Tarek Mabrouki

Bio: Tarek Mabrouki is an academic researcher from Tunis University. The author has contributed to research in topics: Machining & Chip formation. The author has an hindex of 30, co-authored 109 publications receiving 3413 citations. Previous affiliations of Tarek Mabrouki include Institut national des sciences Appliquées de Lyon & University of Lyon.

Statistical analysis of surface roughness and cutting forces using response surface methodology in hard turning of AISI 52100 bearing steel with CBN tool

Abstract: The present work concerns an experimental study of hard turning with CBN tool of AISI 52100 bearing steel, hardened at 64 HRC. The main objectives are firstly focused on delimiting the hard turning domain and investigating tool wear and forces behaviour evolution versus variations of workpiece hardness and cutting speed. Secondly, the relationship between cutting parameters (cutting speed, feed rate and depth of cut) and machining output variables (surface roughness, cutting forces) through the response surface methodology (RSM) are analysed and modeled. The combined effects of the cutting parameters on machining output variables are investigated while employing the analysis of variance (ANOVA). The quadratic model of RSM associated with response optimization technique and composite desirability was used to find optimum values of machining parameters with respect to objectives (surface roughness and cutting force values). Results show how much surface roughness is mainly influenced by feed rate and cutting speed. Also, it is underlined that the thrust force is the highest of cutting force components, and it is highly sensitive to workpiece hardness, negative rake angle and tool wear evolution. Finally, the depth of cut exhibits maximum influence on cutting forces as compared to the feed rate and cutting speed.

Numerical and experimental study of dry cutting for an aeronautic aluminium alloy (A2024-T351)

Abstract: In the present contribution, numerical and experimental methodologies concerning orthogonal cutting are proposed in order to study the dry cutting of an aeronautic aluminium alloy (A2024-T351) The global aim concerns the comprehension of physical phenomena accompanying chip formation according to cutting velocity variation For the numerical model, material behaviour and its failure criterion are based on the Johnson–Cook law The model proposes a coupling between material damage evolution and its fracture energy A high-speed camera was used to capture the chip formation sequences The numerical results show that the chip–workpiece contact and the tool advancement induce bending loads on the chip Consequently, a fragmentation phenomenon takes place above the rake face when the chip begins to curl up The computed results corroborate with experimental ones The numerical results predict the residual stress distribution and show high values, along the cutting direction, on the machined workpiece surface

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

New observations on tool life, cutting forces and chip morphology in cryogenic machining Ti-6Al-4V

Abstract: The use of cryogenic coolant in metal cutting has received renewed recent attention because liquid nitrogen is a safe, clean, non-toxic coolant that requires no expensive disposal and can substantially improve tool life. This work investigates the effectiveness of cryogenic coolant during turning of Ti-6Al-4V at a constant speed and material removal rate (125 m/min, 48.5 cm 3 /min) with different combinations of feed rate and depth of cut. It is found that the greatest improvement in tool life using cryogenic coolant occurs for conditions of high feed rate and low depth of cut combinations. However, this combination of machining parameters produces much shorter tool life compared to low feed rate and high depth of cut combinations. It is found that preventing heat generation during cutting is far more advantageous towards extending tool life rather than attempting to remove the heat with cryogenic coolant. Although cryogenic coolant is effective in extracting heat from the cutting zone, it is proposed that cryogenic coolant may limit the frictional heat generated during cutting and limit heat transfer to the tool by reducing the tool–chip contact length. The effect of cryogenic coolant on cutting forces and chip morphology is also examined.

Mechanism-based Strain Gradient Plasticity 를 이용한 나노 인덴테이션의 해석

Abstract: Recent experiments have shown the 'size effects' in micro/nano scale. But the classical plasticity theories can not predict these size dependent deformation behaviors because their constitutive models have no characteristic material length scale. The Mechanism - based Strain Gradient(MSG) plasticity is proposed to analyze the non-uniform deformation behavior in micro/nano scale. The MSG plasticity is a multi-scale analysis connecting macro-scale deformation of the Statistically Stored Dislocation(SSD) and Geometrically Necessary Dislocation(GND) to the meso-scale deformation using the strain gradient. In this research we present a study of nano-indentation by the MSG plasticity. Using W. D. Nix and H. Gao’s model, the analytic solution(including depth dependence of hardness) is obtained for the nano indentation , and furthermore it validated by the experiments.