Effects of Notch Depth and Direction on Stability of Local Sharp-Notched Circular Tubes Subjected to Cyclic Bending

2018 ◽  
Vol 18 (07) ◽  
pp. 1850099 ◽  
Author(s):  
Kuo-Long Lee ◽  
Kao-Hua Chang ◽  
Wen-Fung Pan
Keyword(s):  
Analytical Data ◽  
Cyclic Hardening ◽  
Notch Depth ◽  
Steel Tubes ◽  
Element Analysis ◽  
Cyclic Bending ◽  
Tube Cross Section ◽  
Number Of Cycles ◽  
The Moment ◽  
The Relationship

Cyclic bending of tubes leads to progressive ovalization of the tube cross-section, and persistent cycling causes catastrophic buckling of the tube. This paper presents the response and stability of SUS304 stainless steel tubes with local sharp-notched depths of 0.2, 0.4, 0.6, 0.8, and 1.0[Formula: see text]mm and notch directions of 0[Formula: see text], 30[Formula: see text], 60[Formula: see text], and 90[Formula: see text] under cyclic bending. The experimental results reveal that the moment–curvature relationship first exhibits cyclic hardening and then a steady loop after a few cycles. Because the notches are small and localized, notch depth and direction show minimal influence on the moment–curvature relationship. In contrast, the ovalization–curvature relationship demonstrates an increasing and ratcheting pattern along with the bending cycle, whereas notch depth and direction show a strong influence on this relationship. Finite-element analysis via ANSYS is used to simulate the moment–curvature and ovalization–curvature relationships, and an empirical model is proposed to simulate the relationship between the controlled curvature and number of cycles required to ignite buckling. The experimental and analytical data agree well with each other.

Finite Element Analysis on the Response of Local Sharp-Notched Circular Tubes under Cyclic Bending

2014 ◽  
Vol 626 ◽  
pp. 34-39
Author(s):  
Kuo Long Lee ◽  
Yun Wang ◽  
Wen Fung Pan
Keyword(s):  
Finite Element ◽  
Experimental Finding ◽  
Experimental Result ◽  
Notch Depth ◽  
Element Analysis ◽  
Cyclic Bending ◽  
Circular Tubes ◽  
Finite Element Software ◽  
Ansys Analysis ◽  
The Moment

In this study, the finite element software ANSYS was used to analyze the mechanical behavior of local sharp-notched circular tubes under cyclic bending. The local sharp-notched depths include: 0.2, 0.4, 0.6, 0.8 and 1.0 mm, and the local sharp-notched directions include: 0, 30, 60 and 90 degrees. According to the experimental result, the notch depth has no influence on the moment-curvature relationship. But the notch depth increases, the unsymmetrical phenomenon of the ovalization-curvature relationship becomes more obvious and the speed of ovalization accelerates. In addition, the ovalization-curvature relationship becomes symmetrical when the direction angle increases. The ANSYS analysis was compared with the experimental finding. Although some differences between the experimental and simulated results, but both trends were very similar.

Collapse of Sharp-Notched 6061-T6 Aluminum Alloy Tubes Under Cyclic Bending

2016 ◽  
Vol 16 (07) ◽  
pp. 1550035 ◽  
Author(s):  
Chen-Cheng Chung ◽  
Kuo-Long Lee ◽  
Wen-Fung Pan
Keyword(s):  
Finite Element ◽  
Aluminum Alloy ◽  
Cyclic Bending ◽  
Finite Element Software ◽  
Buckling Failure ◽  
Simulation Results ◽  
Number Of Cycles ◽  
The Moment ◽  
The Relationship ◽  
Good Agreement

The mechanical behavior and buckling failure of sharp-notched 6061-T6 aluminum alloy tubes with different notch depths subjected to cyclic bending are experimentally and theoretically investigated. The experimental moment–curvature relationship exhibits an almost steady loop from the beginning of the first cycle. However, the ovalization–curvature relationship exhibits a symmetrical, increasing, and ratcheting behavior as the number of cycles increases. The six groups of tubes tested have different notch depths, from which two different trends can be observed from the relationship between the controlled curvature and the number of cycles required to ignite buckling. Finite element software ANSYS is used to simulate the moment–curvature and ovalization–curvature relationships. Additionally, a theoretical model is proposed for simulation of the controlled curvature-number of cycles concerning the initiation of buckling. Simulation results are compared with experimental test data, which shows generally good agreement.

The Influence of Diameter-to-Thickness Ratios on the Response and Collapse of Sharp-Notched Circular Tubes under Cyclic Bending

2012 ◽  
Vol 28 (3) ◽  
pp. 461-468 ◽  
Author(s):  
K.-L. Lee ◽  
C.-M. Hsu ◽  
W.-F. Pan
Keyword(s):  
Experimental Finding ◽  
Empirical Relationship ◽  
Cyclic Hardening ◽  
304 Stainless Steel ◽  
Cyclic Bending ◽  
Circular Tubes ◽  
Parallel Lines ◽  
Number Of Cycles ◽  
The Moment ◽  
Good Agreement

AbstractThis paper discusses an experimental investigation of the behavior of sharp-notched circular tubes subjected to cyclic bending. The sharp-notched circular tubes of 304 stainless steel with three different diameter-to-thickness ratios (Do / t) were tested under symmetric curvature-controlled cyclic bending. It has been shown that the moment-curvature curves exhibited the loops with cyclic hardening and gradually becoming steady after a few cycles for all tested tubes. The ovalization-curvature curves revealed unsymmetric, ratcheting and increasing behavior with the number of cycles. In addition, five almost parallel lines corresponding to five different notch depths for each Do / t ratio were found from the experimental relationship between the cyclic controlled curvature and the number of cycles necessary to produce buckling on a log-log scale. Finally, an empirical relationship was proposed so it could be used for simulating the aforementioned relationship. By comparing with the experimental finding, the derived empirical relationship was in good agreement with the experimental data.

scholarly journals Predicting the Fatigue Life of a Ball Joint

2021 ◽  
Vol 22 (4) ◽  
pp. 453-460
Author(s):  
Kozłowski Edward ◽  
Borucka Anna ◽  
Szymczak Tadeusz ◽  
Świderski Andrzej ◽  
Gil Leszek
Keyword(s):  
Mathematical Model ◽  
Service Life ◽  
Road Safety ◽  
High Reliability ◽  
Ball Joint ◽  
Safety Requirements ◽  
Fatigue Durability ◽  
Number Of Cycles ◽  
The Moment ◽  
The Relationship

Abstract The technical conditions and service life of steering elements of vehicles are an important factor directly affecting road safety. Therefore, high reliability of such kind’s components is required. In the paper, on the basis of the stand test, the fatigue durability of a ball joint of a steering tie rod is determined. It is elaborated together with a prediction for the further number of cycles, enabling to determine the technical state of the tested component containing its service life. The aim of the article is to select an appropriate mathematical model with respect to describing the relationship between the moment of force and the fatigue cycles performed for the ball joint of a steering rod of a vehicle with a GVW above 3.5 tonnes, and identifying the model’s parameters. As a result, the limit number of loading cycles after which the examined joint does not meet safety requirements is estimated.

Viscoplastic Collapse of Thin-Walled Tubes Under Cyclic Bending

1998 ◽  
Vol 120 (4) ◽  
pp. 287-290 ◽  
Author(s):  
Wen-Fung Pan ◽  
Yung-Shun Her
Keyword(s):  
Cross Section ◽  
304 Stainless Steel ◽  
Experimental Result ◽  
Metal Tube ◽  
Controlled Experiments ◽  
Cyclic Bending ◽  
Tube Cross Section ◽  
Thin Walled ◽  
Number Of Cycles ◽  
Tubular Specimens

This paper presents the experimental result on the response and stability of thin-walled tubes subjected to cyclic bending with different curvature-rates. The curvature-ovalization measurement apparatus, designed by Pan et al. (1998), was used for conducting the present curvature-controlled experiments on thin-walled tubular specimens of 304 stainless steel. It is observed that the higher the applied curvature-rate, the greater is the degree of hardening of metal tube. However, the ovalization of tube cross-section increases when the applied curvature-rate increases. Furthermore, due to the higher degree of the ovalization of tube cross-section for higher curvature-rates under cyclic bending, the number of cycles to produce buckling is correspondingly reduced.

scholarly journals Experimental Study of Cyclic Bending Failure for Round-hole Tubes with a Redundant Round Hole in the Same Direction but Different Cross Sections

2020 ◽  
Vol 9 (2) ◽  
pp. 83-92
Author(s):  
Kuo-Long Lee ◽  
Wen-Fung Pan
Keyword(s):  
Aluminum Alloy ◽  
Cross Sections ◽  
Hole Diameter ◽  
Round Hole ◽  
Cyclic Bending ◽  
Number Of Cycles ◽  
The Moment ◽  
Straight Lines ◽  
Bending Failure ◽  
Good Agreement

This paper presents the influence of a redundant round hole in the same direction but different cross sections on the response and failure of round-hole 6061-T6 aluminum alloy tubes subjected to cyclic bending. In this study, round-hole 6061-T6 aluminum alloy tubes with a constant hole diameter of 6 mm were drilled to obtain a redundant round hole in the same hole direction but different cross sections. The experimental results revealed that the moment–curvature relationship exhibited an almost steady loop from the beginning of the first cycle. The redundant round hole showed minimal influence on the moment–curvature relationship. However, the ovalization–curvature relationship demonstrated an asymmetrical, increasing, ratcheting and bow pattern along with the bending cycle, while the redundant round hole showed a significant influence on this relationship. In addition, six groups of round-hole 6061-T6 aluminum alloy tubes were tested, the controlled curvature-number of bending cycles required to ignite failure relationships on double logarithmic coordinates exhibited nonparallel straight lines. Finally, a theoretical model was proposed for simulating the controlled curvature–number of cycles to ignite failure. The simulation result was compared with experimental test data, which showed generally good agreement.

Validation of a 3-Dimensional Finite Element Analysis Model of Deep Water Steel Tube Umbilical in Combined Tension and Cyclic Bending

2009 ◽  
Author(s):  
Vincent Le Corre ◽  
Ian Probyn
Keyword(s):  
Axial Strain ◽  
Steel Tube ◽  
Analytical Models ◽  
Partial Slip ◽  
Analysis Model ◽  
Steel Tubes ◽  
Element Analysis ◽  
Cyclic Bending ◽  
Friction Moment ◽  
Bending Under Tension

This paper focuses upon validation of the 3-D FEA model for cyclic bending under tension load case. An important aspect of accurately modelling the behaviour is the complex stick, partial slip and full slip behaviour of the internal components. Particular attention is paid to the resisting moment resulting from internal friction, known as the friction moment. The effect of increasing tension on the friction moment is studied. The kinematics of sliding are compared to analytical models developed for helically wound structures, such as flexible pipes, and show a very good correlation that confirms the accuracy of the model. Also, the mean axial strain of the steel tubes due to the friction induced by this sliding is highlighted. The hysteretic curves of the axial strain in steel tubes subjected to cyclic bending under tension are derived and validated against full scale experimental data.

Variation of Ovalization for Sharp-Notched Circular Tubes Under Cyclic Bending

2010 ◽  
Vol 26 (3) ◽  
pp. 403-411 ◽  
Author(s):  
K.-L. Lee ◽  
C.-Y. Hung ◽  
W.-F. Pan
Keyword(s):  
Empirical Relationship ◽  
304 Stainless Steel ◽  
Tube Bending ◽  
Steel Tubes ◽  
Cyclic Bending ◽  
Circular Tubes ◽  
Tertiary Stage ◽  
Three Stages ◽  
Number Of Cycles ◽  
Good Agreement

AbstractIn this paper, an experimental investigation on the variation of ovalization for sharp-notched circular tubes subjected to cyclic bending is discussed. The tube bending machine and curvature-ovalization measurement apparatus were used to test the unnotched and sharp-notched 304 stainless steel tubes. For sharp-notched tubes, five different notch depths (0.2, 0.4, 0.6, 0.8 and 1.0mm) were considered in this study. It was found that the experimental curve of the ovalization and the number of cycles could be divided into three stages-an initial, secondary and tertiary stage. An empirical relationship was proposed for simulating the aforementioned curve for the initial and secondary stages in this study. It has been shown that the derived empirical relationship was in good agreement with the experimental data.

Analysis of magnetic force and dynamic characteristic for non-contact permanent magnet linear drive device

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1337-1345
Author(s):  
Chuan Zhao ◽  
Feng Sun ◽  
Junjie Jin ◽  
Mingwei Bo ◽  
Fangchao Xu ◽  
...  
Keyword(s):  
Finite Element ◽  
Permanent Magnet ◽  
Dynamic Characteristic ◽  
Driving Force ◽  
Magnetic Circuit ◽  
Response Speed ◽  
Computation Method ◽  
Element Analysis ◽  
Element Simulation ◽  
The Relationship

This paper proposes a computation method using the equivalent magnetic circuit to analyze the driving force for the non-contact permanent magnet linear drive system. In this device, the magnetic driving force is related to the rotation angle of driving wheels. The relationship is verified by finite element analysis and measuring experiments. The result of finite element simulation is in good agreement with the model established by the equivalent magnetic circuit. Then experiments of displacement control are carried out to test the dynamic characteristic of this system. The controller of the system adopts the combination control of displacement and angle. The results indicate that the system has good performance in steady-state error and response speed, while the maximum overshoot needs to be reduced.

scholarly journals Investigation of Deformation Inhomogeneity and Low-Cycle Fatigue of a Polycrystalline Material

2021 ◽  
Vol 11 (6) ◽  
pp. 2673
Author(s):  
Mu-Hang Zhang ◽  
Xiao-Hong Shen ◽  
Lei He ◽  
Ke-Shi Zhang
Keyword(s):  
Cyclic Loading ◽  
Low Cycle Fatigue ◽  
Strain Tensor ◽  
Equivalent Strain ◽  
Differential Entropy ◽  
Strain Components ◽  
Deformation Inhomogeneity ◽  
Standard Deviations ◽  
Number Of Cycles ◽  
The Relationship

Considering the relationship between inhomogeneous plastic deformation and fatigue damage, deformation inhomogeneity evolution and fatigue failure of superalloy GH4169 under temperature 500 °C and macro tension compression cyclic loading are studied, by using crystal plasticity calculation associated with polycrystalline representative Voronoi volume element (RVE). Different statistical standard deviation and differential entropy of meso strain are used to measure the inhomogeneity of deformation, and the relationship between the inhomogeneity and strain cycle is explored by cyclic numerical simulation. It is found from the research that the standard deviations of each component of the strain tensor at the cyclic peak increase monotonically with the cyclic loading, and they are similar to each other. The differential entropy of each component of the strain tensor also increases with the number of cycles, and the law is similar. On this basis, the critical values determined by statistical standard deviations of the strain components and the equivalent strain, and that by differential entropy of strain components, are, respectively, used as fatigue criteria, then predict the fatigue–life curves of the material. The predictions are verified with reference to the measured results, and their deviations are proved to be in a reasonable range.

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