Research On The Non-contact Measurment System Of Lateral Deformation Based On The Photoelectric Detection Technology

It is well know that, when the object in the process of being loaded in the axial direction, due to the Poisson effect, the objects will produce deformation in the axial direction, and the lateral deformation will occur at the same time. Lateral deformation is one of the most important parameters to characterize the mechanical characteristics, so measuring the lateral deformation can also be used as an important method and means to explore the mechanical response of materials. We design a kind of lateral deformation measurement system based on the photoelectric detection technology.A semiconductor laser is uesd as a light source, a photodetector circuit comsisted with a silicon photodiode is used as the core device for photoelectric conversion, and the high-performance digital oscilloscope is used to capture, store, calculate and analyze the electrical signals.This system can measure the lateral deformation in the real-time, non-contact mode.This paper uses the multi-mode fiber(MMF) to homogenize the Gaussian beam which the semiconductor laser emits, starts from the optical fiber transmission characteristics,presents a detailed analysis of multimode fiber theoretical principles, and a set of system is designed to homogenize the beam energy based on the theoretical analysis, the test shows that the laser beam energy becomes uniform after the processing of multimode fiber.At the same time, in order to reduce the energy attenuation which the multi-mode fiber brings, AR coating technology was used to maintain the stability of the beam energy.The photodetector is another important key components constituting the photoelectric conversion of the testing system, it is used to convert the energy change of the optical signal into the voltage change of the electric signal. To achieve accurate measurement of deformation, photodetectors required to have good linear output characteristics and excellent anti-jamming capability. Based on the analysis of the linearity and noise characteristics of photodetector circuit, a low noise and good linearity photodetector circuit is designed in this paper, and the experimental results show that the circuit has high noise ratio and good linearity.Through micro-controlled electronic material properties testing machine, we conduct the uniaxial tensile experiments of rubber dumbbell-shaped sample which has good elastic properties. We detect the change of electric signal caused by the lateral deformation of the rubber specimens through the photoelectric detection system, then capturing and analyzing the electric signal to calculate the deformation.Comparing the tested result with the actual deformation,and the comparative results show that the testing system: stable performance, strong anti-interference ability,which can meet the needs of accuracy measurement of the transverse strain.At the end of this paper, it summarize the the full text of the research results, pointing out the shortcomings of this article, and put forward the next step of research on this topic.