Three-dimensional grid strain measurement method

Abstract

The invention discloses a three-dimensional grid strain measurement method, which comprises the following steps of: step 1, grid preparation; step 2, sampling and shooting; step 3, picture orientation; step 4, grid node matching; step 5, grid node rebuilding; step 6, grid connection, step 7, grid optimization; and step 8, strain calculation. Through the operation steps, the method can be used for measuring the three-dimensional full field strain information in the metal plate material forming process, and the metal plate material forming performance and the advantages and disadvantages of the mold process design scheme can be evaluated, so the metal plate material forming quality is improved, the manufacture precision is improved, and the production cost is reduced. The three-dimensional grid strain measurement method has the characteristics that the measurement operation is convenient, the automation degree is high, the result is accurate and reliable, the measurement information is rich, the efficiency is high, and in addition, the non-contact measurement is realized.

Description

technical field [0001] The invention relates to a measurement method in the field of measurement technology, and further relates to a new method for measuring the three-dimensional full-field strain in the metal sheet forming process by means of optical photogrammetry. Background technique [0002] With the increasing application of sheet metal stamping technology, the complexity of the process is gradually increasing, and sheet metal tearing often occurs during the sheet metal forming process. The measurement of the three-dimensional full-field strain in the sheet metal forming process can evaluate the sheet metal forming performance and the pros and cons of the mold process design, improve the forming quality, improve the manufacturing accuracy, and reduce the production cost. The original measurement methods mainly include mechanical method, electrical measurement method and binocular stereo vision measurement method. [0003] The mechanical measurement method is a tradi...

AI Technical Summary

Problems solved by technology

The main disadvantages are: poor measurement accuracy, the size of the workpiece that can be measured cannot be too large, manual measurement is very cumbersome, it is repetitive labor, and the entire field strain cannot be measured

The main disadvantages are: the quality and stability of the sensor after pasting are affected by the aging of the substrate, adhesive, protective agent, and the quality of manual work during the pasting process, and it is prone to long-term drift and unstable quality. The amount of strain in some sheet metal forming processes, such as the amount of strain in the stamping process of sheet metal cannot be measured

The main disadvantages are: the camera needs to be calibrated before measurement, which is affected by CCD camera resolution, camera support system structure, environment, etc., the measurement accuracy is low, and the general strain measurement error is about 5%. Secondly, the measurement range is limited. Unsuitable and expensive to measure strain on large sheet metal formed parts

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