Search

The photoelastic technique has seen some renewed interest in past few years with digital images and image processing new methods becoming readily available. However, further research is needed to improve the precision, the accuracy and the automation of photoelastic technique. The aim of this research work is to get new numerical equations for the phase-shifting method in digital photoelasticity using a plane polariscope. The model was developed to plane polariscope because of the simplicity and low cost of this equipment. To develop the phase shift and respective intensity equations only the analyzer is rotated. A ring under diametral compression is used for the experimental validation. From these intensity equations, the equations for isoclinic and isochromatic parameters are deduced by applying a new numerical technique. This approach can be used to calculate the isoclinic and isochromatic parameters using any number of images. Several analysis are performed with different number of photographic images. The results showed errors reduce when more phase-stepped images are utilized. Hence, one concludes that the uncertainties in results due to effects of errors on photoelastic images can be reduced with a larger amount of phase-stepped images. [ABSTRACT FROM AUTHOR]

• Same topology can be obtained for different materials. • Same topology obtained between the Evolutionary and Fosberg and Nilsson [12] methods. • Elements partially removed under only one nodal displacement. • Differences in the values ​​of the objective function and maximum force due to the lower number of displacements. • Greater stability and faster non-linear analysis of finite elements under single nodal displacement. Energy absorbing structures are employed where the collision can cause serious consequences such as injuries or fatalities and structural damage. Because they are highly nonlinear, the optimization of these structures is complex and there are few works in the scientific community. Among the various existing topological optimization methods, evolutionary structural optimization has stood out for its versatility, and can be used in different types of engineering problems. In this sense, this work aims to apply the hard-kill evolutionary method BESO (Bi-directional Evolutionary Structural Optimization) for energy absorption structures. The objective is to compare the topologies with other methods present in the literature. Two examples are made. The first to evaluate the difference in topologies using two different materials and the second to evaluate the topologies with different displacement loads. It was verified that the same topology can be obtained with different materials and also that the same topology can be obtained between the methodologies. [ABSTRACT FROM AUTHOR]

• Structural optimization of wind turbine towers, with geometric simplification of the structure, and reduction of stress concentrations. • Obtaining optimal towers. • Cost reduction in tower construction. In this work, we sought to study the behavior of prestressed concrete wind-turbine tower in circular cross-section. The idea was to use Genetic Algorithm to obtain a structural optimization of the projected tower. Thus, a tower with the shape of a conical section was obtained, which minimizes the appearance of stress concentrations in the structure. The tower has a tapered profile to reduce the area subjected to wind thus lower the total weight and applied moment. It will also enhance the dynamic response of the tower and improve its overall stability. Steel tubular wind turbine towers are most widely utilized for wind turbines, however, the use of concrete material is becoming more attractive for wind towers because concrete towers are more stable for buckling failure. As the turbine size is growing and the towers are rising in height, steel towers are required to be sufficiently strong and stiff, consequently leading to high construction costs. Therefore, the prestressed concrete wind-turbine tower has a reduced construction cost compared to the steel tubular wind turbine towers or the self-supporting steel truss towers with a maximum height of 150 m. For this, Computer-Aided Engineering (CAE) tools were used and a 100 m prestressed concrete tower system for a wind turbine was optimized. It is concluded that the model met all the restrictions described and represents an economy in raw material and greater simplicity of design in relation to the octagonal model used for comparison. A new structural methodology was described for the study and application of prestressed concrete to replace the steel towers currently used. [ABSTRACT FROM AUTHOR]