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The present findings report a significant influence of disc profile and thickness on the order of excitation leading to critical speed condition. Certain transverse modes of vibration of the disc have been obtained to be more susceptible to get excited while recording the lowest critical speeds.

Numerical simulation using finite-element method has been adopted due to the complicated geometry, complex loadings and intricate analytical formulation. A comprehensive analysis of exclusive as well as combination of thermal and centrifugal loads has been taken up to determine the intensity and characteristics of the individual/combined effects.

The typical gas turbine disc profile has been analyzed to predict the critical speed under the factual working condition of an aero-engine. FEM analysis of uniform and variable thickness discs have been carried out under stationary, rotating and rotating-thermal considerations while emphasizing the effect of disc profile and thickness. Centrifugal stresses developed due to rotational effect result in unceasing stiffening of the discs with higher stiffening for a greater number of nodal diameters. On the other hand, a role reversal of thermal effect from stiffening to softening is figured out with increasing numbers of nodal diameters. However, the discs are subjected to an overall stiffening effect on account of the combined centrifugal and thermal loading, with the effect decreasing with an increase in disc thickness. Under the combined loading, the order of excitation leading to critical speed condition is dependent on disc profile and thickness. Moreover, the vibrational modes (0,1) and (0,2) are identified as more prominent adverse modes corresponding to lowest critical speeds.

The present findings are expected to serve as guidelines during the design phase of gas turbine discs of aeroengine applications.

The present work deliberates on the simulation and analysis of gas turbine disc specific to aeroengine application. The real-life disc geometry has been analyzed with due consideration of major factual operating conditions to identify the critical speed. The identification of various critical speed using numerical analysis can help to reduce the number of experimental tests required for certification.

Analysis of the thermal effects during the packaging process or in the actual operating environment is necessary to develop small monolithic integrated sensing chips with heterogeneous integration. The use of multiple layers and various materials in monolithic integrated sensing chips addresses the coefficient of thermal expansion (CTE) mismatch issue. The purpose of this study is to focus on the residual stress analysis of the shielding electrode, which is a metal film that prevents pull-in of proof-mass during anodic bonding in microelectromechanical system (MEMS) chips with pressure sensors embedded in an accelerometer.

The finite element model of the chip was built by the commercial software ANSYS, and the residual stress was evaluated during the die attachment process for the shielding electrode. Various shielding electrode materials and a proposed design with a keep-out zone to reduce the residual stress are discussed, with a focus on the relationship between the geometric parameters of the chip and the residual stress for copper shielding electrodes of different thicknesses.

The results of the finite element analysis showed that the use of polysilicon as a shielding electrode in the proposed design generated the lowest residual stress because of its low CTE. The maximum stresses in both of in-plane and out-of-plane directions in the finite element model were reduced by keep-out zone design for the proposed design of the copper shielding electrode, and had 11 times reduction in out-of-plane direction especially, according to the nonlinear analysis as the stress concentration point in the shielding electrode moved. Moreover, the design with a thinner shielding electrode, thinner glass substrate and higher CTE of the glass substrate also lowered the maximum von Mises stress. On the other hand, the stress level during the operating temperature, without considering residual stress, overestimated up to five times in the proposed design.

In this study, valuable suggestions are proposed for the design of chips with pressure sensors embedded in accelerometers.

A thermal analogy method for the static and dynamic analysis of an electrostrictive beam by incorporating the nonlinear characteristics of the electrostrictive materials is described in this paper. The analogy between thermo elastic finite element formulation and the electrostrictive material finite element formulation developed in this paper was explored. Based on this analogy, the voltage actuation of the electrostrictive beam can be simulated accurately using the conventional elastic finite element model with the thermal actuation. The finite element model includes the quadratic dependence of strain with electric field, valid at constant temperature and mechanical prestress, and excludes hysteresis.

The purpose of this study is to improve life prediction of certain components. Fatigue of the high-stressed structural elements is an essential parameter that affects the lifetime of such components. In particular, aviation engines are devices whose failure due to fatigue failure of one of the important components can lead to fatal consequences.

In this study, two analyses in the turbine disk of the jet engine during the simulated operating load were performed: The first one was the analysis of the heat-induced stresses using the finite element method. The goal of the second analysis was to determine the residual fatigue strength of a loaded disk by the software tool using the Palmgren - Miner Linear Damage Theory.

The results showed a high degree of similarity with the real tests performed on the aircraft engine and revealed the weak points in the design of the jet engine.

It should be mentioned that without appropriate experiments, results of this analysis could not be verified.

These results are helpful in the re-designing of the jet engines to increase their technical feasibility.

Such analysis has been realized in the DV-2 jet engine research and development program for the first time in the history of jet engine manufacturing process in Slovakia and countries of Eastern Europe region.

Introduction Over the last ten years there has been a rapid increase in the architectural use of fabrics. They are mainly used to provide lightweight, large‐span, translucent roofs which are economical and visually exciting. The structures range in scale from pavilions and canopies in the park through to covered retail malls and stadium roofs of 10 acres. The expertise in the design and execution of these structures originally lay with a small number of specialist engineers and fabricators. This expertise has now broadened and, with increasing use of computers for processing the complex geometry and with improvements in the fabrics themselves, it is likely that they will continue to proliferate.

This paper focuses on the design of a superconducting quadrupole prototype. This structure includes many frictional contact zones, and the loading conditions are complex (mechanical, thermal and magnetic). A dedicated computational strategy, based on both a decomposition of the structure and an iterative resolution scheme, has been applied to solve this problem. A simplified approach is used to take complex loading conditions into account. The initial set of results, which are presented herein, demonstrates the interest of this approach with respect to classical finite element methods. This study was conducted within the framework of a joint research contract between the CEA (DSM/DPANIA/STCM) and LMT‐Cachan.

The purpose of the paper is to investigate the linear thermal buckling and vibration analysis of layered and multiphase magneto‐electro‐elastic (MEE) cylinders made of piezoelectric/piezomagnetic materials using finite element method.

The constitutive equations of MEE materials are used to derive the finite element equations involving the coupling between mechanical, electrical, magnetic and thermal fields. The present study is limited to clamped‐clamped boundary conditions. The linear thermal buckling is carried out for an axisymmetric cylinder operating in a steady state axisymmetric uniform temperature rise. The influence of stacking sequences and volume fraction of multiphase MEE materials on critical buckling temperature and vibration behaviour is investigated. The influence of coupling effects on critical buckling temperature and vibration behaviour is also studied.

The critical buckling temperature is higher for MEE axisymmetric cylinder as compared to elastic cylinder.

Linear thermal buckling and vibration analysis of MEE axisymmetric cylinders are studied using the finite element approach. The structure can be used for active vibration control, sensors and actuators. Studying the buckling and vibration behaviour of such structures and influence of coupling effect is extremely useful for the design of magnetoelectroelastic structures.

In response to the common low sensitivity of fiber Bragg grating (FBG) temperature sensors in measurement, an FBG temperature sensor sensitized in a substrate-type package structure is proposed.

The sensitivity of sensors is analyzed theoretically; aluminum alloys with large coefficient of thermal expansion are used; the ANSYS software is used for simulation analysis and optimization design of sensors; real sensors are developed based on simulation results; in this study, a test system was built to test the performance of the proposed sensor.

The results suggested that the sensitivity of encapsulated FBG temperature sensor is 27.3 pm/°C in the range of −20 °C to 40 °C, which is 2.7 times that of bare FBG sensor, while the linearity is up to more than 0.99.

The sensitivity of FBG temperature sensor is greatly improved by the design of the structure.

This study innovatively proposes substrate-type sensitized FBG temperature sensor. The temperature sensitivity of fiber grating can be improved by single metal structure, and the effect of structural strain can be reduced by a tab structure. The study results provide a reference for the development of like sensors and the further improvement in the sensitivity of FBG temperature sensors.

The present study is based on finding the structural response of a tensile membrane structure (TMS) through deformation. The intention of the present research is to develop a basic understanding of reliability analysis and deflection behavior of a pre-tensioned TMS. The mean value first-order second-moment method (MVFOSM) method is used here to evaluate stochastic moments of a performance function with random input variables. Results suggest the influence of modulus of elasticity, the thickness of the membrane, and edge span length are significant for reliability based TMS design.

A simple TMS is designed and simulated by applying external forces (along with prestress), as a manifestation of wind and snow load. A nonlinear analysis is executed to evaluate TMS deflection, followed by calculating the reliability index. Parametric study is done to consider the effect of membrane material, thickness and load location. First-order second moment (FOSM) is used to evaluative the reliability. A comparison of reliability index is done and deflection variations from μ − 3s to μ + 3s are accounted for in this approach.

The effectiveness of deflection is highlighted for the reliability assessment of TMS. Reliability and parametric study collectively examine the proposed geometry and material to facilitate infield design requirements. The estimated β value indicates that most suitable fabric material for a simple TMS should possess an elasticity modulus in the range of 1,000–1,500 MPa, the thickness may be considered to be around 1.00 mm, and additional adjustment of around 5–10 mm is suggested for edge length. The loading position in case of TMS structures can be a sensitive aspect where the rigidity of the surface is dependent on the pre-tensioning of the membrane.

The significance of the parametric study on material and loading for deflection of TMS is emphasized. Due to the lack of consolidated literature in the field combining reliability with deflection limits of a TMS, this work can be very useful for researchers.

The present work outcome may facilitate practitioners in determining effective design methodology and material selection for TMS construction.

The significance of parametric study for serviceability criteria is emphasized. Parameters like pre-stress can be included in future parametric studies to witness in depth behavior of TMS. Due to lack of consolidated literature in the field combining reliability with deflection limits of a TMS, this work can be very useful for the researchers. The present work outcome may facilitate practitioners in determining effective design methodology and material selection for TMS construction.

Presents a non‐linear numerical model for the computations of post‐tensioned plane structures. Generally curved prestressing tendons and reinforcing bars are embedded into the concrete and they are modelled independently of the concrete mesh using one‐dimensional curvilinear elements. Among the losses which influence the decrease in the prestress force, it is possible to compute the losses caused by friction between tendons and the concrete, the losses which result from the concrete deformation and the losses in the anchorage zone. The computation for post‐tensioned structures is organized in phases: the phase preceding prestressing (Phase I), the prestressing phase (Phase II) and the phase following prestressing (Phase III). The load is applied incrementally until failure. The model is tested on a number of examples.