Search results

Friction vibrations and noises which are common in brakes, have attracted a great deal of attention lately. This paper analyses low frequency vibrations in disc brakes excited at high car speed. This vibration, called judder, has a frequency in the range 10 to 300 Hz and usually comes in association with hum noises. The dynamic phenomenon shows two principal components, one normal and the other one tangential to the disc brake surface. It is explained how variations of friction coefficient, and thermoelastic instability caused by the tangential component, contribute to the appearance of judder. A numerical analysis in 3D using the finite element method has been implemented combining both tangential and normal components, and solving the thermoelastic process. Special attention is dedicated to the simulation of the thermoelastic process showing the correlation with experiments.

This paper shows how the evolutionary structural optimization (ESO) algorithm can be used to achieve a multiple criterion design for a structure in a thermal environment. The proposed thermal ESO procedure couples an evolutionary iterative process of a finite element heat conduction solution and a finite element thermoelastic solution. The overall efficiency of material usage is measured in terms of the combination of thermal stress levels and heat flux densities by using a combination strategy with weighting factors. The ESO method then works by eliminating from the structural domain under‐utilized material. In this paper, a practical design example of a printed circuit board substrate is presented to illustrate the capabilities of the ESO algorithm for thermal design optimization in multiple load environments.

This paper aims to study the gravity effects on a micro-elongated thermoelastic layer under a fluid load, utilizing the Lord–Shulman (L-S) theory and the dual-phase-lag (DPL) model.

The analytical method used was the normal mode which partial differential equations transform into ordinary differential equations.

Aluminum epoxy numerical computations are carried out, and the results are graphed. The DPL model and the L-S theory are compared in the complete absence and presence of gravity. Comparisons were also made for three values of and it is observed that the gravity has quite a massive influence on all physical quantities.

In the present paper, the authors shall create the general equation for the energy equation, which includes the two theories (DPL and L-S) as well as the solution of micro-elongated thermoelasticity under fluid load. The problem is pretty important in many dynamical systems.

Sensor Review provides an update on photoelastic and thermoelastic stress analysis.

The thermo-diffusion analysis of an isotropic cylinder under thermal flux and chemical potential impacts has been discussed. Improvements of Green and Naghdi generalized thermoelasticity theory have been proposed.

Some models with and without energy dissipation have been presented as well as the simple forms of Green–Naghdi (G–N) theories. These novel multi- and single-/dual-phase-lag models are presented to investigate the thermo-diffusion of the solid cylinder. The closed-form solution of thermo-diffusion governing equations of solid cylinder has been obtained to deduce all field variables.

A comparison study between the simple G–N II and III models and their improved models has been presented. The validations of outcomes are acceptable and so benchmarks are reported to help other investigators in their future comparisons.

The modified Green and Naghdi theories of types II and III are presented to get novel and accurate models of single- and dual-phase-lag of multiterms. The heat of mass diffusion equation as well as the constitutive equations for the stresses and chemical potential of a solid cylinder is added to the present formulation. The system of three differential coupled equations is solved, and all field variables are obtained for the thermal diffusion of the solid cylinder. Some validation examples and applications are presented to compare the simple and modified Green and Naghdi theories of types II and III. Sample plots are illustrated along the radial direction of the solid cylinder. Some results are tabulated to serve as benchmark results for future comparisons with other investigators. The reported and illustrated results show that the simple G–N II and III models yield the largest values of all field quantities. The single-phase-lag models give the smallest values. However, the dual-phase-lag model yields results that are intermediate between those of the simple and single-phase-lag G–N models.

The boundary integral equation (BIE) numerical technique is applied to several practical pressure vessels and piping problems. Axisymmetric and three‐dimensional formulations of the BIE method for linear elastic stress analysis are reviewed. Isoparametric quadratic elements which exhibit excellent modelling capabilities are used to discretize the surfaces. Several three‐dimensional and axisymmetric structures are analysed.

In this paper, a solid circular cylinder of finite length occupying the space 0⩽r⩽1, 0⩽z⩽h is considered. The purpose of this paper is to adopt a linear hygrothermal effect to analyze the unsteady state responses in a finite long solid cylinder subjected to axisymmetric hygrothermal loading T=T_R and C=C_R at the surface. The analytical solution of temperature, moisture and thermal stresses is obtained by using the integral transform technique. The coupling and uncoupling effects of temperature, moisture and thermal stresses are discussed for a graphite fiber-reinforced epoxy matrix composite material (T300/5208). The numerical results of transient response hygrothermoelastic field are presented graphically.

In the present problem, hygrothermoelastic response of a finite solid circular cylinder has been investigated by integral transform technique consisting of Laplace transform, Hankel transform and Fourier-cosine transform. The problem is investigated subjected to prescribed sources. Numerical algorithm has been developed for numerical computation.

The analytical solution of temperature, moisture and thermal stresses is obtained by using the integral transform technique. The coupling and uncoupling effects of temperature, moisture and thermal stresses are discussed for a graphite fiber-reinforced epoxy matrix composite material (T300/5208). The numerical results of transient response hygrothermoelastic field are presented graphically.

The work presented here is mostly hypothetical in nature and totally mathematical.

It may be useful for composite materials, composite laminated plates in hygrothermal environment. Also it is having the applications in hygrothermal field where porous media exposed to heat and moisture. The problem investigated will be beneficial for the researcher working in the field thermoelastic diffusion and hygrothermoelastic materials.

Till date, the other authors did the research work on hygrothermal effect of an infinitely long cylinder without thickness. In this paper, the authors consider finite solid cylinder with finite length and discuss the hygrothermal effect within a small range. Second, the material properties are both homogenous and isotropic and are independent of both temperature and moisture.

This paper gives a review of the finite element techniques (FE) applied in the analysis and design of machine elements; bolts and screws, belts and chains, springs and dampers, brakes, gears, bearings, gaskets and seals are handled. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of this paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An Appendix included at the end of the paper presents a bibliography on finite element applications in the analysis/design of machine elements for 1977‐1997.

The purpose of this study is to investigate Thermo-mechanical limit elastic speed analysis of functionally graded (FG) rotating disks with the temperature-dependent material properties. Three different material models i.e. power law, sigmoid law and exponential law, along with varying disk profiles, namely, uniform thickness, tapered and exponential disk was considered.

The methodology adopted was variational principle wherein the solution was obtained by Galerkin’s error minimization principle. The Young’s modulus, coefficient of thermal expansion and yield stress variation were considered temperature-dependent.

The study shows a substantial increase in limit speed as disk profiles change from uniform thickness to exponentially varying thickness. At any radius in a disk, the difference in von Mises stress and yield strength shows the remaining stress-bearing capacity of material at that location.

Rotating disks are irreplaceable components in machinery and are used widely from power transmission assemblies (for example, gas turbine disks in an aircraft) to energy storage devices. During operations, these structures are mainly subjected to a combination of mechanical and thermal loadings.

The findings of the present study illustrate the best material models and their grading index, desired for the fabrication of uniform, as well as varying FG disks. Finite element analysis has been performed to validate the present study and good agreement between both the methods is seen.

In this work, the thermoelastic response in a micro-stretch thermoelastic half-space submerged in an unlimited non-viscous fluid under gravity, the medium is studied using the three-phase-lag model (3PHL) and Green-Naghdi theory (G-N III).

The normal mode analysis was the analytic technique used to obtain the exact formula of the physical quantities.

The magnesium crystal element is used as an application to compare the predictions induced by gravity on microstretch thermoelastic immersed in an infinite fluid of the three-phase-lag model with those for Green–Naghdi. Gravity has been noticed to have a major effect on all physical quantities. Comparisons were also made for three values of wave number and three values of the real part frequency.

This work is concerned with the thermoelastic micro-stretch solid immersed in an infinite and inviscid fluid and subjected to a gravitational field. The governing equations are formulated in the context of the 3PHL model and G-N theory. An analytical solution to the problem is obtained by employing normal mode analysis. Comparisons of the physical quantities are shown in figures to study the effects of gravity, wave number and the real part of the frequency.