So as to create innovative car silhouettes, we propose in this paper a model based on an Interactive Genetic Algorithm using an encoding of a design solution by a Fourier analysis approach. This model permits the designer to browse through generations of car profiles from an initial population of existing silhouettes. By qualitatively assessing each individual, the designer converges towards solutions complying with his/her requirements and preferences, possibly creating novelty and generating surprise. We describe here tests for assessing the efficiency of this innovative design platform. These tests are mainly based on a similarity index, a similarity measure being the perceived distance between two cars silhouettes. The results highlight a good convergence toward a satisfactory solution. In addition, this design process turns out to be very flexible because of the local and intuitive modifications allowed on a given individual solution at any moment of the design process.

Shrink fits are low-price connections which are widely used in industry and industrialconnections. In designing shrink fits it is important to consider radial interface foroptimized performance and also to choose an accurate method of fabrication and assembling.Parts which have to be assembled are usually exposed to thermo-mechanical loads. Mode andtime duration of heat transfer have a significant effect on required hydraulic force,stress time rate of creation in parts and joint ability to withstand against externalloads. Therefore, planning a set of appropriate thermal and structural procedures hassignificant role in reducing energy consumption, optimized performance and promoting thespeed of parts assembly. Despite of the fact, few researches have been done on shrink fitoperation and design, rather than dimensional design. In this study, shrink fits arestudied in two main processes: first heating and mounting process and then backing to theambient condition. A 3D coupled thermal and structural simulation based on FEM is done oneach process through well-known Solidworks Premium. To evaluate the accuracy, exactanalytical solution of two steel rings shrink fit is compared with the approach outcomes.Results of validated method are used for choosing the most optimum sub processes of shrinkfit fabrication.

This paper presents an approach for obtaining an optimized geometry for the flank of atooth by minimizing the equivalent contact stress. The stress calculation method is basedon Hertz theory. As the majority of tooth profiles are involute, the geometric variationof the flank of the tooth is achieved variationally relative to the involute profile. Theoptimum profile is obtained by Monte Carlo simulation. During this optimization, apolynomial expression of the tooth geometry is used. The parameters influencing thesimulation are the four characteristic contact points. The approach presented has beenapplied in a representative case. A study of the geometric sensitivity was conducted onthe optimized tooth profile. Two different approaches were considered: by Monte Carlosimulation and analytical propagation. The robust and linear nature of the behavior of thetooth profile was demonstrated when it was subjected to geometric variations.

In this paper, we present the static and dynamic structural characterisation of alow-mobility parallel kinematic manipulator, involving analysis of its stiffness andvibrational dynamic behaviour. The study starts by building numerical models of thebehaviour of the manipulator to be compared to experimental measurements from a prototype.For the case study, we consider a four-degree-of-freedom(x, y, z, θz) manipulatorwith prismatic actuators designed by the COMPMECH research group at the University of theBasque Country. The characterisation allows the behaviour of the static and dynamicstiffness, as well as the natural frequencies of the manipulator, to be mapped in themanipulator workspace. These maps together with kinematic, static and dynamic constraintslead to the definition of operational, static, dynamic and structural workspaces,respectively. Further, we analyse the modes of the manipulator to determine dynamicdisplacements, these being key in the performance in the machining tasks for which therobot was designed.

Fiber metal laminates (FMLs) are widely used in aerospace industries nowadays. Repairingof the cracks in these advanced materials was first done by some aeronautical laboratoriesin early 1970s. In this study, experimental investigations were done on the effect ofrepairing the center-cracked aluminum plates using the FML patches. The repairingprocesses were conducted to characterize the response of the repaired structures totensile tests. The composite patches were made of one aluminum layer and two wovenglass-epoxy composite layers. Three different crack lengths in three crack angles anddifferent patch lay-ups were examined. It was observed that no matter what the cracklength was, the more the crack angle is larger, the more ultimate tensile strength of thestructure became. It was also indicated that the patch lay-up had an important effect onthe tensile response of the repaired specimens. When the aluminum layer of the patches wasfarther from the repair zone, the ultimate tensile strength reached to its maximum value.

The problem of the squeezing of a fluid film with a complex rheology is studied. Thefluid is represented by the Phan-Tien and Tanner (PTT) constitutive equation. The goal ofthe paper is to develop an analytical approach which allows one to describe and quantifythis process, which is often present in classical lubrication problems, but particularlyin human joints. The present approach can potentially supplement time-consuming and costlypurely numerical methods which are also susceptible to misleading artifacts. A parametricstudy reveals the effect of fluid elasticity compared to viscous effects and someexplanation is suggested as to their possible links with joint diseases.

The use of natural fibers in the development of composite materials is a sector in full expansion. These fibers were used for their low cost, their availability and their renewable character. The fibers of the palm (palm tree) were used as reinforcement in polypropylene (PP). The date palm fibers have some potential because of their ecological and economic interest. Both unmodified and compatibilized fibers are used. Compatibilization was carried out with the use of maleic anhydride copolymers. The morphology and mechanical properties were characterized by electron microscopy scanning (SEM) and tensile tests. The influence of fiber content on mechanical properties of composite PP/date palm has been evaluated and demonstrated, that the maximum stress and elongation decreases with increasing fiber volume rate. On the other hand, an increase of the tensile modulus has been noticed, but after the fibers improvement, the maximum stress increases significantly up to 25% weight.

A polydisperse case of an entangled linear polymer melts constitutive equation wasstudied. This constitutive equation, proposed by S. Dhole et al. [J. Non-Newtonian FluidMech. 161 (2009) 10–18], based on the reptation theory and the tube model, was tested on apolystyrene in shear (capillary rheometry) and planar extension in a complex flow(fieldwise measurements in a contraction flow) for different level of strain rates. A goodquantitative prediction of all the set of experiments was obtained, using no adjustablenonlinear parameters.

The bearing is one of the most important components of rotating machines. Nevertheless,in normal conditions of use, it is subject to fatigue which creates a defect called arolling fatigue spalling. In this work, we present a follow-up of the thrust bearingfatigue on a test bench. Vibration analysis is a method used to characterize the defect.In order to obtain the fatigue curve more adjusted, we have studied the vibration levelaccording to statistical indicators: the Root Mean Square value (RMS value), which is oneof the best indicators to show the evolution of the bearing degradation. The approachfollows the working of the bearing until the degradation with an on line acquisition ofvibration statements in form of time signals. With the signal treatment, we obtain thevalues of the vibration amplitudes which characterize the vibration state of the bearing.Consequently, these values allow us to plot the fatigue curves. During our experimentalwork, this operation is applied for a batch of thrust bearings for which we have obtainedsimilar fatigue curves where the evolution trend follows a regression model from thedetection of the onset of the first spall. The result of this work will contribute topredict the working residual time before failure.