Analysis of Embedded Blade Root Carrot and T-Bolt Connections Subject to Cold Weather Conditions Using a Finite Element Model

2010 ◽  
Author(s):  
Patricio Lillo ◽  
Curran Crawford
Keyword(s):  
Finite Element ◽  
Thermal Stresses ◽  
Weather Conditions ◽  
Element Model ◽  
Cold Weather ◽  
Cold Temperatures ◽  
Operational Conditions ◽  
Blade Root ◽  
Applied Loading ◽  
Composite Blades

Canada has aggressive targets for introducing wind energy across the country, but also faces challenges in achieving these goals due to the harsh Canadian climate. One issue which has received little attention in other countries not experiencing these extremes is the behavior of the composite blades in winter conditions. The scope of this work is to determine and analyze the static stresses on the blade root during operational conditions at extreme cold temperatures. The paper analyses the stresses in the root of the composite blades, specifically two blade-hub connection methods: embedded root carrots and T-bolts. Finite element models of the root are proposed to properly simulate boundary conditions, applied loading and thermal stresses for a 1.5 MW wind turbine. Finally, it is shown that the blade root is strongly affected by the thermal stresses caused by the mismatch and orthotrophy of the coefficients of thermal expansion of the blade root constituents.

A Fundamental Study of the Interaction of Residual Stress and Applied Loading on Fracture

2010 ◽  
Author(s):  
C. J. Aird ◽  
M. J. Pavier ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Field ◽  
Crack Closure ◽  
Applied Load ◽  
Element Model ◽  
Residual Stress Field ◽  
Fundamental Study ◽  
Analytical Expression ◽  
Applied Loading

This paper presents the results of a fundamental finite-element based study of the crack-closure effects associated with combined residual and applied loading. First, an analytical expression for a representative two-dimensional residual stress field is derived. This residual stress field contains a central compressive region surrounded by an equilibrating tensile region. The analytical expression allows the size and shape of the field to be varied along with the magnitude of the residual stress. The residual stress field is then used as a prescribed initial stress field in a finite element model, in addition to a far field applied load. By introducing cracks of increasing length into these models, charts of stress-intensity-factor versus crack length are produced for different relative magnitudes of residual stress and applied load and for different sizes and shape of the residual stress field. These charts provide insight into the way in which crack-tip conditions evolve with crack growth under conditions of combined residual and applied loading and also enable conditions of crack closure and partial closure to be identified.

Finite-Element Simulations and Probabilistic Fracture Assessments of the Response of Alternate Rifling Geometries

2007 ◽  
Author(s):  
A. E. Segall ◽  
R. Carter
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Thermal Stresses ◽  
Rotational Symmetry ◽  
Element Model ◽  
Time Dependent ◽  
Uniform Heating ◽  
Thermal Pressure ◽  
Single Firing ◽  
Hoop Stresses

A 3-D finite-element model was used to simulate the severe and localized thermal/pressure transients and the resulting stresses experienced by a rifled ceramic-barrel with a steel outer-liner; the focus of the simulations was on the influence of non-traditional rifling geometries on the thermoelastic- and pressure-stresses generated during a single firing event. In order to minimize computational requirements, a twisted segment of the barrel length based on rotational symmetry was used. Using this simplification, the model utilized uniform heating and pressure across the ID surface via a time-dependent convective coefficient and pressure generated by the propellant gasses. Results indicated that the unique rifling geometries had only a limited influence on the maximum circumferential (hoop) stresses and temperatures when compared with more traditional rifling configurations because of the compressive thermal stresses developed at the heated (and rifled) surface.

An Analysis of Thermo-Mechanical Behavior in a Multilayer Composite Pipe Under Temperature Variation

2010 ◽  
Author(s):  
Wei Yang ◽  
Jyhwen Wang
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Analytical Solution ◽  
Mechanical Behavior ◽  
Temperature Change ◽  
Thermal Stresses ◽  
Element Model ◽  
Functionally Graded ◽  
Element Analysis ◽  
Graded Materials

A generalized analytical solution of mechanical and thermal induced stresses in a multi-layer composite cylinder is presented. Based on the compatibility condition at the interfaces, an explicit solution of mechanical stress due to inner and outer surface pressures and thermal stress due to temperature change is derived. A finite element model is also developed to provide the comparison with the analytical solution. It was found that the analytical solutions are in good agreement with finite element analysis result. The analytical solution shows the non-linear dependency of thermal stress on the diameters, thicknesses and the material properties of the layers. It is also shown that the radial and circumferential thermal stresses depend linearly on the coefficients of thermal expansion of the materials and the temperature change. As demonstrated, this solution can also be applied to analyze the thermo-mechanical behavior of pipes coated with functionally graded materials.

Optimization of Wire Loop Height for a Cavity Down Plastic Pin Grid Array Package

1998 ◽  
Vol 120 (2) ◽  
pp. 194-200 ◽  
Author(s):  
I. Chaudhry ◽  
F. Barez
Keyword(s):  
Finite Element ◽  
Simulation Study ◽  
Thermal Stresses ◽  
Element Model ◽  
Temperature Cycling ◽  
Effect Of Temperature ◽  
Temperature Cycle ◽  
Wire Loop ◽  
Simulation Results ◽  
Test Points

A study has been conducted to resolve wire neck break problem in a cavity-down plastic pin grid array (PPGA) packages with a specific range of parameters when subjected to temperature cycle (−55°C/+125°C). In most cases, a weak or broken neck of the wire was observed after 300 cycles of temperature cycling. The objective of this study is to determine an optimum wire loop height so that the package can pass a 1000 temperature cycles. Results of a simulation study, performed by other researchers, using a finite element model (FEM) were utilized. Their work considered the effect of temperature cycling on PPGA packages identical to those in this report. Several possible factors that can contribute to this failure mechanism were analyzed, and stresses in the wires were evaluated. The simulation results were verified by running an experiment on actual parts. The parts were subjected to temperature cycling, and data was gathered at different test points. The experimental results obtained did concur with simulation results which suggested that the area just above the ball experienced a significant level of thermal stresses, and such stresses could be reduced by determining an optimum loop height.

Investigation of Residual Thermal Stresses in Fiber-Reinforced Composites Incorporating Inhomogeneous Interphase Region

2010 ◽  
Author(s):  
M. M. Shokrieh ◽  
A. R. Ghanei Mohammadi
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Thermal Stresses ◽  
Element Model ◽  
Fiber Reinforced Composites ◽  
Radial Coordinate ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Fe Method

In this paper, a new finite element model has been introduced with the aim of efficient investigation of residual thermal stresses in fiber-reinforced composites, in which the inhomogeneous interphase is considered. For the inhomogeneous interphase modeling, four different kinds of material properties variation of the interphase (power, reciprocal, cubic and exponential variations) with the radial coordinate have been used. A mono fiber circular unit cell is considered using a finite element (FE) method. Extending the mono fiber model, FE models with different arrays of fibers have been created to investigate the effects of neighboring fibers on the results. In order to assure the convergence of results, a convergence analysis has been carried out for each of the models. To verify the finite element model, the FE results are compared with theoretical results available in the literature. In this paper, three different types of RVE configurations, circular, square and hexagonal are modeled and the effects of each type of fiber packing are studied. Performing an extensive study, the appropriate boundary conditions for RVEs are presented. The boundary conditions presented in this research are proved to be able to model the overall behavior efficiently.

PolyVinyliDene Fluoride (PVDF) Material Based Energy Harvesting from Train and Damaged Bridge Interaction

2013 ◽  
Vol 569-570 ◽  
pp. 335-341 ◽  
Author(s):  
Paul Cahill ◽  
Nathan Jackson ◽  
Alan Mathewson ◽  
Vikram Pakrashi
Keyword(s):  
Finite Element ◽  
Energy Harvesting ◽  
Damage Detection ◽  
Polyvinylidene Fluoride ◽  
Element Model ◽  
Element Analysis ◽  
Operational Conditions ◽  
Existing Structures ◽  
Bridge Structures ◽  
New Generation

This paper investigates the potential use of PolyVinyliDene Fluoride (PVDF) for the purposes of damage detection for infrastructural elements, primarily for bridge elements. PVDF based sensors have been created and characterised in the laboratory in this regard. Finite element analysis of vehicle-bridge interactions with varying damage are carried out. The energy harvesting signatures of realistic trains are assessed and quantified for the modelled bridge. The effect of localized damage on the finite element model and its subsequent relationship with energy harvesting from the calibrated PVDF based sensors are investigated using the harvesting signatures of realistic trains. This approach is useful in terms of designing new generation smart bridge structures and for possible retrofit of existing structures. The use of train-bridge interaction ensures that the damage detection is carried out while the bridge is under operational conditions. Consequently, there is minimal to no impact on the existing operation of the bridge or the transport network during damage detection. The paper is expected to be useful for practicing engineers and researchers in the field of application of new materials in the next generation of bridge structures.

scholarly journals Finite element modelling of the dynamics of groovy ball bearings

2018 ◽  
Vol 148 ◽  
pp. 16004
Author(s):  
Olamide Ajala ◽  
Ekaterina Pavlovskaia ◽  
Marian Weircigroch
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Thermal Stresses ◽  
Frictional Heating ◽  
Element Model ◽  
Contact Theory ◽  
Ball Bearings ◽  
Relative Slip ◽  
Thrust Bearings ◽  
Plastic Strength

Geometry modified thrust bearings exposed to rolling and sliding contact are subjected to wear and localized frictional heating caused by relative slip between the two sliding surfaces. This leads to a rise in temperature, thermal stresses and changes in the elastic and plastic strength and physical properties of the material. The changes in the properties in turn alter the stress state, the displacement field, life and reliability of the bearing. Hence, a finite-element model is created to study the dynamics of groovy thrust bearing. In this paper, Hertz contact theory and numerical method are used to simulate the dynamics and kinematics of groovy ball bearings. The optimal loading parameters are identified in this study based on the analysis of the system responses and properties. The results of the numerical analysis and validation are presented. The numerical analysis proves the concept of transforming rotational motion into axial oscillation and demonstrates the capabilities of the numerical simulation to accurately model the dynamics of the groovy ball bearing.

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