Technique de mesures 3D industrielles

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Mesure de Déformations | Test de Composants | Mesure de rigidité
Mesure de rigidité 
  
TRITOP Deformation in automotive racing 
TRITOP
 
Systèmes de mesure: TRITOP
 
Keywords: static deformation measurement, repeatabilty testing
 
TRITOP is a high accuracy, non contact, portable optical measurement system for the measurement of 3D coordinates. In addition TRITOP is the perfect tool to measure and visualize movements and deformation caused by mechanical or thermal loading, eg. on Formula 1 race car components.

Front wings produce 25-40% of the race cars downforce. Their position and height, in relation to the track and car, are of crucial importance for the generation of exactly the right amount of downforce. The front wing of a race car is built from a carbon fiber reinforced polymer (CFRP). CFRP provides great strength, a high modulus of elasticity and an outstanding fatigue resistance. Most importantly, it is lightweight. The front wing may be changed a number of times during a race, depending on race conditions and desired effect on the car’s handling. The wing must therefore fit perfectly but be quick to install, seconds are valuable in Formula 1.

The task was to use the TRITOP photogrammetric system to measure and help understand deformation and repositioning accuracy within the wing when applying force or using the quick release system. The wing should be in exactly the same position after changing or applied load, as when initially attached to the car.

TRITOP is an optical 3D coordinate measuring system. It produces precise measurements using high-resolution digital images, image processing and photogrammetry. TRITOP is extremely mobile, with all of its components contained in just two light weight cases, and it can be used by just one operator. A major advantage of TRITOP is its speed of setup and measurement and with such a user-friendly and simple preparation, no specialist photogrammetric knowledge is required to produce high accuracy measurements.

The first step in the measuring task is the preparation of the object. The TRITOP system uses easily applicable and removable, self adhesive targets (figure 2) or adapters. The targets and the adapters allow precise point determination and the automatic computation of the respective 3D coordinates. For the race car wing, coded and uncoded targets were placed both on the wing and on the race car's body. The targets on the body of the car later act as fixed global reference points when analysing the repositioning and the deformation of the wing.

 
The front wings of Formula 1 racing cars are of crucial importance to their handling
Fig. 1: The front wings of Formula 1 racing cars are of crucial importance to their handling
 
Application of self adhesive targets.Obtaining TRITOP images.
Fig. 2: Application of self adhesive targets.Fig. 3: Obtaining TRITOP images.
 
Once prepared the object is ready to be imaged and measured. A bundle of images is taken from a number of different perspectives, with the wing accurately mounted on the car. TRITOP uses coded and uncoded targets and the process of resection to combine the images in an image bundle. It calculates the points from the bundle quickly and fully automatically and produces the 3D coordinates of the center of the markers and reference points (figure 4). The wing can now be loaded or removed (figure 5), reattached and the second round of measurements can then be obtained.
  
 
Calculated 3D coordinates.Quick release wing is removed and then reattached to the race car.
Fig. 4: Calculated 3D coordinates.Fig. 5: Quick release wing is removed and then reattached to the race car.
 
The second measurement phase, used to calculate movements or deformations, is obtained in the same way as the first one. The images are again inputted into the TRITOP system and the 3D coordinates are obtained.

The TRITOP software is, with the two measurement data sets, able to calculate the movement and the deformation on the wing. The two TRITOP measuring sessions are combined together by using common global reference points, in this case on the main chassis of the car. The displacements of the points on the wing can then be automatically computed. Once the process is complete, the TRITOP software allows easy visualisation of the data and generation of movement and deformation reports.

These reports use actual measurement photos to display the deformation aiding clear visualisation and easy understanding of the results.

Figure 6 shows a report generated from the TRITOP software. The report shows deformation and movements in the X, Y and Z direction along with the overall trend in deformation and movements. The points of maximum and minimum deformation are also displayed showing the magnitude of deformation. As can be seen from the report, the wing is subject to movement of up to 0.23 mm with higher values on the left hand than on the right hand side of the wing. The wing also shows a distinct rotation when examining the results of the measured values in X direction. This shows, the quick mount is not fitting and holding the wing in the same position after a mount. Shifts in Z direction of the wing relative to the chassis, directly at the mounting points, confirm this (figure 7). However, the elasticity of the wing also plays a part in the deformation and explains the differences in magnitude of deformation between the left and right hand side of the wing. Both phenomena are measured and visualized in this case.

 
A report generated by the TRITOP deformation software to analyse the deformation on the wing.
Fig. 6: A report generated by the TRITOP deformation software to analyse the deformation on the wing.
 
Shift in Z direction shows that the quick mount is not holding the wing in the correct position each time.
Fig. 7: Shift in Z direction shows that the quick mount is not holding the wing in the correct position each time.
 
TRITOP has proved to be the perfect tool to measure movements and deformation. Its ability to measure even small deformations enables the TRITOP system to efficiently measure the repeatability on the quick release fixing of the front wing from a Formula 1 race car. The measuring system's ease of use, its speed and accuracy of measurement and automation generate valuable results.
  
 
By courtesy of Digi.Lab (Italy) and the Minardi Formula One Racing Team
  
 

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