Temperature Control of Filament Wound Composites during
the Gelling ProcessBy: 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