Evaluation of the impactive-surface-fracture behavior of glass plates using a back-surface strain measurement

  • PDF / 528,586 Bytes
  • 4 Pages / 612 x 792 pts (letter) Page_size
  • 68 Downloads / 195 Views

DOWNLOAD

REPORT


Nak-Sam Choi and Nahmgyoo Cho Department of Mechanical Engineering, Hanyang University, 1271 Sa-1 dong, Ansan-si, Kyunggi-do 425-791, Korea (Received 10 April 2001; accepted 20 August 2001)

This paper proposes an evaluation method for the surface fracture behavior of coated glass or ceramic plates subjected to an impact with a small particle. The increase of the maximum stress and absorbed fracture energy measured from the back surface indicated the extent of the surface fracture that occurred in the simple soda lime glass and composite-lamina attached glass plates tested in a range of particle velocities up to 119 m/s. Impact surface-fracture indices expressed in terms of the maximum stress and absorbed energy are suggested as an effective evaluation parameter.

The surfaces of ceramic materials in service are commonly subjected to concentrated loads and/or impacts with foreign particles. The stresses arisen by such contacts can cause localized damage on and beneath the surfaces. The surface fracture response of ceramic materials to an impact imposed by a particle has been significantly studied in respects to an improvement of the surface wear and impact resistance. Knight et al.1 studied the occurrence and propagation of several types of cracks under quasi-static indentation. In comparison with quasi-static indentation, Wiederhorn et al.2 predicted the amount of impact loads on the basis of the fracture feature formed by a projectile impact. Shockey et al.3 observed crack patterns using high-speed photography and analyzed rapid cracking. For an improvement in the surface strength, Cook et al.4 investigated the surface fracture behavior of soda-lime glass coated with oxidized metals. Flocker and Dharani5 modeled the impactive surface fracture of a glass laminate using the traditional wave propagation code. Most of the studies, however, were performed on the mechanisms and the amount of the surface fracture as a function of impact velocity. There have been few studies for a quantitative measurement of strength and absorbed fracture energy during the particle impact, as far as the present authors know. In this study, we evaluate the surface fracture behavior of glass plates by measurement of the maximum stress and absorbed fracture energy on the back surface. Transparent soda-lime glass plates were adopted for easy observation of crack propagation-

3042

http://journals.cambridge.org

J. Mater. Res., Vol. 16, No. 11, Nov 2001 Downloaded: 14 Mar 2015

patterns. This study focuses the effect of composite lamina attachment utilized as a coating layer on the surface of glass plates. Two kinds of glass plate specimens were prepared for this study: simple soda-lime glass plate and glass fabric/ epoxy lamina-attached glass plate. The dimensions of glass specimens were 3 mm thick, 30 mm wide, and 120 mm long. A thin composite lamina with a thickness of 0.12 mm was made by curing the glass fabric/epoxy prepreg film in an autoclave. The curing cycle was selected according to the manufacturer’s recommendations. The composite