Observations on percussion figures

Andrews, Joyce

doi:10.1088/0959-5309/43/1/304

Cited by 8 publications

(3 citation statements)

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“…In her experiments on soda lime glass, 25 Tillett measured a 2.5 higher threshold in impact conditions than in static indentation : A static = 6.1 10 4 N/m, and A dynamic = 1.5 10 5 N/m. This dynamic Auerbach's constant was nearly the same as that found in the 1930's by Andrews 26 and Longchambon, 27 also on soda lime glass from diverse providers. A set of impact experiments was later performed by Chaudhri and Brophy with Tungsten Carbide projectiles onto fused silica.…”

Section: Fractures At Surfaces : From Auerbach To High Power Laserssupporting

confidence: 80%

Fracture related initiation and growth of surface laser damage in fused silica

Bercegol

Grua

2008

Laser-Induced Damage in Optical Materials: 2008

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This paper deals with the relation between fracture mechanics and 355 nm laser damage at the surface of fused silica. It is organized in 3 parts. First, we discuss about the link between cracks and laser initiation of surface damage. A 1D model was proposed last year to explain how a nanometer wide, clean, uncontaminated crack could trigger a macroscopic damage event. Here, using the model, we try to express a damage criterion able to reproduce experimental features.In a second part, we consider the relationship between laser damage and mechanical damage by indents or impacts. From Auerbach's law, it is straightforward to derive an energy density threshold for Hertzian crack initiation. With the laser fracture interaction model, a laser fluence threshold of cone crack formation can be calculated. When cone cracks are present, a series of shot at moderate fluence will increase their length exponentially. This is a possible explanation for exponential damage growth at the exit surface of fused silica.

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Section: Fractures At Surfaces : From Auerbach To High Power Laserssupporting

confidence: 80%

Fracture related initiation and growth of surface laser damage in fused silica

Bercegol

Grua

2008

Laser-Induced Damage in Optical Materials: 2008

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“…In these studies, the most dominant aspect of the damage was the Hertzian cone cracking. Early studies of cone cracking in inorganic glasses by impact with hard spheres were made by Raman [11], Benerji [12] and Andrews [13]. Interestingly, all these authors [11][12][13] suggested confidently that the impactgenerated cone cracking was due to the shear stresses.…”

Section: Introductionmentioning

confidence: 99%

“…Early studies of cone cracking in inorganic glasses by impact with hard spheres were made by Raman [11], Benerji [12] and Andrews [13]. Interestingly, all these authors [11][12][13] suggested confidently that the impactgenerated cone cracking was due to the shear stresses. However, this view is not now generally held and it is widely accepted that cone cracking is due to the surface radial tensile stress at the circle of contact between the sphere and the target, generated by the impact.…”

Section: Introductionmentioning

confidence: 99%

Dynamic fracture of inorganic glasses by hard spherical and conical projectiles

Chaudhri

2015

Phil. Trans. R. Soc. A.

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In this article, high-speed photographic investigations of the dynamic crack initiation and propagation in several inorganic glasses by the impact of small spherical and conical projectiles are described. These were carried out at speeds of up to approximately 2 × 10 6 frames s −1 . The glasses were fused silica, 'Pyrex' (a borosilicate glass), soda lime and B 2 O 3 . The projectiles were 0.8-2 mm diameter spheres of steel, glass, sapphire and tungsten carbide, and their velocities were up to 340 m s −1 . In fused silica and Pyrex, spherical projectiles' impact produced Hertzian cone cracks travelling at terminal crack velocities, whereas in soda-lime glass fast splinter cracks were generated. No crack bifurcation was observed, which has been explained by the nature of the stress intensity factor of the particle-impact-generated cracks, which leads to a stable crack growth. Crack bifurcation was, however, observed in thermally tempered glass; this bifurcation has been explained by the tensile residual stress and the associated unstable crack growth. A new explanation has been proposed for the decrease of the included angle of the Hertzian cone cracks with increasing impact velocity. B 2 O 3 glass showed dynamic compaction and plasticity owing to impact with steel spheres. Other observations, such as total contact time, crack lengths and response to oblique impacts, have also been explained.

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