Research On Deformation Measurement Of Building Membrane Based On Digital Speckle Technology

Digital speckle measurement technique is one of the important optical measurement methods.Compared with the traditional deformation measurement tools,it has the advantages of non-contact and full-field measurement,so it has stronger adaptability to the mechanical test of building membrane structure.In this paper,the advantages of digital speckle measurement method are used to the mechanical test of building membrane materials.In view of the problems in actual measurement,the following works are carried out:(1)Based on the basic principle of digital speckle measurement,the theoretical algorithm is improved and supplemented,which effectively improves the success rate of calibration,as well as the calculation accuracy and speed under the circumstance that the optical environment is not ideal;Expand Matlab calibration box function,realize the conversion from pixel information to actual space size information;The existing image matching algorithm is compared and selected,and the matching method based on image frequency domain transform is added.The simulated speckle test was carried out on the software system,and the factors influencing the calculation speed and accuracy were evaluated.(2)According to the improved digital speckle measurement program,the Matlab development platform was integrated into the human-computer interaction interface,and the digital camera was used as the front-end hardware for image acquisition to form a complete digital speckle measurement system;In addition,corresponding constitutive model is added to meet the test requirements of PVC building membrane material,which further enriches the function of obtaining full-field stress information;The speckle production is optimized,and Suggestions for equipment layout are given.(3)Apply the digital speckle measurement system to the mechanical test of membrane structure,record and calculate the process of the single and double axial stretching and tearing tests of PVC membrane material,and determine the actual calculation accuracy of the measurement system;The elastic modulus,poisson’s ratio and other mechanical properties are analyzed.The full-field displacement information,strain information and stress information are obtained,which provides an effective measurement method and analysis Angle for the study of the mechanical response of the membrane structure under different stress states.