scholarly journals Transverse Deformation of Pressurised Pipes With Different Axial Loads

2017 ◽  
Author(s):  
Martin Kristoffersen ◽  
Tore Børvik ◽  
Magnus Langseth ◽  
Håvar Ilstad ◽  
Erik Levold
Keyword(s):  
Internal Pressure ◽  
Axial Load ◽  
Tensile Load ◽  
Displacement Curve ◽  
Design Codes ◽  
Axial Loads ◽  
Axial Tensile ◽  
Local Dent ◽  
Force Displacement ◽  
Good Agreement

Pipelines residing on the seabed are exposed to various hazards, one of them being denting, hooking and release of the pipeline by e.g. anchors or trawl gear. As a pipeline is displaced transversely in a hooking event, an axial tensile load resisting the displacement builds up in the pipeline. This study examines the effect of applying three different axial loads (zero, constant, and linearly increasing) to a pipe while simultaneously deforming it transversely. A fairly sharp indenter conforming to the prevailing design codes was used to deform the pipes. These three tests were repeated with an internal pressure of about 100 bar for comparison. Adding an axial load appeared to increase the pipe’s stiffness in terms of the force-displacement curve arising from deforming the pipe transversely. The internal pressure also increased the stiffness, and produced a more local dent in the pipe compared with the unpressurised pipes. All tests were recreated numerically in finite element simulations. Generally, the results of the simulations were in good agreement with the experiments.

Optimal Design of a Composite Scarf Repair Under Uni-Axial Tension Loading

2008 ◽  
Author(s):  
T. D. Breitzman ◽  
B. M. Cook ◽  
G. A. Schoeppner ◽  
E. V. Iarve
Keyword(s):  
Tensile Load ◽  
Optimal Designs ◽  
Analytical Models ◽  
Linear Elastic ◽  
Repair Patch ◽  
Axial Tension ◽  
Axial Tensile ◽  
Notched Strength ◽  
Tension Loading ◽  
Good Agreement

Benchmark un-notched strength testing was used to characterize material properties for IM6/3501-6 composite material and to establish parameters for critical failure volume (CFV) (see [8]) analysis tools. Critical failure volume was used to predict the strength of scarfed composites, as well as composites having a scarf repair patch. Baseline repairs were created both without and with over-plies. Simplex optimization was performed on the analytical models to determine the repair stacking sequence that would result in the largest tensile strength for the repairs. The repair was optimized in the linear elastic regime, but strength predictions took into account both geometric nonlinearities of the respective materials and the material nonlinearities of the adhesive. Predicted strengths were in good agreement with experimental results, and the resultant optimal designs increased the strength of the repair under uni-axial tensile load by 10–20%.

Modeling and Vibration Analysis of Friction Joints

1989 ◽  
Vol 111 (1) ◽  
pp. 71-76 ◽  
Author(s):  
C.-H. Menq
Keyword(s):  
Simple Model ◽  
Normal Pressure ◽  
Relative Displacement ◽  
Displacement Curve ◽  
Rigid Support ◽  
Axial Loads ◽  
Friction Joint ◽  
Model Of Friction ◽  
The Relationship ◽  
Force Displacement

This paper presents a microslip model of friction joints, which may be viewed as a generalization of the simple model considered by Menq et al. (1986a). Laboratory experiments have shown that microslip of friction joints has important implications in the dynamic response of frictionally constrained structures in which the friction interface is subjected to high normal loads (Menq et al., 1986b). In the simple model, the friction interface is idealized as a bar pressed with a uniform normal pressure against a rigid support. The use of a rigid support in the model shows that a direct link between the model’s parameters and its physical counterparts is lacking. The model presented in this paper consists of two bars held together with uniform clamping normal pressure. In addition to these two bars, the third element, a shear layer, is added to account for the effects of the shear deformation of the two contact bodies. This generalization of the microslip model is to enhance the link between the model’s parameters and the physical configurations of the contacting surfaces of the friction joint. With a physical model like this, the objective is to determine the distribution of the friction force at the contact surface while quasi-steady axial loads applied to the ends of both bars increase gradually. In particular, it is of interest for the analysis of vibration problems to determine the force-displacement curve that describes the relationship, upon first loading, between the applied load and the resulting relative displacement between the two ends where the loads are applied. After the case of first loading, the cases of unloading and reloading of the joint will be examined; and then the hysteresis loop in the course of cyclic loading can be obtained.

FEM Calculations and Evaluation of Sealing Performance in Comparison of Raised Face and Flat Face Flange Connections

2013 ◽  
Author(s):  
Ryou Kurosawa ◽  
Toshiyuki Sawa ◽  
Yuya Omiya ◽  
Takashi Kobayashi ◽  
Kentaro Temma
Keyword(s):  
Internal Pressure ◽  
Fe Analysis ◽  
Displacement Curve ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Flange Connection ◽  
Gas Leakage ◽  
Sealing Performance ◽  
The Relationship ◽  
Good Agreement

The bolted connections inserting gasket such as circular flange connections have been widely used in mechanical structures, which is nuclear and chemical industry, and so on. They are usually used under internal pressure. And they are required the high sealing performance. In the circular flange with non-asbestos compressed sheet gaskets, the two flange surfaces, raised-face and flat-face, are used. The raised-face flange on the sealing performance is examined by many researchers and reported. The flat-face is well known that flange rotation is smaller than that in raised-face flange under the internal pressure. However the sealing performance of the flat-face flange connection isn’t examined. Thus, the sealing performance of the flat-face flange connection is not examined. In this paper, the contact gasket stresses of these connections under internal pressure are analyzed using the finite element method (FEM) of each flange surfaces, taking into account a hysteresis in the stress-displacement curve of the gasket. And then, using the contact gasket stress distributions obtained from FE analysis and the relationship between gasket stress and leak rate obtained from a gasket sealing test (JIS B2490), method for estimating an amount of leakage is examined. The leakage tests were also conducted to measure an amount of gas leakage using an actual circular flange connection with a gasket. The estimated results are in a fairly good agreement with the experimental results.

scholarly journals Improved design criterion for frictionally engaged contacts in overrunning clutches

2021 ◽  
Author(s):  
Nadine Nagler ◽  
Armin Lohrengel
Keyword(s):  
Design Process ◽  
Contact Area ◽  
Axial Load ◽  
State Of The Art ◽  
Tangential Force ◽  
Design Criterion ◽  
Hertzian Contact ◽  
Loss Of Function ◽  
Axial Loads ◽  
Improved Design

AbstractOverrunning clutches, also known as freewheel clutches, are frictionally engaged, directional clutches; they transmit torque depending on the Freewheel clutch rings’ rotation directions. The torque causes a tangential force in the Hertzian contact area. The hitherto “state-of-the-art design criterion” bases on this load situation. In practice, axial loads additionally act on the frictionally engaged Hertzian contact area. This additional axial load can cause the loss of the friction connection and so the freewheel clutch slips. This publication presents an improved design criterion for frictionally engaged contacts in freewheel clutches. It allows to consider tangential as well as axial loads during the design process. Additionally, it offers the possibility to estimate the probability of frictional engagement loss and gross slip based on the freewheel clutch’s application scenario. This publication points out how to use the improved design criterion to design freewheel clutches that are more robust against a loss of function.

Effect of design parameters on stresses occurring at the tooth root in a spur gear pressed on a shaft

2021 ◽  
pp. 095440892199529
Author(s):  
Fatih Güven
Keyword(s):  
Internal Pressure ◽  
Tangential Stress ◽  
Spur Gear ◽  
Design Parameters ◽  
Interference Fit ◽  
Gear Design ◽  
Compact Design ◽  
Fit Tolerance ◽  
Moderate Stress ◽  
Good Agreement

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

scholarly journals Study on improvement of prefolded energy absorption device to constant resistance and its mechanical properties

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110368
Author(s):  
Dong An ◽  
Jiaqi Song ◽  
Hailiang Xu ◽  
Jingzong Zhang ◽  
Yimin Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Compression Test ◽  
Side Wall ◽  
Concave Side ◽  
Displacement Curve ◽  
Static Compression ◽  
Constant Resistance ◽  
The Impact ◽  
Force Displacement

When the rock burst occurs, energy absorption support is an important method to solve the impact failure. To achieve constant resistance performance of energy absorption device, as an important component of the support, the mechanical properties of one kind of prefolded tube is analyzed by quasi-static compression test. The deformation process of compression test is simulated by ABAQUS and plastic strain nephogram of the numerical model are studied. It is found that the main factors affecting the fluctuation of force-displacement curve is the stiffness of concave side wall. The original tube is improved to constant resistance by changing the side wall. The friction coefficient affects the folding order and form of the energy absorbing device. Lifting the concave side wall stiffness can improve the overall stiffness of energy absorption device and slow down the falling section of force-displacement curve. It is always squeezed by adjacent convex side wall in the process of folding, with large plastic deformation. Compared with the original one, the improved prefolded tube designed in this paper can keep the maximum bearing capacity ( Pmax), increase the total energy absorption ( E), improve the specific energy absorption (SEA), and decrease the variance ( S2) of force-displacement curve.

SEM in situ study on the mechanical behaviour of SiCf/Ti composite subjected to axial tensile load

2011 ◽  
Vol 528 (13-14) ◽  
pp. 4507-4515 ◽  
Author(s):  
Kashif Naseem ◽  
Yanqing Yang ◽  
Xian Luo ◽  
Bin Huang ◽  
Guanghai Feng
Keyword(s):  
Mechanical Behaviour ◽  
Tensile Load ◽  
In Situ Study ◽  
Axial Tensile

scholarly journals Young’s Modulus of Polycrystalline Titania Microspheres Determined by In Situ Nanoindentation and Finite Element Modeling

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Peida Hao ◽  
Yanping Liu ◽  
Yuanming Du ◽  
Yuefei Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Deformation Mechanisms ◽  
Displacement Curve ◽  
Element Simulation ◽  
Nanoindentation Experiment ◽  
Force Displacement

In situ nanoindentation was employed to probe the mechanical properties of individual polycrystalline titania (TiO2) microspheres. The force-displacement curves captured by a hybrid scanning electron microscope/scanning probe microscope (SEM/SPM) system were analyzed based on Hertz’s theory of contact mechanics. However, the deformation mechanisms of the nano/microspheres in the nanoindentation tests are not very clear. Finite element simulation was employed to investigate the deformation of spheres at the nanoscale under the pressure of an AFM tip. Then a revised method for the calculation of Young’s modulus of the microspheres was presented based on the deformation mechanisms of the spheres and Hertz’s theory. Meanwhile, a new force-displacement curve was reproduced by finite element simulation with the new calculation, and it was compared with the curve obtained by the nanoindentation experiment. The results of the comparison show that utilization of this revised model produces more accurate results. The calculated results showed that Young’s modulus of a polycrystalline TiO2microsphere was approximately 30% larger than that of the bulk counterpart.

Can indentation technique measure unique elastoplastic properties?

2009 ◽  
Vol 24 (3) ◽  
pp. 784-800 ◽  
Author(s):  
Ling Liu ◽  
Nagahisa Ogasawara ◽  
Norimasa Chiba ◽  
Xi Chen
Keyword(s):  
Critical Strain ◽  
Indentation Test ◽  
Strain Curve ◽  
Spherical Indentation ◽  
Plastic Behavior ◽  
Displacement Curve ◽  
Application Range ◽  
Indentation Technique ◽  
Elastoplastic Properties ◽  
Force Displacement

Indentation is widely used to extract material elastoplastic properties from measured force-displacement curves. Many previous studies argued or implied that such a measurement is unique and the whole material stress-strain curve can be measured. Here we show that first, for a given indenter geometry, the indentation test cannot effectively probe material plastic behavior beyond a critical strain, and thus the solution of the reverse analysis of the indentation force-displacement curve is nonunique beyond such a critical strain. Secondly, even within the critical strain, pairs of mystical materials can exist that have essentially identical indentation responses (with differences below the resolution of published indentation techniques) even when the indenter angle is varied over a large range. Thus, fundamental elastoplastic behaviors, such as the yield stress and work hardening properties (functions), cannot be uniquely determined from the force-displacement curves of indentation analyses (including both plural sharp indentation and deep spherical indentation). Explicit algorithms of deriving the mystical materials are established, and we qualitatively correlate the sharp and spherical indentation analyses through the use of critical strain. The theoretical study in this paper addresses important questions of the application range, limitations, and uniqueness of the indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material constitutive properties.

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