Tag Archives: Resin infusion

-AeroComposit chooses innovative solutions to build MS-21 composite wings

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MS-21´s wing spars, wing skins and six section panels will be manufactured by resin infusion and oven curing

Resin infusion is being applied in the newest commercial aviation programmes. One of them is the Irkut´s Corporation´s (Russia) MS-21 aircraft, which could be rolled out in 2015 (prototype). The post offers some details about the MS-21 aircraft, as well as about the innovative resin infusion technology they are applying in order to push the Russian companies at the the forefront of the worldwide aircraft industry.

Although Irkut will only produce 40 aircrafts/year (compared to approximately 500 each for Airbus and Boeing), the new MS-21 could compete with worldwide market leaders in the single-aisle commercial jet market.

Irkut MS-21 aircraft

Irkut´s MS-21 aircraft

To succeed in this highly competitive market, Irkut´s aircraft will have to offer a good performance and a greater fuel efficiency than its competitors. MS-21 will have a lower empty weight, a better aerodynamics and more efficient engines. The company is confident that if the MS-21 can use composites in a way that reduces weight and manufacturing costs in that 45 percent with a a target price of 35 Million US$.

To this end, in terms of technology, the company has decided to go one step ahead ,since the very beginning of the programme definition, being at the cutting edge of the aircraft industry, using Out of Autoclave methods for structural parts manufacturing.

Infusion and oven curing have been chosen for the MS-21’s large integrally stiffened primary structures including the wing spars, wing skins and six section panels

Infusion and oven curing have been chosen for the MS-21’s large integrally stiffened primary structures including the wing spars, wing skins and six section panels for the centre wing-box. These will be manufactured and assembled at the AeroComposit (also subsidiary of UAC) plant in Ulyanovsk. These process have been chosen due to its potential to reduce costs (avoiding the costly autoclave curing and reducing resin and dry material costs), and its opportunity to create integral constructions.

MS-21 resin infused wing

MS-21 resin infused wing (Diamond Aircraft´s photo)

AeroComposit has worked with a variety of experts worldwide to develop the design, materials and the process to achieve the requisite precision and quality. In terms of raw material, Hexcel and Cytec have been selected to provide dry carbon fiber and compatible liquid epoxy infusion resin. Hexcel´s OoA HiTape (up to 30mm thick) and it´s HexFlow infusion resin have been already tested to be used for the wing manufacturing.  The company affirms that 58 to 60% fiber volume content can be achieved with these  materials. An equivalent system from Cytec is also being used in the project.

The wing is based on the new carbon-infusion technology that allows building big components, like tail units or wings, with high stability at low weight.

Regarding the infusion process, FACC and Diamond Aircraft will be responsible for optimizing the wing and wing-box manufacturing process. Diamond Aircraft has developed the resin infusion process for the wing manufacturing. The wing is based on the new carbon-infusion technology that allows building big components, like tail units or wings, with high stability at low weight. The resin is cured at an aerospace standard of 180°C/356°F with a service temperature of -60°C to 160°C (-76°F to 320°F) while the production cycle can vary from 5 to 30 hours. The manufactured wing meets the requirements of the aircraft industry with a porosity of 0,3%. Diamond Aircraft claims that this achievement does not depend on the type of construction, but instead on the ability to maintain strict control of the process parameters. According to the company, the prototype wing is a a great achievement, that will have a mayor impact on the design of future airlines.

You can find more information in these CompositesWorld, Diamond Aircraft and Russia Beyond the State of the Art articles.

-Resin Infusion techniques in the aerospace industry

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Many methods have been developed to perform the resin infusion in the aerospace industry, once the dry preforms are created manually or automatically. These processes are identified by different names and acronyms, which can lead to some confusion. Here is a description of some of the more widely known infusion methods.

SCRIMP (Seemann Composites Resin Infusion Molding Process) is one of the earliest patented infusion methods. It is used for many marine and Wind blade applications, but was also licensed by some aerospace firms. It relies upon the use of a flow or “distribution media” with high permeability between the layup and vacuum bag to rapidly and evenly distribute resin laterally across the part.

SCRIMP Schematic

SCRIMP Schematic (link)

VARTM (Vacuum Assisted Resin Transfer Molding) is the name of the process used by Lockheed Martin that is similar to SCRIMP, but does not use a flow media. The entire fuselage of the AGM 159 JASSM missile is made using VARTM.

JASSM made with VARTM

JASSM made with VARTM (link)

CAPRI (Controlled Atmospheric Pressure Resin Infusion) was patented by Boeing and is said to reduce thickness variation and result in fiber volumes and mechanical properties equivalent to prepreg/autoclave materials. First it uses vacuum debulking cycles on the dry preform to reduce compressed thickness prior to infusion. During infusion, the resin supply is held at partial vacuum, which assists in degassing the bulk resin but also reduces the pressure differential driving resin into the preform.

CAPRI Schematic

CAPRI Schematic (link)

VAP (Vacuum Assisted Process) was patented by EADS and used in parts like the A380 Aft Pressure Bulkhead and the massive A400 Cargo Door. VAP features a gas permeable membrane placed over the infused layup, which helps to evacuate trapped air and volatiles in the infused layup prior to cure. By letting gases through the membrane (but not the resin) VAP is said to achieve lower voids and higher, more controlled fiber volume for better laminate quality.

VAP membrane

VAP membrane (link)

RTI (Resin Transfer Infusion) is a Bombardier patented process used to produce the wing skins of its CSeries aircraft. Infusion of resin into the preform is performed with vacuum pressure only. However, the mold is located in an unpressurized  autoclave during the infusion step. After the preform is fully infused, the autoclave is pressurized and heated to perform cure. This makes it easier to achieve high laminate quality because positive cure pressure (>14 psi) helps prevent void formation from entrapped air and volatiles. It has the drawback that a suitable size autoclave is still requited. All other methods cited above are true Out of Autoclave processes.

C-Series wing made with RTI

C-Series wing made with RTI (link)

There are also other acronyms for similar processes, which can create a kind of “alphabet soup” confusion about infusion.

The important thing to remember is that many different users have had success making a wide range of parts (some very large and critical) using infusion processes.

-We go dry

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Dry Composites is an initiative by Danobat Composites to share the latest advancements in automation using dry composite material. This online community aims to connect companies, research centers, academics and experts interested in the use of dry composite material to develop structural parts in aerospace.

What do we mean by Dry Composites? There are two distinct methods of making composite structures. The first involves impregnating the fibres in a dedicated off-line machine to make a pre-impregnated material, called pre-preg. This is then transported to a factory that makes structures where it is laid up by machines or manually.

The second, more direct route is to take dry fibres, usually in some textile format and after assembly into a pre-form, infuse them with liquid resin. The infusion process is known by a number of trade names and acronyms such as RTM, VARTM etc.

The pre-preg route involves an extra process and hence cost, but it does result in structures with good consistent properties. Recently, the performance of structures made by infusing Dry Preforms has improved and is now claimed by some, to match that of more conventional pre-preg materials. Working with dry fibers, fabrics and textiles enables thicker layers to be used, saving time and labour costs, plus aiding in the creation of more complex, one-piece structures.

However whereas the pre-preg manufacturing industry is well served by automation with dedicated machine tools, the lay-up of dry fabrics has not received the same attention. Danobat Composites has pioneered the development of Automatic Tape Laying using woven and NCF fabrics. This has improved laminate quality, repeatability and reduced the cost of composite structures by significantly cutting manufacturing labour and material costs. Moreover, it is worth mentioning that the use of dry materials can give rise to out of autoclave curing processes acquiring required properties in primary structural aerospace parts.

Today, manufacturers face the challenge of doing more with less, the aerospace industry needs to adapt quickly to new material and process developments to remain competitive. In doing so, the ultimate goal of a disruptive automation technology is to introduce new processes that may deliver better high efficiencies and control at less cost. This requires broad support from an ecosystem of R&D, manufacturing, engineering teams and material developers.

Dry Composites is an open space for those interested in learning more about how automation using dry composite material can be applied to the aerospace industry. From sharing industry news, information, data and technical solutions about dry composite solutions to interviews and perspectives from expert sources. Our target audience includes decision makers, R&D engineers, global suppliers of advanced materials, software and automation companies.

If you are interested in learning more about advancements in the use of dry material in the aerospace industry, follow us on Twitter @drycomposites and join the LinkedIn Group Dry Composites.

Stay tuned for more!