Fatigue Damage Evolution in Silicon Films for Micromechanical Applications

Self-Healing Polymeric Composite Material Design, Failure Analysis and Future Outlook: A Review

“…LEFM is a straightforward, although complex, concept that deals with sharp cracks in elastic forms [ 112 ]. The basic fundamentals of fracture mechanics may be summarized as manner of a triangle with three critical constraints positioned at each apex: operational stress, fracture toughness and critical defect size [ 113 ].…”

Mechanical Properties of Silicon Microstructures

“…One drawback of this model as stated by Kahn et al [314] is that cyclic stressenhanced oxidation has never previously been observed. Though Allameh et al [317,318] report that their specimens had an initial surface oxide of 2À4 nm, they used the same structures as Muhlstein et al [309], who showed surface oxides of about 30 nm. Another concern is that Allameh et al…”

Atomic origin of hysteresis during cyclic loading of Si due to bond rearrangements at the crack surfaces

“…1 Subsequently, several groups have confirmed that both micron-sized samples of single-crystal and polycrystalline silicon undergo fatigue failure. [2][3][4] However, a recent experiment calls into question these studies by observing similar cracking behavior in both cyclic-and monotonic-loaded micromachined silicons. 5 Kahn et al 6 has compiled and summarized the main experimental observations of silicon fatigue failure as follows: ͑1͒ morphological changes in areas of high stress, including surface roughening and oxide thickening, ͑2͒ a decrease in high cycle fatigue lifetime when the peak stress is increased, ͑3͒ a decrease in low cycle fatigue lifetime when R, the ratio between minimum and maximum stress ͑negative values denote compression͒, is decreased, ͑4͒ a decrease in fatigue lifetime associated with a larger initial flaw, which is assumed to be caused by subcritical crack growth, ͑5͒ no dependence on vacuum or air in fatigue lifetime for low cycle failure, but a significant decrease in lifetime during high cycle fatigue if water is present, and ͑6͒ a fatigue lifetime that depends only on the number of cycles, not the elapsed time or the test frequency.…”

“…7 Other experiments indirectly detect the influence of stress by measuring the oxide thickness in the crack tip region, often in postmortem studies. 2,3 Large-scale hybrid quantum-mechanical/empirical potential simulations 8,9 predict that the dissociation of water molecules in a crack tip region under tension is barrierless. In contrast, ab initio simulation of water interacting with a strained silicon cluster found no evidence for enhanced chemical reactivity.…”