An experimental and numerical study of the mechanical properties of a cross-linked polyethylene subject to low-velocity impacts

2018 ◽  
Vol 233 (8) ◽  
pp. 1604-1618
Author(s):  
Andrew Cummings
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Numerical Study ◽  
Element Model ◽  
Dynamic Mechanical Properties ◽  
Small Scale ◽  
Analysis Model ◽  
Low Velocity ◽  
Element Analysis ◽  
Rate Dependent

The response of a thermosetting cross-linked polyethylene, commercially referred to as Vitrite, has been studied experimentally and numerically. Two different testing programmes have been carried out; the first to characterise the mechanical properties of the material, and the second to provide information to validate a finite element model. Strain-rate dependent stress–strain curves have been obtained to determine the static and dynamic mechanical properties of Vitrite in tension and compression. Guided drop testing of a mass onto small scale samples has been used to study their deformation and rebound response. This has been compared to the deformation results of a finite element analysis model of the drop tests using the data obtained from the material characterisation tests as input to the model.

Effects of Diameter to Thickness Ratio and External Pressure on the Velocity of Dynamic Buckle Propagation in Offshore Pipelines

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Z. Omrani ◽  
K. Abedi ◽  
A. R. Mostafa Gharabaghi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Element Model ◽  
External Pressure ◽  
Thickness Ratio ◽  
Small Scale ◽  
Element Analysis ◽  
Models Comparison ◽  
Buckle Propagation ◽  
Exerted Pressure

In this paper, a numerical study of the dynamic buckle propagation, initiated in long pipes under external pressure, is presented. For a long pipe, due to the high exerted pressure, local instability is likely to occur; therefore, the prevention of its occurrence and propagation are very important subjects in the design of pipelines. The 3D finite element modeling of the buckle propagation is presented by considering the inertia of the pipeline and the nonlinearity introduced by the contact between its collapsing walls. The buckling and collapse are assumed to take place in the vacuum. The numerical results of the nonlinear finite element analysis are compared with the experimental results obtained by Kyriakides and Netto (2000, “On the Dynamics of Propagating Buckle in Pipelines,” Int. J. Solids Struct., 37, pp. 6843–6878) from a study on the small-scale models. Comparison shows that the finite element results have very close agreement with those of the experimental study. Therefore, it is concluded that the finite element model is reliable enough to be used for nonlinear collapse analysis of the dynamic buckle propagation in the pipelines. In this study, the effects of external pressure on the velocity of dynamic buckle propagation for different diameter to thickness ratios are investigated. In addition, the mathematical relations, based on the initiation pressure, are derived for the velocity of buckle propagation considering the diameter to thickness ratio of the pipeline. Finally, a relation for the buckle velocity as a function of the pressure and diameter to thickness ratio is presented.

Material Characteristic for Capability Analysis of Solid Tire by Finite Element Method

2018 ◽  
Vol 777 ◽  
pp. 416-420
Author(s):  
Juthanee Phromjan ◽  
Chakrit Suvanjumrat
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Element Model ◽  
Average Error ◽  
Element Analysis ◽  
Compression Load ◽  
Stress Strain Relation ◽  
The Finite Element Analysis ◽  
Capability Analysis ◽  
The Finite Element Model

The natural rubber compound of each layer of solid tire had determined the mechanical properties in tension. It was found that the stress-strain relation of each material tire layer was fitted very well with the Ogden constitutive model. The R2 which was 0.986, 0.996 and 0.985 represented the certain curve fitting on the internal, middle and tread layer of solid tire, respectively. Subsequently, the Ogden model was implemented in the finite element model of the rubber specimen and solid tire. The finite element analysis results obtained an average error of 18.00% and 14.63% for the specimen and solid tire model by comparing to the physical experiment, respectively. Particularly, the mechanical properties of the natural compounds could be used to predict the ultimate compression load for the solid tire failure.

scholarly journals STUDY ON NONLINEAR PAVEMENT RESPONSES OF LOW VOLUME ROADWAYS SUBJECT TO MULTIPLE WHEEL LOADS / NETIESINĖS KELIO DANGOS PRIKLAUSOMYBĖS NUO MAŽO INTENSYVUMO KELIŲ, VEIKIAMŲ DAUGKARTINĖMIS RATŲ APKROVOMIS, TYRIMAS

2011 ◽  
Vol 17 (1) ◽  
pp. 45-54 ◽  
Author(s):  
Minkwan Kim ◽  
Joo Hyoung Lee
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Asphalt Pavement ◽  
Three Dimensional ◽  
Nonlinear Behavior ◽  
Element Model ◽  
Element Analysis ◽  
Nonlinear Stress ◽  
Low Volume ◽  
Stress Dependent

This paper describes numerical analyses on low volume roads (LVRs) using a nonlinear three-dimensional (3D) finite element model (FEM). Various pavement scenarios are analyzed to investigate the effects of pavement layer thicknesses, traffic loads, and material properties on pavement responses, such as surface deflection and subgrade strain. Each scenario incorporates a different combination of wheel/axle configurations and pavement geomaterial properties to analyze the nonlinear behavior of thinly surfaced asphalt pavement. In this numerical study, nonlinear stress-dependent models are employed in the base and subgrade layers to properly characterize pavement geomaterial behavior. Finite element analysis results are then described in terms of the effects of the asphalt pavement thickness, wheel/axle configurations, and geomaterial properties on critical pavement responses. Conclusions are drawn by the comparison of the nonlinear pavement responses in the base and subgrade in association with the effects of multiple wheel/axle load interactions. Santrauka Straipsnyje aprašoma skaitinė mažo intensyvumo kelių analizė, taikant netiesinį—erdvinį baigtinių elementų modelį. Skirtingi dangų paviršiaus variantai analizuojami siekiant ištirti, kokiąįtaką kelio dangos elgsenai, t. y. poslinkiams ir kelio pagrindo deformacijoms, turi dangų sluoksnių storiai, eismo apkrovos ir medžiagų savybės. Kiekvienas kelio dangos variantas turi skirtingas ratų arba ašies ir geometrinių savybių formas, kad būtų galima išanalizuoti netiesinę plonos asfalto dangos paviršiaus elgseną. Šioje skaitinėje analizėje nagrinėjami netiesiniai įtempių modeliai, kurie buvo taikomi pagrindo sluoksniams, siekiant tinkamai apibūdinti geometrinę kelio dangos elgseną. Baigtinių elementų analizės rezultatai toliau nagrinėjami atsižvelgiant į asfalto dangos storį ar ašies formą ir geometrines savybes, priklausomai nuo kritinės kelio dangos būklės. Išvados buvo gautos lyginant netiesines kelių dangos priklausomybes pagrindo sluoksnyje, atsižvelgiant į jų sąveiką su daugkartine ratų apkrova.

scholarly journals Error estimation of nanoindentation mechanical properties near a dissimilar interface via finite element analysis and analytical solution methods

2010 ◽  
Vol 25 (12) ◽  
pp. 2308-2316 ◽  
Author(s):  
Y. Zhao ◽  
T.C. Ovaert
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Element Model ◽  
Interfacial Region ◽  
Element Analysis ◽  
Probe Size ◽  
Close Proximity ◽  
Sample Data ◽  
Solution Methods ◽  
Quarter Space

Nanoindentation methods are well suited for probing the mechanical properties of a heterogeneous surface, since the probe size and contact volumes are small and localized. However, the nanoindentation method may introduce errors in the computed mechanical properties when indenting near the interface between two materials having significantly different mechanical properties. Here we examine the case where a soft material is loaded in close proximity to an interface of higher modulus, such as the case when indenting bone near a metallic implant. The results are derived from both an approximate analytical quarter space solution and a finite element model, and used to estimate the error in indentation-determined elastic modulus as a function of the distance from the apex of contact to the dissimilar interface, for both Berkovich and spherical indenter geometries. Sample data reveal the potential errors in mechanical property determination that can occur when indenting near an interface having higher stiffness, or when characterizing strongly heterogeneous materials. The results suggest that caution should be used when interpreting results in the near-interfacial region.

Investigation of Broken Cut Spikes on Elastic Fastener Tie Plates Using an Integrated Simulation Method

2018 ◽  
Author(s):  
Yin Gao ◽  
Mike McHenry ◽  
Brad Kerchof
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Simulation Method ◽  
Operating Conditions ◽  
Analysis Model ◽  
Element Analysis ◽  
Integrated Simulation ◽  
Multibody Model ◽  
Track System ◽  
High Degree

Cut spike fasteners, used with conventional AREMA rolled tie plates and solid sawn timber ties, are the most common tie and fastener system used on North American freight railroads. Cut spikes are also used to restrain tie plates that incorporate an elastic rail fastener — that is, an elastic clip that fastens the rail to the tie plate. Elastic fasteners have been shown to reduce gage widening and decrease the potential for rail roll compared to cut spike-only systems. For this reason, elastic fastener systems have been installed in high degree curves on many railroads. Recent observations on one Class I railroad have noted broken cut spikes when used with these types of tie plates in mountainous, high degree curve territory. Broken screw spikes and drive spikes on similar style plates have also been observed. In this paper, a simulation method that integrates a vehicle-track system dynamics model, NUCARS®, with a finite element analysis model is used to investigate the root causes of the broken spikes. The NUCARS model consists of a detailed multibody train, wheel-rail contact parameters, and track model that can estimate the dynamic loading environment of the fastening system. For operating conditions in tangent and curve track, this loading environment is then replicated in a finite element model of the track structure — ties, tie plates, and cut spikes. The stress contours of the cut spikes generated in these simulations are compared to how cut spikes have failed in revenue service. The tuning and characterization of both the vehicle dynamics multibody model and the finite element models are presented. Additionally, the application of this approach to other types of fastening systems and spike types is discussed. Preliminary results have identified a mechanism involving the dynamic unloading of the tie plate-to-tie interface due to rail uplift ahead of the wheel and the resulting transfer of net longitudinal and lateral forces into the cut spikes. Continued analysis will attempt to confirm this mechanism and will focus on the severity of these stresses, the effect of increased grade, longitudinal train dynamics, braking forces, and curvature.

Study on 3-D Finite Element Analysis of Earth Dam

2012 ◽  
Vol 433-440 ◽  
pp. 3489-3494
Author(s):  
Ying Bin Kang ◽  
Ying Bin Kang ◽  
Hui Xia Bian ◽  
Jian Wei Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stability Analysis ◽  
Element Model ◽  
Earth Dam ◽  
Analysis Model ◽  
Element Analysis ◽  
The Earth ◽  
Practical Project

In this paper, the characteristics of the two software ANSYS and FLAC are analyzed. Using the powerful preprocessing capabilities of ANSYS, the earth dam is analyzed by finite element method. And then, the analysis model by the FISH language is imported into FLAC, with the constitutive model and the completed finite element model, the model analysis and processing are studied. Practical project is dam seepage and stability analysis to verify the reliability of the method.

Analysis of Crankshaft Fatigue Strength Based on Integrated Finite Element Model

2010 ◽  
Vol 44-47 ◽  
pp. 1558-1562 ◽  
Author(s):  
Xiao Ping Chen ◽  
Ru Fu Hu ◽  
Shu Hua Zheng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fatigue Limit ◽  
Limit Load ◽  
Element Model ◽  
Response Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Complex Mechanical Systems ◽  
Multi Body

Aiming at the complex mechanical systems for the prediction of the fatigue limit load requirements, this paper examines the relationship among finite element analysis model and the performance models. And a finite element modeling method for fatigue analysis is proposed. The finite element model can support static, modal, fatigue, and multi-body dynamic response analysis in parallel and collaboration. This method helps improve the fatigue limit load analysis.

Influence of Different Shapes to the Dynamic Mechanical Properties of Bioprosthetic Heart Valve

2012 ◽  
Vol 500 ◽  
pp. 417-422
Author(s):  
Xu Huang ◽  
Quan Yuan ◽  
Cheng Rui Zhang ◽  
Hai Bo Ma ◽  
Xin Ye
Keyword(s):  
Mechanical Properties ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Heart Valve ◽  
Dynamic Mechanical Properties ◽  
Bioprosthetic Heart Valve ◽  
Element Analysis ◽  
Geometrical Features ◽  
The Finite Element Analysis ◽  
Different Shapes

The stress with different shapes of the same thickness of the leaflet under the same load is analysed and compared by us. We create the spherical and ellipsoidal curved surface in accordance with geometrical features. The experimental results of the finite element analysis show that stress distribution of the different bioprosthetic heart valve leaflets with the same thickness is different. This work is very helpful to manufacture reasonable shaped valvular leaflets and to prolong the lifetime of the bioprosthetic heart valve.

Periodic and Fixed Boundary Conditions for Multi-Scale Finite Element Analysis of Flexible Risers

2016 ◽  
Author(s):  
M. T. Rahmati ◽  
G. Alfano ◽  
H. Bahai
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Time Saving ◽  
Flexible Risers

In this paper the implementation of two types of boundaries, periodic and fixed in-plane boundaries, for a detailed finite-element model of flexible risers is discussed. By using three-dimensional elements, all layer components are individually modelled and a surface-to-surface frictional contact model is used to simulate their interaction. The approach is applied on several riser models with various lengths and layers. It is shown that the model with periodic boundaries can be effectively employed in a fully-nested (FE2) multiscale analysis based on computational homogenization. In fact, in this model only a small fraction of a flexible pipe is needed for a detailed nonlinear finite-element analysis at the small scale. The advantage of applying periodic boundary conditions in capturing the detailed nonlinear effects and the efficiencies in terms of significant CPU time saving are demonstrated.

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