LE PONT: Didactic Approach for Engineering Science

Description

 

The Original Bridge :

The Chaban-Delmas bridge was inaugurated in 2013 in Bordeaux, a well-known town in Southwestern France. The aim of the bridge was to join the urban boulevards of Bordeaux, by connecting two districts called Bacalan and Bastide.

 

With a length of 433 m, the bridge has 2 lanes for public transport, 4 lanes for road vehicles, and 2 gateways for cyclists and pedestrians.

The fixed spans are made from metal beams on concrete piles.

Four concrete towers of 75 m high allow the central lift span (length 117 m) to provide 50 m clearance for boats sailing towards the historic centre.

The central lift span, weighing 2700 tons and produced in metal housing, is balanced by 4 counterweights of 640 tons each.

 

It is powered by 2 synchronized 132 kW engines, and can be lifted on load in 12 min.

The lift span’s height is controlled by a sensor inside each tower. He control panel, located on the left river bank, allows to monitor traffic, activate the engines and control the passage of boats.

The Civil Engineering Mock-Up :

 

Structure

• Mock-up at 1/100th scale
• Structure of the bridge piles made of lacquered steel with thickness 1.5 mm closed by polycarbonate for visualization of the cables and counterweights
• Pulleys and counterweights on each pile with Kevlar cable
• Identification of the cables by colour: yellow for lifting, blue for retrieving
• Bases of the bridge’s piles composed of motor and gear-motor power 25 W
• Cables winding winch with spooling groove
• Box-type apron made of steel thickness 0.5 mm
• Mounting of the bridge on a cabinet with casters

Instrumentation:

• 1 potentiometric sensor for measuring arrow
• 4 effort sensors on pulleys
• 3 incremental encoders
• 4 apron force sensors
• 2 sensors at apron’s height (cable sensors)
• 4 current consumption’s sensors
• 2 power voltage measurements

Control system:

• WINDOWS laptop environment
• LABVIEW display software
• Connection via USB

 

 

 

Control Software:

• To configure:
  • The control system
  • The measurement channels and the calculated channels
  • The activities
• To measure:
  • Acquire, store in a file, or recover measures
  • Perform channels calculations
• To analyse:
  • View graphs
  • Determine the characteristic values using sliders
  • Play educational animations

Proposed Activities :

“MATERIAL” Activity

M-1  Geometry of the lifting span : Study of the geometrical characteristics of the central box through modelling

M-2  Resistance of the lifting span : Study of the deformation of the apron on load, with different masses. Measurement of the arrow, computation of the constraint of the apron under load.

M-3  Resistance of the lifting cables : Study of the cables resistance allowing the lifting of the the apron

“ENERGY” Activity

E-1  Kinematics of transmission : Study of kinematics of apron lifting: determining the reduction ratio, the winding diameter, from position or speed measurements.

E-2  Simple dynamics : Study of simplified balance of the span lifting power under load. Determining the overall yield from power measurements

E-3  Complete dynamics : Study of the detailed balance of the span lifting power under load. Determining intermediate power measurements and yields.

E-4  Accelerated motion : Dynamic study of the lifting span under load. Power measurement during acceleration and determining yields.

E-5  BLDC motor : Study of electronic switching of a brushless motor depending on the encoder information.

E-6  Friction : Power balance of the reducer in the presence of dry and viscous frictions. Measuring torques and yields, determining constant friction.

E-7  Identification : Identify the response in speed of batteries motors. Determining the mock-up parameters.

 “INFORMATION” Activity

I-1  Incremental encoder : Study of an incremental encoder. Determining the position and speed rotation from measuring signals.

I-2  Absolute encoder : Study of a synchronous serial link. Determining the decoding method.

I-3  Tachometer sensor : Study of an analogue tachometer sensor. Signal measurement and synthesis of the optimal filter.

I-4  Gauges sensor : Study of an analogue device for measuring short displacement. Determining the gauges bridge constants.

I-5  Fieldbus : Study of an asynchronous serial link. Determining the decoding method.

I-6  Adjusting the synchronization : Study of the battery speed control to synchronize the movements of the two banks. Determining adjustment parameters.

I-7  Deck lighting control : Programming of the colours coding and synchronous serial link on micro controller

I-8  Coders reading : Programming of the decoding of the absolute and incremental coders signal on a micro controller.

I-9  Potentiometric sensor : Study of the displacement measurement by two technologies of potentiometric sensors. Determining calibration coefficients.

I-10  Programming of synchronization : Programming the batteries speed control to synchronise the movements of the two banks, from the heights and speeds measured of the instructions of each bank.