Interferometric Tire Testing via Phase Difference Summation
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Solution Overview
Problem
Interferometric tire testing methods face challenges due to whole-body deformations, local deformations, and vibrations, which can lead to decoherence and increased noise in phase difference images, making it difficult to accurately detect defects within tires.
Innovation Solution
The method involves generating phase images at different pressures and forming partial phase difference images between successive images, with the pressure changing in one direction during one measurement phase and the opposite direction during another, and including partial phase difference images from both phases in the overall phase difference image, using shearographic measurements to account for both pressure changes and reduce interference from vibrations and deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple phase difference images are summed to eliminate whole-body deformations, then measurement reliability is improved, but vibration disturbances are amplified and noise increases
Solution Approach 1:
The measurement process is divided into multiple separate measurement phases, each producing individual phase difference images. By segmenting the overall measurement into discrete phases and selectively combining only certain phases (those without whole-body deformation artifacts), the method eliminates harmful whole-body deformations while avoiding amplification of vibration disturbances that would occur if all phases were summed.
Solution Approach 2:
The invention converts the harmful effect of measurement time extension (which would amplify vibrations) into a benefit by using that extended time to perform selective phase combination. Instead of summing all phases and amplifying vibrations, the method uses the available measurement phases to identify and combine only those phases that are free from whole-body deformation artifacts, thereby converting the potential harm of extended measurement into the benefit of selective artifact elimination.
2Measurement precision
If pressure changes are used to induce tire deformation for defect detection, then measurement precision is improved, but tire vibrations are stimulated increasing noise
Solution Approach 1:
The method uses periodic pressure changes with specific timing to induce tire deformation for defect detection. By controlling the pressure to change in a periodic manner and synchronizing the imaging with specific phases of the pressure cycle (when vibrations are minimal), the system achieves precise defect detection while minimizing vibration-induced noise. The periodic action allows selective capture of deformation information at optimal moments.
Solution Approach 2:
The invention employs dynamic pressure control where the pressure changes are adjusted during the measurement process to optimize the balance between inducing sufficient deformation for defect detection and minimizing vibration stimulation. The dynamic adjustment of pressure parameters allows the system to adapt to the tire's response and maintain optimal measurement conditions throughout the test.
3Productivity
If rapid pressure venting is used to create vacuum for phase imaging, then measurement time is reduced, but whole-body deformations are increased
Solution Approach 1:
The method applies preliminary controlled pressure changes before the main measurement phase to prepare the tire in a state that minimizes whole-body deformations during actual imaging. By pre-adjusting the pressure and allowing the tire to stabilize in intermediate states, the system reduces subsequent whole-body deformations that would otherwise occur during rapid pressure venting, thereby maintaining both measurement speed and deformation control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the quality of tire testing by making defects more apparent, reduces the impact of vibrations and whole-body deformations, and allows for lower pressure requirements, leading to cost savings and shorter measurement times.
Implementation Method 1
a shearographic measuring head (5) for generating measurement images of the tire surface
Implementation Method 2
a line generation device for generating a line of coherent radiation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The present application discloses a method for the interferometric testing of a tire in a pressure chamber of a tire testing device, comprising the steps of: - generating phase images at different pressures in the pressure chamber, - forming partial phase difference images between successive phase images, and - summing the partial phase difference images to obtain a total phase difference image. It is provided that in a first measurement phase, the pressure in the pressure chamber is changed in a first direction, and in a second measurement phase, the pressure is changed in the opposite direction, with at least one partial phase difference image from both the first and the second measurement phase being included in the summation.