Laurent Berthe

Laurent Berthe
French National Centre for Scientific Research | CNRS · Laboratoire PIMM

PHD-HDR Université Paris XI

About

367
Publications
56,564
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5,356
Citations
Citations since 2017
117 Research Items
2894 Citations
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20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
20172018201920202021202220230100200300400500600
Additional affiliations
October 1998 - present

Publications

Publications (367)
Article
Full-text available
We investigate the mechanical response of Zr50Cu40Al10 and Zr60Cu30Al10 metallic glasses under laser shock compression to reproduce hypervelocity impact conditions such as high longitudinal stresses and high strain rates in an unknown range of 10^6-10^7 s^(-1) . Hugoniot curves and strength parameters (spall strength and strain rate) are obtained f...
Article
Objectives: The lithotripsy efficiency (LE) in vitro study requires artificial or human stone samples (AS, HS). With the development of dusting lithotripsy, less ex vivo HS are available. We aimed to compare Thulium Fiber Laser (TFL) and Holmium:YAG (Ho:YAG)'s LE and define the most accurate LE parameter. Methods: Hard and soft homogenous- and h...
Article
Full-text available
This study investigates the microstructural, mechanical, high-cycle fatigue, and fracture behaviour of a dissimilar 2017A-T451/7075-T651 Al alloy joint produced by single-pass friction stir welding (FSW) without post-processing. Residual stress analysis revealed low tensile residual stresses in the longitudinal direction on the crown side and compr...
Article
We present a series of shock-wave measurements on aluminum based on the use of a simultaneous Photon Doppler Velocimetry (PDV) and triature velocity interferometer system for any reflector. Our dual setup can accurately measure shock velocities, especially in the low-speed range (<100 m s ⁻¹ ) and fast dynamics (<10 ns) where measurements are criti...
Article
Full-text available
The application of adhesively bonded joints in aerospace structural parts has increased significantly in recent years and the general advantages of their use are well-documented. One of the disadvantages of adhesive bonding is the relevant permanence, when compared to traditional mechanical fastening. End-of-life processes generally require the sep...
Article
Objectifs L’étude in vitro de l’efficacité de la lithotripsie (LE) nécessite des échantillons de calculs artificiels ou humains(AS, HS, respectivement). Avec le développement de la pulvérisation lithiasique (dusting), moins de HS ex vivo sont disponibles. Notre objectif était de comparer LE des lasers Thulium Fibré (TFL) et HolmiumYAG (HoYAG) et de...
Article
The aim of this paper is to develop a model allowing a fast first approximate estimation of the elastic–plastic stress wave propagation caused by a laser impact and the resulting residual stress field. We start by modeling the stress wave propagation, adopting a 1D uniaxial modeling, reducing the behavior of the specimen to the axis of the laser im...
Article
No PDF available ABSTRACT We investigate the propagation of a laser shock wave within a composite material used in aeronautics. This one is made of carbon fibers woven according to a 3D pattern within an epoxy matrix. The shock wave is generated by an impulsive (of order 10 ns) laser beam of power a few GW/cm², focused on the surface of a metallic...
Patent
The present document relates to a method for focussing acoustic waves on an interface between two layers of a multilayer structure, the method comprising : - providing laser means able to emit a laser beam toward an exterior surface of the multilayer with a view to producing a longitudinal wave from the centre of a laser-beam spot projected onto th...
Article
Full-text available
This paper presents an innovative methodology of material characterization under high strain rate (order of 107s-1) laser shock loading coupled with microstructural and mechanical material features. To that scope, experimental and simulation analyses have been conducted for Al alloys (AA7075-T6 and AA2017-T4) and dissimilar Friction Stir Welded (FS...
Article
The mechanical behaviour of polycarbonate and polydimethylsiloxane (Sylgard184) is studied in this work under laser shock conditions that induce high pressure and strain rates. Laser shock, usually used to reinforce metals, is chosen here because of its capacity to produce strain rates in the 106 s1 range and pressures of GPa order. The pressure an...
Article
Full-text available
This paper explores numerical methods dedicated to 3D elastic waves simulations in spatially separable domains such as plates. The objective is to reduce the computation time and the memory requirements associated to these large simulations involving fine space and time discretizations. The 3D problem is decomposed into a sequence of lower dimensio...
Article
Introduction and objectives: The Thulium Fiber Laser(Tm-F) is currently studied as an alternative to the Holmium:YAG laser(Ho:YAG), the gold-standard for endocorporeal laser lithotripsy. We aimed to evaluate the ex vivo effects of an accidental Tm-F laser exposure on bovine eyes and to test the protective action of different eyeglasses in preventi...
Article
Full-text available
This article presents the study of the shock wave propagation through aluminum alloys (pure aluminum and aluminum 2024-T3) produced by laser plasma using experimental and numerical tests. Water confinement regime interaction, pulse duration (7.2 ns), and power density (1-5 GW=cm 2) range correspond to laser shock peening process configuration and p...
Article
Full-text available
Laser-driven shock experiments were conducted at a synchrotron facility to investigate the dynamic response of a polyurethane foam. These experiments were coupled to in-situ X-ray imaging to radiograph foam deformations and determine the propagation velocity of stress waves. To increase the amplitude and the duration of the pressure load generated...
Article
The aim of this paper is to study the effect of microstructure heterogeneity upon elasto-plastic wave propagation generated during laser shot peening. We consider a simplified elasto-plastic laminate specimen subjected to uniaxial strain. The microstructure is composed of two phases alternating periodically and perfectly bonded together. The associ...
Article
Full-text available
Background: Endocorporeal laser lithotripsy (EL) during flexible ureteroscopy (URS‐f) of-ten uses “dusting” settings with “painting” technique. The displacement velocity of the laser fiber (LF) at the stone surface remains unknown and could improve EL’s ablation rates. This in vitro study aimed to define the optimal displacement velocity (ODV) for...
Article
Full-text available
The laser shock peening process (LSP), used to reinforce metals, currently has two major configurations with limitations. (1) Laser irradiation with large spot sizes, but with the need to use a thermal protective coating to avoid detrimental thermal damage (which increases the overall cost of the process) or (2) laser irradiation without thermal co...
Article
Full-text available
This review proposes to summarize the development of laser shock applications in a confined regime, mainly laser shock peening, over the past 50 years since its discovery. We especially focus on the relative importance of the source term, which is directly linked to plasma pressure. Discussions are conducted regarding the experimental setups, exper...
Article
Objetives: To assess the effect of various factors on laser fiber tip degradation with the Thulium Fiber Laser (Tm-fiber): fiber stripping, adjustable laser settings (energy, frequency, peak power), and stone density. Methods: 273µm fibers were used with a 50W Tm-fiber. Firstly, we assessed the evolution of power transmission with stripped and u...
Article
Full-text available
The authors present a new configuration for laser-induced plasmas in confined regimes for a 10 ns-range laser pulse in the green wavelength (532 nm) that repulses the breakdown threshold above 20 GW/cm2 compared to 8 GW/cm2 as generally indicated in previous works. Using this new configuration, pressures above 12 GPa have been reached for the first...
Article
Objectifs Kidney Stone Calculator (KSC) estime la durée de lithotritie laser endocorporelle (LLE) au cours d’une urétérorénoscopie souple(URS-S), à partir du volume lithiasique total (VLT) sur un scanner abdominopelvien préopératoire non injecté (TDM AP IV-). L’objectif de cette étude était de mesurer sa fiabilité et les facteurs influençant cette...
Article
Objectifs Étudier l’interaction laser-tissu à travers les caractéristiques d’ablation, de coagulation et de carbonisation des laser Ho:YAG et Thulium Fibré (LTF) sur un modèle de rein de porc non perfusé. Évaluer la dégradation des fibres laser lors du traitement sur tissus mous. Méthodes Les paramètres identiques entre les deux lasers (énergie et...
Article
Objectifs Comparer le risque de fracture des fibres laser entre les lasers Ho : YAG et Thulium Fibré (LTF) avec différents diamètres de fibre laser, réglages laser et rayons de courbure de fibre. Évaluer l’effet de plusieurs facteurs sur la dégradation des fibres de 273 μm avec le LTF : stripping de la fibre, paramètres laser réglables et densité d...
Article
A method coupling experiments and simulations, is developed to characterize the yield stress and strain hardening of several metals loaded at 106 s−1 and < 25 ns, typically involved during Laser Shock Peening. It was applied to four materials: pure aluminum, 2024-T3 and 7175-T7351 aluminium alloys and Ti6Al4V-ELI titanium alloy. Thin foils have bee...
Article
Full-text available
Through the years, laser shock peening became a treatment of choice in the aerospace industry to prolong the life of certain critical pieces. Water flow is commonly used as a confinement to improve the process capability but some applications cannot allow for water presence in the area of interest. In a previous article, an alternative to the water...
Article
Full-text available
Introduction Kidney Stone Calculator (KSC) is a free, three-dimensional (3D) planning software for flexible ureteroscopy(fURS) with Holmium:YAG(Ho:YAG) endocorporeal lithotripsy (EL). KSC provides the stone volume (SV) and expected duration of lithotripsy (ExDL) estimations based on non-enhanced-CT scan (NECT) DICOM series. We aimed to provide a pr...
Article
Full-text available
An explicit 3D Finite Element (FE) model was developed in the LS-Dyna code to simulate the laser shock paint stripping on aircraft aluminum substrates. The main objective of the model is to explain the physical mechanisms of the laser shock stripping process in terms of shock wave propagation, stress and strain evolution and stripping shape and siz...
Article
Objective: To assess the fiber-tissue interaction through ablation, coagulation, and carbonization characteristics of the Ho:YAG laser and Super Pulsed Thulium Fiber Laser (TFL) in a non-perfused porcine kidney model. To assess the degradation of laser fibers during soft tissue treatment. Methods: A 50W TFL generator was compared to a 120W Ho:YA...
Article
Transient wave propagation problems may involve rich discretizations, both in space and in time, leading to computationally expensive simulations, even for simple spatial domains. The Proper Generalized Decomposition (PGD) is an attractive model order reduction technique to address this issue, especially when the spatial domain is separable. In thi...
Article
Full-text available
Objectives: To compare the risk of laser fiber fracture between Ho:YAG laser and Thulium Fiber Laser (TFL) with different laser fiber diameters, laser settings, and fiber bending radii. Methods: Lengths of 200, 272, and 365 μm single use fibers were used with a 30 W Ho:YAG laser and a 50 W Super Pulsed TFL. Laser fibers of 150 µm length were als...
Chapter
Full-text available
This chapter highlights two advances towards a higher maturity of versatile extended non-destructive testing (ENDT) procedures. Full-scale demonstration tests are presented in realistic user application cases that involve typical production or repair scenarios. Subsequently, the investigations used to assess the probability of detection (POD) are d...
Chapter
Full-text available
We present the results of extended non-destructive testing (ENDT) methods for bond line quality assessment in adhesive joints. The results presented were derived for important application scenarios with regards to aircraft manufacturing and the in-service repair of composite structures. The electromechanical impedance (EMI), laser shock adhesion te...
Article
Full-text available
IntroductionHolmium:YAG(Ho:YAG) is currently the standard for lithotripsy. Superpulsed Thulium Fiber Laser(TFL) has been evaluated as an alternative for lithotripsy, using laser fibers with core-diameters(CDF) down to 50 µm and additional available settings suitable for “dusting” technique. This in-vitro study compared ablation rates, fissures and...
Article
We present a method to investigate the bulk propagation of a shock wave in a thick, opaque metallic plate. The shock wave is generated by laser loading. An elastic plane probe wave, counter-propagative with respect to the shock, is emitted by means of a phase-array device. Shock propagation monitoring is performed by analyzing on the phase-array de...
Article
Full-text available
Laser stripping is a process which typically includes different forms of ablation phenomena. The presented work investigates a mechanical stripping process using high pressure laser-induced shock waves in a water confined regime. Power density is studied as a parameter for selective laser stripping on painted specimens and for adhesion relations wi...
Conference Paper
Full-text available
Using most advanced Diode-Pumped Solid State laser architectures (1 J, 10 ns, 200 Hz), we have developed and optimized a high-frequency configuration for Laser Shock Peening: small laser spots, high-overlap ratios and without thermal coating.
Article
This work aims at demonstrating the ability of an acoustic linear code to model the propagation of a shock wave created by a laser impact over a metallic surface. In this process, a high pressure surface level is reached using a ns laser pulse that heats the surface of the material and generates a dense plasma expansion. The pressure reaches few GP...
Article
Objectives: The Thulium Fiber Laser (TFL) is studied as an alternative to the holmium:yttrium-aluminium-garnet (Ho:YAG) laser for lithotripsy, with the advantage of an induced bubble stream (IBS). This in vitro study compared the TFL's IBS with 150- and 272 μm-core-diameter laser fiber (CDF) and in four irrigant fluids. Methods: A TFL of 50 W (IPG...
Article
Full-text available
IntroductionHolmium:yttrium–aluminium–garnet (Ho:YAG) is currently the gold standard for lithotripsy for the treatment of all known urinary stone types. Stone composition and volume are major determinants of the lithotripsy. This in vitro study evaluated the required energy to ablate 1 mm3 of various stone types with different laser settings using...
Article
Objectifs La vitesse optimale de déplacement (VOD) de la fibre laser pour réaliser la pulvérisation lithiasique est une variable inconnue à ce jour, autant pour le laser thulium fibré (TFL) que pour le laser Holmium :YAG (Ho :YAG). L’objectif était de déterminer in vitro la VOD de la fibre laser lors d’une lithotritie endocorporelle en fonction des...
Article
Introduction Kidney Stone Calculator (KSC) est un outil que nous avons développé pour mesurer le volume lithiasique total (VLT) et estimer la durée opératoire de lithotritie laser endocorporelle (LLE) au cours de l’urétérorénoscopie souple (URS-S), à partir du scanner abdominopelvien préopératoire non injecté (TDM AP IV-). L’objectif de cette étude...
Article
Objectifs L’étude in vitro de la lithotritie laser (LL) utilise des calculs humains (CH) ou synthétiques (CS). Devant l’augmentation de la pulvérisation laser (Dusting), peu d’échantillons humains sont disponibles. Les CS sont donc privilégiés, confectionnés par mélange d’eau et de plâtre, avec la problématique de leur réhydratation lors des LL. L’...
Article
The present work presents the latest development of laser shock adhesion test (LASAT) technology, targeting the weak bond detection in bonded aeronautic structures. This problematic is still holding back a wider use of bonding, which could however be a significant breakthrough in the way of assembling parts. By mechanically loading the bondline tha...
Article
The recent development of LAser Shock Adhesion Test (LASAT) as quantitative Non-Destructive Testing (NDT) process for evaluation of structural bonded assemblies brings new challenges. Applicative assemblies composed of complex materials with poor transverse mechanical properties and highly resistant bonded joints require laser parameters optimizati...
Article
Full-text available
After a brief description of the physical principles involved in the cratering process, the authors present a specific methodology to simulate laser-driven cratering experiments performed with a long pulse duration (100 ns) and a small focal spot diameter (220μm). This methodology can be divided into two steps. First, the 2D-axisymmetrical pressure...
Article
Objectifs Le laser Thulium fibré (TFL) apparaît comme une alternative au laser Holmium:YAG (Ho:YAG) pour la lithotritie endocorporelle, permettant d’utiliser des fibres de diamètres inférieurs à 200 μm. L’objectif était de comparer in vitro les diamètres des fragments, des fissures, et des volumes d’ablation lithiasiques selon le diamètre de fibre...
Article
Objectifs Le Laser Thulium Fibré (TFL) représente une alternative au laser Holmium:YAG pour la lithotritie endocorporelle, permettant d’utiliser des fibres laser (FL) de diamètres inférieurs à 200 μm. L’objectif était de comparer in vitro les dimensions et durée des flux de bulles (FB) entre FL de diamètre 272 μm (272CDF) et 150 μm (150CDF) avec le...
Article
Objectifs L’urétéroscopie flexible avec lithotritie pour calcul rénal est une intervention fréquente en urologie. Un des paramètres pouvant influer sur la durée opératoire est la charge lithiasique. Notre objectif était de développer un outil de mesure tridimensionnel (3D) pour la planification chirurgicale des interventions endo-urologiques pour l...
Article
Objectifs Le laser à fibre Thulium Superpulse (TFL) apparaît comme une alternative au laser Holmium :YAG pour la lithotritie endocorporelle, permettant d’utiliser des fibres de diamètres inférieurs à 200 μm. L’objectif était de comparer in vitro les pertes de puissance (PP) de fibres laser de diamètre 272 μm (272CDF) et 150 μm (150CDF) avec le lase...
Article
Full-text available
This paper presents the first extensive study of the performances of solid polymers used as confinement materials for laser shock applications such as laser shock peening (LSP) as opposed to the exclusively used water-confined regime up to now. The use of this new confinement approach allows the treatment of metal pieces needing fatigue behavior en...
Article
Fused silica samples were subjected to laser induced shock loading. Laser flux was varied in order to obtain different amounts and characteristics of damage in the samples. Three dimensional damage and fracture maps of two identical samples impacted by high and low laser flux values were obtained using both optical microscopy and X-ray computed mic...
Article
This study aims to assess the capability of the LAser Shock Adhesion Test to detect weak bonds in assemblies made of carbon fibre reinforced polymer laminates as well as understand the behaviour of different bonded composite structure under a shock load. A specific setup based on symmetrical laser shocks has been used. After each test, ultrasounds...
Article
Objectifs Avec une émission à une longueur d’onde de 1940 nm, très proche du pic d’absorption de l’eau, le laser fibré au thulium (tfl) devrait être plus efficace que le laser ho:yag. La technologie thulium permet également d’utiliser de très hautes fréquences pour le traitement des calculs. L’objectif de notre étude était de comparer in vitro l’ef...