Multistep hybrid approach applied to material removal operation using cutting tool

Cutting processes are widely used in different industries to cut different engineering parts. Usually the optimization of these processes is made by experimental or numerical simulations but the major inconvenience of those methods is the cost and the time needed. For all these reasons, in manufacturing industry, a highly interest in analytical methods are usually researched because there are very practice to use but those methods don’t take into account all the aspects of the contact between the work material and the tool. In particular ploughing and spring back are usually not considered, what is pertinent for small cutting radius but not for bigger ones (used tools). In this paper en hybrid approach is presented. Both analytical and numerical approaches are used in order to model and understand physic during removal processes. In particular a multi-steps model for orthogonal cutting has been developed in order to study the influence of the cumulated strain and temperature induced by the different steps on the residual stresses. The effect of tool edge radius and heat generated by flank friction on the predicted stress profile is analytically modelled. In fact, in the case of most of industrial processes, like turning, milling, grinding, the cutting tool is in contact with a part of material that was the finished piece in the previous step Commercial finite element software ABAQUS with its Explicit and Implicit modules was used. Computed Numerical predicted stress fields are compared against measured residual stresses obtained by X-Ray diffraction. Moreover, in order to take into account all the physics in the tool-work material interface, spring-back simulation was performed using both ABAQUS Explicit and ABAQUS Implicit

Analyse de signaux physiologiques. Evaluation et implementation de methodes de traitement automatique de signaux de manometrie digestive

SIGLEINIST T 75384 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Choi-Williams time-frequency representation of acoustic signals

International audienceThis work concerns the study of acoustic signals that are backscattered by thin aluminum tubes. This study is done with the help of Choi-Williams time-frequency method by virtue of its interesting properties. This technique was chosen because it reduces the amplitude of the interferences. This can make the interpretation of time-frequency image easier. However, the resolution of time-frequency image is acceptable if the involved parameter is well chosen. As a result, the determination of longitudinal and transverse velocities of aluminum from Choi-Williams time-frequency technique reveals a good agreement with the theoretical method of proper modes as mentioned in scientific literature

Utilisation des réseaux de neurones artificiels en diffusion acoustique et en agriculture sous serres

LE HAVRE-BU Centrale (763512101) / SudocSudocFranceF

A Novel Approach to Estimate the Radius Ratio of an Elastic Tube from Its Form Function Using Soft Computing Techniques

International audienceA number of researches in different areas has been conducted on using the Principal Component Analysis PCA combined with Artificial Neural Networks ANN. In this current research, we use these two techniques to estimate the radius ratio b/a (a: outer radius, b: inner radius) of an elastic tube based on its form function. The PCA technique is used to estimate the component loadings corresponding to form function. Then, the component loadings it's used in the ANN technique to estimate the radius ratio of the tube. To get the optimal network, several configurations are implemented and tested. The optimal configuration selected is a network with 16 inputs, 2 hidden layers composed of 4 and 1 neurons respectively, and trained by the back-propagation algorithm. This configuration is able to estimate the radius ratio í µí±/í µí± with a mean absolute error MAE of about 0.0024 and a mean square error MSE of 0.0008. This study reveals benefits of the combination between PCA and ANN, and also it provides some new ideas for further researches. This current work can be used as a novel approach for the characterization of an elastic tube

Development of an artificial neural network model for estimating the radius ratio of a one-layered cylindrical shell

The results obtained from previous studies on the acoustic scattering of a plane wave by an elastic cylindrical shell, show that the acoustic resonances of the shell are related to its physical and geometrical properties. In order to estimate the radius ratio of an air-field immersed cylindrical shell, an approach based on artificial neural networks was proposed, which uses the reduced cutoff frequencies of circumferential waves that propagate around the cylindrical shell. The reduced cutoff frequencies of circumferential waves are extracted using modal isolation plan representation. The proposed approach allows us to estimate accurately the values of the radius ratio of the copper cylindrical shell, as well as it can help us to resolve other problems related to acoustic scattering. Furthermore, it can be used to estimate other parameters of the cylindrical shell starting from the characteristics of which it is disposed. The approach proposed in this study does not present any approximation as in the case of the proper mode theory

Scattering of an acoustic wave by composite cylindrical shells: Influence of inner and outer layer thicknesses on the circumferential waves

International audienc

Measured and predicted of the longitudinal and transverse velocities of tube material using the Wigner-Ville and fuzzy logic techniques

International audienceIntelligent modelling tools as artificial neural network (ANN) and fuzzy logic approach are demonstrated to be competent when applied individuality to a variety of problems such as modelling and prediction. Recently there has been a growing interest in combining both these approaches, and as a result, neuro-fuzzy computing techniques have evolved. The advantage of using neuro-fuzzy (ANFIS) in this study for field modelling is given by the flexibility to adapt and relies on observed data rather than on analytical model of the system that some once it is difficult to establish it. In this work, we applied the fuzzy logic for modelling, measuring and predicting of the longitudinal and transverse velocities of material constituting the tube. The useful data to train and to test the performances of the model are determined from the values calculated trajectories of the proper modes theory of resonances and those extracted from time-frequency representations of Wigner-Ville. This representation is applied of the acoustic signal backscattered by an aluminium cylindrical shell immersed in water. The obtained values of the longitudinal and transverse velocities of material tube are in good agreement with those given in the scientific literature

Investigation into the bistatic evolution of the acoustic scattering from a cylindrical shell using time-frequency analysis

International audienc

Characterization and prediction of the backscattered form function of an immersed cylindrical shell using hybrid fuzzy clustering and bio-inspired algorithms

International audienc