Plates in Unilateral Contact With Simple Supports: Pressure Loading

1986 ◽  
Vol 53 (1) ◽  
pp. 141-145 ◽  
Author(s):  
N. J. Salamon ◽  
T. P. Pawlak ◽  
F. F. Mahmoud
Keyword(s):  
Support System ◽  
Unilateral Contact ◽  
Response Mode ◽  
Pressure Loading ◽  
Analytical Work ◽  
Simple Supports ◽  
Square Plate ◽  
Lift Off ◽  
Good Agreement ◽  
Shear Fields

The response of a square plate, simply and unilaterally supported, to pressure loading is numerically treated. The support system consists of discrete elastic springs whose stiffnesses range from near-rigid to compliant character. It is found that, except for rather low support stiffnesses, the plate will lift off the foundation. After demonstrating good agreement with a recent analytical work, the deflections and shear fields are provided. The response mode changes dramatically as the supports approach rigidity.

Analysis on Secondary Effect of Corrugated Webs in Steel-Concrete Composite Beams

2011 ◽  
Vol 255-260 ◽  
pp. 596-601 ◽  
Author(s):  
Ke Bin Jiang ◽  
Yong Ding ◽  
Ya Wen Liu ◽  
Feng Zheng
Keyword(s):  
Local Buckling ◽  
Secondary Effect ◽  
Shape Parameters ◽  
Corrugated Webs ◽  
Analytical Work ◽  
Corrugated Web ◽  
Finite Element Package ◽  
First Time ◽  
Numerical And Analytical Methods ◽  
Good Agreement

Some secondary effect introduced by corrugated configuration of corrugated web was studied and formulas were proposed. The deduction for these formulas was resolved into two steps. Step I: to solve the behavior of whole corrugated web by considering it as an orthotropic plate; Step II: to solve the secondary effect according to the shape parameters of corrugation based on the result of Step I. Subsequently, a numerical experiment was designed to validate the analytical work with the help of finite element package ANSYS taking material nonlinearity into consideration. The results obtained from numerical and analytical methods show good agreement. It indicates that the formulas proposed in this paper are convenient and efficient. This research deals with this secondary effect for the first time; more studies are needed for the effect on local buckling of corrugated webs.

Flutter of Supercavitating Hydrofoils-Comparison of Theory and Experiment

1972 ◽  
Vol 16 (03) ◽  
pp. 153-166
Author(s):  
Charles C. S. Song
Keyword(s):  
Leading Edge ◽  
Experimental Program ◽  
Finite Width ◽  
Free Surfaces ◽  
First Order ◽  
Free Jet ◽  
Analytical Work ◽  
Proper Interpretation ◽  
First Order Perturbation ◽  
Good Agreement

Unsteady flow due to harmonic oscillations of a two-dimensional supercavitating flat-plate hydrofoil in a free jet of finite width has been analyzed using first-order perturbation theory. The hydrodynamic loading coefficients thus obtained were used to study the hydroelastic instabilities: flutter and divergence. In conjunction with the analytical work, an experimental program was carried out using a free-jet water tunnel. Special attention was given to the influence of the free surfaces and the point of separation on the critical flutter speed. With proper interpretation of the location of the separation point near the leading edge, the theory and the experimental data were shown to be in fairly good agreement.

scholarly journals Understanding the diesel-like spray characteristics applying a flamelet-based combustion model and detailed large eddy simulations

2019 ◽  
Vol 21 (1) ◽  
pp. 134-150 ◽  
Author(s):  
Eduardo J Pérez-Sánchez ◽  
Jose M Garcia-Oliver ◽  
Ricardo Novella ◽  
Jose M Pastor
Keyword(s):  
Flame Stabilization ◽  
Large Eddy Simulations ◽  
Combustion Model ◽  
Progress Variable ◽  
Auto Ignition ◽  
Large Eddy ◽  
Engine Combustion ◽  
Spatial Fields ◽  
Lift Off ◽  
Good Agreement

This investigation analyses the structure of spray A from engine combustion network (ECN), which is representative of diesel-like sprays, by means of large eddy simulations and an unsteady flamelet progress variable combustion model. A very good agreement between modelled and experimental measurements is obtained for the inert spray that supports further analysis. A parametric variation in oxygen concentration is carried out in order to describe the structure of the flame and how it is modified when mixture reactivity is changed. The most relevant trends for the flame metrics, ignition delay and lift-off length are well-captured by the simulations corroborating the suitability of the model for this type of configuration. Results show that the morphology of the flame is strongly affected by the boundary conditions in terms of the reactive scalar spatial fields and Z–T maps. The filtered instantaneous fields provided by the simulations allow investigation of the structure of the flame at the lift-off length, whose positioning shows low fluctuations, and how it is affected by turbulence. It is evidenced that small ignition kernels appear upstream and detached from the flame that eventually merge with its base in agreement with experimental observations, leading to state that auto-ignition plays a key role as one of the flame stabilization mechanisms of the flame.

scholarly journals Flow-Through Self-Standing Porous Silicon Sensor

Proceedings ◽  
2018 ◽  
Vol 4 (1) ◽  
pp. 17
Author(s):  
David Martín-Sánchez ◽  
Salvador Ponce-Alcántara ◽  
Jaime García-Rupérez
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Multilayer Structure ◽  
Reflectance Spectra ◽  
Flow Through ◽  
Index Changes ◽  
Lift Off ◽  
Theoretical Simulations ◽  
Silicon Sensor ◽  
Good Agreement

A self-standing porous silicon (PS) multilayer structure detached from the substrate by the lift-off method and integrated with a microfluidic cell is presented. Experiments of refractive index changes sensing flow through open-ended pores are reported. We continuously recorded the reflectance spectra of the PS membrane each 30 s and measured the shift as different substances flowed through the structure. The experimental sensitivity values are in good agreement with the theoretical simulations performed.

Linear Stability Analysis and Buckling of Two-Layered Shells Under External Circumferential Loading: A Numerical Investigation

2009 ◽  
Author(s):  
George Papadakis
Keyword(s):  
Critical Load ◽  
Numerical Investigation ◽  
Engineering Practice ◽  
Pressure Loading ◽  
Layered Shells ◽  
Differential Stability ◽  
The Stability ◽  
Volume Method ◽  
Moduli Of Elasticity ◽  
Good Agreement

The aim of the paper is the numerical investigation of the stability of two-layered shells under the action of imposed azimuthal strain on the external surface. Although this type of loading is not common in engineering practice, it appears often in biomedicine (for example buckling of esophagus, asthmatic airways, gastrointestinal tract etc). The differential stability equations are discretised using the finite volume method and the resulting generalised eigenvalue problem is solved using the QZ decomposition technique. The results show that the buckling behaviour under circumferential loading is entirely different compared to hydrostatic pressure loading. More specifically, it is well known that in the latter case the number of folds with the smallest critical load is equal to 2. In the former case however it depends on the thickness of each layer and their moduli of elasticity. Comparison with experimental measurements shows good agreement. The thickness of the inner layer significantly affects the number of folds and the critical load (it was found that the number of folds is reduced with increasing layer thickness). Comparison of the eigenfunctions of radial and azimuthal displacements also shows more complex behavior compared to pressure loading.

A Study of Shear-Spinnability of Metals

1961 ◽  
Vol 83 (4) ◽  
pp. 478-483 ◽  
Author(s):  
Serope Kalpakcioglu
Keyword(s):  
Experimental Data ◽  
Deformation Zone ◽  
Stress System ◽  
Two Dimensional ◽  
Maximum Reduction ◽  
State Of Stress ◽  
Analytical Work ◽  
Sine Law ◽  
Shear Spinning ◽  
Good Agreement

The deformation zone in shear-spinning is idealized for a two-dimensional process and maximum permissible thickness reduction without fracture is predicted in terms of the stress system in this zone. The effect of deviation from the sine law on the maximum reduction before fracture is shown analytically to be due to the influence of distortions of the unspun flange on the state of stress under the roller. The results of analytical work are compared with experimental data and good agreement has been obtained. The phenomenon of back extrusion in shear-spinning is shown to be the result of a compressive stress in the spun section parallel to the mandrel side and is greatly influenced by mandrel angle and deviation from the sine law.

Unbonded Contact of a Square Plate on an Elastic Half-Space or a Winkler Foundation

1988 ◽  
Vol 55 (2) ◽  
pp. 430-436 ◽  
Author(s):  
Hui Li ◽  
J. P. Dempsey
Keyword(s):  
Contact Problem ◽  
Half Space ◽  
Contact Region ◽  
Elastic Half Space ◽  
Unilateral Contact ◽  
Winkler Foundation ◽  
Vertical Loading ◽  
Centrally Symmetric ◽  
Receding Contact ◽  
Square Plate

The unbonded frictionless receding contact problem of a thin plate placed under centrally symmetric vertical loading while resting on an elastic half-space or a Winkler foundation is solved in this paper. The problem is transformed into the solution of two-coupled integral-series equations over an unknown contact region. The problem is nonlinear by virtue of unilateral contact and therefore needs to be solved iteratively. Special attention is given to the edge and corner contact pressure singularities for the plate on the elastic half-space. Comparison is made with other relevant numerical results available.

scholarly journals Assessment of the Effectiveness of Combat Eyewear Protection Against Blast Overpressure

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
A. Sundaramurthy ◽  
M. Skotak ◽  
E. Alay ◽  
G. Unnikrishnan ◽  
H. Mao ◽  
...  
Keyword(s):  
Peak Pressure ◽  
Three Dimensional ◽  
Head Orientation ◽  
Computational Results ◽  
Pressure Loading ◽  
3D Finite Element ◽  
Blast Overpressure ◽  
Explosive Devices ◽  
Peak Pressures ◽  
Good Agreement

It is unclear whether combat eyewear used by U. S. Service members is protective against blast overpressures (BOPs) caused by explosive devices. Here, we investigated the mechanisms by which BOP bypasses eyewear and increases eye surface pressure. We performed experiments and developed three-dimensional (3D) finite element (FE) models of a head form (HF) equipped with an advanced combat helmet (ACH) and with no eyewear, spectacles, or goggles in a shock tube at three BOPs and five head orientations relative to the blast wave. Overall, we observed good agreement between experimental and computational results, with average discrepancies in impulse and peak-pressure values of less than 15% over 90 comparisons. In the absence of eyewear and depending on the head orientation, we identified three mechanisms that contributed to pressure loading on the eyes. Eyewear was most effective at 0 deg orientation, with pressure attenuation ranging from 50 (spectacles) to 80% (goggles) of the peak pressures observed in the no-eyewear configuration. Spectacles and goggles were considerably less effective when we rotated the HF in the counter-clockwise direction around the superior-inferior axis of the head. Surprisingly, at certain orientations, spectacles yielded higher maximum pressures (80%) and goggles yielded larger impulses (150%) than those observed without eyewear. The findings from this study will aid in the design of eyewear that provides better protection against BOP.

scholarly journals Model of the Magnetostrictive Hysteresis Loop with Local Maximum

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 105 ◽  
Author(s):  
Roman Szewczyk
Keyword(s):  
Hysteresis Loop ◽  
Hysteresis Loops ◽  
Local Maximum ◽  
Boltzmann Distribution ◽  
Wall Movement ◽  
Construction Steel ◽  
Proposed Model ◽  
Lift Off ◽  
Power Application ◽  
Good Agreement

This paper presents a model of the magnetostrictive hysteresis loop with local maximum. The model is based on the differential equations describing magnetostriction due to the domain wall movement as well as domain magnetization rotation. The transition between these mechanisms of magnetization is quantified by the Maxwell–Boltzmann distribution. Moreover, the lift-off phenomenon in the magnetostrictive hysteresis loop is considered. The proposed model was validated on the results of measurements of magnetostrictive hysteresis loops of Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel. The results of modeling confirm that the proposed model corresponds well with experimental results. Good agreement was confirmed by determination coefficient R2, which exceeded 0.995 and 0.985 for Mn0.70Zn0.24Fe2.06O4 ferrite for power application and 13CrMo4-5 construction steel, respectively.

scholarly journals An Analytical Model for Prediction of Magnetic Flux Leakage from Surface Defects in Ferromagnetic Tubes

2016 ◽  
Vol 16 (1) ◽  
pp. 8-13 ◽  
Author(s):  
V. Suresh ◽  
A. Abudhahir
Keyword(s):  
Magnetic Flux ◽  
Analytical Model ◽  
Surface Defects ◽  
Experimental Results ◽  
Magnetic Flux Leakage ◽  
Analytical Expression ◽  
Cylindrical Holes ◽  
Lift Off ◽  
Flux Leakage ◽  
Good Agreement

Abstract In this paper, an analytical model is proposed to predict magnetic flux leakage (MFL) signals from the surface defects in ferromagnetic tubes. The analytical expression consists of elliptic integrals of first kind based on the magnetic dipole model. The radial (Bz) component of leakage fields is computed from the cylindrical holes in ferromagnetic tubes. The effectiveness of the model has been studied by analyzing MFL signals as a function of the defect parameters and lift-off. The model predicted results are verified with experimental results and a good agreement is observed between the analytical and the experimental results. This analytical expression could be used for quick prediction of MFL signals and also input data for defect reconstructions in inverse MFL problem.

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