Final Report Summary - PUMA (PUMA)
Executive Summary:
In the framework of the Clean Sky Joint Undertaking Green Regional Aircraft (GRA) a composite forward pressure bulkhead was designed by the National Aerospace Laboratory NLR and Airborne Technology Centre both located in the Netherlands
Based on the requirements provided by the topic leader EADSCASA the bulkhead was designed and two demonstrators were produced using the Liquid Resin Injection (LRI) process.
The project goal, as defined in the CleanSky topic description, can be summarized as follows:
“The essence of the job is to state the bases to come with a cheap but efficient manufacturing process based on LRI to produce a structurally efficient pressure bulkhead concept”
“Justification should take place through the manufacturing of a demonstrator and correspondent preliminary test of coupons extracted from one of the manufactured specimen”
Already at the beginning of the project it became clear that due to the high requirements related to the manufacturing tolerances a relatively expensive tooling was needed but that a “one shot” production by using the Liquid Resin Injection (LRI) process was feasible.
The analysis performed during the detailed design phase showed that the strength and stiffness requirements could be fulfilled by a sandwich composite structure but that, to cope with the bird strike requirements an additional 1.5 mm thick Dyneema add-on protection plate was needed.
Measurements performed on both demonstrators showed that the geometrical accuracy for the first demonstrator was just outside the required limits at some locations. Due to improvements made to the tooling the second demonstrator was inside the required geometrical limits .
The measured weight of the demonstrator (excluding Dyneema plate) is 7.7 Kg which is well below the weight of the aluminium reference, however the addition of the Dyneema plate for bird strike projection increases the total weight to 9 Kg which is just below the 9.2 Kg of the aluminium reference. As a remark it can be stated that the composite bulkhead cannot directly be compared to the reference as the area exposed to the cabin pressure is larger.
Project Context and Objectives:
Based on the requirements provided by the topic leader EADSCASA the bulkhead was designed and two demonstrators were produced using the Liquid Resin Injection (LRI) process.
The first bulkhead demonstrator was assembled into the first GRA cockpit demonstrator, the second bulkhead demonstrator contains some local defects and will be replaced by a third one to be produced by ATC and NLR outside the PUMA project and will be delivered to EADSCASA in the first quarter of 2015 for assembly into the second GRA cockpit demonstrator.
The project goal was defined in the CleanSky topic description:
“The essence of the job is to state the bases to come with a cheap but efficient manufacturing process based on LRI to produce a structurally efficient pressure bulkhead concept”
“Justification should take place through the manufacturing of a demonstrator and correspondent preliminary test of coupons extracted from one of the manufactured specimen”
Already at the beginning of the project it became clear that due to the high requirements related to the manufacturing tolerances a relatively expensive tooling was needed but that a “one shot” production by using the Liquid Resin Injection (LRI) process was feasible.
The manufacturing concept as demonstrated in the project was used to process two demonstrators. The first demonstrator was delivered to EADSCASA for assembly into the cockpit demonstrator. The second demonstrator showed some dry areas and will be repaired outside the scope of the PUMA project.
The analysis performed during the detailed design phase showed that the strength and stiffness requirements are fulfilled. Bird strike requirements were fulfilled by using an additional 1.5 mm thick Dyneema protection plate.
Measurements performed on both demonstrators showed that the geometrical accuracy for the first demonstrator was just outside the required limits at some locations. Due to improvements made to the tooling the second demonstrator was inside the required geometrical limits .
The measured weight of the demonstrator (excluding Dyneema plate) is 7.7 Kg which is well below the weight of the aluminium reference, however the addition of the Dyneema plate for bird strike projection increases the total weight to 9 Kg which is just below the 9.2 Kg of the aluminium reference. As a remark it can be stated that the composite bulkhead cannot directly be compared to the reference as the area exposed to the cabin pressure is larger.
Project Results:
Based on the requirements from EADSCASA (Topic Leader) a preliminary and detailed design of the bulkhead was made. Based on the detailed design the injection tooling was designed and manufactured. Finally two demonstrators were produced. The next paragraphs briefly describe the different activities.
The specifications as defined by EADSCASA contain the definition of the different load cases and requirements for the stiffness and strength. Also geometrical constrains and manufacturing tolerances are part of the design requirements.
The operating temperature of the bulkhead is -55oC ÷ 82oC.
It is noted here, that the pressure domain for the bulkhead differs from the pressure domain for the C-295 reference bulkhead. The reference bulkhead contains holes in the lower half of the bulkhead and it has an open connection from the wheel bay to the unpressurized radome. However, in the GRA cockpit demonstrator the entire bulkhead is pressurized.
The bird impact resistance must be demonstrated by analysis that after an impact by a 4 pounds bird at a relative velocity of 245 knots no bird mass will penetrate the pressure bulkhead and no part loss will occur due to the static loads, reasonably expected to occur at the time of incident and during the completion of the flight.
The weight saving target for the composite bulkhead is minimal 10% of the weight of the aluminium reference (9.2 Kg).
The bird impact analyses show that it is very hard for a composite bulkhead to prevent penetration of the bird. It seems feasible to fulfil the requirements for a design with S2-glass applied in the outer skin of the sandwich, but at the cost of weight increase instead of a 10% reduction.
Therefore, it was decided to adopt a different approach and to use a separate shield to protect the bulkhead from bird impact damage. The bulkhead itself will be designed without considering bird impact.
Two different design approaches were considered; i) a stiffened structure and ii) a sandwich structure.
During the Critical Design Review (CDR) the decision has been made to continue with the sandwich design acombined with a separate add-on (e.g. a Dyneema protection plate) in order to cope with bird strike.
Based on the detailed design of the bulkhead the injection tooling was designed and manufactured. The tooling was made from Hextool material.
Two demonstrators were produced, the first demonstrator was delivered at the EADSCASA facility in Cadiz on 29 September 2014.
The second demonstrator was injected on 4 November 2014. Locations with insufficient resin infiltration were found and after discussion with EADSCASA it was agreed to produce a third demonstrator outside the framework of the PUMA project.
Potential Impact:
Dissemination activities were not performed yet but will be done in 2015.
List of Websites:
No website was established
In the framework of the Clean Sky Joint Undertaking Green Regional Aircraft (GRA) a composite forward pressure bulkhead was designed by the National Aerospace Laboratory NLR and Airborne Technology Centre both located in the Netherlands
Based on the requirements provided by the topic leader EADSCASA the bulkhead was designed and two demonstrators were produced using the Liquid Resin Injection (LRI) process.
The project goal, as defined in the CleanSky topic description, can be summarized as follows:
“The essence of the job is to state the bases to come with a cheap but efficient manufacturing process based on LRI to produce a structurally efficient pressure bulkhead concept”
“Justification should take place through the manufacturing of a demonstrator and correspondent preliminary test of coupons extracted from one of the manufactured specimen”
Already at the beginning of the project it became clear that due to the high requirements related to the manufacturing tolerances a relatively expensive tooling was needed but that a “one shot” production by using the Liquid Resin Injection (LRI) process was feasible.
The analysis performed during the detailed design phase showed that the strength and stiffness requirements could be fulfilled by a sandwich composite structure but that, to cope with the bird strike requirements an additional 1.5 mm thick Dyneema add-on protection plate was needed.
Measurements performed on both demonstrators showed that the geometrical accuracy for the first demonstrator was just outside the required limits at some locations. Due to improvements made to the tooling the second demonstrator was inside the required geometrical limits .
The measured weight of the demonstrator (excluding Dyneema plate) is 7.7 Kg which is well below the weight of the aluminium reference, however the addition of the Dyneema plate for bird strike projection increases the total weight to 9 Kg which is just below the 9.2 Kg of the aluminium reference. As a remark it can be stated that the composite bulkhead cannot directly be compared to the reference as the area exposed to the cabin pressure is larger.
Project Context and Objectives:
Based on the requirements provided by the topic leader EADSCASA the bulkhead was designed and two demonstrators were produced using the Liquid Resin Injection (LRI) process.
The first bulkhead demonstrator was assembled into the first GRA cockpit demonstrator, the second bulkhead demonstrator contains some local defects and will be replaced by a third one to be produced by ATC and NLR outside the PUMA project and will be delivered to EADSCASA in the first quarter of 2015 for assembly into the second GRA cockpit demonstrator.
The project goal was defined in the CleanSky topic description:
“The essence of the job is to state the bases to come with a cheap but efficient manufacturing process based on LRI to produce a structurally efficient pressure bulkhead concept”
“Justification should take place through the manufacturing of a demonstrator and correspondent preliminary test of coupons extracted from one of the manufactured specimen”
Already at the beginning of the project it became clear that due to the high requirements related to the manufacturing tolerances a relatively expensive tooling was needed but that a “one shot” production by using the Liquid Resin Injection (LRI) process was feasible.
The manufacturing concept as demonstrated in the project was used to process two demonstrators. The first demonstrator was delivered to EADSCASA for assembly into the cockpit demonstrator. The second demonstrator showed some dry areas and will be repaired outside the scope of the PUMA project.
The analysis performed during the detailed design phase showed that the strength and stiffness requirements are fulfilled. Bird strike requirements were fulfilled by using an additional 1.5 mm thick Dyneema protection plate.
Measurements performed on both demonstrators showed that the geometrical accuracy for the first demonstrator was just outside the required limits at some locations. Due to improvements made to the tooling the second demonstrator was inside the required geometrical limits .
The measured weight of the demonstrator (excluding Dyneema plate) is 7.7 Kg which is well below the weight of the aluminium reference, however the addition of the Dyneema plate for bird strike projection increases the total weight to 9 Kg which is just below the 9.2 Kg of the aluminium reference. As a remark it can be stated that the composite bulkhead cannot directly be compared to the reference as the area exposed to the cabin pressure is larger.
Project Results:
Based on the requirements from EADSCASA (Topic Leader) a preliminary and detailed design of the bulkhead was made. Based on the detailed design the injection tooling was designed and manufactured. Finally two demonstrators were produced. The next paragraphs briefly describe the different activities.
The specifications as defined by EADSCASA contain the definition of the different load cases and requirements for the stiffness and strength. Also geometrical constrains and manufacturing tolerances are part of the design requirements.
The operating temperature of the bulkhead is -55oC ÷ 82oC.
It is noted here, that the pressure domain for the bulkhead differs from the pressure domain for the C-295 reference bulkhead. The reference bulkhead contains holes in the lower half of the bulkhead and it has an open connection from the wheel bay to the unpressurized radome. However, in the GRA cockpit demonstrator the entire bulkhead is pressurized.
The bird impact resistance must be demonstrated by analysis that after an impact by a 4 pounds bird at a relative velocity of 245 knots no bird mass will penetrate the pressure bulkhead and no part loss will occur due to the static loads, reasonably expected to occur at the time of incident and during the completion of the flight.
The weight saving target for the composite bulkhead is minimal 10% of the weight of the aluminium reference (9.2 Kg).
The bird impact analyses show that it is very hard for a composite bulkhead to prevent penetration of the bird. It seems feasible to fulfil the requirements for a design with S2-glass applied in the outer skin of the sandwich, but at the cost of weight increase instead of a 10% reduction.
Therefore, it was decided to adopt a different approach and to use a separate shield to protect the bulkhead from bird impact damage. The bulkhead itself will be designed without considering bird impact.
Two different design approaches were considered; i) a stiffened structure and ii) a sandwich structure.
During the Critical Design Review (CDR) the decision has been made to continue with the sandwich design acombined with a separate add-on (e.g. a Dyneema protection plate) in order to cope with bird strike.
Based on the detailed design of the bulkhead the injection tooling was designed and manufactured. The tooling was made from Hextool material.
Two demonstrators were produced, the first demonstrator was delivered at the EADSCASA facility in Cadiz on 29 September 2014.
The second demonstrator was injected on 4 November 2014. Locations with insufficient resin infiltration were found and after discussion with EADSCASA it was agreed to produce a third demonstrator outside the framework of the PUMA project.
Potential Impact:
Dissemination activities were not performed yet but will be done in 2015.
List of Websites:
No website was established