Linear sliding wear behavior of aluminium matrix composites reinforced by particulates

Linear sliding wear behavior studied for metal composites. Different types of composites were tested and three different fabrication techniques: two foundry techniques with different volume fraction and particulates size and thermal projection. The results show that the lubrication has a strong effect on the wear rate. The composites did not wear when tested under oil lubrication conditions, while the cable wore rapidly. The opposite phenomena occurred when dry tests were performed: the cable was protected while the specimen wore quickly. The critical volume fraction, i.e. the minimum volume fraction of particulates for protecting the composites, is on the order of 10%, whatever the size of the reinforcement. This minimum volume fraction does not seem to significantly depend on the size of the particulates. Finally, it was observed that the wear rate of the composite is the lowest for composites reinforced by a low percentage of particulates. A mechanical model describes the behavior of both partners (cable and MMC)

Modeling and Optimization of Cutting Parameters during Machining of Austenitic Stainless Steel AISI304 Using RSM and Desirability Approach

In the current paper, cutting parameters during turning of AISI 304 Austenitic Stainless Steel are studied and optimized using Response Surface Methodology (RSM) and the desirability approach. The cutting tool inserts used in this work were the CVD coated carbide. The cutting speed (vc), the feed rate (f) and the depth of cut (ap) were the main machining parameters considered in this study. The effects of these parameters on the surface roughness (Ra), cutting force (Fc), the specific cutting force (Kc), cutting power (Pc) and the Material Removal Rate (MRR) were analyzed by ANOVA analysis.The results showed that f is the most important parameter that influences Ra with a contribution of 89.69 %, while ap was identified as the most significant parameter (46.46%) influence the Fc followed by f (39.04%). Kc is more influenced by f (38.47%) followed by ap (16.43%) and Vc (7.89%). However, Pc is more influenced by Vc (39.32%) followed by ap (27.50%) and f (23.18%).The Quadratic mathematical models, obtained by the RSM, presenting the evolution of Ra, Fc, Kc and Pc based on (vc, f, and ap) were presented. A comparison between experimental and predicted values presents good agreements with the models found.Optimization of the machining parameters to achieve the maximum MRR and better Ra was carried out by a desirability function. The results showed that the optimal parameters for maximal MRR and best Ra were found as (vc = 350 m/min, f = 0.088 mm/rev, and ap = 0.9 mm)

Multi-objective optimization of surface roughness, cutting forces, productivity and Power consumption when turning of Inconel 718

International audienceNickel based super alloys are excellent for several applications and mainly in structural components submitted to high temperatures owing to their high strength to weight ratio, good corrosion resistance and metallurgical stability such as in cases of jet engine and gas turbine components. The current work presents the experimental investigations of the cutting parameters effects (cutting speed, depth of cut and feed rate) on the surface roughness, cutting force components, productivity and power consumption during dry conditions in straight turning using coated carbide tool. The mathematical models for output parameters have been developed using Box-Behnken design with 15 runs and Box-Cox transformation was used for improving normality. The results of the analysis have shown that the surface finish was statistically sensitive to the feed rate and cutting speed with the contribution of 43.58% and 23.85% respectively, while depth of cut had the greatest effect on the evolution of cutting force components with the contribution of 79.87% for feed force, 66.92% for radial force and 66.26% for tangential force. Multi-objective optimization procedure allowed minimizing roughness Ra, cutting forces and power consumption and maximizing material removal rate using desirability approach

Experimental study of a turbo-alternator in industrial environment using cyclostationarity analysis

International audienceThe cyclostationarity method is used in this paper for the diagnosis of a turbo-alternator working in industrial environment for the detection of the defects generated by rolling bearings, journal bearings, and gears. This study shows the advantage of using such analysis as an aid to diagnosis and decision making before a failure caused by bad vibration monitoring of rotating machinery can be produced. In fact, a cyclostationary signal has some hidden periodicities, which mean that it is not strictly periodic, but some statistical properties of the signal are periodic. This periodicity identifies the spectral correlation by integrating the modulation intensity distribution function that depends only of the cyclic frequency, which is an indicator of the presence of modulations. The method was initially applied on a theoretical signal simulating a single bearing fault. The experimental validation is then performed on the machine faults simulator (MFS) for the detection of a bearing fault, and on a turbo-alternator working in real conditions in industrial environment. The application of this method helped to highlight very clearly the presence of defects on the bearings and the gears, which has been difficult to show especially at low frequency by spectral analysis