Thermal stressing of plain and prestressed masonry diaphragm walls

1996 ◽  
Vol 23 (4) ◽  
pp. 850-861 ◽  
Author(s):  
N. G. Shrive ◽  
A. Huizer ◽  
D. Tilleman ◽  
W. Eng
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Thermal Analyses ◽  
Experimental Tests ◽  
Cross Wall ◽  
Thermal Tests ◽  
Simple Method ◽  
Diaphragm Walls

Diaphragm walls constitute a structurally efficient form of masonry. The effects of the large cross-wall temperature differentials which can develop during winter need to be examined. Finite element models of diaphragm walls were analysed to determine if thermal stresses could potentially cause structural distress. For validation, model walls were subjected to flexural loading and the results were compared with those from experimental tests on similar walls. Good agreement was found. Therefore, thermal analyses were performed. It was found that the resulting stresses were heavily dependent on the structural boundary conditions, but indicated the potential of cracking. Series of 2 and 3 m high walls were therefore constructed and subjected to thermal loading. The walls were subjected to different boundary conditions. The 3 m high walls were tested both plain and prestressed. None of the walls cracked as a result of the thermal loading. A simple method is presented for estimating the change in prestress force due to the temperature change in the wall. Key words: masonry, diaphragm walls, cavity walls, thermal tests, post-tensioning finite element modelling.

Influence of Axial Excitations and of Boundary Conditions on the Parametric Instability of a Beam

1995 ◽  
Author(s):  
Régis Dufour ◽  
Alain Berlioz ◽  
Thomas Streule
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ritz Method ◽  
Parametric Instability ◽  
Experimental Tests ◽  
Time Varying ◽  
Periodic Force ◽  
Modal Reduction ◽  
Time Varying Parameter ◽  
The Stability

Abstract In this paper the stability of the lateral dynamic behavior of a pinned-pinned, clamped-pinned and clamped-clamped beam under axial periodic force or torque is studied. The time-varying parameter equations are derived using the Rayleigh-Ritz method. The stability analysis of the solution is based on Floquet’s theory and investigated in detail. The Rayleigh-Ritz results are compared to those of a finite element modal reduction. It shows that the lateral instabilities of the beam depend on the forcing frequency, the type of excitation and the boundary conditions. Several experimental tests enable the validation of the numerical results.

scholarly journals Possible reasons for early artificial bone failure in biomechanical tests of ankle arthrodesis systems

2015 ◽  
Vol 1 (1) ◽  
pp. 507-509
Author(s):  
H. Martin ◽  
N. Gutteck ◽  
J.-B. Matthies ◽  
T. Hanke ◽  
G. Gradl ◽  
...  
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Experimental Tests ◽  
Element Model ◽  
Ankle Arthrodesis ◽  
Artificial Bone ◽  
Basic Model ◽  
Simplified Finite Element Model ◽  
Biomechanical Tests ◽  
Horizontal Displacements

AbstractIn order to demonstrate the influence of the boundary conditions in experimental biomechanical investigations of arthrodesis implants two different models were investigated. As basic model, a simplified finite element model of the cortical bone was used in order to compare the stress values with (Model 1) and without (Model 2) allowing horizontal displacements of the load application point. The model without constraints of horizontal displacements showed considerably higher stress values at the point of failure. Moreover, this investigation shows that the boundary conditions (e.g. constraints) have to be carefully considered, since simplifications of the reality with experimental tests cannot always be avoided.

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.

A Finite Element Investigation of a Bearing/Cartridge Interface for a Fretting Corrosion Study

1985 ◽  
Vol 107 (2) ◽  
pp. 157-163 ◽  
Author(s):  
R. J. Stover ◽  
H. H. Mabie ◽  
M. J. Furey
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Analytical Study ◽  
Experimental Tests ◽  
Tangential Direction ◽  
Rolling Element Bearings ◽  
Interface Conditions ◽  
Finite Element Technology ◽  
Rolling Element ◽  
Contact Pressures

The bearing/cartridge interfaces of a Ship Service Motor Generator Set (SSMG) were modeled by using finite element technology. The purpose of this analytical study was to verify the results of earlier experimental tests made on an actual SSMG unit. This research is part of a larger research project to examine the important parameters influencing the fretting of rolling element bearings. Models for the bearings at both ends of the unit were developed, and loads simulating the ball pass loads were applied to these models; the contact pressures, radial deformations, and relative displacements at the interface were calculated. The resulting data showed the interface conditions to be extremely complex with the contact pressures varying from zero to a maximum of 55.4 MPa (8030 psi) as the balls passed by. The maximum relative displacements occurred in the tangential direction (2.44 μm) and were independent of the axial boundary conditions.

Parametric Instability of a Beam Due to Axial Excitations and to Boundary Conditions

1998 ◽  
Vol 120 (2) ◽  
pp. 461-467 ◽  
Author(s):  
R. Dufour ◽  
A. Berlioz
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Ritz Method ◽  
Parametric Instability ◽  
Experimental Tests ◽  
Time Varying ◽  
Periodic Force ◽  
Modal Reduction ◽  
Time Varying Parameter ◽  
The Stability

In this paper the stability of the lateral dynamic behavior of a pinned-pinned, clamped-pinned and clamped-clamped beam under axial periodic force or torque is studied. The time-varying parameter equations are derived using the Rayleigh-Ritz method. The stability analysis of the solution is based on Floquet’s theory and investigated in detail. The Rayleigh-Ritz results are compared to those of a finite element modal reduction. It is shown that the lateral instabilities of the beam depend on the forcing frequency, the type of excitation and the boundary conditions. Several experimental tests enable the validation of the numerical results.

Thermal Analysis of a Spur Gearbox Part 1: Steady State Finite Element Analysis

1988 ◽  
Vol 202 (4) ◽  
pp. 245-256 ◽  
Author(s):  
D Joule ◽  
S Hinduja ◽  
J N Ashton
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Boundary Conditions ◽  
Experimental Work ◽  
Thermal Analyses ◽  
Element Model ◽  
Transfer Coefficients ◽  
Element Analysis ◽  
Thermal Boundary Conditions ◽  
Spur Gearbox

The accuracy of previously published thermal analyses of machine tools has been severely limited by imprecise thermal boundary conditions, in particular the values and distribution of heat inputs and heat-transfer coefficients. This paper describes an attempt to overcome some of the difficulties by determining the thermal boundary conditions for calculating the temperatures in a gearbox using the finite element method. A spur gearbox test rig has been designed and constructed, and a finite element model of the test gearbox developed. Temperature measurements and lubricant flow observations from experimental work have been combined with relevant theory to derive the boundary conditions. In the first part of this paper the experimental work and finite element steady state results are described. Sufficient agreement is evident between the two sets of results to indicate that the approach adopted here could be usefully extended to the analysis of other similar problems.

Finite Element Analysis of Functionally Graded Shell Panels Under Thermal Loading

Aerospace ◽  
2005 ◽  
Author(s):  
W. Glenn Cooley ◽  
Anthony Palazotto
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Thermal Protection ◽  
Space Shuttle ◽  
Functionally Graded ◽  
Finite Element Software ◽  
Homogeneous Materials ◽  
Curved Panels

Functionally Graded Materials (FGM) have continuous variation of material properties from one surface to another unlike a composite which has stepped (or discontinuous) material properties. The gradation of properties in an FGM reduces the thermal stresses, residual stresses, and stress concentrations found in traditional composites. An FGM’s gradation in material properties allows the designer to tailor material response to meet design criteria. For example, the Space Shuttle utilizes ceramic tiles as thermal protection from heat generated during re-entry into the Earth’s atmosphere. However, these tiles are prone to cracking at the tile / superstructure interface due to differences in thermal expansion coefficients. An FGM made of ceramic and metal can provide the thermal protection and load carrying capability in one material thus eliminating the problem of cracked tiles found on the Space Shuttle. This paper will explore analysis of shell panels under thermal loading and compare performance of traditional homogeneous materials to FGMs using ABAQUS [1] finite element software. First, theoretical development of FGMs is presented. Second, finite element modeling technique for FGMs is discussed for a thermal stress analysis. Third, homogeneous curved panels made of ceramic and metal are analyzed under thermal loading. Finally, FGM curved panels created from a mixture of ceramic and metal are analyzed. FGM performance is compared to the homogeneous materials in order to explore the effect continuously grading material properties has on structural performance.

scholarly journals Shock Tube Testing and Modelling of Annealed Float Glass

2018 ◽  
Vol 183 ◽  
pp. 01035
Author(s):  
Karoline Osnes ◽  
Tore Børvik ◽  
Odd Sture Hopperstad
Keyword(s):  
Finite Element ◽  
Boundary Conditions ◽  
Prediction Model ◽  
Shock Tube ◽  
Fracture Strength ◽  
Blast Loading ◽  
Experimental Tests ◽  
Float Glass ◽  
Strength Prediction ◽  
Glass Strength

Failure of glass is dominantly brittle, and is caused by microscopic flaws randomly distributed on the surface. Fracture mainly initiates in these flaws, and this leads to a high variability in the glass strength, which depends on geometry, boundary conditions and loading situation. Consequently, the identification of the fracture strength, in e.g. finite element analyses, is not straightforward. For rapid loading conditions, as for blast loading situations, the glass strength is generally increased because flaws need time to grow into cracks. The current study aims to identify the probabilistic fracture strength of glass plates under blast loading as a function of the plate?s boundary conditions, geometry and loading by using a newly proposed strength prediction model. To validate this model in some measure, 12 blast tests on annealed float glass were performed in a shock tube. As expected, the tests showed a large scatter in fracture strength. The strength prediction model captured the main trends found in the experimental tests, but a closer investigation of the strain rate sensitivity of glass was deemed necessary. Finally, the results from the strength prediction model were used as input in a simulation of annealed float glass under blast pressure in the finite element program IMPETUS Afea Solver. By use of a node splitting technique, the simulations captured the behaviour displayed in the experimental tests to a great extent.

Simulation of Partial Autofrettage by Thermal Loads

1980 ◽  
Vol 102 (3) ◽  
pp. 314-318 ◽  
Author(s):  
M. A. Hussain ◽  
S. L. Pu ◽  
J. D. Vasilakis ◽  
P. O’Hara
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Finite Elements ◽  
Residual Stresses ◽  
Finite Differences ◽  
Thermal Loading ◽  
Thermal Stresses ◽  
Intensity Factors ◽  
Stress Patterns ◽  
Walled Cylinder

The effect of favorable residual stresses of an autofrettaged tube is well known [1]. In many instances there is redistribution of these stresses due to changes of geometrical configurations such as the presence of keyways, riflings, cracks, etc. The problem, in general, can be studied by discretization carrried out either by finite elements or by finite differences; however, it is usually not possible to incorporate the redistributed residual stress patterns due to the presence of such geometrical changes. This difficulty is overcome by simulation of residual stresses by certain active loadings. The simulation by dislocation and equivalent thermal loading for a fully autofrettaged tube is well known. In this paper we extend the thermal loading to simulate a partially autofrettaged case. Thermal stresses due to the simulated thermal loading computed from finite elements (NASTRAN) and finite differences are in excellent agreement with residual stresses for various degrees of overstrain. The simplicity of the method to incorporate the redistribution of residual stress due to the presence of geometrical discontinuities is illustrated by a finite element (APES) computation of stress intensity factors at an OD crack tip in a partially autofrettaged, thick-walled cylinder.

Computational Analysis on the Use of Various Nimonic Alloys As Gas Turbine Blade Materials

2019 ◽  
Author(s):  
Rayapati Subbarao ◽  
Nityanando Mahato
Keyword(s):  
Boundary Conditions ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Stresses ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Analyses ◽  
Equivalent Stress ◽  
Gas Turbine Blade ◽  
Nimonic 80A ◽  
Blade Failure

Abstract Blade failure is triggering more problems to the gas turbine engines, while being used in airline and jet engines. In this paper, causes of blade failure with respect to various Nimonic alloys is investigated by performing structural and thermal analyses. Using Ansys, both these analyses on turbine blade are carried out, which is utilized for determining equivalent stresses, deformation and thermal stresses by applying different turbine inlet temperatures and pressures. Turbine blade model is prepared using Solid Works. The computational model is then imported to Ansys workbench. Before importing to the solver, the domain is meshed and boundary conditions are applied. Properties like coefficient of thermal expansion and thermal conductivity are given as material conditions. Ambient temperature, rotational speed, inlet pressure and temperature are considered as boundary conditions. For various configurations and alloy materials, deformation, strain and thermal stresses are plotted and analyzed. After thorough investigation, the turbine blade failure region is identified and the trend is compared for different input temperatures and pressures. At the root of the blade, the stresses and strains are found to be more. Of all the materials considered, Nimonic-90 has less deformation and thermal stresses. Nimonic-80A has more equivalent stress, strain and deformation. Out of the other two materials, Nimonic-263 is showing favourable properties than Nimonic-105. However, the values of stresses and strains are comparable. Thus the present work is beneficial in identifying suitable Nimonic alloy as gas turbine blade material in order to avoid the frequent turbine blade failures.

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