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About four years ago, Kineco developed India’s first front-end cab for a DEMU train, including a driver’s desk and cab interior panelling. Based on the satisfactory field performance of this cab, Indian Railway decided to introduce composite aerodynamic front-end cabs with modern looks and enhanced driver comfort in other trains.
(Published on July-August 2008 – JEC Magazine #42)
RAVI SHRIVASTAVA GENERAL MANAGER, MARKETING & PROJECTS, KINECO
Unlike conventional materials such as metals, composite materials are easy to mould into complex shapes, which gives the designer more freedom to design the front end with desirable aerodynamic curves.
These materials also have a high strength-to-weight ratio, i.e. low density (100 MPa) and rigidity (E~10,000 MPa). This combination produces a lightweight construction which reduces the tare weight of driver coaches. Composites also reduce the drag force of train fronts by improving their aerodynamic shape, while demonstrating high corrosion resistance, which minimizes maintenance in such applications. Finally, large composite parts are easy to process and offer component integration opportunities together with improved aesthetic appeal.
Composite aerodynamic front-end cab for DEMU trains
As its first ever developmental project, Kineco was awarded a turnkey contract by Indian Railway for an all-composite front-end cab for short distance DEMU (Diesel Electric Multiple Unit) passenger trains. The project included the product & engineering design, CFD validation of the engineering design, prototyping, mass manufacturing and installation. An entire structural front-end cab was designed along with the driver’s desk and interior components, in line with the following design criteria specified by the customer:
meter of the coach’s cab flooring The whole cab was designed in a single-piece construction with a separate back panel. A stiffened structure was used, consisting of a glass fibre composite skin supported by composite stiffeners with a solid rectangular cross section.
The composite front-end cab was designed by Kineco and the structural design was vetted by an external engineering company. A detailed design analysis was carried out considering various load cases, including 1) a CFD aerodynamic analysis to define the pressure distribution and drag forces, 2) an FEA stress analysis of the aerodynamic load and other loads, 3) a simplified crash analysis based on the energy absorption criteria for a composite cab vis-à-vis a conventional metal cab, and 4) a natural frequency analysis of the structure for minimum specified values.
To achieve superior quality with a very low void content, all the composite structural components were moulded using the vacuum infusion technique, thereby ensuring substantially enhanced glass contents and mechanical properties for the laminate.
The interior panels and the driver’s desk were manufactured using the conventional hand lay-up process.
This may be the largest railway composite component ever produced by resin infusion in India. Extensive field trials were carried out with these aerodynamic fronts and a fuel saving of around 6% was observed.
Composite aerodynamic front-end cab for MEMU trains
Kineco was awarded another contract by Indian Railway for a front-end cab for MEMU (Mainline Electric Multiple Unit) trains. The only difference was that the cab was supported by a car body metal structure. The composite front was designed in three pieces including two side panels to simplify fitting onto the metal car body support structure. The front part was made of a glass-polyester construction, using a fire-retardant resin complying with Indian standards. Exterior components like the front, side panels, side skirts, coupler cover, etc. were made using the resin infusion process, while the cab interior panels and the driver’s desk were manufactured using the hand lay-up process. An advanced noncrimp glass reinforcement was used for the exterior components of this particular front to optimize design in combination with the resin infusion process.
Composite front end for metro trains
Kineco is also working on a developmental contract for manufacturing glassphenolic autoclavemoulded front ends for metro trains. The front end is made from glassphenolic prepregs and moulded by vacuum bagging in an autoclave. A very high glass content – more than 60% – can be reached with this advanced moulding process, which ensures high mechanical properties and good fire performance (the resin content is quite low), thus complying with BS 6853, Category 1a. Good mechanical properties help optimize design with respect to the required thickness of the GRP laminate.
In view of the successful local development and satisfactory field performance, Indian Railway is now considering the mass introduction of composite front-end cabs for various trains. To move forward with composite fronts and modernize their fleet, the company recently awarded Kineco another turnkey contract for the development of locomotive frontend cabs.