Thermal ratchetting of axially loaded tubes operating in the creep range

1982 ◽  
Vol 17 (4) ◽  
pp. 243-251 ◽  
Author(s):  
T H Hyde ◽  
J J Webster ◽  
H Fessler
Keyword(s):  
Finite Element ◽  
Creep Behaviour ◽  
Practical Interest ◽  
Model Material ◽  
Strain Gauges ◽  
Lead Alloy ◽  
Temperature Variations ◽  
Finite Element Calculations ◽  
Cyclic Temperature ◽  
Axially Loaded

Finite element predictions of ratchetting and creep behaviour are compared with experimental data for axially loaded tubes subjected to axisymmetric cyclic temperature variations. Eleven tubes made of a lead alloy model material which creeps at ambient temperature were tested. Strain gauges were used to measure the ratchet and creep strains. In the finite element calculations it was assumed that no plasticity-creep interactions occur. Reasonably good predictions of ratchet strains were obtained, particularly in the range of most practical interest. Some of the discrepancies between ratchet and creep results can be accounted for by considering the results from a small number of uniaxial plasticity-creep interaction tests.

Predicting the thermal ratchetting and creep behaviour of a component with a stress concentration

1982 ◽  
Vol 17 (4) ◽  
pp. 263-268 ◽  
Author(s):  
T H Hyde ◽  
J J Webster
Keyword(s):  
Stress Concentration ◽  
Electrical Resistance ◽  
Creep Behaviour ◽  
Strain Gauges ◽  
Temperature Variations ◽  
Alloy Material ◽  
Cyclic Temperature ◽  
Plain Tube ◽  
Chill Cast ◽  
Dwell Period

Finite element and ‘upper bound’ predictions of ratchetting and creep are compared with experimental data from two axially loaded shouldered tubes subjected to axisymmetric cyclic temperature variations. The shouldered tubes were machined from chill-cast bars of a lead alloy material. Electrical resistance strain gauges were used to measure the ratchet and creep strain. The results show that ratchet strains can accumulate significantly faster in stress concentration regions when compared with plain tube regions. Acceptable predictions were obtained for the ratchet strains. The discrepancies between the predicted and measured dwell period strains were due to neglecting the material plasticity-creep interactions. Some simple methods for estimating the strains are suggested.

Elasto-plastic and creep behaviour of axially loaded, shouldered tubes

1980 ◽  
Vol 15 (1) ◽  
pp. 21-29 ◽  
Author(s):  
R J Dawson ◽  
H Fessler ◽  
T H Hyde ◽  
J J Webster
Keyword(s):  
Finite Element ◽  
Creep Behaviour ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Equivalent Strain ◽  
Uniaxial Tensile ◽  
Plastic Strain Increment ◽  
Axially Loaded ◽  
Initial Strains ◽  
Creep Strains

This paper compares the finite element predictions of elasto-plastic and creep behaviour with experimental data for axially loaded, shouldered tube models. Four shouldered tube models were made of a lead alloy and tested at 61°C, using strain gauges to measure the elasto-plastic and creep strains in the plain tube and fillet regions of the models. Instantaneous stress-strain and creep data were obtained from strain-gauged, uniaxial tensile specimens. The finite element solutions are based on the incremental Prandtl-Reuss equations. The elasto-plastic iterative solutions use a ‘negative gradient’ from the calculated point to the equivalent stress-equivalent strain curve to get the next estimate of the plastic strain increment. A time incremental method is used to obtain the creep solutions. Tests with the mean tube stress below, at and above the yield stress showed very good agreement between prediction and measurement of initial strains in the fillets. Differences between predictions and measurements of creep strains are attributable to cast-to-cast variations.

Cold expansion of rail-end-bolt holes: finite element predictions and experimental validation by DIC and strain gauges

2021 ◽  
pp. 106275
Author(s):  
Giovanni Pio Pucillo ◽  
Alessandro Carrabs ◽  
Stefano Cuomo ◽  
Adam Elliott ◽  
Michele Meo
Keyword(s):  
Finite Element ◽  
Experimental Validation ◽  
Strain Gauges ◽  
Cold Expansion ◽  
Bolt Holes

Investigated Effect of Points Charge of the Receptors on the Conduction of Semiconductor Nanowire

2015 ◽  
Vol 1109 ◽  
pp. 167-170
Author(s):  
M. Wesam Al-Mufti ◽  
U. Hashim ◽  
Mijanur Rahman ◽  
Tijjani Adam ◽  
A.H. Azman ◽  
...  
Keyword(s):  
Finite Element ◽  
Oxide Layer ◽  
Point Charge ◽  
Potential Distribution ◽  
Silicon Nanowire ◽  
Comsol Multiphysics ◽  
Functional Layer ◽  
Semiconductor Nanowire ◽  
Finite Element Calculations

The paper reported a study on an effect of the point charge of the bio-interface of a nanowire field biosensor on the conductance of the nanowire, through finite element calculations using COMSOL Multiphysics. A model with 5 layers starting with silicon nanowire of radius 10nm surrounded by a 2-nm oxide layer, and the oxide layer were surrounded by a 5 nm thick functional layer and 2 points charge were considered for this study and last layer is for electrolyte. The results shows that is different voltages with points change is that effected on the conductance of nanowire that is clear from different of potential distribution of point charge.

Exact analysis of the bending of wide beams by a modified elastica approach

2011 ◽  
Vol 225 (11) ◽  
pp. 2759-2764 ◽  
Author(s):  
L F Campanile ◽  
R Jähne ◽  
A Hasse
Keyword(s):  
Finite Element ◽  
Substantial Reduction ◽  
Short Review ◽  
Computational Effort ◽  
Two Dimensional ◽  
Finite Element Calculations ◽  
Dimensional Finite Element ◽  
Wide Beams ◽  
Insight Into ◽  
Selection Of

Classical beam models do not account for partial restraint of anticlastic bending and are therefore inherently inaccurate. This article proposes a modification of the exact Bernoulli–Euler equation which allows for an exact prediction of the beam's deflection without the need of two-dimensional finite element calculations. This approach offers a substantial reduction in the computational effort, especially when coupled with a fast-solving schema like the circle-arc method. Besides the description of the new method and its validation, this article offers an insight into the somewhat disregarded topic of anticlastic bending by a short review of the published theories and a selection of representative numerical results.

Incompressibility and mesh sensitivity analysis in finite element simulation of rubbers

2016 ◽  
Vol 7 (1) ◽  
pp. 7-12 ◽  
Author(s):  
D. Huri
Keyword(s):  
Finite Element ◽  
Material Characterization ◽  
Numerical Stability ◽  
Material Parameters ◽  
Linear Finite Element ◽  
Element Simulation ◽  
Finite Element Calculations ◽  
Mesh Density ◽  
Rubber Component

Non-linear finite element calculations are indispensable when important information of the material response under load of a rubber component is desired. Although the material characterization of a rubber component is a demanding engineering task, the changing contact range between the parts and the incompressibility behaviour of the rubber further increase the complexity of the investigations. In this paper the effects of the choice of the numerical material parameters (e.g. bulk modulus) are examined with regard to numerical stability, mesh density and calculation accuracy. As an example, a rubber spring is chosen where contact problem is also handled.

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