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Titanium alloys Ti-6Al-4V, have been broadly utilized in industries, particularly aerospace and medical manufacturing, owing to their good mechanical properties. In this work, high energy CO2 laser cutting of 3 mm-thick titanium alloys sheets is investigated with the aim of estimating the effects of the various laser cutting parameters such as, laser power (Pu), cutting speed (V) and of assist gas pressure (p), on the integrity of the cutting area. The objective of this study is to analyze the cut edge microstructure and to optimize the surface roughness using Taguchi method. Performances denote optimum cutting condition was obtained to be 3 kW for the laser intensity, 2400 mm/min for the cutting speed and 8 bars for gas pressure.

International audience; Rubber modified epoxy based composites were designed by low cost production methods. Basically, clean and recycled materials were used to provide a solution for manufacturing of lightweight, cost efficient composites in industrial applications such as automotive and aeronautical engineering. In the present study four different compositions have been developed and characterized for their potential usage as structural materials. The matrix was prepared by treatment of epoxy with 10% recycled rubber. Nano-magnetic iron oxide, Fe3O4, was added to the matrix as reinforcement elements in different percentages. Nickel and aluminium were also add as auxiliary additional elements. Measurements of magnetic permeability and dielectrically properties have been carried out for electronic devise applications basically in aeronautical engineering. Dynamic Scanning Calorimeter (DSC) and Dynamic Mechanical Analysis (DMA) were carried out to determine thermo-mechanical properties. Static tests have been carried out by 3-point bending (3PB) tests for mechanical characterization. Furthermore, creep and wear behaviour of these compositions were evaluated by means of nanoindentation tests to analyze time dependent behaviour of these composites. Macro scratch tests were made in very high cycle test conditions for their measurements in long time resistance. Microstructural and fracture surface analyses have been carried out on the scanning electron microscopy (SEM).All of the experiments; scanning electron microscopy, nanoindentation, static (3PB), test results expose a combined effect of toughening mechanisms high strength and ductile, lightweight and low-cost composites based on the rubber modified epoxy composites reinforced with nano magnetic iron oxide and auxiliary fine nickel and nano aluminium powders.

In modern technology, analysis of fatigue behaviour of engineering components is obligatory to develop engines and mechanical parts to improve the performance and to increase lifetime up to 109 cycles. On the other hand, the estimations and analysis of the mechanism of fatigue failure must be known in detail for steel industry to develop high quality steels. In this research, different alloys, failed under high frequency fatigue conditions, used in the automotive industry, were studied: steels, heat treated at different conditions, cast iron and cast aluminium with different tensile strength ranging from 220 to 2350 MPa. These alloys were tested at very high cycle–gigacycle-fatigue (VHCF, >107), using a piezoelectric fatigue system (20 kHz) under tension–compression conditions with a stress ratio of R = −1. The central part of each specimen was cooled by compressed air to keep the temperature constant at room temperature. Fatigue failure values were usually located between 107 and 1010 cycles. Effects of defect types on failure mechanism in very high cycle fatigue range are discussed here in detail with fracture surface analysis by using Scanning Electron Microscopy (SEM).

The study of microstructure and damage mechanism of elastomeric matrix (EMC), wooden plastic (WPC) and also metal matrix (MMC) composites involves a complicated interplay between material properties and service conditions. So, the study of texture deformation and fatigue behaviour of EMC, WPC and MMC specimens is of considerable practical interest. On the other hand, the occurrence of defect in specimens in working conditions is an important problem. It is necessary to improve the microstructure for delaying instability, in order to obtain a higher service capacity. This paper presents the in-situ observation of damage by using χ -rays computed tomography (CT) Medical Scanner installed in the ITMA research centre for evaluating the fatigue behaviour of EMC, WPC and MMC. A tomographic inner-health analysis will be given from 2D slices of the examined parts in laboratory scale on the WPC, EMC and MMC specimens used in automotive industry and aeronautical fields.

Fatigue crack initiation behaviour is investigated at room temperature in the (α 2 -Ti 3 Al and γ-TiAl) alloy. High cycle fatigue tests ranging up to 10 10 cycles are carried out on the powder metallurgy (P/M) bar specimens under different loading conditions with a stress ratio of R =0.1 and R =0.5. Microstructural characterization and fracture surface analysis are also investigated by optical (OM) and scanning electron microscopy (SEM). Ti–Al alloy studied here shows two phases in microstructure (nearly refined lamellar thickness) composed of α 2 -Ti 3 Al and γ-TiAl (hereafter called γ+α 2 alloys) and fracture mechanism is explained with different plastic incompatibilities between the two phases.