Operations Research
Walid Meslameni; Chokri Ben Salem
Abstract
Bending is one of the most frequently used processes in the sheet metal products industry. The major users are mainly the automotive, aeronautics and electrical engineering industries. It is necessarily a cold forming operation of a flat material, with or without lubricant, obtained notably by exceeding ...
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Bending is one of the most frequently used processes in the sheet metal products industry. The major users are mainly the automotive, aeronautics and electrical engineering industries. It is necessarily a cold forming operation of a flat material, with or without lubricant, obtained notably by exceeding its elastic limit. After retraction of the tools and relaxation of the stresses, a springback consequently occurs and a permanent deformation persists causing certain geometric modifications of the product. As a matter of fact, this phenomenon, will absolutely affect the angle and curvature of the bend, for such reason it must be taken into consideration in order to manufacture sheet metal parts bent within acceptable tolerance limits. However, the value of this springback is influenced by a multiplicity of process parameters, such as the thickness of the sheet, the hold time of the bending operation, the material properties and last but not least the depth of strike of the tool. In this paper, we have developed a model for predicting springback in the air V-bending process using the design of experiments method. Four three-level factors were considered in order to model springback in using the response surface method (RSM). The experimental tests were carefully carried out on a HACO press brake and on aluminum, ordinary steel and stainless steel specimens with different thicknesses. The in-depth study of the response surfaces to the different tests with the method of analysis of variance (ANOVA), allowed us to determine a robust empirical model linking the springback to the variables of the study. In addition, several relevant numerical simulations using the finite element method (FEM) with software (Abaqus) were performed to predict the evolution of springback when varying the parameters in the field of design of experiments. In fact, the comparison of the values predicted by the two approaches shows a satisfactory agreement.
Case studies in industry and services
Walid Meslameni; Taoufik Kamoun
Abstract
The evolution of the means aimed at improving the availability of strategic equipment requires a credible level of maintenance with the development of original monitoring techniques such as vibration diagnostics. The vibration monitoring of strategic equipment through a vibration diagnosis requires mainly ...
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The evolution of the means aimed at improving the availability of strategic equipment requires a credible level of maintenance with the development of original monitoring techniques such as vibration diagnostics. The vibration monitoring of strategic equipment through a vibration diagnosis requires mainly the identification of vibrational images of the different types of damage. However, one of the important vibration problems is essentially due to the phenomenon of imbalance. This phenomenon corresponds to an imbalance of the rotor due to the offset between the axis of inertia and the axis of rotation, which causes significant and cyclical vibrations. The aim of this study is to analyze the vibratory behavior of a screw compressor to improve its reliability and consequently its availability. To identify the imbalance fault, two sets of vibration measurements on April and January were fundamentally examined at the compressor level. Fourier transform based on spectral analysis was used to create a vibration detection approach with vibration signals. The comparison of the results obtained with that of the simulation resulting from the model of dynamic behavior of the compressor is conclusive.
