Effect of Backstop for Strain and Deformation Behavior on Strengthened Porcelain Plate upon Impact Test Akemi Hayashi*, **, Hideaki Tsuge***, Kazumasa Kurachi**, Masatoshi Mizuno**, Nobuyasu Adachi*, Toshitaka Ota* *Ceramic Research Laboratory, Nagoya Institute of Technology 1-6-29, Asahigaoka, Tajimi, Gifu, 57-71 JAPAN **Gifu prefectural Ceramics Research Institute 3-11 Hoshigadai Tajimi Gifu, 57-811 JAPAN ***Research Institute for Machinery and Materials Gifu Prefectural Government 1288, Oze, Seki, Gifu, 51-3265 JAPAN Abstract The impact strengths of strengthened porcelain plates were evaluated using an impact examination machine based on JIS S 242. A strain waveform developed upon impact was measured by a strain gauge adhered to the inside surface on the porcelain plate. The deformation of the porcelain plates was observed by high-speed camera. The strain waveforms showed two noteworthy peaks. The first peak was found to be caused by the initial impact, and the second peak was found to be caused by the restorative force generated by the deformation of plate, which acted as a backstop. The high-speed camera also revealed that the plate re-collided with the hammer or pushed the hammer again as the plate returned to its original shape and position, resulting in the second peak. The variation of the strain waveform was found to be related to the size of plate and the open angle of the backstop. 2 3 2MPa 3MPa 1) 7MPa 1MPa 3 5 18 33 2)-6)
7) 8) 9) 1) 7) 8) 2 2 139mm 1 169mm 2 Table1 Table 1 Features and properties of the strengthened porcelain Diameter (mm) Height (mm) Weight (g) Flexural Strength (MPa) Bulk density(g/cm 3 ) Porosity(%) Young s modulus (GPa) Impact Strength(J) plate 1 (small) plate 2 (large) 139 31 13 244 2.8.5 122.41 169 39 233 257 2.8.4 123.79 A field of view by high speed camera α β B S contact points with backstops TH B Impact point (a) front view (b) top view Fig. 1 Schematic illustration of impact test.:(a) front view (b) top view ( S:Test specimen, B:back stop,h: hammer, α: open angle, β: apex angle)
Table. 2 Peak time and time lag on impact point First peak Second peak Time lag between first peak and second peak Bowl 1.5msec 1.2msec.7msec Bowl 2.5msec 1.5msec 1.msec Plate 1.5msec 1.msec.5msec Plate 2.5msec 1.3msec.8msec JCRS23-1996 Table1 Table1 RA-112 JIS S 242 Fig.1 1.4J 1.2J 12 9 12 15 Fig.1 β 15 3 45 α 18g.2J Table1 ( KFG-3-12 DPM713B LeCroy, WaveSurfer 422 1k-με 1k Hz impact point (contact point) 2 11) photron FASTCAM SA MRPG Model 12k-3M 1, fps Fig.2 1 2 2.5msec 1:1.msec, 2:1.3msec 1.5msec 2.8msec 1 2 Table. 3 Peak time and time lag on contact point. First peak (Delay time from impact point) Second peak (Delay time from impact point) Time lag between first peak and second peak Bowl 1.85msec (.35msec) 1.55msec (.35msec).7msec Bowl 2 1.msec (.5msec) 2.msec (.5msec) 1.msec Plate 1.75msec (.25msec) 1.25msec (.25msec).5msec Plate 2.9msec (.4msec) 1.7msec (.4msec).8msec
1 8 (a) 1 8 (b) (b) Strain/1-6 6 2 Strain/1-6 6 2-2 -1 1 2 3-2 -1.. 1. 1 2. 2 3. 3 Fig. 2 Strain waveforms at impact point for (a)plate 1 small and (b) plate 2 large with backstops 1 8 (a) 1 8 (b) Strain/1-6 6 2 Strain/1-6 6 2-2 -1.. 1. 2. 3. -2-1.. 1. 2. 3. Fig. 3 Strain waveforms at the contact point with backstops for (a) plate 1 small and (b) plate 2 large. Table 2 Fig.3 1 2.75msec 1.25 msec 2.9msec 1.7msec 1.25msec 2.4msec Table 3 Fig.4 (a) (a ) msec (a) (d) (a ) (d ) (d) (h) (d ) (h ) 2(d ) 2(e ) Fig.4(e ) Fig.2 Fig.4 2 Fig.5 Fig.5(a) Fig.5(b) Fig.5(c) Fig.5(d) Fig.3 1 2 1 2
(a)sec (a )sec (b).3msec (b ).3msec (c).5msec (c ).5msec (d).8msec (d ).8msec (e)1.msec (e )1.msec (f)1.2msec (f )1.2msec (g)1.5msec (g )1.5msec (h)2.msec (h )2.msec Fig. 4 Photo images of bowl and hammer an impact point by high speed camera(a) to (h)plate 1 small, (a ) to (h ) plate 2 large.
B S H B (a) At msec (b) to.3 msec (c) At.5 msec (d) Around 1. msec (e) Around 1.5 msec (f) Over 2.1 msec :The direction of movement :The area of strain Fig. 5 Exaggerated illustrations for the deformation of the plate 2 large on impact. 12) Fig.6 Fig.6 Fig.6 Fig.2 Fig.3 Fig.3 Fig.2 Fig.3 1.25msec 2.4msec Fig.7 2 Fig.2 11) Fig.8 α 1 2 12) 1 2
2 1) Y. Kobayashi and M. Mizuno, Taikabutu, 6, 642-651 (28). 2) Y. Kobayashi, O. Ohira, Y. Ohashi and E. Kato, J. Ceram. Soc. Japan, 99, 495-52 (1991). 1 8 (a) 1 8 (b) Strain/1-6 6 2 Strain/1-6 6 2-2 -1.. 1. 2. 3. -2-1.. 1. 2. 3. Fig. 6 Strain waveforms at impact point for (a) plate 1 small and (b) plate 2 large without backstop. 8 8 6 6 Strain/1-6 2 Strain/1-6 2-2 -1.. 1. 2. 3. -2-1.. 1. 2. 3. Fig. 7 Mechanism of two maximum peaks appeared in the strain waveform: (a) plate 1 small; (b) plate 2 large. : strain waveforms by the initial impact itself, which are identical with the strain waveforms in Fig. 6. : strain waveforms returned from the backstop, which are equivalent to the strain waveforms in Fig. 3 after a delay of.25 msec for the plate 1 small and.4 msec for plate 2 large. : strain waveforms estimated by the combination of and Strain/1-6 12 1 8 6 2 (a) 9 12 15 Strain/1-6 1 8 6 2 (b) 9 12 15-2 -1 1 2 3-2 -1 1 2 3 Figure.8 Variation of the strain waveforms at the impact point with the open angle of backstop (α): (a) plate 1 small and (b) plate 2 large.
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