Search results for "finite element method"
showing 10 items of 746 documents
Modeling of interference fits taking form defects of the surfaces in contact into account
2011
Abstract The technique of assembly by shrink fit is increasingly used today. However, the methodology of parts sizing has not changed in 50 years. Assembled parts are assumed to have accurate dimensions and very low form defects. This has the disadvantage of increasing the cost of parts production. To reduce manufacturing costs, the study of the influence of form defects on the characteristics of assembly strength is essential. Taking default form into account assumes that the tightening (difference between the diameters of the shaft and the bore) is defined. In the case under consideration, the tightening depends locally on the radius. Two definitions of the tightening are proposed: maximu…
An alternative space-time meshless method for solving transient heat transfer problems with high discontinuous moving sources
2016
International audience; The aim of this work is the development of a space-time diffuse approximation meshless method (DAM) to solve heat equations containing discontinuous sources. This work is devoted to transient heat transfer problems with static and moving heat sources applied on a metallic plate and whose power presents temporal discontinuities. The space-time DAM using classical weight function is convenient for continuous transient heat transfer. Nevertheless, for problems including discontinuities, some spurious oscillations for the temperature field occur. A new weight function, respecting the principle of causality, is used to eradicate the physically unexpected oscillations.
Micron-precision in cleaving glass using ultrafast bessel beams with engineered transverse beam shapes
2017
International audience; Ultrafast lasers in association to beam shaping have shown to be excellent candidates for transparent material processing. Non-diffractive solutions such as Bessel beams allows for precise energy deposition since they are robust to undesired non-linear effects and as they do not distort along the propagation. This offers important opportunities in laser-assisted cleaving, i.e. mechanical medium separation after single-pass laser illumination. Here we break the Bessel beam cylindrical symmetry using a novel anisotropic and non-diffractive solutions to investigate both lateral intensity contributions on material response and induced processing effect for non-cylindrica…
Guiding and confinement of interface acoustic waves in solid-fluid pillar-based phononic crystals
2016
International audience; Pillar-based phononic crystals exhibit some unique wave phenomena due to the interaction between surface acoustic modes of the substrate and local resonances supported by pillars. In this paper, we extend the investigations by taking into account the presence of a liquid medium. We particularly demonstrate that local resonances dramatically decrease the phase velocity of Scholte-Stoneley wave, which leads to a slow wave at the solid/fluid interface. Moreover, we show that increasing the height of pillars introduces a new set of branches of interface modes and drastically affects the acoustic energy localization. Indeed, while some modes display a highly confined pres…
Numerical vibroacoustic analysis of plates with constrained-layer damping patches
2011
International audience; A numerical vibroacoustic model that can manage multilayered plates locally covered with damping patches is presented. All the layers can have an on-axis orthotropic viscoelastic behavior. Continuity of displacements and transverse shear stresses at each interface is enforced, which permits to write the entire displacement field in function of the displacements of the-common-first layer, leading to a two-dimensional plate model. The problem is then discretized by Rayleigh-Ritz's method using a trigonometric basis that includes both sine and cosine functions in order to treat various boundary conditions. The excitation can be of mechanical kind (concentrated or distri…
Material flow analysis in dissimilar friction stir welding of AA2024 and Ti6Al4V butt joints
2016
The complex material flow occurring during the weld of dissimilar AA2024 to Ti6Al4V butt and lap joints was highlighted through a dedicated numerical model able to take into account the effects of the different materials as well as the phase transformation of the used titanium alloy.
Inversion of Left Atrial Appendage Will Cause Compressive Stresses in the Tissue: Simulation Study of Potential Therapy
2022
In atrial fibrillation (AF), thromboembolic events can result from the particular conformation of the left atrial appendage (LAA) bearing increased clot formation and accumulation. Current therapies to reduce the risk of adverse events rely on surgical exclusion or percutaneous occlusion, each of which has drawbacks limiting application and efficacy. We sought to quantify the hemodynamic and structural loads of a novel potential procedure to partially invert the “dead” LAA space to eliminate the auricle apex where clots develop. A realistic left atrial geometry was first achieved from the heart anatomy of the Living Heart Human Model (LHHM) and then the left atrial appendage inversion (LAAI…
Design of Reliable and Efficient Banki-Type Turbines
2020
A new shape for the external surface of the Crossflow turbine blades is proposed, which allows for the preservation of hydraulic efficiency in spite of a significant maximum blade thickness providing mechanic robustness and reliability. The final shape of the blades is assessed using an iterative solution for two uncoupled models: a 2D computational fluid dynamic (CFD) and a structural 3D finite element method (FEM) analysis of a single blade. Application of the proposed methodology to the design of a power recovery system (PRS) turbine, a new backpressure Crossflow-type inline turbine for pressure regulation, and energy production in a real Sicilian site follows.
Crimping Profile Optimization on the Air Spring Using Finite Element Method
2018
Abstract Due to the fact that the requirements of the industry aim to improve the dynamics, the safety and the comfort during the use of the vehicles, it is recommended to use the finite element method for component quality optimization. The purpose of this paper is to provide an overview of the current state of analysis through the finite element method of the crimping process used to assemble air springs produced in the automotive industry. Starting from the prototype of an air spring, the researches are focused on the study of the assembly of the piston with the bellow and the crimping ring through the crimping process. After analysis with the finite element method and static tests, impr…
Simulation of laser-generated ultrasonic wave propagation in solid media and air with application to NDE
2009
Ultrasonic methods are well known as powerful and reliable tool for defect detection. In the previous decades focus and interest have been directed to non-contact sensors and methods, showing many advantages over contact techniques where inspection depends on contact conditions (pressure, coupling medium, contact area). The non-contact hybrid ultrasonic method described here is of interest for many applications, requiring periodic inspection in service or after manufacturing. Despite the potential impact of laser-generated ultrasound in many areas of industry, robust tools for studying the phenomenon are lacking and thus limit the design and optimization of non-destructive testing and evalu…