1994 Volume 20 Issue 4 Pages 556-563
To investigate the process of creep failure phenomena in fine powder beds, the change in the tensile failure strength and the displacement of powder beds during the creep failure process was analyzed. The increasing displacement is divided into three sections (I, II, III). The increasing rate of displacement slows in the first stage (section I), almost constant in section II, and rapidly increases and falls in section III. By using the experimental equation to relate the creep failure life to the increasing rate of displacement in section II, the change in tensile strength of powder beds can be estimated during the creep failure process. No decrease in tensile strength is observed during the first stage (section I). However, in the second and third stages (section II and III), the strength decreased remarkably with increasing creep time. The increasing displacement can be fitted by a Voigt model in the region of section I, in which the tensile strength is almost constant. According to the elastic/viscous parameters of a Voigt model decrease in relation to the decrease in fracture strength of powder beds, the complex increase of displacement in the region of sections II and III can be quantitatively estimated. The deformation resistance of powder beds was quantitatively related to the fracture strength.
