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.

Directional solidification of Al2O3-Al2TiO5 system

Abstract: Directional solidification of Al2O3–Al2TiO5 eutectic system was investigated to design in situ composites that could exhibit optimized properties of strength and toughness Directional solidification of an alumina rich melt was expected to produce primary Al2O3 dendrites, these would act as load bearing component of the structure, separated by a Al2O3–Al2TiO5 eutectic matrix and Additional aim was to utilize the differential expansion coefficient between the two phases to produce microcracks and thus weak interfaces for load deflection Three different melt compositions were investigated; two off-eutectic compositions, at 11, 26 mol% TiO2, and one eutectic at 439 mol% TiO2 The crystallized phases were different than as one would expect from the published phase diagram Off-eutectics were composed of Al2O3 dendrites separated by a Al6Ti2O13 matrix Eutectic structure was composed of Al2TiO5 lamellae in an aluminum titanate matrix This matrix consisted of a superstructure made of 5 cells of Al6Ti2O13 for one cell of Al2TiO5 along [0 0 1] direction Al6TiO13 phase decomposed by a eutectoid reaction into Al2O3 and Al2TiO5 Eutectoid reaction occurred during post heat treatment at 1400 °C and decomposition of Al6Ti2O13 was completed after 10 h of annealing at 1500 °C Based on these observations, a modification of the alumina rich part of Al2O3–TiO2 phase diagram was proposed A second intermediate compound, Al6Ti2O13 is introduced as a high temperature phase Two invariant points, a peritectic (L + Al2O3 → Al6Ti2O13) and a eutectic (L → Al6Ti2O13 + Al2TiO5) are also added between Al6Ti2O13 and Al2TiO5

Functional gait analysis of trans-femoral amputees using two different single-axis prosthetic knees with hydraulic swing-phase control: Kinematic and kinetic comparison of two prosthetic knees.

Abstract: This paper reports a comparison of the gait patterns of trans-femoral amputees using a single-axis prosthetic knee that coordinates ankle and knee flexions (Proteor's Hydracadence® system) with the gait patterns of patients using other knee joints without a knee–ankle link and the gait patterns of individuals with normal gait. The two patient groups were composed of 11 male trans-femoral amputees: six patients had the Hydracadence® joint (Group 1) and five patients had other prosthetic knees (Group 2). The reference group was made up of 23 normal volunteers (Group 3). In this work, trunk, hip, knee, and ankle 3-D motion was assessed using the VICON® system. Kinetic data were collected by two AMTI® force plates, and the knee moment was calculated via the 3-D equilibrium equations. An original questionnaire was used to assess the participants' activity level and clinical background. The results reveal that, during stance, all knee types guaranteed security. After heel strike, the plantar flexion of the ankl...

Detection of the Presence of Broken Wires in Cables by Acoustic Emission Inspection

Abstract: Safety of suspension or stay cable bridges depends on the durability of their cables; stay cable bridges may present a healthy aspect on observable lengths but may be damaged in the nonvisible parts (anchorages). It is important to be able to detect as early as possible the defects affecting them. In this study, the acoustic emission (AE) technique is employed to detect the presence and location of broken wires in anchorage. Allowing a cable to vibrate can induce AE from interwire fretting. The study of the behavior of a broken wire during bending contributed to the understanding of the origin of the AE, that is, interwire fretting and the definition of the most suited bending conditions. For the identification of interwire friction, the main parameters of the acoustic signals are the number of events, their energy, and frequency distribution. These parameters are very dependent of roughness, lubrication, contact strength between wires, and recovery length. Several cables were studied with various surface conditions including corroded, dry, and oiled.

A study of composite material damage induced by laser shock waves

Abstract: A laser shock wave technique has been used to study the damage tolerance of T800/M21 CFRP (Carbon Fiber Reinforced Polymer) composite material with different lay_ups. Different levels of damage have been created according to various laser irradiation conditions. Several characterization methods such as Optical Microscopy, X-ray Radiography, or Interferometric Confocal Microscopy have been used to quantify these defects. The nature of the defects induced by the shock wave propagation has been studied. The sensitivity of the composite material damage to the shock conditions has been shown and quantified. Moreover, the experimental results gathered with each technique have been compared to each other and it leads to a better understanding of the CFRP behavior under high dynamic loading. These original results have enabled the definition of a specific damage criterion for CFRP under dynamic loading.