Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

作者：Sih, G. C.^*

来源：Theoretical and Applied Fracture Mechanics, 2010, 53(2): 94-112.

DOI：10.1016/j.tafmec.2010.03.007

• Multiscale
• Scale shift
• Small and large
• Energy density
• Absorption
• Dissipation
• Representative Tip
• Singularity
• Accelerated test
• Inhomogeneity
• Crack
• Particle
• Transitional
• Atomic
• Subatomic
• Local
• Global
• Galaxial

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say macro, micro, nano, and pico,-, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.
Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions f(j)(j+1) and/or f(j/j+1), are introduced to quantify these characteristics. They are represented, respectively, by (f(mi)(ma),f(na)(mi),f(pi)(na)), and (f(mi/ma),f(na/mi),f(pi/na)). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.
Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10(-12), 10(-9), 10(-6), 10(-3) m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.
Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales. RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.

• 出版日期2010-4
• 单位华东理工大学