scholarly journals Experimental comparison of a macroscopic draping simulation for dry non-crimp fabric preforming on a complex geometry by means of optical measurement

2016 ◽  
Vol 51 (16) ◽  
pp. 2363-2375 ◽  
Author(s):  
Annegret Mallach ◽  
Frank Härtel ◽  
Frieder Heieck ◽  
Jan-Philipp Fuhr ◽  
Peter Middendorf ◽  
...  
Keyword(s):  
Measurement System ◽  
Complex Geometry ◽  
Optical Measurement ◽  
Three Dimensional ◽  
Detailed Comparison ◽  
Experimental Comparison ◽  
Three Dimensional Model ◽  
Blank Holder ◽  
Optical Measurement System ◽  
Set Up

Scope of the presented work is a detailed comparison of a macroscopic draping model with real fibre architecture on a complex non-crimp-fabric preform using a new robot-based optical measurement system. By means of a preliminary analytical process design approach, a preforming test centre is set up to manufacture dry non-crimp-fabric preforms. A variable blank holder setup is used to investigate the effect of different process parameters on the fibre architecture. The real fibre architecture of those preforms is captured by the optical measurement system, which generates a three-dimensional model containing information about the fibre orientation along the entire surface of the preform. The measured and calculated fiber orientations are then compared with the simulation results in a three-dimensional overlay file. The results show that the analytical approach is able to predict local hot spots with high shear angles on the preform. Macroscopic simulations show a higher sensitivity towards changes in blank holder pressure than reality and limit the approach to precisely predict fibre architecture parameters on complex geometries.

Non-Contact Online Detection of Concentricity Error

2015 ◽  
Vol 733 ◽  
pp. 611-614
Author(s):  
Hong Zheng
Keyword(s):  
Measurement System ◽  
Three Dimensional ◽  
Error Evaluation ◽  
Dimensional Model ◽  
Online Detection ◽  
Three Dimensional Model ◽  
Geometric Tolerance ◽  
Structural Principle ◽  
Circularity Error ◽  
Cylindricity Error

This paper researches on the non-contact online detection of concentricity error, which mainly focus on the structural principle of the measurement system and the concentricity error evaluation methods. The paper using the method of projection, converting the three-dimensional model to a two-dimensional model and evaluating coaxially error. And it is validated by the simulation of MATLAB. In theory, the proposed measurement system can measure geometric tolerance, including coaxially error, cylindricity error, circularity error, etc.

scholarly journals Alignment Method of an Axis Based on Camera Calibration in a Rotating Optical Measurement System

2020 ◽  
Vol 10 (19) ◽  
pp. 6962
Author(s):  
Yanli Hou ◽  
Xianyu Su ◽  
Wenjing Chen
Keyword(s):  
Camera Calibration ◽  
Measurement System ◽  
Optical Measurement ◽  
Ccd Camera ◽  
Least Square ◽  
Optical Center ◽  
External Parameter ◽  
Optical Measurement System ◽  
Rotation Center ◽  
Projection Center

The alignment problem of a rotating optical measurement system composed of a charge-coupled device (CCD) camera and a turntable is discussed. The motion trajectory model of the optical center (or projection center in the computer vision) of a camera rotating with the rotating device is established. A method based on camera calibration with a two-dimensional target is proposed to calculate the positions of the optical center when the camera is rotated by the turntable. An auxiliary coordinate system is introduced to adjust the external parameter matrix of the camera to map the optical centers on a special fictitious plane. The center of the turntable and the distance between the optical center and the rotation center can be accurately calculated by the least square planar circle fitting method. Lastly, the coordinates of the rotation center and the optical centers are used to provide guidance for the installation of a camera in a rotation measurement system. Simulations and experiments verify the feasibility of the proposed method.

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