Bio-inspired dental multilayers: Effects of layer architecture on the contact-induced deformation

Creep-assisted slow crack growth in bio-inspired dental multilayers

“…Niu et al (2009) and Rahbar and Soboyejo (2011) also showed similar reductions in stress concentrations in the top ceramic crown layer by using FGMs. These were later confirmed by the experimental work by Niu et al (2009) and Du et al (2013), who conducted contact loading experiments on actual FGM structures that were fabricated with nanocomposite layers. These had ~ 20-40% greater critical pop-in loads than flat conventional dental multilayers without FGMs.…”

“…Furthermore, the differences between critical loads of structures with and without FGM were observed to be greater at slower loading rates than at faster loading rates (Du et al, 2013;Niu et al, 2009). These differences suggest that creep effects should be considered in the modeling of layer properties.…”

“…The Hertzian contact tests were performed under load control with a hemi-spherical tungsten carbide indenter with a diameter of 20 mm. The tests conducted at clinically relevant loading rates between 1 N/s and 1000 N/s (Du et al, 2013). The loads and displacements were recorded by the computer attached to the Instron tester.…”

“…The elastic moduli for the FGM composites materials were measured using nanoindentation techniques described in detail in a prior study (Du et al, 2013). The Poisson's ratio was assumed to be 0.2 for ceramic materials and 0.4 for polymeric and composite materials.…”

Functional Biomimetic Dental Restoration

“…In addition, promotion of improvements in the critical crack size was reported because of these bioinspired functionally graded layers. Du et al [116] also found that the bioinspired functionally graded layers were also shown to promote improvements in the critical crack size. Suresh [117] established that controlled gradients in mechanical properties offer unprecedented opportunities for the design of surfaces with resistance to contact deformation and damage that cannot be realized in conventional homogeneous materials.…”