Theoretical substantiation of new features of rolling bearings operation under combined loading conditions

Rolling bearings are widely used in the products of aviation and space technology. To ensure their long-term trouble-free operation, it is necessary to have accurate and reliable information about the forces acting on the bearings. The required values of forces and, accordingly, the required durability of bearings are usually determined on the basis of the traditional design scheme of a double-support beam (smooth beam mounted on two hinged supports). The paper presents a new interpretation of the features of the operation of bearing units on ball radial single-row bearings installed according to the cross located arrangement. It is shown that under conditions of combined loading, including radial and axial forces, the generally accepted theoretical model of a doublesupport beam is not implemented. There is no single calculation model that adequately reflects the nature of the interaction of bearing parts over the entire range of external loads. In the most general case, this model can be represented by a sequence of five statically indeterminate calculation schemes, which are modified and transformed into one another. So, with an increase in the external radial force, the cantilevered beam with additional hinge support scheme is first implemented, which, then, is transformed into the double-sided jamming scheme, and that, later, is transformed into the two double hinge supports scheme. It is also possible to implement two intermediate transition schemes. A specific example shows that in the products of aviation and space technology, determining the durability of bearings based on the traditional model is not advisable, since it can give an overestimated value with an error of 28,37 to 26663,9 times.

Model Based Design of a Low Cost and Compliant Low Profile Prosthetic Foot

This paper describes the design of a simple and low cost compliant low profile prosthetic foot based on a cantilevered beam of uniform strength. The prosthetic foot is developed such that the maximum stress experienced by the beam is distributed approximately evenly across the length of the beam. Due to this stress distribution, the prosthetic foot exhibits compliant behavior not achievable through standard design approaches (e.g. designs based on simple cantilevered beams). Additionally, due to its simplicity and use of flat structural members, the foot can be manufactured at low cost. An analytical model of the compliant behavior of the beam is developed that facilitates rapid design changes to vary foot size and stiffness. A characteristic prototype was designed and constructed to be used in both a benchtop quasistatic loading test as well as a dynamic walking test for validation. The model predicted the rotational stiffness of the prototype with 5% error. Furthermore, the prototype foot was tested alongside two commercially available prosthetic feet (a low profile foot and an energy storage and release foot) in level walking experiments with a single study participant. The prototype foot displayed the lowest stiffness of the three feet (6.0, 7.1, and 10.4 Nm/deg for the prototype foot, the commercial low profile foot, and the energy storage and release foot, respectively). This foot design approach and accompanying model may allow for compliant feet to be developed for individuals with long residual limbs.

Free Vibration Analysis Of Layered Beams With Delamination Damage-An ANSYS®-Based FEM Investigation

Identifying delamination has been a focal point for many researchers. The reason for this interest arises from criticality of delamination in a variety of industries: automotive, aerospace, and construction. Therefore, vibration-based damage identification method is applied to detect, locate and characterize the damage in a mechanical structure. In this method, natural frequency as a diagnostic tool to determine the integrity of a structure has been utilized. The current research presents a FEM-based investigation into free vibrational analysis of defective layered beams with free mode delamination. It is shown that the size, type and location of delamination directly influence system non-dimensional frequencies. Based on an existing 1D model, the investigation is extended to 2D modelling for single-and-double-delamination cases. In each case, Fixed-Fixed and cantilevered beam configurations, both centred and off-centred delamination conditions are studied. Further, a 3D model is also developed for single delamination of a Fixed-Fixed beam. All simulation results show excellent agreement with the data available in the literature. The ANSYS ® FEM-based modelling approach presented here is general and accurately predicts delamination effects on the frequency response of beam structures.

Free Vibration Analysis Of Layered Beams With Delamination Damage-An ANSYS®-Based FEM Investigation

Identifying delamination has been a focal point for many researchers. The reason for this interest arises from criticality of delamination in a variety of industries: automotive, aerospace, and construction. Therefore, vibration-based damage identification method is applied to detect, locate and characterize the damage in a mechanical structure. In this method, natural frequency as a diagnostic tool to determine the integrity of a structure has been utilized. The current research presents a FEM-based investigation into free vibrational analysis of defective layered beams with free mode delamination. It is shown that the size, type and location of delamination directly influence system non-dimensional frequencies. Based on an existing 1D model, the investigation is extended to 2D modelling for single-and-double-delamination cases. In each case, Fixed-Fixed and cantilevered beam configurations, both centred and off-centred delamination conditions are studied. Further, a 3D model is also developed for single delamination of a Fixed-Fixed beam. All simulation results show excellent agreement with the data available in the literature. The ANSYS ® FEM-based modelling approach presented here is general and accurately predicts delamination effects on the frequency response of beam structures.

Static Analysis of the Effect of Shape Memory Alloy in Laminated Beam

This study deals with the effect of shape memory alloy in carbon/epoxy laminated beam. In this study we analyses static response of laminated beam under the load of 10 KN at the mid span of the beam. In this study a cantilevered beam of dimension 1000mm length, 100mm width and 30mm height which is divided in 3 layers of 10mm each is considered. The study includes three cases. In first case all the 3 layers of beam is laminated with carbon/epoxy. In second case the top and the bottom layers are laminated with carbon/epoxy and middle layer is2qw laminated with shape memory alloy. In the third case the top and the bottom layers are laminated with shape memory alloy while the middle with carbon/epoxy. Loading and boundary conditions are same for all the three cases. All the analysis is done using ANSYS workbench 15.0

Effect of an Added Mass On the Vibration Characteristics for Raster Scanning of a Cantilevered Optical Fiber

Piezoelectric tube actuators with cantilevered optical fibers have enabled the miniaturization of scanning image acquisition techniques for endoscopic implementation. To achieve raster scanning for such a miniaturized system, the first resonant frequency should be on the order of 10's of Hz. We explore adding a mass at an intermediate location along the length of the fiber to alter the resonant frequencies of the system. We provide a mathematical model to predict resonant frequencies for a cantilevered beam with an intermediate mass. The theoretical and measured data match well for various fiber lengths, mass sizes, and mass attachment locations along the fiber.

Scour monitoring of a bridge pier through eigenfrequencies analysis

This paper presents an innovative method for scour monitoring, based on the analysis of the dynamic response of a bridge pier embedded in the riverbed. Apart from the mechanical and physical characteristics of the pier itself, soil-structure interaction (SSI) has an impact on the dynamical behaviour of the system. This is particularly the case for eigenfrequencies of the pier which decrease when the free length increases. In this paper, analytical developments are carried out for an Euler–Bernoulli beam, modelling the pier which is embedded in the soil with Winkler springs for SSI. By using Hamilton’s principle and endowing the specific boundary conditions, the system frequencies are assessed by looking for roots of the characteristic equation of the system. These eigenfrequencies are then compared with those of an equivalent cantilevered beam, which can be expressed analytically. Moreover, experiments are carried out to validate the concept of equivalent length as a parameter of the inverse problem, linking the dynamic behaviour of the system and the embedded length.