Research On DTS Technology Of Body-in-white Welding Based On Fiber Bragg Grating Sensing

In the manufacture of Body-in-White(BIW)doors,welding Dimensional Tolerance Specifications(DTS)is a mandatory inspection link.The inner clearance of the door is a key parameter that affects the closing force and the quality of the BIW.However,most of the current inspection methods have insufficient accuracy and cannot meet the requirements of the parts on site.It is unable to meet the requirements of rapid inspection of parts on site and other issues,so a rapid inspection equipment that can ensure accuracy is needed.This subject takes the internal gap of the BIW as the detection object,and builds a measurement system based on fiber Bragg grating sensing technology.By consulting related literature and design requirements,the sensor structure model for gap and flush difference measurement is proposed,and the mechanical model of the contact sensor body is established using COMSOL,ANSYS and other software,and the contact stress and fatigue life analysis of the sensor body under different materials and sizes are carried out.Draw the law of the influence of different materials and sizes on its contact stress.Finally,a cantilever beam with a contact arc of 0.8mm and a contact line length of 1mm is selected as the sensing component.The service life of the gap sensor body is 3.4462×10~5 times,which meets the actual use requirements.Then through the comparison and analysis of commonly used fiber grating temperature compensation methods,combined with the sensor structure,select the reference grating method for temperature error compensation.Carried out the sensor manufacturing process research,after completing the sensor manufacturing,proceeded forward and reverse stroke experiments,fine-tuning experiments,and then the linearity,sensitivity,hysteresis,repeatability and other sensing characteristics of the sensor were analyzed,and the reasons for the errors and improvement methods were put forward.Then it explores the influence of the sensor on the relevant measurement results and its influence trend under the condition of environmental temperature change and magnetic field action.Finally,discuss the pros and cons of spot welding and laser welding in the production of BIW door welding,and use ANSYS Workbench to establish the door welding model,conduct thermal-structural coupling simulation analysis,and compare the deformation and residual stress of the model.Based on this,research on workpiece deformation and residual stress under different welding parameters is carried out,and the influence parameters of the inner gap of the car door are obtained,Thus obtain the feedback information detected by the sensor and the method of improving the welding error.