Research on Thermal Deep-drawing Technology of Magnesium Alloy (AZ31B) Sheets

Forming technology of Mg alloy (AZ31B) sheets can be investigated by thermal deep drawing experiments. In the experiments, the blank holder and die contacting with the blank were heated to the same temperature as the blank by using the heating facility. The circular blank heated in an oven is formed at a temperature range of 100~400 ℃ to obtain the optimum forming temperature range and the effects of major technical parameters on the workpiece quality. It is found that the blank is brittle at temperatures lower than 200℃. Temperatures higher than 400℃ are not suitable for forming of the sheets because of severe oxidation and wrinkling. AZ31B shows an excellent formability at temperatures from 300 to 350℃ and can be formed into a workpiece with good quality. When the blank holder force is 9 kN, extruded sheets with a thickness of 1 mm can be formed into cups without wrinkling. Workpieces show strong anisotropic deformation behavior on the flanges.

Thermally Drawn Multi‑material Fibers Based on Polymer Nanocomposite for Continuous Temperature Sensing

With increasing personalized healthcare,fiber-based wearable temperature sensors that can be incorporated into textiles have attracted more attention in the field of wearable electronics.Here,we present a flexible,well-passivated,polymer–nanocomposite–based fiber temperature sensor fabricated by a thermal drawing process of multiple materials.We engineered a preform to optimize material processability and sensor performance by considering the rheological and functional properties of the preform materials.The fiber temperature sensor consisted of a temperature-sensing core made from a conductive polymer composite of thermoplastic polylactic acid,a conductive carbon filler,reduced graphene oxide,and a highly flexible linear low-density polyethylene passivation layer.Our fiber temperature sensor exhibited adequate sensitivity(−0.285%/℃)within a temperature range of 25–45℃with rapid response and recovery times of 11.6 and 14.8 s,respectively.In addition,it demonstrated a consistent and reliable temperature response under repeated mechanical and chemical stresses,which satisfied the requirements for the long-term application of wearable fiber sensors.Furthermore,the fiber temperature sensor sewn onto a daily cloth and hand glove exhibited a highly stable performance in response to body temperature changes and temperature detection by touch.These results indicate the great potential of this sensor for applications in wearable,electronic skin,and other biomedical devices.

In-Fiber Structured Particles and Filament Arrays from the Perspective of Fluid Instabilities

In-fiber structured particles and filament array have been recently emerging,providing unique advantages of feasible fabrication,diverse structures and sophisticated functionalities.This review will focus on the progress of this topic mainly from the perspective of fluid instabilities.By suppressing the capillary instability,the uniform layered structures down to nanometers are attained with the suitable materials selection.On the other hand,by utilizing capillary instability via post-drawing thermal treatment,the unprecedent structured particles can be designed with multimaterials for multifunctional fiber devices.Moreover,an interesting filamentation instability of a stretching viscous sheet has been identified during thermal drawing,resulting in an array of filaments.This review may inspire more future work to produce versatile devices for fiber electronics,either at a single fiber level or in large-scale fabrics and textiles,simply by manipulating and controlling fluid instabilities.