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