The required elevation of temperature for curing of composite repairs is usually achieved by resistance heating blankets, controlled through spot temperature measurements. Although this method is simple and works adequately for small repairs, when larger areas are heated, cold or hot spots frequently occur, due to variable heat losses, caused by geometrical asymmetry etc. For this reason, autoclave curing of large repairs is currently used, as the most reliable curing methodology, which is however accompanied by high cost, wastes and energy consumption. The scope of this proposal is to enable the extension of heating blankets technology for the treatment of large repairs (e.g. reversers), currently requiring autoclave heating. A five step process is proposed:a)Thermal transfer simulation, to retrieve the “thermal signature” of the part and experimental validation using heat flux sensors,b)Manufacturing of thermal blankets, namely adapted Variable Heating Elements (VHE), with denser or coarser heating elements inside, and standard Compensation Heating Elements (CHE), in order to compensate for dissimilar heat losses,c)Development of universal Advanced Heating Control Unit (AHCU), with innovative programmable closed loop control,d)Development of a specialized High Power Supply Unit (HPSU,e)Process validation. It is expected that, this innovative methodology will allow the performance of structural repairs, either totally out-of-autoclave or in combination with autoclave treatment, as required, thus improving the overall heating process and achieving large scale economies compared to current autoclave solutions. Given that specified repairs are generally standardized, steps (a) and (b) will only need to be performed once per P/N to be repaired, while the developed equipment described in steps (c) and (d) will be totally reusable, thus significantly decreasing the non-recurring cost encountered per repair.
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