothed Particle Hydrodynamics (SPH) method to simulate the deformation and the failure process. The failure of the foam materials in the range of intermediate to high impact velocities is related to the plastic yielding and crushing of the foam cell, while that in the hypervelocity impact regime is related to the cell material erosion. Dynamic effects in different impact velocity ranges also lead to shock and strain-rate effects. Understanding of the dependence of the deformation/failure mechanisms on the impact velocity helps to determine the application of foam materials in the relevant range of impact velocities.

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Foreign Object Damage in Gas-Turbine Grade Silicon Nitrides by Silicon Nitride Ball Projectiles

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation; Education; Electric Power; Awards and Honors ◽

10.1115/gt2009-59031 ◽

2009 ◽

Cited By ~ 4

Author(s):

Sung R. Choi

Keyword(s):

Silicon Nitride ◽

Gas Turbine ◽

Impact Velocity ◽

Impact Damage ◽

Hertzian Contact ◽

Foreign Object ◽

Silicon Nitrides ◽

Foreign Object Damage ◽

Critical Impact Velocity ◽

Grade Silicon

Foreign object damage (FOD) behavior of two gas-turbine grade silicon nitrides (AS800 and SN282) was determined with a considerable sample size at ambient temperature using impact velocities ranging from 50 to 225 m/s by 1.59-mm diameter silicon nitride ball projectiles. The degree of impact damage as well as of post-impact strength degradation increased with increasing impact velocity, and was greater in SN282 than in AS800 silicon nitride. The critical impact velocity in which target specimens fractured catastrophically was remarkably low: about 200 and 130 m/s, respectively, for AS800 and SN282. The difference in the critical impact velocity and impact damage between the two target silicon nitrides was attributed to the fracture toughness of the target materials. The FOD by silicon nitride projectiles was significantly greater than that by steel ball projectiles. Prediction of impact force was made based on a yield model and compared with the conventional Hertzian contact-stress model.

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