Experimental Tests on Buckling of Torispherical Heads and Methods of Plastic Bifurcation Analysis

1986 ◽  
Vol 108 (2) ◽  
pp. 138-145 ◽  
Author(s):  
R. L. Roche ◽  
B. Autrusson
Keyword(s):  
Bifurcation Analysis ◽  
Experimental Tests ◽  
General Purpose ◽  
Experimental Results ◽  
Steel Plates ◽  
Practical Result ◽  
General Purpose Computer ◽  
Elastic Shear ◽  
Good Agreement ◽  
Incremental Theory Of Plasticity

Sixteen torispherical heads were tested under internal pressure. These heads, which were 500 mm in diameter, had diameter/thickness ratios ranging from 330 to 1000. They were all prepared by spinning mild steel plates. Deflections along the axis and in the knuckle area were recorded. The most practical result is the buckling pressure and this can be exceeded without fracturing the head. The tests show that the buckling pressure is relatively unaffected by geometric imperfections. These experimental results are used to assess the validity of the different plastic bifurcation analysis methods. Five different methods were employed using the CASTEM general-purpose computer program. The method based on the incremental theory of plasticity proved to be incapable of correctly predicting head buckling. If this method is modified by replacing the elastic shear modulus by the secant modulus, the results obtained show good agreement with experimental results.

scholarly journals Numerical and Experimental Study on the Locally Blast Loaded Polyurea Coated Steel Plates

2019 ◽  
Vol 56 (3) ◽  
pp. 492-499
Author(s):  
Florina Bucur ◽  
Eugen Trana ◽  
Adrian Rotariu
Keyword(s):  
Experimental Tests ◽  
Cost Effective ◽  
Experimental Results ◽  
Steel Plates ◽  
Coated Steel ◽  
Quick Response ◽  
Blast Mitigation ◽  
Private Research ◽  
Set Up ◽  
Research Facilities

The damages and casualties inflicted by mine and IED attacks in security challenging areas generated a strong and quick response from nations all over the world. As a part of this response several national and private research facilities increased their efforts in identifying and implementing new ways or technologies to enable blast wave mitigation. The current paper aim to investigate the opportunity of using polyurea coated steel plates as a possible new blast mitigation approach, as suggested by several investigators. In order to objectively conclude about the ability of polyurea coated plates to sustain locally blast loads several experimental tests were performed according to STANAG 4569 demands for a 1/6 scaled plate structure. In order to numerically validate the experimental results several Autodyn simulations were set-up. The numerical and experimental results exibits a fair correlation, both pointing towards a dismiss of the idea of using polyurea coated steel plates as structural and cost effective blast mitigation approach.

One Dimensional Modeling of Catalyst for Internal Combustion Engine Simulation

2006 ◽  
Author(s):  
David Chalet ◽  
Jose´ Galindo ◽  
He´ctor Climent
Keyword(s):  
Shock Wave ◽  
Steady Flow ◽  
Experimental Test ◽  
Test Bench ◽  
Experimental Tests ◽  
Experimental Results ◽  
One Dimensional ◽  
Set Up ◽  
Experimental Test Bench ◽  
Good Agreement

The aim of this paper consists of establishing a methodology for oxidation catalyst modeling based on experimental tests and the development of a theoretical model with zero and one dimensional elements. Related to the theoretical work, the main aspects of such modeling are presented. It consists of describing the inner catalyst geometry by a combination of volumes and simple pipes network. The gas properties in volumes are calculated with a filling and emptying approach whereas the unsteady flow in pipes elements is considered to be one-dimensional and solved by using a finite difference scheme. Concerning the experimental tests, a study is carried out on a shock tube bench. The advantage of this experimental test bench is to study the propagation of a shock wave in the catalyst under controlled and convenient conditions, i.e. cold and non steady flow. Later, the model is set up by comparing the upstream and downstream pressure signals with the simulation results. Since the model lacks of relevant information of pressure losses at the inlet and outlet of the channels, which are rather difficult to compute due to the complex phenomena and flow maldistributions if the use of a 3D CFD code is avoided, the calibration of the model to match the experimental data is the decided approach. In this context, the shock wave test bench is used in order to excite the catalyst with non-steady flow conditions rather than to reproduce the conditions that will appear in real engine operation. The comparison shows good agreement between one-dimensional and experimental results. In order to validate this new modeling on a real engine configuration, an experimental validation is carried out in a four-stroke turbocharged Diesel engine. This experimental test bench allows to measure the main engine characteristics and performance as well as the instantaneous pressure upstream and downstream the catalyst. A simulation code has been also set up to model the engine and the comparison in terms of exhaust pressure pulses propagation inside the catalyst shows good agreement between the one-dimensional model and the experimental results.

Hybrid Effect on Hybrid Composite Reinforced Carbon Fibers and Flax Fibers

2019 ◽  
Vol 801 ◽  
pp. 101-106
Author(s):  
Anh Vu Nguyen ◽  
Karine Charlet ◽  
Belhassen Chedli Bouzgarrou ◽  
Ky Nam Pham ◽  
Trong Dai Vu ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Hybrid Composite ◽  
Hybrid Composites ◽  
Experimental Tests ◽  
Experimental Results ◽  
Woven Composites ◽  
Hybrid Effect ◽  
Flax Fibers ◽  
Homogenization Model ◽  
Good Agreement

In this paper, hybrid composite made of carbon woven fibers and flax woven fibers is studied. This hybrid composite structure takes advantages of high resistance, high stiffness of carbon fibers and high damping and low density of flax fibers. Different structures of flax woven composites, carbon woven composites and hybrid composites were fabricated and tested experimentally. With aim of predicting the properties of the hybrid composite, a homogenization model of the composite is established. The homogenization model is based on the rule-of-mixture and iso-strain assumption. The results of the analytical homogenization model (AHM) are then compared with the results of experimental tests. The results show a good agreement between the AHM and the experimental results at the homogenization level of the woven composite. However, at the hybrid composite homogenization level, the experimental results present considerably higher stiffness than analytical results that is explained by hybrid effect on the hybrid composite.

Failure Conditions from Push-Out Tests of a Steel-Concrete Joint: Experimental Results

2011 ◽  
Vol 488-489 ◽  
pp. 714-717 ◽  
Author(s):  
Peter Helincks ◽  
Wouter de Corte ◽  
Jan Klusák ◽  
Stanislav Seitl ◽  
Veerle Boel ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Experimental Tests ◽  
Experimental Results ◽  
Steel Plates ◽  
Element Analysis ◽  
Concrete Core ◽  
Concrete Joints ◽  
Failure Conditions ◽  
Push Out

Steel-concrete joints can suffer from premature fail due to inadequate shear bond between the two surfaces. In this paper the shear bond strength between steel and self-compacting concrete (SCC) without mechanical shear connectors is evaluated through push-out tests. The test samples consist of two sandblasted steel plates (10 and 6 mm) and a concrete core, with connection between steel and concrete obtained by a 2-component epoxy resin, gritted with granulates. During the tests, the ultimate shear force is recorded as well as the slip between steel and concrete. All test members exhibited a concrete - adhesive failure, and indicate nominal shear bond stresses between 2.20 and 4.22 MPa. In addition, a substantial difference in measured shear bond stresses is found between the 6 and 10 mm steel plates, indicating unwanted secondary effects with the 6 mm plates. During testing, maximum slip values between 0.02 and 0.05 mm are recorded. In addition to the experimental tests, shear stress distribution in the epoxy – concrete interface is examined by finite element analysis (FEA). In this way, a non-uniform stress distribution between steel and concrete is found with the maximum shear value about 2.5 times higher than the nominal shear stress value. The FEA combined with the experimental results provide a reasonable understanding of the shear induced failure conditions at a steel-concrete joint, and create test data for a fracture mechanics approach.

scholarly journals Simulations and Experiments of a Nonlinear Aircraft Braking System With Physical Dispersion

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Fabrice Chevillot ◽  
Jean-Jacques Sinou ◽  
Nicolas Hardouin ◽  
Louis Jezequel
Keyword(s):  
Time History ◽  
Experimental Tests ◽  
Experimental Results ◽  
Dynamic Equations ◽  
Experimental Conditions ◽  
Braking System ◽  
Nonlinear Dynamic Equations ◽  
The Coefficient Of Friction ◽  
Time History Response ◽  
Good Agreement

This paper deals with the simulation of nonlinear vibration induced by friction in an aircraft braking system. Experimental tests reveal that in similar experimental conditions the mechanism can generate vibrations of various amplitudes. The aim of this study is to simulate the behavior of the brake by taking into account the dispersion of parameters, which produce the variability of the response. A nonlinear model of the brake is presented. The time-history response is obtained by integration of the full set of nonlinear dynamic equations. Based on experimental results, the dispersions of the coefficient of friction and of the damping configuration are introduced. Monte Carlo simulations are performed and show a very good agreement with the experimental results.

Characterization of the torsional vibration behavior of circular and rectangular cross-sectional arc springs: Theory and experiments

2021 ◽  
Vol 63 (2) ◽  
pp. 113-118
Author(s):  
Samet Fidanciogullari ◽  
Ahmet Yildiz
Keyword(s):  
Torsional Vibration ◽  
Experimental Tests ◽  
Experimental Results ◽  
Experimental Characterization ◽  
Cross Sectional ◽  
Vibration Behavior ◽  
The Masses ◽  
Theory And Experiments ◽  
Good Agreement

Abstract This paper is about the theoretical and experimental characterizations of the torsional vibration behavior of circular and rectangular cross-sectional arc springs. Firstly, the dynamic behaviors of arc springs with different cross-sectional wire profiles designed for a dual mass flywheel are modeled by mathematical formulations. After that, experimental tests are performed to verify these models and it is observed that the stiffness characterizations are in good agreement with experimental results. Lastly, the masses of two different arc springs are compared by regarding the same vibration stiffness criteria and it is demonstrated that the rectangular wire provides an arc spring with a 9.44 vol.-% lighter structure. Thus, the outcomes of this paper can be good references for the manufacturer about the numerical and experimental characterization of dual mass flywheel springs, especially for rectangular wire arc springs.

Static and dynamic behaviour of soils : a rational approach to quantitative solutions. I. Fully saturated problems

1990 ◽  
Vol 429 (1877) ◽  
pp. 285-309 ◽  
Keyword(s):  
Computer Program ◽  
Mechanical Model ◽  
Dynamic Behaviour ◽  
Solid Phase ◽  
General Purpose ◽  
Experimental Results ◽  
Physical Models ◽  
Rational Approach ◽  
General Purpose Computer ◽  
Purpose Computer

The behaviour of all geomaterials, and in particular of soils, is governed by their interaction with the pore fluid. The mechanical model of this interaction when combined with suitable constitutive discription of the solid phase and with efficient, discrete, computation procedures, allows most transient and static problems involving deformations to be solved. This paper describes the basic procedures and the development of a general purpose computer program (SWANDYNE-X). The results of the computations are validated by comparison with experimental results obtained on physical models tested in the Cambridge Centrifuge.

Compiler-Aided Run-Time Performance Speed-Up in Super-Scalar Processor

10.28945/3391 ◽  
2009 ◽  
Author(s):  
Moshe Pelleh
Keyword(s):  
Embedded Systems ◽  
Embedded System ◽  
General Purpose ◽  
Experimental Results ◽  
Medium Size ◽  
Organic System ◽  
Software Application ◽  
Organic Systems ◽  
Special Cases ◽  
Run Time

In our world, where most systems become embedded systems, the approach of designing embedded systems is still frequently similar to the approach of designing organic systems (or not embedded systems). An organic system, like a personal computer or a work station, must be able to run any task submitted to it at any time (with certain constrains depending on the machine). Consequently, it must have a sophisticated general purpose Operating System (OS) to schedule, dispatch, maintain and monitor the tasks and assist them in special cases (particularly communication and synchronization between them and with external devices). These OSs require an overhead on the memory, on the cache and on the run time. Moreover, generally they are task oriented rather than machine oriented; therefore the processor's throughput is penalized. On the other hand, an embedded system, like an Anti-lock Braking System (ABS), executes always the same software application. Frequently it is a small or medium size system, or made up of several such systems. Many small or medium size embedded systems, with limited number of tasks, can be scheduled by our proposed hardware architecture, based on the Motorola 500MHz MPC7410 processor, enhancing its throughput and avoiding the software OS overhead, complexity, maintenance and price. Encouraged by our experimental results, we shall develop a compiler to assist our method. In the meantime we will present here our proposal and the experimental results.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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