Optical Stress Field Measurement Device Development

Abstract

This thesis details the design, prototyping, testing, and validation of a three-point bending testing machine for brittle materials and polymers. In addition to the machine, the system incorporates 2D Digital Image Correlation analysis to evaluate displacements and deformations using specialized software (Ncorr). To control the machine, a program was developed in LabVIEW that controls the motors, relays, sensors, and the actuator responsible for applying force to the specimen. Additionally, the graphical interface developed for the program generates a real-time force-displacement graph during the flexural test. The DIC application uses a camera, lighting, and a speckle pattern on the specimen to ensure precise tracking of the points. The experimental results confirmed the expected behavior of the materials tested prior to failure, verifying the presence of pure bending by showing consistent displacement results along the X and Y axes, and horizontal deformation indicating the presence of compression and tension zones on the specimen’s surface, in addition to shear strain values close to zero.