Using Hertzian Indentation to Understand the Strength and Ballistic Resistance of Silicon Carbide

Abstract

This article presents an initial evaluation of the usefulness of spherical or Hertzian indentation for the determination and/or validation of constitutive models and for a potential link to ballistic resistance (interface defeat). Recent advancements in producing more confident elevated stress levels in Hertzian indentation make the usefulness of this test much more feasible. There are very few experimental techniques that can produce the high stresses, strains, and pressures produced in Hertzian indentation tests. Additionally, they are also relatively simple, repeatable, timely, and inexpensive. There is still the disadvantage that the stresses, strains, and pressures are not explicit outputs of the experiments requiring the constitutive response to be inferred by performing computations and comparing the computed force–deflection results to the experiment. Preliminary results indicate that Hertzian indentation can be used to help define the constitutive response but it is still uncertain if it can be used to rank a ceramic's ability to produce interface defeat.

Intact and Predamaged Boron Carbide Strength under Moderate Confinement Pressures

“…For even higher pressures, indentation or plate‐impact techniques need to be used. See Holmquist and Wereszczak for a comparison of constants obtained for SiC using both techniques. Of particular interest for this work are the plate‐impact results obtained by various authors as they provide an independent measurement of the strength of the ceramic with a technique different than compression under confinement.…”

Elastic, Plastic, Cracking Aspects of the Hardness of Materials

“…The associated plastic deformation was interpreted in terms of dislocation velocities reaching up to 700 m/s. Leavy, Brannon and Strack [169] have reported on spherical indentation experiments employed to characterize damage in ceramics and particular results have been reported for silicon carbide material by Holmquist and Wereszczak [170].…”

“…The foregoing references on rate dependence of hardness determinations for glassy ceramic and polymer materials give an indication of progress made from the early 20 th century with metal deformations in mind, for example, involving the pendulum hardness test of Herbert [373] and reported time dependence of hardness measurements reported by Hargreaves [374]; see also Walley [1]. A particular interest in metals at the present time is to look into hardness testing for the purpose of developing constitutive relations for use in material dynamics calculations, particularly under dynamic loading conditions so as to relate to material penetrations; see [163][164][165][166][167][168][169][170]. In addition to previous work mentioned above [164,165], Sundararajan and Tirupataiah have produced a pair of articles on dynamic indentation loading and analysis of results [375].…”

Hardness Measurements and Interface Behavior of SiC-B4C-Si Multiple Phase Particulate Composites Made with Melt Infiltration and Additive Manufacturing

“…In both cases, the hardness is directly correlated to the strength. It is also known that the Hertzian indentation method estimates the strength in fully dense monolithic ceramics [31,32]. It has not been the case in particulate composites because of the indent size and amount of each phase captured in the affected zone of the indent, but a better understanding of the measurements and interfaces can aid in future correlations.…”