At the Arts et Métiers campus Arts et Métiers , three doctoral students from the LAMPA laboratory defended their theses.
VALENTIN SPIROUX
THESIS IN PARTNERSHIP WITH ICARTS AND REHABBYEXO ON "OPTIMIZING A HIP AND KNEE EXOSKELETON FOR THE REHABILITATION OF HEMIPLEGIC PATIENTS."
Summary
This thesis is part of the RehabByExo project, which aims to develop a rehabilitation exoskeleton for hemiplegic patients. The goal is to optimize therapy by improving movement trajectories and repetitions. LAMPA, which is responsible for the exoskeleton's structure, has identified an area for optimization in the motor-hip torque transmission components, which require both lightness and rigidity.
The study proposes the use of composite materials and develops an innovative process combining filament winding and mold forming. The first part of the research focuses on mastering this process in order to guarantee lightweight and rigid parts that are adapted to mechanical constraints.
The second part analyzes internal defects in the parts, particularly fiber deviation caused by the hybrid process. A digital model is designed to estimate this deviation in a non-destructive manner.
Finally, the third part evaluates the bending stiffness of the parts using mechanical tests and an image correlation method. A digital model is used to estimate the properties of the materials and simulate the behavior of parts with different parameters. All of this work aims to improve the design and manufacture of exoskeleton parts for more effective rehabilitation.
Composition of the jury
- Mr. JULIEN CHAVES-JACOB, University Professor, University of Aix-Marseille Rapporteur
- Mr. DAMIEN SOULAT, University Professor, ENSAIT Roubaix Rapporteur
- Mr. BENOIT FURET, University Professor, IGHBC Paris Examiner
- Ms. HELENE PILLET, University Professor, IGHBC Paris Examiner
- Ms. SANDRINE THUILLIER, University Professor, IRDL Lorient Examiner
- Mr. LAURENT GUILLAUMAT, University Professor, ENSAM Angers Examiner
- Mr. DANIEL BELLETT, Research Engineer, AMVALOR, Angers Center Examiner
- Mr. JEAN-BAPTISTE CROUE, Engineer, AMVALOR, Angers Center Guest
Thesis supervised by: Mr. LAURENT GUILLAUMAT & Mr. PHILIPPE DAL SANTO and co-supervised by: Mr. DANIEL BELLETT & Mr. JEAN-BAPTISTE CROUE.
VALENTIN COURQUIN
THESIS IN PARTNERSHIP WITH ESSCA IN ANGERS ON THE SUBJECT OF "CHARACTERIZATION, IMPACTS, AND MANAGEMENT OF CLIMATE VARIABILITY ON THE ACTIVITIES OF EUROPEAN COMPANIES."
Summary
In a context of increasingly stringent regulations, European companies are facing growing challenges in managing physical climate risks. The CSRD directive now requires companies to assess the impact of these risks on their activities, making accurate and actionable solutions essential. This thesis proposes to meet these requirements by developing a Climate Vulnerability Diagnosis (CVD) to assess and quantify physical climate risks for each of a company's geolocated assets. The methodology is based on the analysis of climate data and the calculation of climate indicators using the latest reanalysis and climate projection models. These indicators are used to develop specific metrics, such as climate anomalies and accelerations, in order to more accurately assess the impact of physical climate risks. The CVD is therefore a key tool for designing climate risk adaptation strategies, with a particular focus on flood risks.
Keywords: Physical climate risks, Climate change adaptation, Climate vulnerability assessment, Risk management, Climate indicators.
Composition of the jury
- Catherine DEFFAINS-CRAPSKY University Professor, University of Angers Rapporteur
- Antonio FALCÓ MONTESINOS University Professor, CEU Cardenal Herrera University Rapporteur
- Fodil MERAGHINI University professor, LEM3, Arts et Métiers
- Jean-Louis BERTRAND Professor, ESSCA School of Management Examiner
- Francisco CHINESTA SORIA University professor, PIMM, Arts et Métiers
- Amine AMMAR University Professor, LAMPA, Arts et Métiers
- Miia CHABOT Professor and Research Director, ESSCA School of Management Examiner
Thesis supervised by: Mr. Amine AMMAR, University Professor, LAMPA, Arts et Métiers, and co-supervised by: Ms. Miia CHABOT, Professor and Director of Research, ESSCA School of Management
MARION AUFFRAY
THESIS IN PARTNERSHIP WITH THE CEA IN GRENOBLE ON "THE EFFECT OF SURFACE MICROGEOMETRY ON THE CORROSION FATIGUE RESISTANCE OF STEELS PRODUCED BY ADDITIVE MANUFACTURING."
Summary
This study focuses on powder bed fusion laser additive manufacturing (PBF-LM) applied to 316L stainless steel. This process makes it possible to produce complex and resistant metal parts, but also generates internal defects, a rough surface, and residual stresses, affecting their fatigue resistance.
The objective is to analyze the impact of surface and subsurface parameters on fatigue performance through an experimental campaign. Uniaxial tests are conducted on several batches with different microstructural states (as-built, heat-treated) and surface states (net-shape, polished, with artificial defects). The microstructure of net-shape parts combines a heterogeneous core and a refined-grain subsurface, with pores and lack of fusion mainly located at the contour-core interface.
The results show that critical defects strongly influence fatigue strength:
- Net-shape as-built parts are most sensitive to residual stresses and surface defects (ejecta, valleys, pores).
- Heat treatment improves strength by reducing residual stresses.
- Defects larger than 200 µm, whether natural or artificial, are a determining factor, regardless of roughness.
- The microstructure beneath the surface also plays a key role.
Finally, synchrotron tomography analysis and numerical simulations highlight the interaction between surface roughness and small underlying defects, explaining the dispersion of results. A model based on the Kitagawa-Takahashi diagram makes it possible to unify these observations and optimize the design of FLLP parts.
Composition of the jury
- Mr. Mauro MADIA, Federal Institute for Materials Research and Testing, Examiner
- Mr. Anis HOR, ISAE-SUPAERO, Examiner
- Mr. Franck MOREL, LAMPA, Arts et Métiers, Examiner
- Mr. Etienne PESSARD, LAMPA, Arts et Métiers, Examiner
- Ms. Linamaria GALLEGOS MAYORGA, LAMPA, Arts et Métiers, Examiner
- Mr. Thierry BAFFIE, CEA, Examiner
- Mr. Eric CHARKALUK, École Polytechnique, Examiner
Thesis supervised by: Mr. Franck MOREL and co-supervised by: Ms. Linamaria GALLEGOS MAYORGA and Mr. Etienne PESSARD.
