Search results for "020303 mechanical engineering & transports"
showing 10 items of 407 documents
Analysis of the road traffic-induced pollution in two areas of Sibiu, Romania
2017
The current paper details a computer-aided research of the emission levels in two areas of the city of Sibiu, Romania. The research started from the numbers of motor vehicles passing through key segments of those two areas, located at entry points into the city of Sibiu. Using the software package Synchro Studio 7 and SimTraffic 7, the targeted crossroad areas were modelled and key indicators for the road traffic efficiency and for the emission levels were determined. These emission levels were then compared to real measured pollution values, which allowed both to assess the accuracy of the modelling and the influence of other pollution sources on the emission levels in those areas.
Damage accumulation in a carbon/epoxy composite : Comparison between a multiscale model and computed tomography experimental results
2012
International audience; High-resolution computed tomography has been carried out for carbon/epoxy laminates loaded in situ to failure. The experimental data allows major damage mechanisms to be quantified in 3D, in an unambiguous and mechanically representative way, where previous experimental analysis is limited. A multi-scale model that predicts damage accumulation in tensile loaded composites is compared to the experimental analysis, to validate the underpinning assumptions within the model and overall performance. The model considers the random nature of fibre-strengths, stress transfer resulting from fibre breaks, fibre/matrix debonding and viscosity of the matrix. Assumptions within t…
A new constructive method using the theory of invariants to obtain material behavior laws
2006
International audience; The aim of this paper is to present a constructive method to derive mechanical behavior laws using the Theory of Invariants and Continuum Thermodynamics. More precisely, we want to construct, in a general way, the state or dissipation potential in a polynomial form given a set of variables V and the material symmetry group S. For this purpose, we show how to obtain a set of generators for the S-invariant polynomials of V. Then, using the Grœbner basis concept, we write all the decompositions of a polynomial of a given degree.
A family of higher-order single layer plate models meeting Cz0-requirements for arbitrary laminates
2019
Abstract In the framework of displacement-based equivalent single layer (ESL) plate theories for laminates, this paper presents a generic and automatic method to extend a basis higher-order shear deformation theory (polynomial, trigonometric, hyperbolic…) to a multilayer C z 0 higher-order shear deformation theory. The key idea is to enhance the description of the cross-sectional warping: the odd high-order C z 1 function of the basis model is replaced by one odd and one even high-order function and including the characteristic zig-zag behaviour by means of piecewise linear functions. In order to account for arbitrary lamination schemes, four such piecewise continuous functions are consider…
Novel algorithms for 3D surface point cloud boundary detection and edge reconstruction
2019
Abstract Tessellated surfaces generated from point clouds typically show inaccurate and jagged boundaries. This can lead to tolerance errors and problems such as machine judder if the model is used for ongoing manufacturing applications. This paper introduces a novel boundary point detection algorithm and spatial FFT-based filtering approach, which together allow for direct generation of low noise tessellated surfaces from point cloud data, which are not based on pre-defined threshold values. Existing detection techniques are optimized to detect points belonging to sharp edges and creases. The new algorithm is targeted at the detection of boundary points and it is able to do this better tha…
Hygrothermal effect on moisture kinetics and mechanical properties of hemp/polypropylene composite: Experimental and numerical studies
2015
The exposition of thermoplastic composites reinforced with natural fibers to moisture and heat is likely to lower their mechanical properties and restrain their use in the design of parts. The present work is focussed on investigating the effects of hygrothermal aging on the mechanical behaviour of injected polypropylene reinforced with short hemp fibers. Moreover, the kinetic of isothermal moisture absorption has been studied for four immersion temperatures. The experimental results show that the time taken to reach saturation decreases significantly with increase in immersion temperature. These tests also reveal that moisture absorption in this type of materials does not follow Fick's law…
Study of the Formability of Laminated Lightweight Metallic Materials
2017
The main objective of this work was to test the formability of laminated materials. Laminated materials are considered a good choice when parts with reduced weight are considered. Thus, a laminated material, aluminum - polypropylene - aluminum (Al-PP-Al), as sheet 1.2 mm and 1.4 mm thickness was used. Before processing the material by means of unconventional plastic deformation, its formability was determined by running the Nakajima test. After obtaining the forming limit curves, the material was machined by means of incremental forming.
An evaluation of the environmental factors for supply chain strategy decisions using grey systems and composite indicators
2020
[EN] The purpose of this work is to assess the importance of environmental factors in a supply chain with four partners as a preliminary step to select the competitive strategies and objectives. To achieve this purpose, a real case study was carried out in a footwear supply chain, in which two approaches were used: the grey system theory and uncertainty analysis tools for composite indicators. In order to validate both approaches, a seven-phase research methodology was developed and applied to our case study. In addition, the priorization of environmental factors was calculated individually for each partner. The results allow managers to establish the competitive strategy that best suits th…
Modelling of Moisture Sorption by Cfrp Rebars with Vinylester Matrix
2004
The results of experimental investigation and modelling of moisture sorption by CFRP rebars and vinylester matrix are presented. Experimental values of the rebar diffusion coefficients essentially differ from those predicted using structural approach. Essential anisotropy of sorption process in longitudinal and transverse directions is observed. Quasi three phase model is suggested for description of the CFRP rebar sorption. The model is based on consideration of sorption process of the diffusion character in the composite consisted of two phases: resin and microplastic, which includes fibres and fibre-resin interphase. The suggested model describes the experimental sorption data quite sat…
Experimental and numerical assessment of subsurface plastic deformation induced by OFHC copper machining
2015
Strain distributions in the machined surface and subsurface of OFHC copper workpieces were determined experimentally and through numerical simulations. An experimental setup, comprising a double frame camera and a pulsed laser, was developed to measure the displacement fields using the digital image correlation (DIC) technique; strain distributions were then calculated. A numerical orthogonal cutting model was also developed and applied in order to predict such distributions. Comparison between simulated and measured results enabled an understanding of the fundamental mechanisms of plastic deformation of the machined surface of OFHC copper.; International audience; Strain distributions in t…