Patrick Guillaume

Patrick Guillaume
Vrije Universiteit Brussel | VUB · Applied Mechanics (MECH)

Prof. dr. ir.

About

438
Publications
95,778
Reads
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9,580
Citations
Citations since 2017
70 Research Items
3972 Citations
20172018201920202021202220230200400600
20172018201920202021202220230200400600
20172018201920202021202220230200400600
20172018201920202021202220230200400600
Additional affiliations
October 1997 - present
Vrije Universiteit Brussel
Position
  • Head of Department MECH
Education
October 1987 - June 1992
Vrije Universiteit Brussel
Field of study
  • PhD in Engineering (Doctoraat in de Toegepaste Wetenschappen)
September 1982 - July 1987
Vrije Universiteit Brussel
Field of study
  • Electromechanical Engineering (Werktuigkunde-Elektrotechniek)

Publications

Publications (438)
Article
Residual stresses present one of the major challenges within additive manufacturing as they lead to part distortion and cracking, production issues, scrapped parts and mechanically underperforming components. The current work presents a method to determine full-field residual stress information by deploying in-situ Digital Image Correlation during...
Article
Real-time control of melt pool temperature, deposition width, and height has shown to deliver significant improvements in both material properties and part geometry during the laser based directed energy deposition process. For accurate controller design a mathematical model of the complex DED process is required. In this paper an experimental freq...
Chapter
During operation, wind turbine blades are subjected to varying loads, making them vulnerable, reducing performance, and increasing mechanical failures. Furthermore, blade maintenance is both time-consuming and costly. Optical methods, such as DIC, are attractive to measure deformations on this kind of structures because they do not require electric...
Article
Operational Modal Analysis allows to assess the modal model of rotating machinery. However, it is needed to pre-process the measured vibration data such that the influence of the harmonic content is suppressed. In this paper, such pre-processing techniques are discussed. The main focus is on evaluating the effects of amplitude modulation, originati...
Article
Directed energy deposition (DED) is a widespread laser additive manufacturing process characterized by the simultaneous laser and powder delivery. During the layerwise bounding of the material, many complex interconnected physical phenomena take place in a very short time. Presently, one of the main challenges faced by DED is to enhance the powder...
Article
The effective structural health monitoring (eSHM) system fully exploits the flexibility offered by the 3D printing process for analysis of the structural integrity of additive manufactured parts by integrating a smart technology inside the component. The eSHM system relies on the propagation of pressure waves through capillaries/small ducts embedde...
Chapter
Due to changes in generator topology, wind turbines are operating in much wider speed ranges and thus at more varying operating conditions. This has a positive influence on the energy production, but results in much wider gear mesh excitation ranges that can lead to tonalities. As such, a high-quality characterization of the modal model of the gear...
Article
Full-text available
Surface Acoustic Wave inspection is a well-known non-destructive testing technique that receives considerable attention to become implemented as a Structural Health Monitoring system. The current work presents a novel approach to embed Surface Acoustic Wave-based Structural Health Monitoring technology inside additively manufactured components. A c...
Article
Additively manufactured components are questioned for their fatigue performance and therefore not adopted for safety critical applications so far. The components might contain material imperfections and residual stresses due to the high temperature gradients during the printing process. These stresses alter the component’s structural integrity and...
Article
Full-text available
Automatic ball balancing is a technique adopted in rotordynamics to reduce unknown rotor unbalance automatically. This technique sounds appealing as it can ease a panoply of balancing issues considerably. The presence of stiction, however, scatters consistent qualitative balancing and led to a limited implementation in the industry. Temporary speed...
Article
The negative pressure wave propagation method is an established Structural Health Monitoring (SHM) technique to locate leakages and defects in pipelines. The amplitude of negative pressure waves can be exploited to obtain information about the severity of the damage (e.g. leak flow rate and leak area) and are useful to determine the smallest detect...
Conference Paper
Wind energy is one of the largest sources of renewable energy in the world. To further reduce the operations and maintenance (O&M) costs of wind farms, it is essential to be able to accurately pinpoint the root causes of different failure modes of interest. An example of such a failure mode that is not yet fully understood is white etching cracks (...
Article
Full-text available
For as long as Automatic Ball Balancers are used as a means to automatically reduce unbalance in rotating machinery, it is known that these are prone to some statistical scatter in their balancing behaviour due to stiction. This diffusion leads to non-repetitive runs which has lead to a limited implementation in industry. Presented in this paper is...
Article
This work compares the microstructure and corrosion resistance of 316 L stainless steel samples prepared using two different additive manufacturing methods: selective laser melting (SLM), and laser metal deposition (LMD). A wrought material was used as reference. The specimens showed marked differences in their microstructure, as a result of the sp...
Article
In multi-axis vibration control testing, the power required by the excitation system for replicating the user defined test specifications is a limiting factor which cannot be overlooked. Excessive power, on top of over-stressing the often expensive test equipment, could cause data acquisition overloads which inevitably interrupt the test even befor...
Article
Full-text available
The formation of a melt pool, during an additive manufacturing process, is a complex multi-physical process. Apparent factors, contributing to its complexity, are among others: the high temperatures, the existence of the material in multiple physical states and the involved high dynamics. However, it is a challenge to have full real-time control ov...
Article
Full-text available
One of the major challenges faced by laser-based Directed Energy Deposition (DED) is the process efficiency. This efficiency is significantly affected by the percentage of blown powder that effectively reaches the spherical metal melt pool. Increasing the powder efficiency would allow to reduce the overall costs of the DED process and consequently...
Article
Full-text available
The MiCLAD machine designed at the VUB, Belgium, allows for closed-loop controlled laser metal deposition including various in-situ optical based measurement systems. These integrated sensors collect information on deposition geometry and temperature during the building process. Hence, each cubic millimeter of material that is either added or remov...
Article
Full-text available
Laser metal deposition is an additive manufacturing process that allows the production of near net shape structures. In order to obtain structures with reproducible and excellent material properties, it is necessary to understand the behaviour of the process better. Also the monitoring and the development of useful control approaches require a bett...
Article
Full-text available
In the field of additive manufacturing the implementation of real time process monitoring is required to enhance the quality and repeatability of the printed parts. Laser metal deposition (LMD) is a technique where the deposition of material is done in a melt pool created by a high-power laser beam. This paper presents the geometrical properties of...
Article
Full-text available
This paper addresses the influence on the fatigue life induced by the implementation of a capillary-based structural health monitoring methodology, patented under the name eSHM. It consists in integrating structurally small and pressurized capillaries into the component, so that when a fatigue crack breaches the capillary network, it results in a l...
Article
Full-text available
Noise, vibration and harshness (NVH) problems are critical issues to be tackled for wind turbine drivetrains. Tracking the behavior of modal parameters of the machines’ fundamental modes during operation it is of high interest to validate complex simulation models. A powerful approach for this purpose is represented by operational modal analysis (O...
Article
Full-text available
Multiple-Input Multiple-Output (MIMO) sine sweep is nowadays acknowledged to be one of the best excitation techniques for the modal testing of large aerospace structures, being an optimal solution in the tradeoff between high-quality FRFs testing time. Due to the test levels that can be reached during the sine sweeps and the increasing complexity a...
Article
Full-text available
Additive Manufacturing (AM) offers new manufacturing solutions for the integration of smart functionalities in engineering structures. In this manuscript, an analytical model is presented for an embedded load sensing element based on a liquid-filled capillary. During the additive manufacturing process, the capillary is integrated in the region wher...
Conference Paper
Detailed knowledge about the modal model is essential to enhance the NVH behavior of (rotating) machines. To have more realistic insight in the modal behavior of the machines, observation of modal parameters must be extended to a significant amount of time, in which all the significant operating conditions of the turbine can be investigated, togeth...
Article
Although there is no doubt about the tremendous industrial potential of metal additive manufacturing techniques such as laser metal deposition, the technology still has some intrinsic quality challenges to overcome before reaching its industrial maturity. Noncontact in situ monitoring of the temperature evolution of the workpiece could provide the...
Article
Full-text available
In additive manufacturing of metals as compared to conventional processing, the directional track-by-track and layer-by-layer nature of the fabrication process can lead to residual stresses that locally are both directionally and spatially heterogeneous. Much of the existing literature has focused either on the macroscale residual stress inside the...
Article
Full-text available
An effective structural health monitoring system fully exploits the flexibility offered by the 3D printing process by integrating a smart structural health monitoring technology inside the 3D-printed components. The system relies on the propagation of pressure waves with constant propagation speed through circular capillaries embedded in the struct...
Article
Full-text available
Turbomachine rotors, supported by little damped rolling element bearings, are generally sensitive to unbalance excitation. Accordingly, most machines incorporate squeeze film damper technology to dissipate mechanical energy caused by rotor vibrations and to ensure stable operation. When developing a novel geared turbomachine able to cover a large p...
Article
Squeeze film dampers (SFDs) are widely used to dissipate mechanical energy caused by rotor vibrations as well as to improve overall stability of the rotor system. Especially turbomachine rotors, supported on little damped rolling element bearings (REBs), are primarily sensitive to unbalance excitation and thus high amplitude vibrations. To ensure s...
Article
In this paper, a new feature added to the MLMM modal parameter estimation method (Maximum Likelihood estimation of a Modal Model) will be introduced. The MLMM method tackles some of the remaining challenges in modal analysis, e.g. modal analysis of highly-damped cases where a large amount of excitation locations is needed such as the modal analysis...
Conference Paper
Full-text available
Perhaps the most used approach for vibration-based instantaneous angular speed estimation is based on phase demodulation of a shaft-speed related harmonic. While this approach can deliver very accurate IAS estimations in cases where such a single, constantly present, and dominant harmonic is existing, there are ample cases where this approach has i...
Article
Full-text available
Typical rotating machinery drive trains are prone to torsional vibrations. Especially those drive trains that comprise one or more couplings which connect the multiple shafts. Since these vibrations rarely produce noise or vibration of the stationary frame, their presence is hardly noticeable. Moreover, unless an expensive torsional-related problem...
Conference Paper
Full-text available
Additive manufacturing (AM) has proven in a number of demonstrators its tremendous potential for structural components. AM has gone beyond being a prototyping process and is now firmly being explored as production process in numerous domains. The objective of the paper is to provide an overview of remaining challenges in the field of AM and structu...
Conference Paper
Full-text available
Fatigue performance of additively manufactured (AM) components is still uncertain and inconsistent. Structural health monitoring (SHM) systems offer a solution to continuously monitor the structural integrity of a structure. The effective Structural Health Monitoring (eSHM) system is the first SHM principle developed with the principal purpose to m...
Conference Paper
Full-text available
In modal identification, the value of the model parameters and the associated uncertainty depends on the quality of the measurements. The maximum likelihood estimator (mle) is a consistent and efficient estimator. This means that the value of the parameters trends asymptotically close to the true value, while the variance of such parameters is the...
Article
This paper presents an algorithm for the localization of forces applied to a structure. The force estimation is performed in the frequency domain based on a limited number of sensors and a linear dynamic system model and it involves minimizing an objective function penalized with a group sparsity term. The minimization of this objective function is...
Article
Full-text available
Wind energy is one of the most promising renewable energy available today. The continuous demand of wind energy production led the interest of the wind industry towards bigger turbines. This upscaling trend has imposed bigger (not quasi-static) loads that are significantly influencing the fatigue life of the wind turbine components and the tonaliti...
Article
During launch a spacecraft is subjected to a variety of dynamical loads transmitted through the launcher to spacecraft interface or air-born transmission excitations in the acoustic pressure field inside the fairing. As a result, spacecraft are tested on ground to ensure and demonstrate the global integrity of the structure against these loads, to...
Article
Multiple-Input Multiple-Output (MIMO) vibration control tests are able to closely replicate, via shakers excitation, the vibration environment that a structure needs to withstand during its operational life. This feature is fundamental to accurately verify the experienced stress state, and ultimately the fatigue life, of the tested structure. In c...
Article
Full-text available
This paper addresses the influence of the efficient Structural Health Monitoring system (eSHM) on the fatigue life of straight lug components. The eSHM system is a mechanical fatigue crack detection system developed at the Vrije Universiteit Brussel (VUB). It consists in integrating pressurized capillaries into the to-be-monitored component, so tha...
Article
Laser cladding is a technique that is frequently used for the coating and repair of metallic components. More recently, the technology is used in the additive manufacturing domain for building freeform three-dimensional parts. A lot of attention is dedicated to the optimization of the process parameters and to real-time feedback control strategies....
Article
Full-text available
Additive manufacturing (AM) of metals offers new possibilities for the production of complex structures. Up to now, investigations on the mechanical response of AM metallic parts show a significant spread and unexpected failures cannot be excluded. In this work, we focus on the detection of fatigue cracks through the integration of a Structural Hea...
Conference Paper
Full-text available
Accurate speed estimation is essential for dynamic analysis of rotating machinery; particularly for condition monitoring and operational modal analysis of applications with significant load and speed variation. The wind turbine is such an application. However, a sufficiently accurate tachometer, to keep track of the instantaneous speed, is not alwa...
Article
The detection and diagnosis of incipient rolling element bearing faults is not an undemanding task and signal analysis of vibration measurements therefore often incorporates the use of various complex processing techniques. One of the key steps in the processing procedure is the proper separation of the bearing signal from other influencing sources...
Conference Paper
Full-text available
Traditionally, modal parameters are experimentally extracted from FRFs measured in laboratory conditions. However, most of the real structures (e.g. bridges, in-flight testing of aircrafts) have to be tested in their real operational conditions rather than the laboratory conditions; this is called operational modal analysis (OMA). In OMA, the real...
Article
Additive manufacturing (AM) is a novel and innovative production technology that can produce complex and lightweight engineering products. In AM components, as in all engineering materials, fatigue is considered as one of the principle causes of unexpected failure. In order to detect, localise and characterise cracks in various material components...
Article
Full-text available
Most processing tools based on frequency analysis of vibration signals are only applicable for stationary speed regimes. Speed variation causes the spectral content to smear, which encumbers most conventional fault detection techniques. To solve the problem of non-stationary speed conditions, the instantaneous angular speed (IAS) is estimated. Wind...
Article
Full-text available
An offshore wind turbine (OWT) is a complex structure that consists of different parts (e.g., foundation, tower, drivetrain, blades, et al.). The last decade, there has been continuous trend towards larger machines with the goal of cost reduction. Modal behavior is an important design aspect. For tackling noise, vibration, and harshness (NVH) issue...
Chapter
The paper addresses the methodologies required to derive a reliable and representative simulation environment for virtual shaker testing to predict the outcome of Spacecraft vibration tests numerically prior to its physical execution. The simulation environment needs to comprise the coupled dynamical models of the testing facility, structure under...
Chapter
In Random Vibration environmental testing, it is a common practice to specify the requirements as acceleration power spectral densities (PSDs) that need to be reproduced at user-defined control channels. Such a test is typically performed in a single-axis setting, where the test article is subjected to vibrations in one direction only. If more than...
Chapter
Frequency domain modal parameter estimation from input–output data requires direct measurement or estimation of the input and output signals. In different applications those measurements, especially the excitation signals, are difficult to obtain and/or the assumptions could be poor or inappropriate (high uncertainty or high levels of noise). In th...
Chapter
Offshore Wind Turbine (OWT) is complex structure that consists of different parts (e.g. foundation, tower, drivetrain, blades, …). The last decade there is a continuous trend towards larger machines with the goal of cost reduction. Modal behavior is an important design aspect. For tackling NVH issues and validating complex simulation models it is o...
Chapter
In this paper, the recently-developed MLMM method (Maximum Likelihood estimation of a Modal Model) will be introduced and applied to challenging industrial cases. Specific about the method is that the well-established statistical concept of maximum likelihood estimation is applied to estimate directly a modal model based on measured Frequency Respo...
Article
Full-text available
Currently, research on structural health monitoring systems is focused on direct integration of the system into a component or structure. The latter results in a so-called smart structure. One example of a smart structure is a component with integrated strain sensing for continuous load monitoring. Additive manufacturing, or 3D printing, now also e...
Article
Critical mechanical faults in wind turbine systems lead to considerable downtime and repair costs. Improving the detection and diagnosis of such faults thus brings about significant cost reductions for operations and maintenance (O&M) and electricity production. One of the most common defects in drivetrains are rolling element bearing faults. Detec...
Article
Full-text available
A contactless temperature measurement system is presented based on a hyperspectral line camera that captures the spectra in the visible and near infrared (VNIR) region of a large set of closely spaced points. The measured spectra are used in a nonlinear least squares optimization routine to calculate a one-dimensional temperature profile with high...
Article
Full-text available
Laser cladding is a technique that is used for the coating, repair and production of metallic parts. Material is added to the surface of the part by injecting a flow of powder into a melt pool that is created with a high power laser beam. When the beam scans the surface of the substrate, strong local heating and cooling results. A good knowledge of...