Ball Impact Response of Unstrengthened and Chemically Strengthened Glass Bars

Abstract

Ball impact experiments were conducted at impact velocities of 52–345 m/s on unstrengthened and chemically strengthened lithium aluminosilicate glass bars to assess the damage propagation characteristics. The damage was captured by high‐speed imaging at frame rates up to 500 000 frames per second (fps). Upon impact, the damage front in the unstrengthened glass reached a maximum velocity of 1626–2135 m/s, and rapidly fell to zero within a short distance. On the contrary, the damage front in the strengthened glass reached an initial velocity of 1791–2275 m/s, but then stabilized to a constant velocity of 1920 m/s until the entire glass bar was consumed. In addition, the cascading release of stored energy due to strengthening led to self‐sustained damage propagation preferentially within the outer layers of the glass bar (predominantly within the compressive zones) at a higher rate than in the interior region (dominated by residual tension). This is counter to what has been traditionally reported in the literature. Stress wave reflection from the rear of the unstrengthened bar caused tensile cracking (i.e., spallation), but the ultrahigh residual compression in the strengthened bar prevented similar damage initiation. Finally, it is suggested that strengthened glasses are most suitable as intermediate layers in laminate window panels for impact applications.

Measurement of stress build‐up of ion exchange strengthened lithium aluminosilicate glass

“…The validity of the measured stress profiles was tested by the criteria of stress equilibrium (difference in the areas of compressive and tensile zones) and by comparison with Na + ion concentration profiles. Our results are compared to analogous studies by Varshneya et al, Jannotti et al and Inaba et al…”

“…Over the past decade, a great deal of research on chemically strengthened lithium aluminosilicate (LAS) glass has been published by Varshneya and Jannotti . Earlier stress studies of the same type of glass were conducted by Donald and Hill .…”

Gradient scattered light method for non-destructive stress profile determination in chemically strengthened glass

“…The ion exchange process is started by immersing the glass substrate into a molten salt bath, where smaller ions are replaced with larger ones in the surface layer of glass. Consequently, a residual stress profile develops in the glass [2][3][4][5][6][7][8][9][10][11]. Reviews on chemical strengthening of glass in general have been published by many authors [15,52,55,[61][62][63][64][65].…”

“…Chemically strengthened aluminosilicate glass is used as protective cover glass due to its high scratch and impact resistance [3,4]. In a recent report, chemically strengthened aluminosilicate glass was proven suitable as mirror foil for future X-ray telescopes [5] and as protective coating of space solar cells [6].…”

“…In a recent report, chemically strengthened aluminosilicate glass was proven suitable as mirror foil for future X-ray telescopes [5] and as protective coating of space solar cells [6]. The unique mechanical properties of lithium aluminosilicate glass-ultrahigh surface compression stress, deep compressive stress layer, and impact resistance-have made this glass type suitable as a layer of composite armor plate [2,3]. Those mechanical properties are directly determined by the residual stress profile in the surface layer of chemically strengthened glass.…”