Vibrations in buildings impact the behaviour of structures and humans, for sourcesdefined as internal or external to the building. Besides the comparison of vibrations tofixed limits, the choice of a relevant indicator is unavoidable and this indicator isdefined differently according to the selected reference text. Various standards (ordirectives similar to standards) exist and this paper focuses on the most important andthe most used ones, for ground vibrations induced to buildings or for human exposureinside buildings. In addition to the interest of comparing values to well-defined andwell-known limits, the knowledge of these standards allows the use of suitable indicators.Various vibration signals are used, from a simple harmonic signal to complex vibrationsgenerated by railway traffic, in order to present a relevant analysis of severity of eachnorm. It turns out that criteria noticeably vary from one reference to another one, andthat the thresholds are different for each standard.

Nowadays, backache risks due to professional activities remain high, while theirquantitative estimation is not well-known. Different methods have been developed todetermine the exposure of the spinal column to risk of damage. In Belgium, the “Fond desMaladies professionnelles” (FMP) suggests to use the “Mainz Dortmund Dosis” (MDD) methodto compute the exposure dose accumulated during the whole professional life. This methoduses the so-called biomechanical model “The Dortmunder” where the skeleton of the humanbody is represented by 30 rigid bodies to which certain abdominal and back muscles arelinked. This paper presents an implementation of the Dortmunder model with EasyDyn, aC++ library developed by theDepartment of Theoretical Mechanics, Dynamics and Vibrations of the University of Mons forsolving multibody problems, among others. Our model is first validated by comparing theobtained results with the one found in the literature. It is then used in a posture thatis not considered yet by the FMP. It is shown that working on ones knees can induce forcesin the back that increase the risk of backage.

The aim of this study is to approach the possibilities of stimulated infraredthermography to the carpal tunnel syndrome diagnosis. Eleven patients were studied. Six ofthem were affected by the carpal tunnel syndrome. The five others were healthy. The studyconsists in exciting the patients’ hands and in analyzing their thermal response. Theinfrared thermograms obtained show that the hands infected by the carpal tunnel syndromegive a different thermal response.

Shape memory alloys (SMA) are good candidates especially for being used as passivedampers. In order to develop the use of these alloys in structural vibrations control, thedynamical behavior of a NiTi helical spring is led, and the damping effect investigated.First, compression tests on the spring are carried out. These tests allow us to notice theeffect of the maximal compression displacement, the cyclic behavior and the compressionrate on its mechanical behavior. A finite element model analysis of the compression testsis then proposed. In consequence, the materials parameters have been identified after anumerical convergence test. In order to characterize the dynamical behavior of the spring,the innovative tool called equivalent complex stiffness is developed and used. Finally,the one degree of freedom vibration equation is solved with this equivalent complexstiffness. The solution of this equation clearly shows the non linear dynamical behaviorof the SMA spring and its damping potential.

This paper falls within the context of diagnosis of rotating machines in speed variableregime. Based on simulation signals, this work has the purpose to find relevant indicatorsfor the diagnosis of gear transmissions in a variable regime. Two indicators are proposed;the first indicator is the RMS value applied to the vibration signal divided by itscorresponding instantaneous frequency. The second is the normalised gear frequency byaveraging speed. The gear frequency and averaging speed are estimated from thespectrogram. To test the proposed indicators simulate signals have been used. Thesesignals are the results of a dynamic modelling of the gears transmission and arecalculated by using the Newmark integration diagram. This dynamic modelling takes intoaccount the eccentricity defect.

This project represents a straight continuation of the research activities of the LTI andwhich helped to simulate and understand the electrical response of multi-contact systems.In order to make further progress in the electrical modeling, the electrical transfermodel is applied to the case of bearing operation. The 2D modeling by discrete elementsreproduces the dynamic bearing. The method proposes to take measurements of electricalresistance on bearings to detect defects. This is an original method that stems from workpublished in MSSP. Indeed, while many studies have been conducted on monitoring bearingdefects by analyzing vibration signals, the use of localized electrical measurements onbearings is a promising approach, not yet exploited. The introduction of the firstdefects, as a local breaking of mechanical contact causes periodic disturbances in thecalculation of the electrical resistance. One of our objectives is to characterize thedefects position and the size of the defects, by analyzing disturbances in the electricalmeasurement.

This study focuses on the phenomenon of oil trapping in the tooth spaces of spur gears.It presents the first obtained results in order to provide an estimation of the powerlosses due to the compression of the oil trapped between the inter teeth meshing spaces ina high-speed transmission for internal and external spur gears. It first allows, to modelthe inter teeth spaces at any time and offers limits for the trapped fluid volume andaxial and radial discharge surfaces. The discretization impact result is discussed.Then,the influence of certain design and operating parameters such as module, pressure angle,addendum modification coefficient and rotational speed on these discharge surfaces andtrapped volume is presented.

In this paper, a computational investigation of thermohydrodynamic performance andmechanical deformations of a fixed-geometry thrust bearing with artificial surfacetexturing is presented. A parallel eight-pad bearing is considered; the surface of eachpad is partially textured with square dimples. Here, a CFD-based thermohydrodynamicmodeling approach, recently introduced by the authors, is used to calculate theperformance of the bearing; the THD results are then used to quantify the deformations ofthe bearing mechanical parts. The bearing is modelled as a sector-shaped channel,consisting of a smooth rotating wall (thrust collar) and a partially textured stationarywall (bearing pad). The bearing performance characteristics are computed by means ofnumerical simulations, based on the numerical solution of the Navier-Stokes and energyequations for incompressible flow, as well as on the solution of the elasticity equationsfor the bearing solid parts. Here, a reference texture geometry is considered, whileproper thermal and structural boundary conditions are implemented. For representative filmthickness values, the effect of rotational speed and collar thickness on bearingperformance is quantified, and the resulting pad and rotor deformation fields arecomputed. It is found that, due to oil heating, the load carrying capacity decreases withrotational speed for values higher that approximately 2000 rpm. The computed rotordeformation field is representative of a fixed support beam, characterized bysubstantially higher levels than those of the bearing pad. Rotor deformations increasesubstantially at low values of collar thickness.

Current demands of higher damage-tolerance in the Aerospace industry resulted inresurging interest in β, or near β, titanium alloys. The combination of attractiveproperties of this class of alloys also led to the consideration of beta alloys forcastings. Such alloys, however, are more difficult to cut than α-β titanium alloys due totheir limited ability to work harden and the effect of β-stabilizers on ductility.These factors affect failure modes and active wear mechanisms of cutting inserts. Thispaper investigates some of the wear modes exhibited by WC-Co inserts when end milling theαnear-βalloy Ti-x.In addition to being of near-β composition, this alloy is characterized by a finesized microstructure (range of 1−5 μm). The study focuses on SEM and EDS observations ofthe wear patterns exhibited by two groups of inserts. The first is uncoated WC-Co, whereasthe second is coated with multi layers of TiAlN. The results of this post-mortem study arecompared to wear patterns, observed under identical conditions, while milling theα-β alloy Ti6Al4V. Results show that inserts used inmachining the Ti-x alloy exhibit wear modes that contrast thoseexhibited when machining Ti64. The paper discusses factors leading to such occurrences andstudies the influence of the alloy microstructure on tool effectiveness and failure modes.

For qualitative prediction of chip morphology and quantitative prediction of burr size,2D and 3D finite element (FE) based turning models have been developed in this paper.Coupled temperature-displacement machining simulations exploiting the capabilities ofAbaqus® with a particular industrial turning insert and a newly proposed geometricalversion of this insert have been performed. Limitations of 2D models in defining the chipmorphologies and surface topologies have been discussed. The phenomenological findings onthe Poisson burr (Side burr) formation using 3D cutting models have been highlighted.Bespoke geometry of the turning insert has been found helpful in reducing the Poisson burrformation, as it reduces the contact pressures at the edges of tool rake face-workpieceinterface. Lower contact pressures serve to decrease the material flow towards workpieceedges (out of plane deformation). In contrast, higher contact pressures at tool rakeface-workpiece interface lead to more material flow towards workpiece edges resulting inlonger burr. Simulation results of chip morphologies and cutting forces for turning analuminum alloy A2024-T351 have been compared with the experimental ones. Finally, it hasbeen concluded that the newly proposed geometry of the insert not only decreases the burrbut also helpful in lessening the magnitude of tool-workpiece initial impact.

This study focused on numerical analysis of the parameters influencing the oil mist flow(MQL) outside a rotating tool, in non-contact configuration. This approach was a mandatorystep for the parameter optimizations before taking into account the material removing. Theoptimization of inner canalization geometries to a milling tool was performed to transferthe oil mist. The Reynolds Average Navier Stokes (RANS) and Lagrangian equations were usedto simulate the oil mist flow inside the canalizations by integrating the standardk-ε turbulence model with the STAR CCM+ commercial software. The dynamic numericalcalculation was used to optimize the inner canalizations of a milling tool. Because of theparticular external tool shape, the micro spray cooling is not guaranteed to reach thecutting edge. The external tool geometry, the inlet pressure, the shape and theorientation of the inner canalization geometries in the tool body and the rotation speedhave significant influence on the lubrication efficiency. The main goal of this study wasto improve this efficiency as function of these parameters. Thus, parameter sets givinggood lubrication were determinate for a type of tool.

We present a promising approach to reduce the difficulties associated with meshingcomplex curved domain boundaries for higher-order finite elements. In this work,higher-order XFEM analyses for strong discontinuity in the case of linear elasticityproblems are presented. Curved implicit boundaries are approximated inside an unstructuredcoarse mesh by using parametric information extracted from the parametric representation(the most common in Computer Aided Design CAD). This approximation provides local gradedsub-mesh (GSM) inside boundary elements (i.e. an element split by the curved boundary)which will be used for integration purpose. Sample geometries and numerical experimentsillustrate the accuracy and robustness of the proposed approach.

The Bayesian approach is a stochastic method, allowing to establish trend studies on thebehavior of materials between two periods or after a break in the life of these materials.It naturally integrates the inclusion of the information partially uncertain to support inmodeling problem. The method is therefore particularly suitable for the analysis of thereliability tests, especially for equipment and organs whose different tests are costly.Bayesian techniques are used to reduce the size of estimation tests, improving theevaluation of the parameters of product reliability by the integration of the past (dataavailable on the product concerned) and process, the case “zero” failure observed,difficult to treat with conventional statistical approach. This study will concern thereduction in the number of tests on electronic or mechanical components installed in amechanical lift knowing their a priori behavior in order to determine their a posterioribehavior.

The present research study includes thermal energy performance analysis of a flat platesolar collector, in order to cover a sensitivity analysis about effective variablescontributed to performance increasing approach. To obtain that, energy and momentumgoverning equations on a flat plate thermal collector were developed to achieve air outputtemperature and velocity profiles both in model and experiment. The model theory isvalidated with experiments by a set of flat plate thermal collectors, those located in(35◦44′35′′ N, 50◦57′25′′ E) coordinates and then were applied to carry outexperimental activities. Quantitative results depicted that the mean difference betweenpredicted and measured output air temperature in natural and forced convection scenarii is1.47 ◦C (3.5%) and0.9 ◦C (1.5%),respectively; however earlier research works and studies mentioned in literature, includeerror percentages in the range of 4–10%. Another quantification about, the average errorpercentages of estimated amounts of output air velocity profile values in natural andforced convection scenarii is 9% and 4%, respectively. This issue realizes the developedmodel in forced convection scenario more accurate than natural convection scenario.