Temperature Control of Filament Wound Composites during the Gelling Process By: Matt Ballard and Brooks Lively

Problem  New low viscosity epoxy resin Must be gelled at 80°C or above.  Wanted to make sure the inside of the composite was getting gelled as well as the outside  Cannot directly measure the inside of the composite, as thermocouple leads would ruin the composite

Test Set-up  Attached thermocouple leads to the inside of composite and inside of hollow steel mandrel.  Measured and recorded temperatures at the two nodes at time intervals of 1 min for 60 min

Analysis  From collected data, determined that the process had reached steady state at about t = 45 min  Used temperatures at the two nodes to determine an average q”, which in turn can be used to approximate Tm,o from known Tm,i  Fairly accurate after about 15 minutes

Analysis (cont.)  Steady-state heat flux through the mandrel was determined using a thermal circuit analysis (with mandrel properties and temperatures known)  Where  Found that (on average, once steady state is reached) :  This can now be used to determine the outer mandrel temperature from the inner mandrel temperature Fiber Reinforced Epoxy Composite Hollow Low Carbon Steel Mandrel q” r

Conclusions  Determined that inside of composite does reach 80°C  This method can be used to predict temperature at the mandrel-composite interface  Simple, inexpensive solution, but can only be used with specific settings