Keeping High Speed Trains Moving Efficiently Case Study: SNCF MSC Software | CASE STUDY The optimized design developed with MSC Software showed an improvement of 17% in the maximum force, 3% in mean force and 14% in standard deviation. Overview The limiting factor on the speed of high speed trains typically comes down to the ability to supply the proper amount of power required to run the engines through the catenary-pantograph interface. The pantograph is mounted on the roof of the train and consists of a head with contact strips and a variable height frame assembly. The catenary supports the messenger wire that runs above the track and from it is suspended the contact wire. The single most important feature of this system is the quality of the contact between the contact wire and the contact strips. An average of 400 catenary incidents are reported each year on the rench rail network. Catenary delays are sometimes substantial, up to 3 hours. Catenary incidents represent about 6% of all delays on the rail systems. When delays occur during periods of heavy traffic, they may require changing schedules throughout the railroad network.
Transcript
Keeping High Speed Trains Moving Efficiently
Case Study: SNCF
MSC Software | CASE STUDY
The optimized design developed with MSCSoftware showed an improvement of 17%in the maximum force, 3% in mean forceand 14% in standard deviation.
OverviewThe limiting factor on the speed of high speed trains typically comes down to the ability to supply the proper amount of power required to run the engines through the catenary-pantograph interface.
The pantograph is mounted on the roof of the train and consists of a head with contact strips and a variable height frame assembly. The catenary supports the messenger wire that runs above the track and from it is suspended the contact wire. The single most important feature of this system is the quality of the contact between the contact wire and the contact strips.
An average of 400 catenary incidents are reported each year on the rench rail network. Catenary delays are sometimes substantial, up to 3 hours. Catenary incidents represent about 6% of all delays on the rail systems. When delays occur during periods of heavy traffic, they may require changing schedules throughout the railroad network.
“Accurate simulation required capturing the geometric nonlinearities in the catenary,large displacements of the pantograph mechanism, flexibility of the pantographcomponents, contacts between the contact wire and contact strips, and pneumaticactuation and controls. ”
Challenge The performance of the catenary and pantograph was traditionally evaluated using physical testing. For example, testing was required to ensure that older catenaries maintain the ability to support high speed train operation. But cost constraints have limited the amount of physical testing that can be performed at the same time that pressures are rising to improve the catenary-pantograph performance. Simulation is challenging because of the enormous complexity involved in the catenary-pantograph interface. Achieving an accurate simulation requires capturing the geometric nonlinearities in the catenary, large displacements of the pantograph mechanism, flexibility of the pantograph components, contacts between the contact wire and contact strips, and pneumatic actuation and controls.
Solution/ValidationSD Tools developed OSCAR (Outil de Simulation du CAptage pour la Reconnaissance de défauts) to simulate the catenary using a 3D finite element model of the catenary components such as the contact wire, messenger wire, steady arms and unilateral droppers. OSCAR accurately captures the local dynamic behavior of the catenary under the transient loading conditions generated by several pantographs carried by a high speed train.
Key components of pantograph for multibody modeling
Product: MSC Nastran, Adams, Easy5, SimXpert
Industry: Rail
Benefits:
•Reduced physical testing
•Accurate modeling of complexmechanisms and contact behaviour
•Increased performance
Key Highlights:MSC Software worked with SNCF to develop a complementary solution that couples SimXpert Motion with OSCAR, and includes an industry specific graphic user interface to set up the simulation. The solution utilizes large displacement dynamics with Adams by leveraging SimXpert Motion workspace modeling capabilities, as well as structural components flexibility with MSC Nastran using SimXpert Structures workspace modeling capabilities, and pneumatic actuation and controls using Easy5 within the SimXpert Systems and Controls workspace.
The MSC SimXpert Motion solution can be used to model complex pantograph mechanisms. The model incorporates the arms and rods in the frame of the pantograph that undergo large displacements. The frame is actuated by a pneumatic piston that applies a torque to the lower arm through a camcable link. The upper part of the pantograph, called the bow, incorporates the contact strips that make contact with the catenary.
Mechanical and structural parameters for flexible body modeling were fitted from laboratory measurements to reproduce pantograph dynamic behavior up to 200 Hz. The first three modes in this frequency bandwidth include: 1st vertical mode: main frame and bow moving in phase; 2nd vertical mode: main frame and bow moving in opposition; 3rd vertical mode: upper arm flexion and phase opposition between main
frame and bow. The pneumatic actuator delivers a pressure determined by the control system that is based mainly on the train speed.
Co-simulation process Co-simulation between the OSCAR model of the catenary and the SimXpert Motion model of the pantograph is carried out through communications between the two software packages. The contact loads computed by SimXpert Motion are sent to OSCAR and applied on the catenary model. OSCAR calculates the dynamics of the catenary and sends the contact wire displacements to the SimXpert Motion model at the updated pantograph position along the catenary. The co-simulation process was validated by comparing it to a pure OSCAR simulation.
Results Proposed pneumatic damping devicePantograph head suspensions, comprised of a spring box, rod and ball bearings, ensure the dynamic uncoupling between the contact strips and the pantograph main frame, particularly above 10 Hz. Decreasing the working suspension stiffness could provide improvements in pantograph-catenary interaction but requires an increase in spring length because of preload adjustments.
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SCNF engineers developed a proposed solution that uses a pneumatic damping device. The design parameters for the new pantograph suspension were optimized using the co-simulation method over a simulation distance of 400 meters.
Co-simulation was initially performed with a rigid body model. The variables that were evaluated included pneumatic vs mechanical suspension, stiffness of the pneumatic suspension, damping clearance and bow mass. The results provided by the co-simulation included the maximum catenary-pantograph force, the mean force and the standard deviation of the force. The results showed that suspension stiffness is the design parameter with the biggest impact on catenary-pantograph force. Using a pneumatic suspension with the same stiffness as the mechanical suspension had minimal impact on the dynamic behavior. The best results were obtained by using a stiffness of 1/10 the value of the mechanical suspension.Adding 2 cm of clearance was shown not to improve the mean force and to increase the maximum force. Further calculations showed that the pneumatic suspension was insensitive to increase in the mass of the bow.
The best design had a pneumatic suspension, 1/10 the stiffness of the original mechanical suspension, zero clearance and the same bow mass as the current design. Rigid body simulation showed this design provided a 21% reduction in maximum force, a 1% reduction in mean force and an 18% reduction in standard deviation. The optimal design was re-analyzed using flexible bodies for the primary components on the pantograph.The flexible body simulation showed that
Proposed pneumatic damping device
Co-simulation results on pneumatic damping device with rigid body model
the optimized design developed with rigid body analysis showed an improvement of 17% in the maximum force, 3% in mean force and 14% in standard deviation.
About SNCF The SNCF is France’s national state-owned railway company that operates the country’s national rail services,
including the TGV, France’s high-speed rail network. The company operates a railway network consisting of about 20,000 miles (32,000 km) of track including 1,100 miles (1,800 kilometers) of high speed lines. The SNCF’s TGV (Train à Grande Vitesse, meaning “High-Speed Train”) has set many speed records including the world speed record for conventional railway trains at 357.2 mph (574.8 km/h).
