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Gear Drive Engineering
Published in Stephen P. Radzevich, Advances in Gear Design and Manufacture, 2019
The axial force developed in the helical mesh is usually taken by the shaft bearings. This results in asymmetrical deformations of the gear bodies, shafts, and housings and, finally, in nonuniform load distribution across the face width. With the growing size of gear drives, this problem aggravates, and certain precautions shall be taken to reduce the influence of the axial forces. Primarily, these measures include the stiffening of elements transmitting load and reasonable design aimed at mutual compensation of oppositely directed deformations (where it is possible). In big-sized gear drives, the axial force is usually blocked in the immediate vicinity of its origination and not transferred to the bodies of gears and further. There are two methods to do this: double-helical gears and thrust collars. The advantages and limitations of these methods are discussed, for example, in [37].
Design of Composite Structures
Published in Manoj Kumar Buragohain, Composite Structures, 2017
Composites structural design is addressed in many standard texts, articles, and research papers. Discussions on the general features of the design of composites structures and process of design are addressed by several authors [1–5]. Laminate design and analysis are an essential part in any composite product design and many texts and articles are available on the subject [1–4,6–13]. Joints are involved in many composite products. They are typically the weak links in a composite structure and their behavior, failure modes, and design aspects are more complicated than those in metals [1,5,7,8,11–17]. Another critical aspect in design is stiffening of panels, which is required for higher stiffness in many structural applications. Composite stiffened structures are different from their metallic counterparts in respect of several issues related to the anisotropic nature of composites and their unique manufacturing methods; these issues associated with stiffened composite plates and shells are addressed by many [1,3,9,18,19]. Extensive work has been done in the areas of general design philosophy, design, analysis and optimization of laminates, design and analysis of joints, stiffened structures, fracture behavior, performance under fatigue loads and impact, and other related topics. While a detailed review of such works is not intended in this book, limited reference is made to indicate the direction of work that has been carried out.
ANSYS: Finite Element Analysis
Published in Paul W. Ross, The Handbook of Software for Engineers and Scientists, 2018
Geometric Nonlinearities. Geometric nonlinearities occur when the displacements of a structure significantly change its stiffness. The ANSYS program accounts for several types of geometric nonlinear effects. Large strain geometric nonlinearities account for the large localized deformations that occur as a structure deflects. The program accounts for large strain by adjusting element shapes to reflect the changing geometry.Large deflection represents a change in global structural stiffness resulting from a change in element spatial orientation as the structure deflects (Fig. 58.9). The program accounts for large deflection by updating the element orientations as the structure deflects. Another program capability for large deflection analysis is the simulation of follower loads, which always act normal to the structure’s elements and are described as element pressures.Stress stiffening (also known as geometric, initial stress, incremental, or differential stiffening) accounts for changes in structural stiffness due to the stress state. It represents the coupling between the in-plane and transverse deflections in a structure. The program’s stress stiffening analysis option can be used for any structure, but is most appropriate for structures that are weak in bending resistance, such as pressurized membranes or turbine blades rotating at high speed. The program can also determine stress stiffening effects in what are otherwise linear problems.Spin softening in rotating bodies models a decrease in stiffness due to the deflections of a body, such as a turbine blade, in the plane of rotation. This capability is usually used together with stress stiffening in analyses of spinning bodies.
RC walls in Australia: displacement-based seismic design in accordance with AS 1170.4 and AS 3600
Published in Australian Journal of Structural Engineering, 2021
Scott J. Menegon, Hing-Ho Tsang, John L. Wilson, Nelson T. K. Lam
Implementing the CSM approach for an RC building in a design office scenario introduces many difficult technical issues if one wants to comply with the Australian Standard for concrete structures, AS 3600, when calculating the non-linear capacity curve of the structure. The Standard has a number of requirements for non-linear analysis methods, of which little guidance is provided in either the standard itself or the commentary. These requirements include the adoption of an appropriate tension stiffening model, nonlinear stress-strain material curves, mean material properties and material strain limits. Each of these items is addressed in subsequent sections of this paper in the context of the non-linear performance of an RC wall building, which utilises RC walls and RC building cores as the primary lateral load resisting elements. AS 3600 also requires a sensitivity analysis to be performed to assess how sensitive the results of the analysis are to variations in the input data and modelling parameters. A sensitivity analysis is performed as part of the case study example at the end of the paper. The results of this analysis and key observations are discussed accordingly.