Volume 1, No. 11 (2005)
Articles
SIMULATION AND EXPERIMENTAL INVESTIGATION OF THE BLANKHOLDER FORCE INFLUENCE ON SPRING BACKEFFECT FOR TAILOR WELDED BLANKS
ALBUŢ AURELIAN
This paper deals with some numerical simulation and experimental tests related to forming and springback of a rectangular part manufactured from tailor welded blanks. Final shape of the parts manufactured by TWB is seriously affected by springback effect. This paper work is trying to prove out the important role that blankholder force has on the springback reduction. The influence of the blankholder force on the TWB springback is examined using the simulation by finite element method (ABAQUS). Experimental tests have been carried out using different blankholder force and maintaining constant all other parameters. The resulted parts were measured using a 3D scanning machine. An optimum holding force is established and the results are presented in the final section of this paper.
INVESTIGATION BY SIMULATION OF THE BLANKHOLDER INFLUENCE ON SPRINGBACK EFFECT OF A RECTANGULAR PART MANUFACTURED BY TAILOR WELDED STRIPES
ALBUŢ AURELIAN
This paper deals with some numerical simulation issue related to tailor welded stripes forming and springback. Final shape of the parts manufactured by TWB is greatly affected by springback effect.The intensity of this phenomenon depends on the parameters of the forming process. This paper work is trying to reveal the important role that blankholder force has on the springback reduction. The influence of the blankholder force on the TWB springback is examined using the simulation by finite element method.
COMPUTER ANALYSIS OF DYNAMIC RESPONSE OF GEAR TRANSMISSIONS WITH BACKLASH CONSIDERATION
ATANASIU VIRGIL
The paper presents an analytical and computer-aided analysis of the dynamic characteristics of spur gear transmissions. The dynamic analysis of geared systems is difficult to accurately investigate due to the nonlinear characteristics accounting for periodic changes of tooth stiffness and gear backlash. An improved model to calculate the cyclic mesh stiffness of gear pairs is developed in order to obtain reliable data for the prediction of gear dynamic behavior. The relation between gear ratio and stiffness function is presented. A comparative study has been performed to investigate the effects of the mesh stiffness variation and the backlash between contacting teeth on the dynamic characteristics of gear systems.
EFFECT OF FRICTION CONDITIONS ON THE SPRINGBACK PARAMETERSOF THE CYLINDRICAL DRAWPARTS
AXINTE CRINA
Springback is an inherent phenomenon in all sheet metal forming processes. It affects the shapeand dimensional precision of the drawn parts and, in its turn, depends on the interaction of tools design,process parameters and part geometry. In the present work the effect of the friction conditions on thespringback parameters of the cylindrical drawn parts is analyzed.
EXPERIMENTAL ANALYSIS OF THE SPRINGBACK PARAMETERS OF THECYLINDRICAL DRAWN PARTS
AXINTE CRINA
Springback is an instability phenomenon that affects the dimensional accurace of the drawn part.In order to find a method which allow to eliminate or at least to control the springback, it is necessary first to analyze the variables which influence its magnitude.The present work deals with the effect of the blankholder force coupled with the friction conditions on the springback parameters of the cylindrical drawn parts.
THE NEW SIEMENS COLLABORATIONS IN ROMANIA
BĂICUŞI ADRIAN, TANZEGLOCKE DIRK, FLANDORFER WOLFGANG
This paper proposes to present the activity of Siemens in Romanian industry. Also are presented the most new aspects of Siemens and Romanian firm’s collaborations and modernization of the country’s infrastructure.
MANUFACTURING TECHNOLOGY FOR A NEW TYPE OF PROFILEDROTOR
BARAN N., DONTU O., BESNEA D., DUMINICA D., MENGHER R.
The paper presents the sketch and the functioning principle of a new type of volumetric rotating pump using two identical profiled rotors.Achieving such a pump involves, in a first phase, the building of a functional model defined by the dimensions previously established. A computation method was elaborated for the outline of the rotor profile, as well as the manufacturing technology. The advantages of the new type of volumetric rotating pump are also presented.
Considerations on the methods using to measure the mechanical properties of the human bones
BÎTCĂ CONSTANTIN, BÂRSĂNESCU PAUL-DORU, MIHĂLCUŢ MIHAI
This paper presents some of the important methods to measure the properties of bone under loading, used successfully in testing laboratories. This list remains open for other methods. The knowledge of the dynamic behavior has an important influence to design the human bone prosthesis. The experimental studies can contribute to understand the biomechanical phenomenons, to increase the quality of prosthesis and to increase the lifetime of these. The obtained results can be used in the Finite Element Methods.
Application of the Taguchi method for the compensation of errors determined by springback in the case of a conical lied made from metal sheets
BRABIE GHEORGHE, SCHNAKOVSZKY CAROL, CHIRIŢĂ BOGDAN, CHIRILĂ CIPRIAN, AXINTE CRINA
Springback of draw parts considerably affects their accuracy and deviations from the theoretical profile, this instability phenomenon determining the following changes of the part shape and geometric parameters: arching of the part sidewall, modification of the angle formed by the part bottom and the sidewall, modification of the angle between the flange and the sidewall. The methods applied in order to reduce or eliminate springback are based on tools correction after designing and testing, on the utilization of special tools and devices, on the optimization of process parameters based on some methods that establish a link among springback parameters and the influencing factors of this phenomenon. These methods are expensive and necessitate a big number of experimental tests. Based on these conclusions, it is necessary the development of a method for the reduction or the elimination of the springback from the designing stage.
Application of the Taguchi method for the compensation of errors determined by springback in the case of a draw half-rim with stiffness channels made from metal sheets
BRABIE GHEORGHE, SCHNAKOVSZKY CAROL, AXINTE CRINA, CHIRILĂ CIPRIAN, CHIRIŢĂ BOGDAN
Springback of draw parts considerably affects their accuracy and deviations from the theoretical profile, this instability phenomenon determining the following changes of the part shape and geometric parameters: arching of the part sidewall, modification of the angle formed by the part bottom and the sidewall, modification of the angle between the flange and the sidewall. The methods applied in order to reduce or eliminate springback are based on tools correction after designing and testing, on the utilization of special tools and devices, on the optimization of process parameters based on some methods that establish a link among springback parameters and the influencing factors of this phenomenon. These methods are expensive and necessitate a big number of experimental tests. Based on these conclusions, it is necessary the development of a method for the reduction or the elimination of the springback from the designing stage.
MATHEMATICAL MODELING OF TOOL WEARING IN CASE OF FRONTALMILLING
CHIRILĂ CIPRIAN, GHERGHEL MIHAI
In this paper are presented the steps needed in order to determine the mathematical model of toolwearing as a linear or quadratic polynomial function using the Taguchi method. In order to obtain themathematical models, a plan of fractional factorial design experiments was elaborated. The computationtask required to determine the coefficients of polynomial function was carried out using dedicated software.
ANALYSIS OF STRESS – STRAIN STATE IN U BENDING OF SHEET METALSUSING FINITE ELEMENT METHOD
CHIRIŢĂ BOGDAN
Nowadays there is an increasing tendency to use the finite element methods in the design ofsheet metal forming processes. The classical trial and error procedures are replaced with simulations of theprocesses. In order to obtain valuable data that can be used in real life it is necessary to create accuratesimulations that should reproduce as close as possible the conditions of the real process. This paperpresents a series of simulations of the U bending process and analyses the evolution of the stress – strainstate in different conditions. The results of the simulations will be compared with experimental ones.
REDUCTION OF SPRINGBACK PHENOMENON IN U BENDING OF SHEETMETAL USING DESIGN EXPERIMENT
CHIRIŢĂ BOGDAN
Springback is the most important failure mode for the sheet metal parts obtained by U-bending.Numerous studies have been conducted in order to develop a method for an accurate prediction andlimitation or elimination of this phenomenon. As there is not possible to use an analitical method for thisproblem, numerical methods, especially finite element method, have been developed and applied for sheetmetal forming. This paper uses U-bending simulation by finite element analysis combined with a fractionalfactorial design in order to establish a method for the reduction of springback parameters.
THE STATIC CAPACITY OF THE INNEAR THREADS EXECUTEDBY PLASTIC DEFORMATION
CRISTEA ION, DRAGOI DAN
The static durability of the threads is settled by iso rules and determined by the test of turn tearing onthe bolt.The fact that the threading by deformation insure to the threading turns a continuos fibre unlike the basismaterial insures a growth of the durability comparing to the threads obtained by splinteringThe process of thread deformations, leads to a greater concentration of the steel pearlite grains under thepression of deformation, ( it is realized in this way a thickening of the pearlite grains ). Consequently thereoccurs a general deformation of the chrystal grating of the deformed metal layer, that influences the quality ofthe piece
ELASTO-PLASTIC DEFORMATION FOR INNERTHREADS EXECUTED BY PLASTIC DEFORMATION
CRISTEA ION, DRAGOI DAN
When analysed in section, the stratum of plastically deformed material, shows that, no matter thewhay we realise the deformation of the thread the changes of structure occur on a longitudinal direction,transversal and cross the working surface. Plastic deformations are accompanied by a series of fenomenawhich lead almost totally to an improving of the caracteristics of the threading. In exchange, the elasticdeformations have negative impacts, especially for the production of the threads. Using the electroniccomputer, it was realised a diagram of the state of deformation in the sectionof a spiral of of the threadwhich can be used quantitatively and qualitatively for the analysis of the machanic characteristics of thethreads obtained by plastic deformation.
SIEMENS ROMANIA – AUTOMATION AND DRIVE
DOROFTEI MIHAI, MOLCUTI NICOLAE
This paper proposes to present the collaboration a Siemens with Romanian industrial anduniversity partners. Emblem for this department is SINUMERIK equipments. There under name (mark) isoffered a large spectrum of product hardware and software for machines tools automation with numericalcontrol.
EXPERIMENTAL RESEARCHES CONCERNING THE INFLUENCE OF THEEDGE RADIUS R AND PITCH FEED SD ON THE ROUGHNESS OF THESURFACES MECHINED BY FINISHING MILLING OF CAST IRON
GHERGHEL MIHAI, CHIRIŢĂ BOGDAN
The first part of the paper presents the results of the experimental researches that were realizedin order to establish the dependency of the parameters Ra and Rz on the edge radius r and pitch feed Sd atthe finishing milling of cast iron. In the second part of the paper the obtained results are analysed and theconclusions of the experimental research are presented.
EXPERIMENTAL RESEARCHES CONCERNING THE INFLUENCE OFCUTTING EDGE RADIUS R AND FEED SD ON WEARING AND DURABILITYOF A CARBIDE TOOL IN CASE OF FINISHING MILLING FOR SILVERY PIGIRON
GHERGHEL MIHAI, CHIRILĂ CIPRIAN
In this paper are presented the results of experimental researches made in order to establish theinfluence of cutting edge radius r and feed Sd on wearing and durability of a carbide tool in case offinishing milling for silvery pig iron, class K10. In this paper are also analyzed the particularities ofwearing process in case of high speed finish milling.
SIEMENS – 100 YEARS IN ROMANIA
HAAS BERHNARD, DOROFTEI MIHAI
This paper proposes to present the activity of Siemens in Romanian industry. Also are presentedthe beginning historical aspects from Siemens and Siemens Romanian collaborations.
COMBINED RESEARCHES ON THE SAFETY EVALUATION OF A PRESSED JOINT
ILIESCU NICOLAE *, ATANASIU COSTICĂ *, NĂSTĂSESCU VASILE **
The torsion moment transmitted by the driving axle of a electric locomotive, in the skidding regime of the wheels, was experimentally determined by a special measuring transducer. The contact pressure in the pressed joint between the axle and the locomotive wheel was determined by calculus using a finite element analysis (FEA). The stress state, both in the wheel hub as well as in the axle, was also investigated. Using the average value of the contact pressure, the maximum torsion moment transmitted by the pressed joint was calculated. By calculating the ratio between the maximum torsion moment value obtained by calculus and the torsion moment value determined experimentally, in the skidding regime of the driving wheels, the safety coefficient of the pressed joint was established.
DETERMINATION OF SAFETY AND SECURITY FACTOR OF A GAS PIPE EXHIBITING A CORROSION DEFECT BY USING SINTAP PROCEDURE COUPLING WITH PROBABILISTIC METHOD (PART I)
JALLOUF S., CARMASOL A., SCHMITT C., PLUVINAGE G.
In this paper, the goal is to compute the remaining safety and security factors after apparition of corrosion crater in a gas pipe using probabilistic approaches. For these purposes, we propose to use the failure assessment diagram SINTAP level I coupled with Monte Carlo, FORM or SORM methods.Application is made for a pipe of diameter 219,1mm and thickness 6.1mm submitted to internal pressure of70 bars. Corrosion crater is assumed to be a crack like defect of depth equal to half thickness and crack aspect ratio.
DETERMINATION OF SAFETY AND SECURITY FACTOR OF A GAS PIPE EXHIBITING A CORROSION DEFECT BY USING SINTAP PROCEDURE COUPLING WITH PROBABILISTIC METHOD (PART II)
JALLOUF S., CARMASOL A., SCHMITT C., PLUVINAGE G.
In this paper, the goal is to compute the remaining safety and security factors after apparition of corrosion crater in a gas pipe using probabilistic approaches. For these purposes, we propose to use the failure assessment diagram SINTAP level I coupled with Monte Carlo, FORM or SORM methods.Application is made for a pipe of diameter 219,1mm and thickness 6.1mm submitted to internal pressure of70 bars. Corrosion crater is assumed to be a crack like defect of depth equal to half thickness and crack aspect ratio a/c = 0.2. The safety factor obtained by applying SINTAP procedure is found equal to fs = 4.5.The security factor obtained from a probability of failure of 10-6 is found equal to fS = 2.5.
ADVANTAGES AND DISADVANTAGES OF YIELD CRITERIA FORANISOTROPIC MATERIALS - SINTESIS
JUDELE ADRIAN
During many years yield criteria had been developed by different researchers. All of themhaving the same purpose, modeling the behavior of anisotropic materials. Differences between them are theyield functions, mechanical parameters, and other. Subject of this paper is a synthesis of the yield criteriadeveloped during the years.
F.E.M. ANALYSIS OF IMPACT PROBLEMS
NĂSTĂSESCU VASILE, PINTILIE GHEORGHE, ZICHIL VALENTIN
Using of the finite element method for analysis of the impact problems became an usual solving way. Thereare some very powerful programs, specialized in this type of problems, which are able to say not only if aprojectile perforates or not an armor plate, but to calculate some parameters used in protection appreciation,in characterizing of the materials etc. Next to these aspects, using of the finite element method allow us tosimulate just the fracture of the material in a manner very closed of reality. The modeling of the materialfracture can be made using appropriate material models.This paper presents some consideration upon the most used material models which can simulate thematerial fracture. A special attention is paid to the Cowper-Symonds coefficients and to the Johnson-Cookmaterial model.
CONSIDERATIONS ABOUT COWPER-SYMONDS COEFFICIENTS
NĂSTĂSESCU VASILE, ZICHIL VALENTIN, PINTILIE GHEORGHE
One of the most used material model for impact analysis and material fracture simulating is theElastic Plastic with Kinematic Hardening Model, being strain rate dependent plasticity for isotropicmaterials.This material model uses the constants and which are strain rate parameters, known as Cowper-Symonds (from 1983 and Jones) coefficients. Determination of these coefficients is very difficult becausespecial machines are necessary. On the other hand, the technical literature is very poor as these coefficientsare concerned.This paper presents a methodology for determination of C and P coefficients if an experimental curveexists.
THE LIFETIME OF MECHANICAL STRUCTURESUNDER FATIGUE CONDITIONS
PĂUNESCU MIHAELA
This paper is presenting a lifetime calculation method of welding joint between flange and the cylindrical vessels body, under variable pressure conditions. This method is based on fracture mechanics concept and it is applicable without difficulty, when the strains, the material property and the geometrical elements are known.
THEORETICAL ANALYSIS OF A CIRCULAR THIN PLATE UNDER PRESSURECLAMPED TO RIM IN THE PLASTIC RANGE DEFORMATION
PERNEVAN IOAN*, PERNEVAN MARIA*
This work presents a computational method for solving the plane-plastic-stress and strains withaxial symmetry problems applied in the sheet hydro forming technology. The sheet hydro formed may beapproximate to a circular membrane under pressure clamped at the rim.
LIFE TIME ESTIMATION OF A BUTTERFLY LAPPET VALVE
PINTILIE GHEORGHE, ZICHIL VALENTIN, ALBUŢ AURELIAN
Butterfly valves are widely used in hydraulic installations transporting the water needed in petrolindustry. The butterfly lappet is periodically loaded during opening and closing, the fluid pressure. Thisload generates normal bending stresses which are maximal on the lappet surface, around the rotation axle.Usually, the butterfly lappet fails due to crack initiation, leading to pressure-tight loss before braking. Forthis reason, estimation of the lappet life time is very important way to assure its functional safety. Thispaper gives the basic theoretical elements used in the proposed analysis and a case study is presented for alappet having the diameter of 600 mm used in a hydraulic installation for water transportation at 20atmospheres pressure (2MPa)
EXPERIMENTAL AND SIMULATION ANALYSIS OF SPRING BACK IN THECASE OF A CONICAL DRAW LIED MADE USING TOOLS CORRECTED BYAPPLYING THE TAGUCHI METHOD OF OPTIMIZATION
SCHNAKOVSZKY CAROL, BRABIE GHEORGHE, CHIRILĂ CIPRIAN, CHIRIŢĂ BOGDAN, AXINTE CRINA
Springback of draw parts considerably affects their accuracy and deviations from the theoreticalprofile, this instability phenomenon determining the following changes of the part shape and geometricparameters: arching of the part sidewall, modification of the angle formed by the part bottom and thesidewall, modification of the angle between the flange and the sidewall. Hence, in order to obtain thedesired accuracy of the draw parts it is necessary the development of a method for the reduction or theelimination of the springback. The paper presents the results of an experimental analysis of the springbackparameters resulted in the case of conical draw lied manufactured by using tools corrected in the designingstage by applying the optimization Taguchi’s method.
EXPERIMENTAL AND SIMULATION ANALYSIS OF SPRINGBACK IN THECASE OF A DRAWN HALF-RIM MADE USING TOOLS CORRECTED BYAPPLYING THE TAGUCHI METHOD OF OPTIMIZATION
SCHNAKOVSZKY CAROL, BRABIE GHEORGHE, CHIRIŢĂ BOGDAN, CHIRILĂ CIPRIAN, AXINTE CRINA
Springback of draw parts considerably affects their accuracy and deviations from the theoreticalprofile, this instability phenomenon determining the following changes of the part shape and geometricparameters: arching of the part sidewall, modification of the angle formed by the part bottom and thesidewall, modification of the angle between the flange and the sidewall. Hence, in order to obtain thedesired accuracy of the draw parts it is necessary the development of a method for the reduction or theelimination of the springback. The present paper presents the results of an experimental analysis ofspringback parameters resulted in the case of a draw half-rim manufactured by using tools corrected in thedesigning stage by applying the optimization Taguchi’s method.
THE ENHANCED SPECIMEN AND TESTING DEVICE FOR PLANAR SHARESTRAIN TEST OF SHEET METAL
UNGUREANU VIOREL, JUDELE ADRIAN
A technique for share strain test of sheet metal has been developed allowingthe equivalent stress-equivalent strain curve determination. Because an previous versionof testing device and specimen shows strain concentration at the corner of tested area,was performed a FEM optimization of the specimens shape and dimensions. Changingthe length of tested area and the testing device design, allows more accurate results ofsharing test. The method of strain share test is quite reliable and can be used in the studyof forming behaviour of sheet metals, and compared with the tensile and other testingmethods.
THE TENSOR OF LOGARITHMIC AND CONVENTIONAL STRAINS
UNGUREANU VIOREL
The focus of this paper is the presentation of linear and angularcomponents of logarithmic strain tensor useful in the description of large plasticdeformation. The definition of logarithmic strain is obtained from law of energytransformation and conservation. The linear and angular components of logarithmic straintensor are compared with the conventional strain. The differences between theconventional and logarithmic (true or natural strain) are presented in some obtaineddiagrams. The components of logarithmic strain are useful in the experimental analysis ofstrain field in the cold forming processes, and in the mechanical characteristics of thematerials determination.
THE STUDY OF COMPRESSIVE STRESS AND DEFORMATION FOR THE ELEMENTS OF FRICTION COUPLE FOR THE BRAKES WITH AXIAL MOVEMENT
UNGUREANU MIORIŢA
The paper does the part from a series research to the substitution of the block brakes from the machines of mining extraction with brakes with axial movement( brakes with disks) and he does advert to the machine of extraction 2T3000X1500 produced by UNIO Satu Mare. With this end in view I am analyzed the elements of friction couple with help of the method with finite element
F.E.M. ANALYSIS OF STRESS AND STRAIN STATE AT THE EXTERNAL LINKPLATE OF THE CAMSHAFTCHAIN OF A D.I. DIESEL ENGINE
ZICHIL VALENTIN, NASTASESCU VASILE, PINTILIE GHEORGHE, SAVIN CARMEN, JUDELE ADRIAN, ALBUŢ AURELIAN
The paper presents theoretical and experimental analysis of the induced and cripplingstress and strain of the external link on the camshaft chain of a Direct Injection Dieselengine. For the experimental tests, tensometry and photoelasticimetry were used in orderto obtain an overall image of the induced stress state. For the present time, the authorscould not find an analytic solution but in the limits of some hypotheses far from thereality. That is why, the experimental results was followed by a numerical analysis, usingfinite elements method. The values obtained after the model running using F.E.M.,correspond with the numerical results, so the devices used are validated, and may beused as standards for further researches in future.
F.E.M. ANALYSIS OF THE FRACTURE CONDITIONSAT THIN WALL ALUMINIUM PIPES
ZICHIL VALENTIN, NASTASESCU VASILE, PINTILIE GHEORGHE, SAVIN CARMEN, JUDELE ADRIAN, ALBUŢ AURELIAN
The paper present the installation and the methodology for numerical analysis, usingfinite elements method that has been used for the breaking test of the aluminum pipes andalso the general characteristics of the experimental results. The tested pipes have thesame diameter D = 18 mm, but different wall-thickness: 2 mm for the civil constructionpipes and 0.9 mm for the hydro melioration pipes. The time - pressure diagram ispresented. The value of the breaking pressure for each tested pipe is determined, firstfrom the theoretical approach and second, from the experiment. The solutions based onthe classic beam structural theory and the detailed finite element analysis results havebeen confronted.