Observation of Crack Growth Behavior of 400μm Cracks in 4.762mm Silicon Nitride Balls under Cyclic Compressive Load

Abstract

In order to investigate the effect of pre-crack lengths on silicon nitride balls under cyclic pressure loads, the pre-crack lengths ranging from 400μm to 500μm were observed. Their growth behavior was compared to that of 200μm to 300μm pre-cracks. Furthermore, the initial threshold limits of their maximum stress intensity factors were measured.

Observation of Crack Growth Behavior of Various Cracks in 4.762mm Diameter Silicon Nitride Balls under Cyclic Compressive Load

“…Figure 2 shows results of the fatigue tests. This includes Kida's results of 200µm~300µm length pre-cracks [6], Toriki's results of 400µm~500µm length [7] and the present data of 600~700µm length. Circle marks mean non-failure, and square marks are for failure.…”

“…They performed cyclic pressure load tests of 400µm~500µm pre-cracks in silicon nitride balls and found that the pre-crack length strongly affected the fatigue strength. The threshold limits of the initial KImax values decreased with the increase of the pre-crack length [7].…”

“…Table 1 Mechanical properties of the Si3N4 specimens [6] . We performed fatigue tests using the ball holding apparatus used in our previous study [7]. The apparatus consists of plates, tightening bolts and bars (hardened JIS-SUJ2).…”

“…Structural and Smart Materials III 200µm~300µm [6], black marks are for 400µm~500µm [7] and blue marks are for 600µm~700µm. The initial values of the maximum stress intensity factors KImax were plotted on the vertical axis.…”

“…Figure 3 Relation between initial increase in the maximum stress intensity factor and pre-crack length during N=0 to N=1000 cycles. (6) were calculated from Kida's results (220µm) (6) , and (7) were calculated from Toriki's results (440µm) (7) .…”