scholarly journals Experimental and numerical investigation on the components of a pantograph slider suspension

2019 ◽  
Vol 252 ◽  
pp. 05003
Author(s):  
Paweł Zdziebko ◽  
Adam Martowicz ◽  
Tadeusz Uhl
Keyword(s):  
Numerical Model ◽  
Material Properties ◽  
Model Building ◽  
Young Modulus ◽  
Experimental Procedure ◽  
Proper Material ◽  
Stiffness And Damping ◽  
Python Programming ◽  
Damping Model

Mechanical properties of the components of a pantograph’s slider suspension system have large influence on the quality of pantograph-catenary interaction. In the paper the authors present the results of their experimental research on the springs that are used in the pantograph being currently in operation in Europe. Static and dynamic tests were performed, which were aimed at determining the stiffness and damping coefficients respectively. Subsequently, the procedure for automated numerical model building for the pantograph’s springs was prepared employing the Python programming language and the MSC Marc solver. When a spring model is build (accordingly to the geometric properties of the springs used in tests), the elaborated algorithm iteratively tunes the material properties and computes static and dynamic load-cases, making direct reference to the experimental procedure. After completing several iterations the numerical model is finally validated, and proper material properties, as the Young modulus and the coefficients of Rayleigh damping model, are found. Then, the obtained model can be used to determine the damping and stiffness coefficients for springs characterizing various diameters, wire diameters, numbers of turns, etc. The presented modelling tool is useful for determining the pantograph sliders suspension characteristics.

scholarly journals The Use of Model Atmospheres for Temperature-Gravity Calibration

1973 ◽  
Vol 54 ◽  
pp. 173-221
Author(s):  
J. C. Pecker
Keyword(s):  
Model Building ◽  
Stellar Atmosphere ◽  
Line Formation ◽  
Early Type ◽  
New Concepts ◽  
Total Luminosity ◽  
Classical Models ◽  
Early Type Stars ◽  
Two Parameters

Regardless of the degree of elaboration of series of models, just how can they be used for calibration purposes? And how much is this calibration sensitive to the quality of the model theory? These two questions are the basis of our discussion, which covers : I – The general principles of the use of model atmospheres in stellar calibration (1 – The two dimensional classifications; 2 – The use of the total luminosity; 3 – The cases of Vega and Sirius; 4 – The calibration of ST – Teff relation); II – The failures of the two parameters model atmospheres (1 – The observational need for more-than-two-parameters classification; 2 – The abundance of elements, the line formation, and the model atmospheres; 3 – Various sources of unadequacy of models; 4 – Envelopes or shell features; their influence on model-building; 5 – The case of HD 45677. Diagnostic of early-type stars; 6 – Various unexplained spectral features); III – The present state of the model factory (1 – The classical models; 2 – New concepts in the description of a stellar atmosphere; 3 – New approaches in model making; 4 – Conclusions).

Effect of material properties and process parameters on quality of friction stir forming

2021 ◽  
Vol 70 ◽  
pp. 553-559
Author(s):  
Francesco Gagliardi ◽  
Mahsa Navidirad ◽  
Giuseppina Ambrogio ◽  
Wojciech Z. Misiolek
Keyword(s):  
Process Parameters ◽  
Material Properties ◽  
Friction Stir

Research on Stiffness and Damping Characteristics of Fixed Oily Porous Materials Joint Interface

2011 ◽  
Vol 422 ◽  
pp. 575-579
Author(s):  
Chong Nian Qu ◽  
Liang Sheng Wu ◽  
Jian Feng Ma ◽  
Yi Chuan Xiao
Keyword(s):  
Porous Material ◽  
Porous Materials ◽  
Parallel Plate ◽  
Joint Interface ◽  
Force Model ◽  
Equivalent Stiffness ◽  
Contact State ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Damping Model

In this document, using the anti-squeezed force model in the narrow parallel plate when fluid is squeezed, the equivalent stiffness and damping model is derived. It is further verified that it can increase the stiffness and damping while there are oil between the joint interfaces theoretically. Because the contact state of oily porous material can divide into liquid and solid parts, the document supposes that it is correct and effective to think the stiffness and damping of the two parts as shunt connection.

Influence of Leaning Materials on the Quality of Building Ceramics

2021 ◽  
Vol 903 ◽  
pp. 197-202
Author(s):  
Ruta Švinka ◽  
Visvaldis Švinka ◽  
Maris Rundans ◽  
Inta Timma ◽  
Laila Petersone
Keyword(s):  
Thermal Expansion ◽  
Glass Fibre ◽  
Material Properties ◽  
Quartz Sand ◽  
Main Method ◽  
Different Types ◽  
Ceramic Building ◽  
Formation Of Cracks

Clay of the deposit Liepa is used for the production of ceramic building and finishing bricks in the factory “Lode” in Latvia. In the present work different types of these clays were investigated and “quartz effect” was determined using quartz sand as a leaning material. The substitution of quartz sand with milled E-glass fibre from Valmiera Glass was investigated and the changes in the magnitude of the quartz inversion effect were analysed. Thermal expansion was the main method for the determination of possible formation of cracks during technological process. Powder of milled glass fibre in amount of 5–10 % affects such properties as water uptake, porosity and apparent density and provides the required material properties at a lower firing temperature.

Numerical Prediction of Rock Fracturing During the Process of Excavation

2012 ◽  
pp. 225-237 ◽  
Author(s):  
Zhangtao Zhou ◽  
Zheming Zhu ◽  
XinXing Jin ◽  
Hao Tang
Keyword(s):  
Equation Of State ◽  
Numerical Model ◽  
Failure Criterion ◽  
Material Properties ◽  
Igneous Rock ◽  
Surrounding Rock ◽  
Rock Blasting ◽  
Rock Fracturing ◽  
Fracturing Process ◽  
Blasting Excavation

During the process of excavation, blasting can induce cracking inside the surrounding rock. Considering the effects of material properties and loading conditions, a rock blasting excavation model with two successive excavation steps was developed through the use of AUTODYN code. Four kinds of equation of state (EOS), linear, shock, JWL, and compaction were applied to the materials employed in this numerical model. A modified principal stress failure criterion was applied to determining material statuses, and TNT explosive and a relatively homogeneous igneous rock, diorite, were used in this numerical model. By using this numerical model, rock fracturing process during blasting excavation was simulated, and rock fracturing process during two successive excavations is presented.

scholarly journals First two bilateral hand transplantations in India (Part 3): Rehabilitation and immediate outcome

2017 ◽  
Vol 50 (02) ◽  
pp. 161-167
Author(s):  
Mohit Sharma ◽  
Subramania Iyer ◽  
P. Kishore ◽  
Jimmy Mathew ◽  
Sundeep Vijayaraghavan ◽  
...  
Keyword(s):  
Management Strategies ◽  
Standard Of Care ◽  
Daily Basis ◽  
Substantial Improvement ◽  
Outcome Analysis ◽  
Functional Magnetic Resonance ◽  
Experimental Procedure ◽  
Management Protocol ◽  
Second Dual

ABSTRACT Introduction: This report covers the strategies adopted for rehabilitation for the first and second dual hand transplants performed in India. Materials and Methods: The team, under a trained physiatrist, including physiotherapy and occupational therapy personnel, was involved in the management of both these patients. The management protocol was developed considering previous reports as well as our management strategies in the rehabilitation of the replanted hands. The involvement of the team with the patients started in the 1st week itself and continued on a daily basis for the entire year. Results: Outcome analysis was performed at 6 months and 1 year using the disability of shoulder and hand evaluation and hand transplant scoring system. Functional magnetic resonance imaging was done at the end of 1 year to assess the cortical integration of the transplanted hand. Conclusion: Despite more than 110 hands being transplanted worldwide, hand transplant remains an experimental procedure. It is still not considered the “standard of care” for hand amputees. Outcome analyses performed worldwide do indicate that the procedure can provide a substantial improvement in the quality of life for the hand amputee, especially the bilateral amputees.

Analysis and Prediction of Surface Integrity in Machining: A Review

2014 ◽  
Vol 610 ◽  
pp. 1002-1020 ◽  
Author(s):  
Yuan Gao ◽  
Xin Huang ◽  
Ming Jie Lin ◽  
Zheng Guo Wang ◽  
Rong Lei Sun
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Material Properties ◽  
Cutting Parameters ◽  
Mechanical Parameters ◽  
Factors Affecting ◽  
Grain Size And Shape

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

Stability Analysis of Chatter System on Ultrasonic Honing

2013 ◽  
Vol 712-715 ◽  
pp. 1241-1247
Author(s):  
Yun Peng Shao ◽  
Xi Jing Zhu ◽  
Meng Liu ◽  
Zhen Liu
Keyword(s):  
Combustion Engine ◽  
Damping Ratio ◽  
Stability Limit ◽  
Cylinder Liner ◽  
Spindle Speed ◽  
Machining System ◽  
Motion Speed ◽  
The Stability ◽  
Stiffness And Damping

The chatter caused by the inner factors of the machining system in the ultrasonic honing process would seriously affect the surface quality of combustion engine. A dynamical model of ultrasonic honing chatter system was established, which involved with ultrasonic honing mechanism and dynamic honing depth, the relationship between the limit honing width and honing speed was deduced based on the theory of regenerative chatter; the simulation was carried out to obtain the effect of different parameters including stiffness coefficient, damping ratio, spindle speed and reciprocation motion speed on the stability limit curve of the chatter system. It can be concluded that the ultrasonic honing chatter system have better stability with low spindle speed, high stiffness and damping ratio, which providing foundation to eliminate ultrasonic honing system chatter in the precision machining of cylinder liner.

Thermal Cycling Simulation during Remelting Process of the Steel ASTM A743-CA6NM

2014 ◽  
Vol 1082 ◽  
pp. 100-105
Author(s):  
Camila Almeida Martins ◽  
Jhon Jairo Ramirez-Behainne
Keyword(s):  
Numerical Model ◽  
Thermal Cycling ◽  
Material Properties ◽  
Three Dimensional ◽  
Fusion Line ◽  
Maximum Deviation ◽  
Experimental Measurements ◽  
Ansys Fluent ◽  
Simplifying Assumptions ◽  
Volume Method

This study aimed to model numerically the thermal cycling resulting from the steel ASTM A743-CA6NM remelting process. The problem was solved with the support of the commercial software ANSYS / FLUENT ® 14.5 for the three-dimensional case using the finite volume method. The following simplifying assumptions were adopted: heat loss by natural convection, absence of radiation, no phase change, concentrated heat source, and thermophysical properties independent of temperature. The results were analyzed for two different current intensities: 90A and 130A, and compared with experimental measurements. The peak temperatures of the thermocouples near the fusion line for the current of 130A were well represented by the numerical model, with a maximum deviation of 9.62%. In the case of the more remote thermocouples from the fusion line, the best results were obtained for the current of 90A, not exceeding 5% of deviation. In general, it was found that the tested body is heated faster than in simulations. This can be considered as a consequence of the simplification in material properties, which were assumed constants with temperature. The results of this study demonstrate that, given the adopted simplifications, the numerical model was able to satisfactorily reproduce the experimentally measured thermal cycles.

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