International audienceIn this paper, a deep study of constitutive parameters definition effect is done in order to guarantee sufficient reliability of the finite element machining modeling. The case of a particular biphasic titanium alloy Ti6Al4V known by its low machinability is investigated. The Johnson-Cook (JC) elasto-thermo-visco-plastic-damage model combined with the energy-based ductile fracture criteria is used. Segmentation frequency, chip curvature radius, shear band spacing, chip serration sensitivity and intensity, accumulated plastic strain in the formed chip segments, and cutting forces levels are determined where their dependency to every constitutive coefficient is examined and highlighted. It is demonstrated from the separate variation of every plastic and damage parameters that an interesting finite element modeling (FEM) relevance is reached with the adjustment of JC strain hardening coefficients term, thermal softening parameter, exponent fracture factor, and damage evolution energy. Moderate and high cutting speeds are applied to the cutting tool in the aim to test their impact on shear localization, chip segmentation, and numerical forces levels as well as to approve previous highlighted findings related to constitutive parameters definition. In general, this study focuses on a prominent decrease in identification process cost with the previous knowledge of the most affecting constitutive coefficients while keeping an interesting agreement between numerical and experimental results

Increasing aircrafts' productivity and reducing their riveting time have created the need of one-shot drilling of dissimilar materials. The present work had followed this strategy on 4 shaft satin weave carbon fiber and epoxy matrix (AS-4 woven CFRP) and aluminum alloy (AA 2189) in order to study the effect of drilling direction on Al and carbon fiber reinforced polymer thrust force evolution and holes' quality. It presents a comparison between CFRP, CFRP/Al, and Al/CFRP results using the same drilling tool and cutting parameters to understand the influence of adding metal layers on CFRP drilling defects. It was observed that the increase of the thrust force is related to cutting parameters. It causes thermal degradation of composite matrix when drilling CFRP/Al, and it impacts the aluminum surface roughness. One-shot drilling strategy does not affect thrust force evolution whenever the layers' position in the stack. Drilling defects exist especially in the composite part such as uncut fibers, chipping, and spalling. It was found that the cutting speed had the dominant influence on surface damage. Holes' quality differs from one configuration to another. Adding Al layer on the top reduces seriously the composite drilling defects and causes groove in the Al holes. Composite matrix smearing was observed when drilling CFRP/Al. It seems that drilling CFRP sheet between to supports improves composite holes' quality.

Part manufacturing estimation cost is a critical and important task for industrial firms. Price evaluation helps the enterprise occupy a successful competitiveness in the market. In fact there are three main approaches for the manufacturing cost evaluation the analytic approach, the analogic approach and the parametric approach.This paper presents a cost estimation system of manufacturing dies based on a semi-analytic approach. The developed system uses a semi-analytic approach based on the principle of the analogic approach and analytic approach. This principle has recourse to the analogic approach to search for analogies between the shapes to be machined before grouping them into complex machining features [1]. For each feature parameter the system generates a process to be used as a sample and consequently a model of machining time. In a second stage and by using the analytic approach, the cutting time is determined either by removal rates of metal units for rough operation (cm 3 /min) or from the finishing operation surface (cm 2 /min) or by both production ways [1]. The after cutting return time is calculated through the equations developed for each machining type [2].

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