ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Residual stress. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

Observation of the shock wave propagation induced by a high-power laser irradiation into an epoxy material

Abstract: The propagation of laser-induced shock waves in a transparent epoxy sample is investigated by optical shadowgraphy. The shock waves are generated by a focused laser (3?ns pulse duration?1.2 to 3.4?TW?cm?2) producing pressure from 44 to 98.9?GPa. It is observed that the shock wave and the release wave created by the shock reverberation at the rear face are both followed by a dark zone in the pictures. This corresponds to the creation of a tensile zone resulting from the crossing on the loading axis of the release waves coming from the edge of the impact area (2D effects). After the laser shock experiment, the residual stresses in the targets are identified and quantified through a photoelasticimetry analysis of the recovered samples. This work results in a new set of original data which can be directly used to validate numerical models implemented to reproduce the behaviour of epoxy under extreme strain rate loading. The residual stresses observed prove that the high-pressure shocks can modify the pure epoxy properties, which could have an influence on the use made of these materials.

Intraoperative three dimensional correction during in situ contouring surgery by using a numerical model.

Abstract: Study Design. A numerical study was conducted by simulating in situ contouring (ISC) surgery. Objective. To quantify intraoperative correction during ISC surgery. Summary of Background Data. Surgical techniques correcting scoliosis, like the ISC one, lead to a complex 3-dimensional correction of the spine. Using motion analysis devices to analyze the effect of intraoperative surgical maneuvers was tedious and limited the study to the kinematics of exposed vertebrae. An alternative method consisted in simulating the surgical gestures. However, proposed models were based on rigid instrumentations, and focused attention on specific gestures of the rod-rotation and the distraction techniques through operator-dependent simulations. Methods. This study included 10 patients with severe idiopathic scoliosis treated by ISC surgery. From a patient-specific finite-element model (T1-L5 and pelvis), all main steps of the ISC surgery were automatically simulated. A specific algorithm was developed to determine the sequences of bending maneuvers according to the rod shapes chosen by the surgeon. The accuracy of the automated surgery simulation was assessed regarding the virtual postoperative spinal configuration and postoperative clinical data. For each maneuver, vertebral kinematics was computed as well as the evolution of various clinical parameters. Results. The bending maneuvers of both the first and the second rods provided complementary effects inside, but also outside the fused spinal area. These main maneuvers combined the intraoperative spinal corrections induced by maneuvers specific to the rod-rotation surgery. Conclusion. The automated patient-specific simulation of ISC surgery may improve the understanding of the main mechanisms involved in the scoliosis surgical correction.

Integrated Traction/Charge/Air Compression Supply Using Three-Phase Split-Windings Motor for Electric Vehicles

Abstract: High cost, no-ideal driving range, and charge time limit electric vehicle market share. Facing these challenges, an integrated motor drive/battery charger system has been proposed by Valeo. A further advancement, based on this system, is present in this paper; for the first time, the integration of traction, charging, and air-compressor supply modes is proposed and tested by real-time experimentation. This integrated system is expected to increase the vehicle component compactness and power, therefore potentially reducing the cost and battery charging time. An overall and unique control scheme is detailed to achieve the three main operating modes: traction, charging, and air-compressor supply modes. The real-time experimentation results show the system feasibility.