Thermal buckling of a thin uniform circular disk: a comparison of predictions

AbstractThe conditions for thermally-induced buckling of an unloaded thin, circular disk are compared from two well-known but unconnected studies: an approximate solution by Freund for a constant thickness disk, which must neglect the free edge condition, and an exact solution by Mansfield but only for a disk whose thickness tapers to zero in a particular manner. It is shown that buckling occurs at slightly higher values compared to a finite element analysis of a constant thickness disk but that the case of variable thickness seems to offer a closer result, which suggests that it better models the boundary layer behaviour near the free edge.

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Structural Analysis of Centrifugal Fan Impeller Using CATIA Software

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.809-810.859 ◽

2015 ◽

Vol 809-810 ◽

pp. 859-864

Author(s):

Dănuţ Zahariea

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Structural Analysis ◽

Design Methods ◽

Constant Thickness ◽

Blade Design ◽

Centrifugal Fan ◽

Element Analysis ◽

The Finite Element Analysis ◽

Modes Of Vibration

In this paper, the finite element analysis for stress/deformation/modes of vibration for the centrifugal fan impeller with constant thickness backward-curved blades using CATIA software will be presented. The principal steps of the finite element analysis procedure using CATIA/Generative Structural Analysis environment will be presented: creating the 3D model; configuring the mesh; applying the restraints; applying the loads; running the numerical static analysis and the numerical frequency analysis; interpreting the results and observing the modes of vibration correlating with the impeller mode shape. This procedure will be used for 4 different centrifugal fan impellers according with the 4 blade design methods and the results will be comparatively analyzed. For each design method, two materials will be used: steel with density of 7860 kg/m3 and aluminium with density of 2710 kg/m3. Two important results have been obtained after the structural analysis: under the working conditions considered for the analysis, all 4 blade design methods leads to impellers with very good mechanical behaviour; any frequency of the main modes of vibrations for all blade design methods and for both materials is not in phase with the impeller speed, thus the possibility of resonance being eliminated.

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Performance of composite sandwich structures under thermal cycling

Journal of Composite Materials ◽

10.1177/0021998319862324 ◽

2019 ◽

Vol 54 (2) ◽

pp. 271-283

Author(s):

Sandesh Rathnavarma Hegde ◽

Mehdi Hojjati

Keyword(s):

Crack Formation ◽

Mechanical Performance ◽

Crack Density ◽

Free Edge ◽

Element Analysis ◽

Thermally Induced ◽

Composite Sandwich ◽

Composite Sandwich Structures ◽

Number Of Cycles ◽

Microscopic Inspection

Effect of thermally induced microcracks on mechanical performance of a space grade laminated sandwich panel is investigated. A simple non-contact setup using liquid nitrogen is developed to subject the material to low temperature of −170℃ with cooling rate of 24℃/min. Then the samples are exposed to the elevated temperature of 150℃ inside oven. Microcracks formation and propagation are monitored through microscopic observation of cross-section during the cycling. Flatwise tensile test is performed after a number of cycles. A correlation is made between number of cycles and flatwise mechanical strength after quantifying the microcracks. It is observed that the crack formation gets saturated at about 40 cycles, avoiding the need to conduct more thermal cycles. Microcrack formation both at the free edge and middle of laminate was observed. The crack density at the middle was comparatively less than the ones found on the free edges. Results for non-contact cooling are compared with samples from direct nitrogen contact cooling. Microscopic inspection and flatwise test show differences between contact and non-contact cooled samples. Flatwise tensile strength for non-contact cooled samples shows 15% reduction, while the contact cooled samples have about 30% decrease in bond strength. A 3D finite element analysis is conducted to qualitatively identify the location of stress concentration which can be possible sites of crack formation. Good agreement is observed between the model and experimental results.

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A Nonlinear and Time Dependent Finite Element Analysis of Solder Joints in Surface Mounted Components Under Thermal Cycling

MRS Proceedings ◽

10.1557/proc-226-23 ◽

1991 ◽

Vol 226 ◽

Cited By ~ 18

Author(s):

Yi-Hsin Pao ◽

Kuan-Luen Chen ◽

An-Yu Kuo

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Thermal Cycling ◽

Solder Joints ◽

Free Edge ◽

Time Dependent ◽

Element Analysis ◽

Finite Element Program ◽

Element Program ◽

Peel Stress

AbstractA nonlinear and time dependent finite element analysis was performed on two surface mounted electronic devices subjected to thermal cycling. Constitutive equations accounting for both plasticity and creep for 37Pb/63Sn and 90Pb/10Sn solders were assumed and implemented in a finite element program ABAQUS with the aid of a user subroutine. The FE results of 37Pb/63Sn solder joints were in reasonably good agreement with the experimental data by Hall [19]. In the case of 9OPb/1OSn solder in a multilayered transistor stack, the FE results showed the existence of strong peel stress near the free edge of the joint, in addition to the anticipated shear stress. The effect of such peel stress on the crack initiation and growth as a result of thermal cycling was discussed, together with the singular behavior of both shear and peel stresses near the free edge.

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