This research aims to find a new way to get the intensity equations for the phase-shifting model in digital photoelasticity. The procedure is based on the rotation of the analyzer itself. From the intensity equations, the isoclinic and isochromatic equations parameters are deduced by applying a new numerical technique. This approach can be done to calculate how many images allow the resolution of the polariscope. Each image indicates the stress forces in the object. In this study the plane polariscope was used. The amount of images will determinate the number of errors and uncertainties of the study, due to the observation that the veracity of the equations increases considerably with a large amout of images. Several analyses are performed with different amounts of photographic images. The results showed the possibility to measure stress forces with high precision using plane polariscopes.
Digital photoelasticity is an important segment of optical metrology for stress analysis by digital photographic images. Advances in digital image processing, data acquisition, standard recognition and data storage allow the utilization of computer-aided techniques in the automation and improvement of the digital photoelastic technique. The objective of this study is to develop new techniques using 3D rapid prototyping with transparent resins in digital photoelasticity. Some innovations are proposed (e.g., a tapered roller bearing built with 3D rapid prototyping with transparent resin and the final assembly with the specimens prototyped separately). A metrology study is carried out with the new techniques developed.
The study of the human gait through the joints angles is an important branch of the biomechanics. The joints angles define the behavior of a segment in relation to another and, consequently, the overload on the tissues. The hip joint centre (HJC), regression equations system based on pelvic anatomy, is a parameter frequently used as reference point to determinate the hip and knee angles, therefore, is considered in the literature as an important factor in the kinemactics analysis of the human gait. Two analytical methods are recognized in the HJC estimation, the predictive method uses the difference between the anatomical points of the human body in the data collect, and the functional method uses a sphere adjustment approach. In the present research, it was used kinemactics data from seven volunteers, collected by Qualisys® system on a treadmill, and through algorithms developed in MATLAB®, the HJC were estimated by two predictive method systems (Bell and Davis) and one system of the functional method (with sphere adjustment approach based on the StarArc movement) and the joints angles which describes the flexion/extension movement of the hip and the knee were determined. Finally, a study was carried out on the influence of the methods for HJC estimation in the determination of hip and knee joints angles. The errors presented in the HJC estimated by the three methods were documented, but did not present significant influence in the values found by the angles of the joints.
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