Engineering December 2004 Vol 10/4 []

CONTENTS & ABSTRACTS

In English. Summaries in Estonian

Proceedings of theEstonian Academy of Sciences.

Engineering



Volume 10 No. 4December 2004



Selected papers of the 4thInternational DAAAM Conference INDUSTRIAL ENGINEERING – INNOVATION ASCOMPETITIVE EDGE FOR SME



Preface; 235

Jüri Papstel †

Acomparative analysis of global search procedures; 236–250

Alexander Janushevskis, Teodor Akinfiev, JanisAuzins and

Alexander Boyko

Abstract. This paper presents abrief overview and a comparison of global optimization methods and theirsoftware. By solving a set of recognized test problems, the reliability ofobtaining the global extremums is compared. It is shown that the Edaoptalgorithm, developed formerly by the authors, is more efficient than moderngenetic algorithms. In most cases the Edaopt algorithm takes also noticeablyless computation time.

Key words: optimization,stochastic global search, genetic algorithms.

A 3Dturning system to reduce geometry errors of flexible rotors; 251–260

Thomas Widmaier, PetriKuosmanen, Janne Haikio and

Pekka Väänänen

Abstract. Increased running speed and reduction of accepted vibration levelsin paper machines have set new demands for the roundness and cylindricity ofpaper machine rolls. The diameter variation is mainly caused by the slidewaystraight­ness error of the machine tool. The rotational er­rors during themachining process come about because of the changing dis­tance between the rollaxis and the tool and are copied to the roundness error in the roll. A3D turning system, including a measuring device, was developed tocompensate systematic roll geometry errors. The non-circular turning method wasapplied to a supercalender roll. The 3D turning reduced the averageroundness error in the test roll by 62 %, the diameter variation in theaxial direction was reduced by 83 % and the 3D geometry error by78 %.

Key words: roll, roundness, measuring, non-circular turn­ing.

Modellingand optimal design of the incremental forming process;261–269

Meelis Pohlak, ReinKüttner and Jüri Majak

Abstract. Recently, a new sheet metal forming technique, incremental forming,has been introduced. It is based on the use of a universal spherical tool,which is moved along the CNC controlled tool path. For optimal design of theincremental forming process, application of non-linear mathematical programmingis suggested. To estimate the limitations and main parameters of the process, acomplex model for process design has been developed. Incremental formingprocesses are investigated using experiments and finite element analysis.

Key words: incremental sheet metal forming, finite element analysis,optimal design, non-linear programming.

Advanced dynamic models for evaluation ofaccuracy of machining on lathes; 270–280

Gennady Aryassov, Tauno Otto and Svetlana Gromova

Abstract: This paper describes the influence of lathe vibrations on the accuracyand roughness of machined parts. The calculation schemes involve systems withone and two degrees of freedom, representing vibrations of the blank as a rigidbody, hinged in the spindle and elastically supported in the tailstock of thelathe. Experimental measurements were performed on lathes of type 1K62 atdifferent cutting speeds, feeds and depths of cut. The analysis of roughnessmeasurement data confirmed the accuracy of the proposed calculation model.Surface roughness parameters of the blank satisfactorily agreed with thecorresponding data of the theoretical investigation. To study the influence ofgyroscopic forces on the surface roughness, the calculation model with twodegrees of freedom was used. The results of experimental and theoreticalinvestigations coincided satisfactorily.

Key words: lathe, vibration, calculationmodel, natural frequency, surface roughness.

Linearstability analysis of shear-flexible thin-walled beams;281–289

Domagoj Lanc, Goran Turkaljand Josip Brnić

Abstract.This paper presents finite element based numericalstability analysis of thin-walled beam structures. Using the linearized virtualwork principle with the assumption of large displacements, large rotations butsmall strains, a finite element equation is derived. Effects of cross-sectionalshear deformations are also taken into account. To include large rotationeffects, non-linear displace­ment field of the cross-section is used. A newtwo-node shear-flexible finite element with seven degrees of freedom per nodeis developed. Complete exact 14×14 elastic and geometric stiffness matrices areevaluated. An original computer program THINWALL-SHEAR is developed. Obtainedresults are compared with analytical and numerical results of other authors.

Key words: thin-walled beam, largedisplacements, large rotations, shear deformations.

Torquedistribution control unit in automotive propulsion systems;290–299

Jüri Resev and Lembit Roosimölder

Abstract. The paper considers energy flow modellingin automotive propulsion systems to provide basic data for the selection of theparameters of the differential, bearing in mind its impact on the vehiclelateral dynamics. The characteristicsand operational conditions of the limited-slipdifferen­tial gear train are found. A virtualdifferential (algorithm of energy flow) has been created.

Key words: planetary gear train, limitedslip, torque transmission, energy loss, modelling.

Designof sandwich support structures; 300–307

Martin Eerme, Mart Enok, Lembit Roosimölder and ReinKüttner

Abstract. In modernengineering industry the weight reduction of support structures of machines isimportant. One possibility to reach that is to use sandwich structures.Mechanical properties of sand­wich structures are characterized by higherstrength/weight and stiffness/weight ratios than those of stiffened steel platestructures. This paper studies the possibility of replacing welded structuresby sand­wich ones using topology optimization. In the conceptual phase,topological optimization has been performed that allowed to find a structurallysound initial model for further design and para­metri­cal optimization.Topological and parametrical optimization has been performed using a commercialFEM software system. This method is flexible by designing products withdifferent con­figura­tions that is important by shortening the time to marketnew products. Welded steel structures, consisting of walls and ribs, areconsidered. Strength properties, depending on the ribs’ configuration and onthe length of welds, have been examined. Technology of manufacturing sandwichframes are described. As an example, the design and reduction of mass of abrush-cutting machine has been investigated.

Key words: metal structures, optimization, FEM.

Performanceof hard alloys in abrasive-erosive and sliding wear conditions;308–314

Jakob Kübarsepp, Heinrich Klaasen and Vello Vainola

Abstract. The wear behaviour of some carbidecomposites differing in composition and structure (WC hardmetals, TiC and Cr3C2cermets), has been investigated in abrasive-erosive and sliding wearconditions. Comparative trials in the same conditions with tool steels,complemented by SEM studies, have been performed. It has been shown that inabrasive-erosive as well as in sliding wear conditions the performance of ahard alloy (carbide composite, tool steel) is controlled primarily by itscarbide phase (its properties and amount in the alloy).

Key words: abrasive-erosive wear, sliding wear, cemented carbides, tool steels.

Recycledhardmetal-based powders for thermal spray; 315–325

Valdek Mikli, Priit Kulu, Riho Tarbe, PriiduPeetsalu and

Sergei Zimakov

Abstract. The paper focuses on low-cost tungstencarbide based spray powders with particle size of 15–50 mm, produced fromrecycled hardmetal. Their properties are comparable with commercially produced(Tafa Inc., Sulzer Metco Inc., etc.) powders. Different methods of WC-Cohardmetal powder preparation (plating, milling and mixing) were used to producespray powders. The composition and structure of recycled hardmetal-based spraypowders, produced by the disintegrator, attritor and ball milling, wereinvestigated. Powders were chemically and mechanically plated with Co oragglomerated, using different plating techniques and heat treat­ment. Chemicalcomposition of powder particles was studied by energy-dispersive X-ray micro­analysisand element distribution inside powder particles was investigated on particlecross-sections with the X-ray mapping technology. Best results were obtainedusing monomodal initial WC-Co and Co powders with the mixing, agglomeration,sintering and crushing techniques.

Key words: recycling, disintegration, milling andmixing, agglomeration and sintering, double-cemented hardmetal powder, particlecomposition.

Contents of volume 10; 326–328