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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers A
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Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 22, Issue 4 - Apr 1998
Volume 22, Issue 3 - Mar 1998
Volume 22, Issue 2 - Feb 1998
Volume 22, Issue 1 - Jan 1998
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Thermo-viscoplastic finite element analysis of orthogonal metal cutting considered tool edge radius
Kim, Kug-Weon ; Lee, Woo-Young ; Sin, Hyo-Chol ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 1~15
DOI : 10.22634/KSME-A.19126.96.36.199
In this paper, thermo-viscoplastic finite element analysis of the effect of tool edge radius on cutting process are performed. The thermo-viscoplastic cutting model is capable of dealing with free chip geometry and chip-tool contact length. The coupling with thermal effects is also considered. Orthogonal cutting experiments are performed for 0.2% carbon steel with tools having 3 different edge radii and the tool forces are measured. The experimental results are discussed in comparison with the results of the FEM analysis. From the study, we confirm that this cutting model can well be applied to the cutting process considered the tool edge radius and that a major causes of the "size effect" is the tool edge radius. With numerical analysis, the effects of the tool edge radius on the stress distributions in workpiece, the temperature distributions in workpiece and tool, and the chip shape are investigated.estigated.
A study on relaxation of thermal stresses of heat-resistant systems
Choi, Deok-Kee ; Kim, Chang-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 16~22
DOI : 10.22634/KSME-A.19188.8.131.52
This paper addresses a method which can be used for analyzing thermal stresses of a functionally graded material(FGM) using semi-analytical approach. FGM is a nonhomogeneous material whose composition is changed continuously from a metal surface to a ceramic surface. An infinite one dimensional FGM plate is considered. The temperature distribution in the FGM is obtained by approximate Green's function solution. To expedite the convergence of the solutions, alternative Green's function solution is derived and shows good agreement with results from finite difference method. Thermal stresses are calculated using temperature distribution of the plate.
Shape estimation of the composite smart structure using strain sensors
Yoon, Young-Bok ; Cho, Young-Soo ; Lee, Dong-Gun ; Hwang, Woon-Bong ; Ha, Sung-Kyu ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 23~32
DOI : 10.22634/KSME-A.19184.108.40.206
A shape estimation is needed to control actively a smart structure. A method is, hence, proposed to predict the deformed shape of the structure subjected to unknown external load using the signal from sensors attached to the structure. The shape estimation is based on the relationship between the deformation of the structure and the signal from the sensors. The matrix containing the relationship between the deformation and signal is obtained using fictitious force or eigenvector of global stiffness matrix. Then the deformed shape can be predicted using the linear matrix and signal from sensors attached to the structure. To verify this method, experiment and FEM were performed and it was shown that the shape estimation method based on the fictitious force predicts deflections well and more accurately than that based on eigenvector.
Temperature increase of the spindle bearing system having a gear on the bearing span
Choi, Jin-kyung ; Lee, Dai-Gil ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 33~43
DOI : 10.22634/KSME-A.19220.127.116.11
High cutting speeds and feeds are essential requirements of a machine tool structure to accomplish its basic function which is to produce a workpiece of the required geometric form with an acceptable surface finish at as high a rate of production as is economically possible. Since the bearings in high speed spindle units are the main heat source of the total cutting system, in this work, the thermal characteristics of the spindle bearing system with a tilting axis were investigated using finite element methods to improve the performance of the spindle bearing system. Based on the theoretical results, a specially designed prototype spindle bearing system has been manufactured. Using the manufactured spindle bearing system, the thermal characteristics were measured. From the comparison of the experimental results with the theoretical ones, it was found that the finite element method predicted well the thermal characteristics of the spindle bearing system.
A study on the application of electrochemical method for degradation evaluation
Kwon, Jae-Do ; Moon, Yun-Bae ; Kim, Sang-Tae ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 44~51
DOI : 10.22634/KSME-A.1918.104.22.168
In order to develop the evaluation methods of degradation for the Ni-Cr-Mo-V steel, which is in use for turbine rotor in nuclear power plant, the degraded materials were prepared by simulated degradation methods. The result of impact test and fatigue crack growth test shows that the FATT(Fracture Appearance Transition Temperature) and fatigue crack growth rate increased with the increase of degradation. And the result of new electrochemical polarization test method was suggested for the evaluating FATT, fatigue crack growth exponent and coefficient C values based on the results of relationship between corrosion current density(Icorr) & FATT, and the m & C and Icorr.
A study on the impact pulse analysis with various shapes and materials of impactor
Lee, Yeong-Sin ; Kim, Dong-Jin ; Gang, Geun-Hui ; O, Jong-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 52~63
DOI : 10.22634/KSME-A.1922.214.171.124
The impact programmer for impact test was designed and the impact analysis was conducted. The effects of the material and geometric parameters on the impact force and pulse shape were investigated. The impact characteristics were examined by experimental and finite element method. The impact test was conducted with free drop impact tester. The ABAQUS/Explicit 5.5 version was used for finite element analysis. The geometric parameters of the conical and dome type impact programmer were analyzed. The polyurethane impact programmers were fabricated and tested. The effects of the hardness and thickness of the impact programmer were studied. The peak acceleration and time duration of impact programmer have close correlation with the hardness, impact energy and thickness of the impactor. The experiment was good agreement with analytical predictions. The impact pulse shape generated with polyurethane impact programmer was half sine shape. The maximum impact force was proportional to impact energy. The impact acceleration was decreased with thickness of impact programmer. The maximum impact time duration level was about 2 msec.
A study on the fracture toughness evaluating method for cryogenic structural material
Kwon, Il-Hyun ; Chung, Se-Hi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 64~72
DOI : 10.22634/KSME-A.19126.96.36.199
This paper was undertaken to develop the fracture toughness testing method using small and single specimen compared to the conventional method in evaluating elastic-plastic fracture toughness of the superconducting magnet structural material at cryogenic temperature. The elastic-plastic fracture toughness test was conducted by using the unloading compliance method recommended by ASTM E813-89 to accomplish the above purpose. And, the 20% side-grooved 0.5TCT and 1TCT specimens were used to evaluate the fracture toughness by using as possible as miniaturized CT specimen. The unloading compliance method was a very useful method in evaluating elastic-plastic fracture toughness at cryogenic temperature. It could be taken valid fracture toughness values by using 20% side-grooved 0.5TCT specimen recommended by ASTM E813-89.
Thermal shock characteristics of FGM for gas turbine blade
Lim, Jae-Kyoo ; Song, Jun-Hee ; Kim, You-Jig ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 73~79
DOI : 10.22634/KSME-A.19188.8.131.52
The development of a new material which should be continuously usable under severe environment of very high temperature has been urgently requested. The conventional thermal barrier coating(TBC) is a two layer coating, but a composition and a microstructure of functionally graded material(FGM) are varied continuously from place to place in ways designed to provide it with the maximum function of mitigating the induced thermal stress. The purpose of this study is to evaluate the heat-resistant characteristics by thermal shock of laser and furnace heating. The fracture behaviors of non-FGM(NFGM) and FGM were investigated based on acoustic emission(AE) technique during thermal shock test. Therefore, it can be concluded that FGM gives higher thermal resistance compared to NFGM by AE signal and fracture surface analysis.
Structural strain measurement using a 3*3 passive demodulated fiber optic michelson interferometric sensor
Gwon, Il-Beom ; Gang, Hyeon-Gyu ; Kim, Cheon-Gon ; Hong, Chang-Seon ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 80~89
DOI : 10.22634/KSME-A.19184.108.40.206
The measuring method of structural strain by a 3*3 passive-demodulated fiber optic interferometric sensor was developed to implement the real-time monitoring of structural status. A 3*3 fiber optic Michelson interferometric sensor was constructed to sense the value and the direction of structural strain. This sensor was applied on the cantilevered aluminum beam to experiment the sensing of the structural deformation. The digital signal processing was programmed by LabVIEW to determine the structural strain from the fiber optic signals. This program was verified by various simulated fiber optic signals. Finally, the structural was well determined by this developed program from real fiber optic signals.
Scheduling of flexible manufacturing systems with the consideration of tool set-up times
Yim, Seong-Jin ; Lee, Doo-Yong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 90~101
DOI : 10.22634/KSME-A.19220.127.116.11
This paper presents a scheduling method that uses Petri net modeling and heuristic search to handle the tool setup. In manufacturing systems, a tool is attached to a particular machine to process a particular operation. The activity to attach a tool to a particular machine and detach the tool from the machine requires time. The processing time of operations varies according to the attached tool and the machine used. The method proposed in this paper uses Petri net to model these characteristics and applies a search algorithm to the reachability graph of the Petri net model to generate an optimal or near-optimal schedule. New heuristic functions are developed for efficient search. The experimental results that show the effectiveness of the proposed method are presented.
Hydrodynamic forces of impeller shroud and wear-ring seal on centrifugal pump
Ha, Tae-Woong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 102~110
DOI : 10.22634/KSME-A.1918.104.22.168
The analysis of lateral hydrodynamic forces in the leakage path between a shrouded pump impeller through wear-ring seal and its housing is presented. Governing equations are derived based on Bulk-flow and Hirs' turbulent lubrication model. By using a perturbation analysis and a numerical integration method, governing equations are solved to yield leakage and rotordynamic coefficients of force developed by the impeller shroud and wear-ring seal. The variation of rotordynamic coefficients of pump impeller shroud and wear-ring seal is analyzed as parameters of rotor speed, pressure difference, shroud clearance, wear-ring seal clearance, and circumferential velocity at the entrance of impeller shroud for a typical multi-stage centrifugal pump.
Three-dimensional Finite Element Analysis of Rubber Pad Deformation
Shin, S.J ; Lee, T.S ; Oh, S.I ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 111~120
DOI : 10.22634/KSME-A.1922.214.171.124
This paper is the first one of two-parted research efforts focusing on the modeling of rubber pad forming process. The rubber pad, driven by the pressurized fluid during the forming process, pushes the sheet metal to solid tool half and forms a part to final shape. In this part of the paper, a numerical procedure for the FE analysis of the rubber pad deformation is presented. The developed three-dimensional FE model is based on the total Lagrangian description of rubber maerial characterized by nearly incompressible hyper-elastic behavior under a large deformation assumption. Validity of the model as well as effects of different algorithms corresponding to incompresibility constraints and time integration methods on numerical solution responses are also demonstrated.
Three-dimensional Finite Element Analysis of Rubber Pad Deformation
Sin, Su-Jeong ; Lee, Tae-Su ; O, Su-Ik ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 121~131
DOI : 10.22634/KSME-A.19126.96.36.199
This paper applies the FE analysis procedure, developed in the Part I of the companion article, to the three-dimensional rubber pad deformation during rubber-pad forming process. Effects of different algorithms corresponding to incompressibility constraint and time integration methods on numerical solution responses are investigated. Laboratory scale experiments support the validity of the developed FE procedure an demonstrate the accuracy of the numerical models. Full scale model responses are also predicted using the reasonable method and parameters obtained in laboratory modeling.
Parallelization of sheet forming analysis program using MPI
Kim, Eui-Joong ; Suh, Yeong-Sung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 132~141
DOI : 10.22634/KSME-A.19188.8.131.52
A parallel version of sheet forming analysis program was developed. This version is compatible with any parallel computers which support MPI that is one of the most recent and popular message passing libraries. For this purpose, SERI-SFA, a vector version which runs on Cray Y-MP C90, a sequential vector computer, was used as a source code. For the sake of the effectiveness of the work, the parallelization was focused on the selected part after checking the rank of CPU consumed from the exemplary calculation on Cray Y-MP C90. The subroutines associated with contact algorithm was selected as targe parts. For this work, MPI was used as a message passing library. For the performance verification, an oil pan and an S-rail forming simulation were carried out. The performance check was carried out by the kernel and total CPU time along with theoretical performance using Amdahl's Law. The results showed some performance improvement within the limit of the selective paralellization.
Fatigue properties of nitrided titanium using fluidized bed furnace
Kim, Min-Gun ; Ji, Jueng-Keun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 142~147
DOI : 10.22634/KSME-A.19184.108.40.206
Rotary bending fatigue tests were carried out on the nitrided titanium in order to investigate the effect of nitriding layer on fatigue limit. Main results obtained are as follows. (1) The fatigue limit of nitrided pure titanium is remarkably reduced because of enlargement of grain size at high heat treating temperature and high stress field created from the elastic interaction in the compound layer. (2) Further test using specimen which was removed nitrified layer gradually, were also conducted and it was found that by removing the compound layer the fatigue limit recovered as the level of basic material and rather increased by coming of a diffusion layer. Therefore it is concluded that the surface compound layer generated by nitriding treatment reduced the fatigue limit but diffusion layer increased it.
Development of CAD tool for optimal spot weld joints
Ryu, Si-Uk ; Lee, Jong-Chan ; Lee, Tae-Soo ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 148~159
DOI : 10.22634/KSME-A.19220.127.116.11
Spot welding palys a key role in increasing productivity and weight reduction of the final products. This paper proposes a systematic approach on the design of spot weld configuration, dealing with the requried number and location of spot weld joints under the given design parameters, such as the applied loads, lap area, and individual spot weld strength. The optimal design of a spot-welded joint is postulated as a state when the safety factors of all spot weld points (i) are evenly distributed and (ii) reach maximum value. A CAD program is developed to arrange the optimal location of each spot weld based on the derived objective function and constraints. The CAD tool integrates the optimization procedure with Finite Element Analysis (FEA) code through an interface. The interface automatically provides geometrical data and mesh configuration for different spot weld locations to FEA model. It also extracts the transmitted load of each spot weld from the FEA code, and allows the optimization code predict an improved arrangement of spot weld locations. The feasibility of the developed approach is demonstrated by the selected examples.
Analysis of small surface crack growth of round bar under rotary bending stress
Oh, Hwan-Seop ; Lee, Byeong-Gwon ; Park, Cheol-Hui ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 160~169
DOI : 10.22634/KSME-A.1918.104.22.168
The purpose of this study for the prediction of fatigue crack propagation behavior, Stress Intensity Factor(F) of round bar with 3-Dimensional half circular, semi-elliptical icro surface crack under rotary bending stress for the variable aspect, size, rotation angle was analyzed by Boundary Element Method (BEM). It is predicted that behavior of crack growth is half circular or circular crack (b/a.geq.1) and propagate to b/a.leq.0.85.
A dynamic analysis for constrained multibody systems using pseudo-inverse and projection matrix
Kim, Oe-Jo ; Yoo, Wan-Suk ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 170~176
DOI : 10.22634/KSME-A.1922.214.171.124
In this paper, the column space and null space of the Jacobian matrix were obtained by using the pseudo-inverse method and projection matrix. The equations of motion of the system were replaced by independent acceleration components using the null space matrix. The proposed method has the following advantages. (1) It is simple to derive the null space. (2) The efficiency is improved by getting rid of constrained force terms. (3) Neither null space updating nor coordinate partitioning method is required. The suggested algorithm is applied to a three-dimensional vehicle model to show the efficiency.
A study on the evaluation for material degradation of 0.0Cr-0.5Mo steel by a electrochemical polarization method
Na, Eui-Gyun ; Kim, Hoon ; Lee, Jong-Gi ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 177~189
DOI : 10.22634/KSME-A.19126.96.36.199
The contents of this paper include a non-destructive technique for evaluating the degradation of the boiler superheater tube in a fossil power plant through an electrochemical polarization test. Correlation between Ip of polarization parameter and SP-DBTT for the superheater tubes in long-term use was obtained. 1.0Cr-0.5Mo steel was degraded by softening, and the degree of degradation was dependent upon carbides with Cr and Mo elements. Since brittle fracture at low temperature and ductile fracture mode at high temperature were shown, similarity between standard Charpy and small punch tests could be found. In addition, SP-DBTT showing the degree of degradation was higher, as the time-in use of the materials got longer. Electrolyte including picric acid of 1.3 g in distilled water of 100ml at 25.deg. C temperature and sodium tridecylbenzene sulfonate with 1g could be applied to evaluate the degradation of 1.0Cr-0.5Mo steel by means of the electrochemical polarization test. Ip and Ipa values measured through the electrochemical test are the appropriate parameters for representing the degradation of the superheater tube(1.0Cr-0.5Mo steel) for the fossil power plant. It is poassible to evaluate the degradation of materials with different time histories electrochemically, by Ip value only, at field test.
Vibration analysis of a pretwisted rotating blade with a concentrated mass
Kwak, Joo-Young ; Yoo, Hong-Hee ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 190~197
DOI : 10.22634/KSME-A.19188.8.131.52
Equations of motions of a pretwisted rotating blade with a concentrated mass in an arbitrary position are derived. The flapwise and chordwise equations are coupled to each other due to the pretwist angle of the blade. As the angular speed, hub radius ratio, pretwist angle and concentrated mass vary, the vibration characteristics of the blade change. It is found that eigenvalue lociveering phenomena occur between two closing loci due to the pretwist angle. The effect of the pretwist angle on the critical angular speed and location of the concentrated mass on the natural frequencies are also investigated.
A study on the dynamic characteristics of an epicyclic gear trains supported with journal bearing
Lee, Jeong-Han ; Ryu, Hyeong-Tae ; Cheon, Gil-Jeong ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 198~205
DOI : 10.22634/KSME-A.19184.108.40.206
In this paper, the dynamic characteristics of a star type epicyclic gear train have been analyzed. Nonlinear stiffness of a gear pair were obtained considering the bending and shear deformation, Hertz contact deformation, as well as tooth fillet deformation. Nonlinear stiffness coefficients and damping coefficients around the static equilibrium position were obtained by perturbation method. The loci of the planet gears and sun gear were estimated. Tooth meshing forces and bearing reaction forces were calculated. The effects of bearing clearance and oil viscosity on the gear behavior were also analyzed.
Evaluation of stress intensity factor for a crack normal to bimaterial interface using cubic isoparametric finite elements
Lim, Won-Gyun ; Jeong, Gyu-Cheol ; Song, Chi-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 206~214
DOI : 10.22634/KSME-A.19220.127.116.11
When a crack meets bimaterial interface stress singularity depends on the elastic constants of the adjacent materials. In the present study we are going to describe the finite element formulation for problems with a crack to be embedded in the stiffer material
. The cubic isoparametric singular element, represented by adequately shifting the mid-side nodes adjacent to the crack tip is constructed to enclose the crack tip. An alternative method to obtain the optimal position of the mid-side nodes of cubic isoparametric elements is presented. In addition, a proper definition for the stress intensity factors of a crack normal to bimaterial interface is provided. It is based upon near a tip displacement solutions. Models for numerical analysis are two dimensional elastic bodies with a through crack under plain strain. The results obtained are compared with the previous solutions.
Study on tolerance and reliability analysis of mechanical systems with uncertainty
Choe, Jin-Ho ; Lee, Se-Jeong ; Choe, Dong-Hun ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 215~226
DOI : 10.22634/KSME-A.1918.104.22.168
This paper addresses an analytical approach to tolerance and reliability analysis of mechanical systems with uncertainty. Many mechanical systems consist of links and lubricated joints. The mobility method is applied to consider lubrication effects and the clearance vector model is used to stochastically define a mechanism for tolerance and reliability analysis. To show the validity of the proposed method, a four-bar path generator and a slider-crank mechanism are considered. The results obtained by applying the proposed method are compared with those by Monte-Carlo simulation.
Thermal deformation and thermal stress analysis of pipe during pipe internal fluid freezing
Park, Yeong-Don ; Byeon, Sang-Gyu ; Gang, Beom-Su ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 227~237
DOI : 10.22634/KSME-A.1922.214.171.124
In case the systems have radioactivity, toxic liquid or expensive fluid, and have to be performed repair work at one point of the system pipe, the formation of an internal ice plug by the removal of heat from the pipe is often consideredas a useful method. In this procedure, an annular jacket is placed around the pipe, and the jacket is then filled with liquid Nitrogen(-196.deg. C). Thermal analysis by the finite element method based on the laboratory experiments has been constructed. The result of the finite element analysis on the experimental model shows to be reasonable, and thus the finite element analysis for different pipe size, material and thickness has been performed to see if the ice plugging procedure in various applications can be safely performed without possibility of damage to the pipe. It has been confirmed that in carbon steel pipes the maximum stress is found around the boundary of the freezing jacket, and the stress increases as pipe thickness increases, but the maximum stress shows no consistency along the increment of the pipe diameter. The maximum stresses appear lower than yield stress in carbon steel. It has been also shown that in stainless steel pipes the maximum stresses are also found around the boundary of the freezing jacket, but almost the same value in spite of different pipe size an thickness, and the maximum stresses show slightly higher than the yield stress of the stainless steel.
Geometric variations and surface residual stresses in U-bending processes of an UNS N06690 row-1 heat exchanger tubes
Kim, Woo-Gon ; Jang, Jin-Sung ; Kuk, Il-Hiun ; Joo, Jin-Won ; Kim, Sung-Chung ;
Transactions of the Korean Society of Mechanical Engineers A, volume 22, issue 1, 1998, Pages 238~246
DOI : 10.22634/KSME-A.19126.96.36.199
Surface residual stresses as well as wall thickness and ovality changes after U-bending process on UNS N06690 row-1 heat exchanger tubes, were estimated. Surface residual stresses were measured by Hole Drilling Method(HDM), calculating the stresses from relieved strains of 3 rosette strain gages. After bending of the tubes, dimensional tolerances for wall thickness and ovality were satisfied with ASTM requirements. Residual stresses at the extrados were introduced with compressive stress(-) by bending operations, and its maximum value reached-319 MPa in axial direction at
in position. Tensile residual stresses(+) of
MPa were introduced in the intrados surface at position of
Maximum tensile residual stress of 170 MPa was detected on the flank side at position of ,
i.e., at apex region. It appeared that higher stress gradients were generated at the irregular transition regions. In the trend of residual stress changes with U-bend position, the extrados is related with the changes of ovality and the intrados is related with the changes of wall thickness.