Thermoplastic Materials

About

Background The manufacturing process for high performance composite materials is typically slow due to labour intensive lay-up processes followed by long cure cycles of thermosetting resins. Thermoplastic materials be can processed by fusion bonding, a welding process based on the diffusion of polymer molecules across the bond interface at elevated temperatures. This process can be orders of magnitude faster than a typical thermoset cure. Furthermore, when coupled with a placement technology such as automated tape placement (ATP) or filament winding, the composite can be bonded in situ as it is placed. The part is ready for finishing as soon as placement or winding has completed. This approach shows much potential for flexible and automated manufacture of lightweight and high performance automotive structures, including high pressure storage vessels for gaseous fuels. The placement rate must be maximised for production, however maintaining composite quality is nontrivial due to the highly dynamic behaviours at the nip point. Opportunity A laser-assisted tape placement system was instrumented with temperature and pressure sensors so as to measure the temperature and pressure profiles experienced at the bond interface in the nip point region. The recorded temperature and pressure profiles were fed into a bonding model to predict the resulting strength. Key features Simply heat the interface and apply pressure – consolidation within seconds Out-of-autoclave (traditional thermal treatments require hours) Lasers can deliver very high heat flux to a specific, targeted area. Modern diode lasers have high plug in efficiencies (~45%) and a small footprint. Optics can be used to modify the beam geometry for processing requirements. In-situ thermal imaging and pressure sensing Optical and thermal modelling Process modelling and optimization Characterisation of mechanical properties, including thermal diffusivity.