Shock response of polycrystalline silicon carbide undergoing inelastic deformation

Abstract

Longitudinal stress profiles have been measured in polycrystalline silicon carbide (SiC) shocked to peak stresses from 7.3 to 23 GPa. Dispersive wave fronts, consistent with the expected inelastic response, were observed beyond the previously reported Hugoniot elastic limit (HEL) of 11.7 GPa. Detailed numerical analyses were carried out to interpret the observed inelastic response using both a strain-hardening, plasticity model and a pressure-dependent strength, stress relaxation model. Both models show good agreement with the data; the latter provides a better fit to the transient features in the measurements suggesting rate dependence in the material response. The computed Hugoniot curve matches all of the peak state data for two different types of SiC that display more than 20 % variation in HEL. This suggests that the measured HEL for SiC is not a proper indicator of the material strength in the shocked state. The results also show that the longitudinal data and analyses are insufficient to resolve issues related to material strength and mechanisms governing inelastic deformation in shocked SiC. The need for a more complete characterization of the shock response of a high-strength brittle material is discussed.

A Survey of Compression Studies on Silicon Carbide (SiC)

“…The shock compression data reported by Sekine and Kobayashi [13,14] complements the results of low magnitude shock compression experiments designed to measure stress wave profiles and obtain the associated properties of SiC-B and other ct-SiC, such as the HEL, and the nature of inelastic deformation, shear strength retained under plane shock wave compression, and release behavior reported in references [16][17][18][19][20].…”

“…This table shows that the calculated values of shear stress and those obtained through the simultaneous measurements of longitudinal and lateral stresses agree with one another. The highest magnitude of longitudinal shock experiments were done by Crawford and reported by Feng et al [17]. Results of two experiments reported in their Table 3 are given in Table 4 for these experiments are based on the calculation of longitudinal stress and u using the elastic perfectly plastic model and the pressure-dependent strength, stress relaxation model proposed by Feng et al [17].…”

“…The highest magnitude of longitudinal shock experiments were done by Crawford and reported by Feng et al [17]. Results of two experiments reported in their Table 3 are given in Table 4 for these experiments are based on the calculation of longitudinal stress and u using the elastic perfectly plastic model and the pressure-dependent strength, stress relaxation model proposed by Feng et al [17]. These calculations indicate that the values of shear stresses based on the pressure-dependent strength, stress relaxation model are consistent with the other values of the shear stress given in this table.…”

“…In addition, over the past four decades a large number of shock wave compression experiments have been conducted on polycrystalline SiCs to determine their compressibility and shear strength retained under plane shock wave compression [10][11][12][13][14][15][16][17][18][19][20]. This list excludes shock wave investigation studies dealing with spallation in SiC because Dandekar and Bartkowski [21] recently covered this subject.…”

Uniaxial and triaxial compression tests of silicon carbide ceramics under quasi-static loading condition.

“…On the table, is defined as ((V 0 /V)-1). There are four separate studies represented in this table : Feng et al (1996: Feng et al ( , 1998, Grady and Kipp (1993) and Bourne et al (1997). Plate Impact Test Data Grady and Moody (1996) performed plate impact tests on various silicon carbide materials, including SiC-B and SiC-N. Table E-6 contains the data for four of the materials tested by Grady and Moody (1996); the SiC-B material is represented by the data for Material No.…”