International Journal of Mechanics


ISSN: 1998-4448
Volume 6, 2012

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Issue 1, Volume 6, 2012


Title of the Paper: Buckling Analysis of Quasi-Isotropic Symmetrically Laminated Rectangular Composite Plates with an Elliptical/circular Cutout Subjected to Linearly Varying In-Plane Loading Using Fem

Authors: A. Lakshminarayana, R. Vijaya Kumar, G. Krishna Mohana Rao

Pages: 1-8

Abstract: In this paper the effects of circular and elliptical cutout on the buckling behavior of a sixteen ply quasi-isotropic graphite/epoxy symmetrically laminated rectangular composite plate [0°/+45°/-45°/90°]2s, subjected to various linearly varying in-plane compressive loads, numerically. Further, this paper addresses the effects of size of elliptical cutout, orientation of elliptical cutout, plate aspect ratio (a/b), plate length/thickness ratio(a/t) , boundary conditions on the buckling bahaviour of symmetrically laminated rectangular composite plates subjected to various linearly varying in-plane compressive loading is carried out using Finite element method (FEM). The results show that the buckling loads of rectangular composite plates subjected to linearly varying in-plane loads are decreased by increasing of cutout positioned angle β and increasing of c/b and d/b ratios . The magnitudes of buckling loads are decreased by increasing the plate aspect ratio (a/b) and length/thickness (a/t) ratio. It is observed that the buckling loads for composite plates under CC type boundary conditions are higher than those under CS type boundary conditions, irrespective of cutout shape ,size ,orientation of cutout and type of linearly varying in-plane compressive load. It is observed that the buckling loads for composite plates under L4 type loading are higher than those under L1, L2 and L3 type loading, irrespective of cutout shape ,size ,orientation of cutout and boundary conditions.


Title of the Paper: Acoustics and Instability of High-Speed Boundary Layers

Authors: Sergey A. Gaponov, Boris V. Smorodsky

Pages: 9-16

Abstract: Present paper is devoted to those acoustical problems which are also related to the problem of the turbulence onset in highspeed boundary layers. Basic equations governing linear development of both hydrodynamic and acoustic waves in high-speed boundary layers are presented. Results of the theoretical investigation on external acoustic wave influence on the flat plate boundary layer are described. The intensity of disturbances excited by an acoustic wave inside the boundary layer has been studied. It has been found that interaction of sound with the boundary layer lead to an increase of the amplitude of disturbances inside the boundary layer and thisincrease depends on the angle of incidence. It has been established, that maximal amplification of fluctuations inside the boundary layer takes place for the external acoustic wave with the wave-vector orientation parallel to the model surface which is called streamwise acoustic wave. It has been shown that in this case the amplitude of fluctuations inside the boundary layer may exceed the amplitude of the external acoustic field in many times. Besides in the paper nonlinear generation of increasing perturbations by external acoustics is studied.


Title of the Paper: Experimental Damage Analysis of Concrete Structures Using the Vibration Signature - Part I: Diffuse Damage (Porosity)

Authors: Z. Boukria, A. Limam

Pages: 17-27

Abstract: This paper reports on an experimental non-destructive method for characterizing the damage of concrete structures using the vibration signature. The frequency of the material is an indicator of damage to the structure. Pathologies such porosity induces stiffness degradation in the concrete and thus causes damage. The determination of the elastic modulus and resistance characteristics of pecimens through bending and compression tests is used to study the variation of dynamic modulus during cycles of wetting and drying (porosity).


Title of the Paper: Experimental Damage Analysis of Concrete Structures Using the Vibration Signature - Part II: Located Damage (Crack)

Authors: Z. Boukria, A. Limam

Pages: 28-34

Abstract: This paper reports on an experimental non-destructive method for characterizing the damage of concrete structures using the vibration signature. The frequency of the material is an indicator of damage to the structure. The presence of cracks induces stiffness degradation in the concrete and thus causes damage. The determination of the elastic modulus and resistance characteristics of specimens through bending and compression tests is used to study the variation of dynamic modulus with characteristics of crack.


Title of the Paper: Performance Evaluation of a Model Thermocompressor using Computational Fluid Dynamics

Authors: Kavous Ariafar

Pages: 35-42

Abstract: Thermocompressors are widely used in a large number of industries that use steam as their heating medium or as a power generating utility. They are devices that use the energy of a high pressure fluid to move a low pressure fluid and enable it to be compressed to a higher pressure according to the principle of energy conversion. They work like a vacuum pump but without usage of any moving part and so they can save energy. The performance of a thermocompressor highly depends on its geometry and operating conditions. This paper first describes the flow behavior within a designed model of a thermocompressor using the computational fluid dynamics code, FLUENT. Since the flow is turbulent and supersonic, CFD is an efficient tool to reveal the phenomena and mixing process at different part of the thermocompressor which are not simply obtained through an experimental work. Then its performance is analyzed by choosing different operating conditions at the boundaries and also different area ratios which is one of the significant geometrical factors to describe the thermocompressor performance. Finally, the effect of various nozzle exit plane diameters which cause different Mach numbers at the nozzle exit is investigated on the thermocompressor performance. The results indicate that these variables can affect both the entrainment ratio and critical back pressure. This device uses water vapor as the working fluid and operates at 7.5 bar motive pressure, 63°C and 80°C for suction and discharge temperatures, respectively.


Title of the Paper: Effect of Residual Stresses Embedded within Workpieces on the Distortion of Parts after Machining

Authors: Jean-François Chatelain, Jean-François Lalonde, Antoine S. Tahan

Pages: 43-51

Abstract: The life of a structural part for aerospace use is usually a function of the interactions between the existing component defects, the loading conditions in service as well as the existing residual stresses within the parts. Depending on their type, distribution or magnitude, the residual stresses can be beneficial or destructive for the component. Each of the many manufacturing processes used to produce components always adds to the residual stresses, resulting in a final distribution affecting the mechanical properties and producing dimensional and geometrical distortions for the part features. These may lead to high rejection rates and quality-related problems during component assembly. This paper proposes an experimental approach to determine the influence of existing residual stresses within workpieces on the distortion of parts following machining operations. This study compares parts machined from a special 7475-T7351 aluminum alloy material exempt of residual stresses with those machined using the same alloy type but processed through standard approach leading to embedded residual stresses within the rolled material. The residual stresses were measured before and after the machining process for both material types, using the neutron scattering non-destructive inspection technique. The part deformations were evaluated using a coordinate measuring machine equipped with a laser high density scanning head. The results show that the sample parts machined from standard raw materials underwent deformations while those machined from raw materials with a controlled process underwent none or very few deformations. It was observed that the distribution, signs, and magnitudes of the residual stresses may be at the origin of the deformations measured, which indicates that residual stresses embedded within the raw material are partly responsible for the distortion of the part following the machining operation.


Title of the Paper: A Comparison of Special Helical Cutter Geometries Based on Cutting Forces for the Trimming of CFRP Laminates

Authors: Jean-François Chatelain, Imed Zaghbani

Pages: 52-59

Abstract: Various tool materials exist that are capable of withstanding the abrasiveness and strength of Carbon fiber reinforced plastics (CFRPs), namely Diamond, Polycrystalline diamond (PCD) and coated carbide. While these materials offer high hardness, which is a key property for successfully machining CFRPs, only solid carbide offers the flexibility of different cutter geometries, accompanied by reasonable costs. This research analyzes the effects of two non-standard features added to cutters designed for CFRP machining. A standard helical geometry is compared to a cross-cut helical tool and a grooved flute tool based on cutting force analysis, surface roughness and delaminating. The cutters were used for detouring quasi-isotropic laminates with different thicknesses under various machining conditions. It was found that unstable cuts may occur during the machining of CFRP laminates. Some stable speeds and feeds were identified for the different cutters, and for these stable conditions, the force amplitude and profile were compared. It was found that adding features to the standard geometry significantly affects the cutting forces. While the cross cut geometry generates a compressive thrust force, the grooved geometry induces a quasi-null thrust force accompanied by less fluctuation of the feed force and the normal cutting force. It was also found that the cross cut tool damaged the laminates in terms of fibers pullout, voids and instability marks.


Title of the Paper: Flexural-Torsional Response of FRP I-Section Members

Authors: Mojtaba B. Sirjani, Stella B. Bondi, Zia Razzaq

Pages: 60-67

Abstract: Presented herein is the outcome of an experimental and theoretical study on Fiber Reinforced Plastic (FRP) beams with an I-shaped cross section subjected to four-point loading revealing the significance of lateral bending and warping strains due to practical imperfections. The paper also addresses the problem of combined bending and applied torsion. The results show that, for the case of combined bending and induced torsion, the sum of lateral and warping strains in FRP beams is not negligible even in the presence of only the in-plane or vertical loads. Based on measured strains, tentative strain-slenderness relationships are generated which account for the presence of lateral and warping strains in practical FRP beams. The effects of both induced and applied torsion combined with bending are explained with the help of numerical examples. It is also demonstrated that the boundary warping restraints in the form of member end plates cause a substantial decrease in the maximum warping normal stress in a torsionally loaded FRP member.


Title of the Paper: Impact Response of Circular Pre-Stressed Orthotropic and Transversely Isotropic Plates

Authors: Yury A. Rossikhin, Marina V. Shitikova

Pages: 68-87

Abstract: The problem on normal low-velocity impact of an elastic falling body upon a pre-stressed orthotropic plate possessing curvilinear anisotropy is studied with consideration for the changes in the geometrical dimensions of the contact domain. At the moment of impact, shock waves (surfaces of strong discontinuity) are generated in the target, which then propagate along the plate during the process of impact. The classification of transient waves propagating in a thin pre-stressed plate possessing curvilinear orthotropy is presented. Behind the wave fronts upto the boundary of the contact domain, the solution is constructed with the help of the theory of discontinuities and one-term ray expansions. Nonlinear Hertz’s theory is employed within the contact region. For the analysis of the processes of shock interaction of the elastic sphere with the pre-stressed orthotropic plate, a nonlinear integro-differential equation has been obtained with respect to the value characterizing the local indentation of the impactor into the target, which has been solved analytically in terms of time series with integer and fractional powers. The particular case of a pre-stressed transversely isotropic plate is analyzed in detail. A critical review of the approaches for investigating the transient wave propagation in isotropic and pre-stressed orthotropic plates impacted by falling objects is presented.


Title of the Paper: Practical Active Force Control with Iterative Learning Scheme Applied to A Pneumatic Artificial Muscle Actuated Robotic Arm

Authors: M. Mailah, H. M. Hooi, S. Kazi, H. Jahanabadi

Pages: 88-96

Abstract: The precise motion control of a pneumatic artificial muscle (PAM) actuated system poses a great challenge to researchers due to the inherent nonlinearities, time-varying parameters, and high sensitivity to payload of the PAM mechanism. This paper highlights the effective practical implementation of an active force control (AFC) technique incorporating an iterative learning (IL) algorithm known as AFCAIL applied to a two-link planar robotic arm actuated by a pair of PAMs. The iterative learning is primarily used as a technique to compute the best value of the estimated inertia matrix of the robot arm required for the AFC loop that is complemented with a conventional proportional-integral-derivative (PID) control. An experimental rig utilizing a hardware-in-the-loop simulation (HILS) configuration was designed and developed based on suitable hardware and software installation. A number of experiments were carried out to validate the theoretical counterpart considering the independent joint control and coordinated motion control of the system for a given operating and loading conditions. The results of the experimental works verify the effectiveness and robustness of the proposed PAM actuated AFCAIL scheme in executing a number of trajectory tracking tasks.


Issue 2, Volume 6, 2012


Title of the Paper: An Appropriate Approach for Misalignment Fault Diagnosis Based on Feature Selection and Least Square Support Vector Machine

Authors: H. Ahmadi, A. Moosavian, M. Khazaee

Pages: 97-104

Abstract: A study is presented to diagnosis of misalignment fault using feature extraction and selection technique and support vector machine (SVM) classifier. The time-domain vibration signals of a compressor with normal and misalignment conditions in driven end (DE) are gained for feature extraction. The features are extracted by using the statistical and vibration parameters. Then stepwise backward selection is applied for selecting the significant features. The selected features are used as inputs to the classifier for two-class (normal or misalignment) identification. The roles of stepwise backward selection technique and SVM classifier are investigated. The results indicate the potential of the proposed intelligent method in misalignment fault diagnosis of the compressor.


Title of the Paper: The Flow Structure on Drag-Reduced Riblet Surfaces

Authors: Feng Beibei, Chen Darong, Wang Jiadao

Pages: 105-112

Abstract: The structure of air flow on riblet surfaces has beenstudied with direct numerical simulations. Drag reduction wasachieved through optimization of riblet geometry affecting the flowstructure in riblet grooves. Force analysis and flow structure is studiedbased on k-ε turbulence model, and drag reduction and increasemechanism on riblet surfaces is related to the flow alteration.Reynolds shear stress is significantly decreased which is consideredthe dominant factor resulting in drag reduction. Through force analysis,the significant decrease of viscous force is considered the dominantfactor resulting in drag reduction.Pressure drag on riblet surfacesgenerating from the deviation of static pressure on the front and rearend of the riblet occurred and grew exponentially with the flow rate.Near-wall vortical structures, Reynolds shear stress, static pressureand velocity field on riblet surfaces is analyzed in detail.


Title of the Paper: 3D Turbulent Flow Field of an Annular Jet

Authors: B. Patte-Rouland, A. Danlos, E. Rouland

Pages: 113-120

Abstract: The present study relies on an experimental investigation of a large diameter ratio annular air jet by the use of stereo Particle Image Velocimetry (P.I.V.), Laser Doppler Anemometry (L.D.A.). Annular jets are made of a round nozzle in which an internal obstacle is placed in its center. These jets are thus defined by an external diameter Do and an internal diameter Di corresponding respectively to the round nozzle lips and the diameter of the obstacle. The ratio between these two diameters defines the behavior of the flow across a characteristic diameter called diameter ratio. In most applications in the industrial domain these jets have large diameter ratios, superior to 0.7.The annular jet is an example of complex shear flow situations. Two axisymmetric shear layers, originating at the jet exit, one at the nozzle lip and the other at the centre body, eventually meet downstream or interact with each other. The main aim of this study is to observe and analyze the 3D turbulent flow field on an annular jet with a great diameter ratio (r= 0.91). Measurements are conducted with a Reynolds number ReDo=107800. This work will permit us essentially to have a better knowledge of annular jets which present the effect of asymmetries in the experimental jet exit velocities and to meet manufacturers' needs.


Title of the Paper: Strength and Resource of the Melting Tool under Thermomechanical Loading

Authors: Konstantin A. Goncharov, Yury B. Chechulin

Pages: 121-129

Abstract: High-purity titanium alloys are used to produce the most critical elements of aircraft structures. Refractory metals such as titanium, tungsten, molybdenum, niobium, zirconium are smelted in electron-beam furnaces. The melting point of these metals is much higher than the melting point of copper, this is the material, from which made melting tool. Therefore, a necessary condition for the smelting process is the forced cooling of the tool. Melting water-cooled tool is an essential structural component of vacuum-arc, plasma-arc and electron-beam furnaces, which are used to produce high-purity metals with high melting points. A characteristic feature of the design of the melting tool is limited resource. The paper is devoted to the calculation of the stress-strain state and the resource of a melting instrument under thermomechanical loading.


Title of the Paper: Athens Metro Extension Project to Piraeus Ground Borne Noise and Vibration Assessment and Control

Authors: Konstantinos E. Vogiatzis

Pages: 130-139

Abstract: ATTIKO METRO S.A., the state company ensuringthe development of the Athens Metro network, has recently initiateda new extension of 7,6 Km, has planned for line 3 of Athens Metrofrom Haidari to Piraeus “Dimotikon Theatre” towards “University ofPiraeus” (forestation), connecting the major Greek Port with“ELEFTHERIOS VENIZELOS” International Airport. Piraeusextension is consists of a TBM (Tunnel Boring Machine) 2 tracks &NATM, tunnel sections, as well as 6 stations and a forestation (inNATM tunnel) at the end of the alignment. In order to avoid thedegradation of the urban acoustic environment from ground bornenoise and vibration during metro operation, the assessment of therequired track types & possible noise mitigation measures wasexecuted, and for each section and each sensitive building, theground borne noise and vibration levels will be numericallypredicted. The calculated levels were then compared with groundborne noise and vibration levels criteria. The necessary mitigationmeasures were defined in order to guarantee, in each location alongthe extension, the allowable ground borne Noise and Vibration max.levels inside nearby sensitive buildings taking into accountalternative Transfer Functions (TF) for ground borne noise diffusioninside the buildings. Ground borne noise levels were proven to behigher than the criterion where special track work is present and alsoin the case of the sensitive receptor : “Dimotikon Theatre”. In orderto reduce the ground borne noise levels to allowable values in thesesections, the installation of tracks and special track work on afloating slab (FS) was assessed and recommended.


Title of the Paper: Research on the Working Life at Steel Wire Ropes in Contact

Authors: Vîlceanu Lucia, Ghita Eugen, PuĊ£an Vasile

Pages: 140-147

Abstract: In this paper, the authors thought contact pressurewires and the rope take-up roller played an important role in steelropes’ working life and investigate it by using experiments andnumerical methods. During the examination of the wires that makeup an out of order rope, evidence was found that the request oflocal compression between wires had such high values that a printappeared on the wire on the contact area. The contact stressappears between the wires of the same rope strand, of two adjacentrope strands and between the wires and the rope take-up roller. Thepaper shows the research regarding the induced and deformingstress at the moment of contact between wires and the tractioncable take-up roller. The results got after running the program,post-processed in strips with equal stress and displacementindicated symmetry of the stress-strain state according with thetheory. The results will be used to calculate the fatigue crackpropagation and to estimate the steel rope working life.


Issue 3, Volume 6, 2012


Title of the Paper: Influence of Concrete Strength on the Behavior of Steel Tubular Columns Filled by Concrete

Authors: Pavla Bukovská

Pages: 149-157

Abstract: This paper deals with the effectiveness of using circular steel columns filled by high strength concrete in case of structural members subjected to compression. The paper was worked out within the research programme focused on true behavior of steel tubular columns filled by concrete. Attention is focused on influence investigation of concrete strength on the behavior of columns. The paper includes the interpretation and evaluation of the results of experimental analysis, initial results of numerical model and sensitivity analysis. Circular steel tubes filled by normal concrete and circular steel tubes filled by high-strength concrete have been taken into account within the solution. The behavior of tubular columns filled by concrete is compared based on the results of experimental analysis. The behavior of columns without concrete is included into comparison. Numerical model has been developed in order to ensure consistency of the output of the numerical calculation and the data obtained at the test specimens. Finally sensitivity analysis is presented which gives some information about influence of input parameters on the buckling strength. At the conclusion parameters with the greatest influence on the buckling resistance are discussed whereas the efficiency of using high-strength concrete is observed.


Title of the Paper: Analysis of the Actual Behaviour, Stress and Moment Capacity of Composite Beams Composed of Steel and Glass-Fibre-Concrete

Authors: Marcela Karmazínová

Pages: 158-167

Abstract: The paper deals with the problems of the theoretical and experimental analysis directed towards the actual behaviour, strain and failure mechanism and load-carrying capacity of steel-concrete composite beams using glass-fibre-concrete (GFC) slab. The part of this research presented here is focused on the theoretical analysis and experimental verification of the negative bending moment capacity. This paper presents some selected results of the theoretical analysis of the bending moment capacity based on the various conceptions (plastic behaviour, elastic behaviour and their combination, respectively) and experimental verification of the actual bending moment capacity of steel-concrete composite beams with glass-fibre-concrete slab in connection with their actual behaviour and corresponding relevant failure mechanism. Within the framework of the analysis following basic types of beams are investigated, all ones composed of 3 different steel IPE cross-sections (IPE 180, IPE 200, IPE 220) and various types of concrete slab: (i) beams with non-reinforced glass-fibre-concrete slab subjected to negative bending moment, to investigate the contribution of GFC (only) to the negative moment capacity; (ii) beams with steel-reinforced glass-fibre-concrete slab (reduced amount of steel reinforcement) subjected to negative bending moment, to compare the cases (i), (ii); (iii) beams with plain concrete (PC) slab subjected to the negative bending moment, to compare these results with the case (i) for the verification of contribution of GFC (only); (iv) beams with non-reinforced glass-fibre-concrete slab subjected to positive bending moment. During the experimental parts of this research in common 25 steel-concrete composite beams have been tested so far and 11 test specimens have been already prepared for subsequent investigation. The attention was mainly paid to the efficiency of GFC usage in steel-concrete composite beams subjected to negative bending moments, especially to the contribution of GFC to the moment capacity in comparison with normal reinforced concrete. The paper is also focused on the actual stress distribution in steel-concrete section (obtained from the tests) and its evaluation and analysis from the viewpoint of the usual theoretical approaches used for the bending capacity calculation.


Title of the Paper: Theoretical Analysis and Experimental Verification of Moment Resistance of Steel and Timber Beams Strengthened by External CFRP Composites

Authors: Marcela Karmazínová

Pages: 168-178

Abstract: The paper is focused on problems of the application of external reinforcement based on FRP composites for strengthening steel and timber beams to increase their bending moment resistance. Strengthening steel or timber beams using external bonded CFRP composites can appear the advanced way, but the result effect of this reinforcing can be questionable. In this paper the brief information on some results of the research oriented to the investigation of the actual behaviour and resistance of steel and timber beams strengthened by CFRP reinforcement is presented. With respect to practical usage and requirements the attention is paid to the strengthening by externally bonded carbon lamellas. For this problem solution the theoretical analysis and experimental verification mainly are utilized. This paper shows the results and evaluation of experiments realized so far, to verify the actual behaviour and to obtain the objective resistance of reinforced (i.e. externally strengthened by bonded CFRP lamellas) steel and timber beams in comparison with the objective resistance of non-reinforced steel and timber beams obtained from the tests and also in comparison with the predicted resistances, which have been calculated using general principles of the determination of composite cross-section bending resistance, and based on these results to assess the efficiency of CFRP lamellas strengthening. This research is realized on the author’s workplace in co-operation with the company of “PREFA KOMPOZITY Inc.” focusing on the development and production of the reinforcement based on glass-fibre or carbon-fibre reinforced composites, among others.


Title of the Paper: Application of Artificial Neural Networks in Prediction Tool Life of PVD Coated Carbide When End Milling of Ti6al4v Alloy

Authors: Salah Al-Zubaidi, Jaharah A.Ghani, Che Hassan Che Haron

Pages: 179-186

Abstract: Nowadays, the application of artificial neural networks (ANN) is often utilized in solving numerous problems in machining processes. There has been evidence of the significance of a tool life prediction of coated and uncoated cutting tools. The current study aims at applying ANN in the prediction of the tool life of PVD cutting tools using low experimental data sets. It used a feed forward back propagation neural network with a Levenberg-Marquard (L-M) training algorithm is used in modeling the tool life of a PVD insert cutting tool when end milling of Ti6Al4V under dry cutting conditions. One hundred and ten (110) models were designed, trained and tested using Matlab neural network tool box. Based on the same experimental data, a regression model (RM) has been constructed employing SPSS software, and based on the mean square error of ANN and RM models, the two models were compared. The findings revealed that the ANN model resulted into minimum mean square error compared with RM model.


Title of the Paper: Simulation Analysis of Spinning Forming of D6AC Ultrahigh-Strength Low-Alloy Steel

Authors: Cheng-Shun Chen, Jen-Hsin Ou, Huei-Guo Hu

Pages: 187-194

Abstract: Spinning forming is a continuous and complex deformation process. In this paper, a finite element numerical simulation software, ANSYS/LS-DYNA is used to analyze the spinning forming of D6AC ultrahigh-strength low-alloy steel, and the distribution rules of spinning force, forming stress and strain under different wall thickness in a single pass of forward flow forming. Preliminary results indicate that the spinning force will be greater in accord with the increase of reduction rate and the reduction rate can be up to 70%, which can provide an important reference for spinning process.


Title of the Paper: Aircraft Family Concept for High Performance Transport Aircrafts

Authors: Prasetyo Edi

Pages: 195-202

Abstract: The objective of this research is to make a feasibility study of the aircraft family concepts using a combined Hybrid Laminar Flow Control - Variable Camber Wing (HLFC-VCW) for a high performance Advanced Technology Regional Aircraft (ATRA). The prediction of ATRA’s performance used computational fluid dynamic and empirical methods. The aircraft family concept using a combined HLFC–VCW is feasible for ATRA aircraft family from aerodynamic point of view.


Issue 4, Volume 6, 2012


Title of the Paper: Path Planning of Mobile Robot for Autonomous Navigation of Road Roundabout Intersection

Authors: Mohammed A. H. Ali, Musa Mailah, Tang Howe Hing

Pages: 203-211

Abstract: The aim of this research is to develop a robust navigation system for mobile robot in a road roundabout setting using laser range finder (LRF) and vision system. A new algorithm for combining the LRF and vision system is investigated to detect the open space area in a road roundabout. The study focuses on the simulation and experimentation of the mobile robot ability to effectively track the path when countering a roundabout with and without obstacle and considering a number of scenarios. The system is simulated using MATLAB with the grid map used to create the road roundabout environment and select the path according to the respective road rules. The experiments are performed using simple platform with laser range finder and the data are processed in real-time in Matlab. Good results from both simulation and experiments show the effectiveness of the proposed algorithm.


Title of the Paper: A Novel Method for Ring Spinning Performance Evaluation based on Computer Aided Analysis of Yarn Geometry

Authors: R. Furferi, L. Governi, Y. Volpe

Pages: 212-221

Abstract: Yarn hairiness and yarn hand represent keyparameters to be strictly assessed and controlled in textile processessince they affect many aspects such as visual appearance of yarns(and consequently of fabrics), handle, thermal insulation, pleasantsensation during touch and smoothness. This is particularly truewhen fancy yarns, such as jasp? or fris?, are produced using ringspinning: colored natural fibers composing the fancy yarns arerequired to protrude, to some extent, from the yarn core, usuallycomposed by synthetic material, so as to impart the desiredproperties in terms of smoothness and luster. With the aim ofrealizing highest performing fancy yarns, a novel ring spinningsystem, equipped with a double drafting unit, has been realized byUniversit? di Firenze thanks to the contribute of Tuscany Region(Italy). Once the fancy yarns are obtained, the performance of thisinnovative ring spinning is evaluated by means of a Computer Aidedanalysis of yarn geometry able to provide a novel measurement ofyarn hairiness and to quantitatively define a yarn hand-relatedparameter.A Machine Vision system has been devised in order to acquireyarn geometry so that an accurate analysis can be carried out. Suchcomputer aided-based analysis allows to determine two parametersused for determining hairiness and hand: the “equivalent yarnhairiness” and the “yarn hand index”.Such parameters are evaluated for yarns obtained using both theinnovative and a conventional ring spinning machine so that theyarns quality can be effectively compared.Based on the obtained results that the proposed method proved tobe suitable and effective for evaluating yarn hairiness within anaverage error of about 5.40% with respect to the Uster tester.Furthermore, a good correlation (93%) between objective andsubjective assessment of yarn hand was reached.


Title of the Paper: Monte Carlo Approach Applied in the Design of Machine Parts and Structures

Authors: Karel Frydrysek

Pages: 222-229

Abstract: This article focuses on the probabilistic (i.e. directMonte Carlo) numerical solution of the problems in mining, machineindustry and biomechanics. Theory and applications of theSimulation-Based Reliability Assessment (SBRA) method (i.e.Monte Carlo approach) are presented in the solution of the hard rock(ore) disintegration process (i.e. the bit moves into the ore andsubsequently disintegrates it, the results are compared withexperiments, new design of excavation tool is proposed), in theproposal design of machine for fatigue testing of railway axles and inthe solution of designing of the external fixators applied intraumatology and orthopaedics (application for the treatment of openand unstable fractures or for lengthening human or animal bonesetc.). Applications of the SBRA method connected with FEM inthese areas are new and innovative trends in mechanics anddesigning.


Title of the Paper: Application of SBRA Method in Mechanics of Continental Plates

Authors: Karel Frydrysek, Ivo Wandrol, Pavel Kalenda

Pages: 230-237

Abstract: This paper shows how the probabilistic SBRA (Simulation-Based Reliability Assessment) Method (i.e. Monte Carlo approach) is applied to the model of the behaviour of the lithosphere of the Earth. The method extends our initial work where we created the geomechanical model of the lithosphere. The basic idea was about the genesis of thermoelastic waves due to thermal expansion of the rock mass and the ratcheting mechanisms. SBRA method applied in this problem is a new and innovative trend for modelling in mechanics.