Printed Nanocarbon Heaters for Stretchable Sport and Leisure Garments

The ability to maintain body temperature has been shown to bring about improvements in sporting performance. However, current solutions are limited with regards to flexibility, heating uniformity and robustness. An innovative screen-printed Nanocarbon heater is demonstrated which is robust to bending, folding, tensile extensions of up to 20% and machine washing. This combination of ink and substrate enables the heated garments to safely flex without impeding the wearer. It is capable of producing uniform heating over a 15 × 4 cm area using a conductive ink based on a blend of Graphite Nanoplatelets and Carbon Black. This can be attributed to the low roughness of the conductive carbon coating, the uniform distribution and good interconnection of the carbon particles. The heaters have a low thermal inertia, producing a rapid temperature response at low voltages, reaching equilibrium temperatures within 120 s of being switched on. The heaters reached the 40 °C required for wearable heating applications within 20 s at 12 Volts. Screen printing was demonstrated to be an effective method of controlling the printed layer thickness with good interlayer adhesion and contact for multiple printed layers. This can be used to regulate their electrical properties and hence adjust the heater performance.

Improvement of Heating Uniformity by Limiting the Absorption of Hot Areas in Microwave Processing of CFRP Composites

Carbon fiber reinforced polymer (CFRP) composites are integral to today’s industries. Curing or consolidation are vital processes for manufacturing CFRP components. Microwave processing has many advantages compared with conventional processing technologies using ovens or autoclaves; however, the uneven temperature distribution caused by the non-uniform microwave field has a significant influence on the quality of the cured products. In this study, we propose a new idea to solve this problem, i.e., limiting the absorption of hot areas. Under such circumstances, cold ones can catch up with them more easily. To adjust the absorbing capability of the CFRP laminate, periodically arranged metallic resonance structures supported by a dielectric spacer are introduced on its surface. The dielectric spacer, made of epoxy matrix and strontium titanate particles, is designed to possess a dielectric constant positively related to temperatures. In this situation, the microwave absorption (2.45 GHz) of the metal-dielectric-CFRP configuration is changed from 97.6% at room temperature to 55.9% at 150 °C continuously. As a result, a reduction of 43.1% in maximum temperature difference and 89% in standard deviation has been achieved.

Automated system for design and calculation of heating devices for hot die forging

Methods of mathematical modeling, basic technologies and methods of modeling in various design systems of the stamping process are considered. The canonical equations of temperature stresses are obtained, which make it possible to obtain a picture of the temperature distribution over the workpiece area during heating. A mathematical model has been developed for a thin metal strip during heating; thermal stresses arising in it due to uneven heating have been described. Numerical modeling has been carried out on the basisof field data, which will allow verification of the automated environment for the selection of functional and design schemes and the calculation of the parameters of heating devices in hot volumetric stamping of workpieces in terms of speed, energy efficiency, heating quality: accuracy of achieving specified temperatures and maximum heating uniformity. By areas, ease of use and readjustment, resource, reliability and maintainability. The proposed system will include the following CAD elements: databases and rules for operating with them, calculation modules, modules for selecting and matching options.