Resumo em Inglês:

Abstract This research proposes an innovative method to convert the modeling of three-dimensional structures to the modeling of two-dimensional structures for the stability analysis of long tubular buildings. The process of the proposed method is in the form of modeling the equivalent frame and then modeling the reduced frame using the equivalent moment of inertia for beams and columns. The second-order elastic analysis has been performed considering the effects of P-Δ and P-δ. Framed-tube and frame tube-in-tube systems have been used for modeling. Newton's Raphson and Crisfield's Arc Length methods have also been used for nonlinear analysis. The accuracy and speed of analysis of the new method have been checked by comparing the displacements and drifts in the modeled systems for 40 and 50 stories tall buildings. For each structure, two framed-tube and tube-in-tube systems are considered. In the presented method, the number of nodes and elements in the reduced model is much less. The method presented in this research can reduce the amount of calculating the response of tall structures and the duration of the analysis. One of the advantages of the presented method is the acceptable accuracy of the analysis along with the high speed of the analysis. The results show that the proposed method has reduced the amount of calculations by 80% along with a 5% reduction in the accuracy of structural responses.

Resumo em Inglês:

Abstract Analytical methods for calculating the buckling loads in laminated panels often assume uniform edge loads without any openings, overlooking real-world conditions with diverse non-uniform edge loads and varying cutout sizes. This study aims to explore the buckling behavior of composite panels with and without stiffeners under different non-uniform edge load distributions by developing a robust and computationally efficient finite element (FE) formulation. Buckling loads are determined for different plate aspect ratios, number of stiffeners under various non-uniform edge-loading cases. Furthermore, it addresses the effects of different layup schemes and stiffener eccentricities.The analysis employs a 9-noded heterosis plate element and a compatible 3-noded beam element, incorporating shear deformation and rotary inertia for both the plate and stiffeners. Additionally, due to the non-uniform stress distribution in the stiffened panels, a unique dynamic technique has been implemented to account for the stability performance by employing two sets of boundary conditions. The study demonstrates that maintaining stiffener eccentricity (est) within the range of 2.0 to 3.0 notably improves buckling strength depending on the type of edge loads.

Resumo em Inglês:

Abstract Tower sprayers play a vital role in agriculture, being designed to apply pesticides and fertilizers effectively. The dynamics of this equipment, especially the vibration of the tower, play a crucial role in the success of agricultural operations. Analyzing and understanding this vibration is critical to ensuring application accuracy while minimizing variations in chemical distribution. This understanding directly contributes to uniform plant coverage, improving spraying efficiency and reducing input losses. In addition, practical vibration analysis extends the life of tower components, optimizes operational safety, and promotes energy efficiency by reducing fuel consumption. Tower stability becomes crucial to prevent spills and ensure efficient use of available resources. In short, dynamics and vibration analysis in tower sprayers are critical elements for the precise, efficient, and safe application of agricultural inputs. This approach promotes sustainable practices and contributes significantly to the success of farming operations. As a result of this study, a 23.68% reduction in trailer vibration amplitude was achieved.

Resumo em Inglês:

Abstract Computational mechanics has become an essential tool in engineering, just as the use of hyperelastic materials has seen remarkable growth in everyday applications. Therefore, it is fundamental to study hyperelastic models that represent the behavior of these materials, such as elastomers and polymers. With that in mind, the Mooney-Rivlin, Neo-Hookean, Ogden, and Yeoh models were implemented in a computational code in FORTRAN using the Positional Finite Element Method with Reissner kinematics and the Newton-Raphson method for nonlinear analysis of plane frames with samples of elastomers added with different percentages of carbon black. Ultimately, it was concluded that the Yeoh and Ogden models presented coherent values and that the use of the formulation for nonlinear analysis of plane frame performs well after the modifications proposed by this work. These modifications consisted of adding the first and second strain invariants of the simple shear formulation to include the consideration of distortion in the specific strain energy of hyperelastic models.