Theoretical Model of Impact Damage in Structural Ceramics

Abstract

This paper presents a mechanistically consistent model of impact damage based on elastic failures due to tensile and shear overloading. An elastic axisymmetric finite element model is used to determine the dynamic stresses generated by a single particle impact. Local failures in a finite element are assumed to occur when the primary/secondary principal stresses or the maximum shear stress reach critical tensile or shear stresses, respectively. The succession of failed elements thus models macrocrack growth. Sliding motions of cracks, which closed during unloading, are resisted by friction and the unrecovered deformation represents the “plastic deformation” reported in the literature. The predicted ring cracks on the contact surface, as well as the cone cracks, median cracks, radial cracks, lateral cracks, and damage‐induced porous zones in the interior of hot‐pressed silicon nitride plates, matched those observed experimentally. The finite element model also predicted the uplifting of the free surface surrounding the impact site.

Erosive Wear Mechanism of New SiC/SiC Composites by Solid Particles

“…Considerable effort has been expended develop methods for evaluating silicon carbide (SiC) or erosion-related ceramic and ceramic composite materials used in engineering components in such applications as gas turbine parts, sealing bearings, and burner parts [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. These applications may involve solid-particle impact and erosive wear, and it is therefore necessary to have some knowledge of behaviours and mechanisms before the materials can be used with confidence.…”

Foreign Object Damage Phenomenon by Steel Ball Projectiles in a SiC/SiC Ceramic Matrix Composite at Ambient and Elevated Temperatures

“…Therefore, foreign object damage (FOD) associated with particle impact needs to be considered when ceramic materials are designed for structural applications. A considerable amount of work on impact damage of brittle materials by sharp particles as well as by blunt particles or by plates has been performed both experimentally and analytically, including the assessments of FOD for turbine engine applications 1–18 …”

“…A considerable amount of work on impact damage of brittle materials by sharp particles as well as by blunt particles or by plates has been performed both experimentally and analytically, including the assessments of FOD for turbine engine applications. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In previous studies, 19,20 FOD behavior of two representative gas-turbine grade silicon nitrides, AS800 and SN282, was determined at ambient temperature using both flexure bars and disks. Fully supported ceramic target specimens were impacted at their centers by steel ball projectiles with a diameter of 1.59 mm in a velocity range from 220 to 440 m/s.…”

Mechanics of Components with Treated or Coated Surfaces

“…Failure of brittle materials under impact has been studied by Evans (1978), Ritter et al (1984), Ritter (1985) and by Liaw et al (1984Liaw et al ( , 1986; the last of these papers being devoted to failure of ceramic coatings.…”