The solidification of pure aluminum has been studied by a large-scale molecular dynamic simulation. The potential energy, position D, height H, and width W of the first peak and valley of PDF curves, and the local structures were investigated. It was found that the FCC-crystallization ability of pure Al is so strong that still local crystal regions exist in the amorphized solid. As the temperature decreases, besides the counter-intuitive increase in D_p (D of the first peak), H_p increases monotonically; W_p, D_v, and H_v decrease monotonically; only W_v first decreases and then increases. They all change critically when phase transition happens. After the nucleation, orientation-disordered HCP-regions, as the grain boundaries or defects of FCC crystals, rapidly transform into FCC structures, and then the surviving HCP-regions regularize into few parallel layers or orientation-disordered HCP-regions. If parallel layers result in dislocation pinning, structural evolution terminates; otherwise, it continues. These findings will have a positive impact on the development of the solidification and nucleation theory.

In our previous study, a distributed long-gauge fibre optic sensing system (with the ability to obtain effective average strain, or macro-strain, distributions) for practical adaptation in civil structural health monitoring was developed and verified. The present paper is devoted to proposing an integrated health monitoring scheme for elastic beam-like structures, where flexure dominates structural responses, based on static testing and measurements using the developed sensors. A series of experimental investigations on steel beams with different levels of damage are first carried out. The static strain measurements from distributed sensors are characterised and some concerns on the data processing and feature extraction are discussed. On the basis of the extracted features, structural health monitoring (SHM) investigations are deployed in three parts: damage identification with no requirement for a structural analytical model, parametric estimation based on finite element (FE) models, and evaluation of structural global behaviour. By comparing to traditional transducers such as linear variable displacement transducers (LVDTs) and foil ‘point’ strain gauges, the ability and ascendancy of the sensors developed here for SHM purposes are verified. A comprehensive health monitoring strategy for steel flexural structures based on the distributed strain sensors array is proposed finally.

The crystallization characteristics in supercooled liquid Zn during isothermal relaxation were investigated using molecular dynamics simulations by adopting the cluster-type index method (CTIM) and the tracing method. Results showed that the crystallization process undergo three different stages. The size of the critical nucleus was found to be approximately 90–150 atoms in this system; the growth of nuclei proceeded via the successive formation of hcp and fcc structures with a layered distribution; and finally, the system evolved into a much larger crystal with a distinct layered distribution of hcp and fcc structures with an 8R stacking sequence of ABCBACAB by adjusting all of the atoms in the larger clusters according to a certain rule.