scholarly journals PROCEDURE AND ALGORITHM FOR DETERMINING THE COEFFICIENT OF THE FREIGHT WAGON STABILITY IN COMPLIANCE WITH CURRENT REQUIREMENTS

2021 ◽  
pp. 31-53
Author(s):  
Oleksandr Safronov ◽  
◽  
Andrii Sulym ◽  
Pavlo Khozia ◽  
Yurii Vodiannikov ◽  
...  
Keyword(s):  
Equivalent Stress ◽  
Safety Margin ◽  
Dynamic Loads ◽  
Railway Track ◽  
Longitudinal Impact ◽  
Voltage Amplitude ◽  
Maximum Discharge ◽  
Fatigue Damage Accumulation ◽  
The Impact ◽  
Freight Wagons

Improving the reliability of test results is achieved by applying more advanced methods of recording and processing the results. Therefore, an important part of the study of the strength of freight wagons is the choice of methods for obtaining, processing and analyzing experimental data. The article outlines the procedure and algorithms for determining the equivalent stresses under longitudinal and dynamic loads acting during operation. It is shown that algorithms for determining stresses generated by dynamic longitudinal and vertical forces are significantly different due to various load application schemes. Thus, the testing of freight wagons under dynamic longitudinal loads is carried out by the impact against an experimental wagon, and testing under dynamic vertical forces is performed during the wagon motion in the composition of the experimental train on the characteristic, pre-selected (planned) sections of the railway track at specified speeds. To estimate the level of loading of the freight wagon structureunder vertical dynamic loads, a method based on the replacement of a real random process is used by some schematized process, which in terms of the fatigue damage accumulation should be equivalent to a real process. From the whole variety of schematic methods, two methods stand out, i.e., the full cycle method and the rainflow method, which most fully represent the real process.The advantage of the rainflow method is the ability to process the process in real time. However, the algorithm of the rainflow method is quite complicated and does not allow processing large amounts of information. In this regard, a method of maximum discharge was proposed, which is a kind of full cycles method and allows you to process an unlimited amount of information online. An example specified in GOST 25.101 was used for a comparative analysis of the rainflow and maximum discharge methods. Analysis showed a satisfactory matching of both methods. Based on the procedure outlined, the block structure of the computational process is proposed to determine the equivalent reduced voltage amplitude. Each block displays the impact of the forces depending on the loading condition, that is, longitudinal impact force and dynamic forces when the wagon is moving on straight track sections, curves and switches of the railway track. Key words: wagon car, process, dynamic load, longitudinal load, voltage, amplitude, algorithm, equivalent stress, safety margin, strength.

Wind-Induced Performance of Long-Span Bridge with Modified Cross-Section Profiles by Stochastic Traffic

2014 ◽  
Vol 548-549 ◽  
pp. 1753-1757
Author(s):  
Jun Wu
Keyword(s):  
Wind Tunnel ◽  
Cross Section ◽  
Dynamic Loads ◽  
Dynamic Interactions ◽  
Buffeting Response ◽  
Long Span ◽  
Long Span Bridge ◽  
Fatigue Damage Accumulation ◽  
Section Model ◽  
The Impact

The presence of traffic on a slender long-span bridge (SLB) deck has two types of primary impacts: (1) modification of the bridge cross-section profiles, which may influence the flutter derivatives and in turn, wind-induced aeroelastic loads acting on the bridge; and (2) additional dynamic loads acting on the bridge including dynamic interactions from the vehicles. As compared to the investigations on the impact of traffic as external dynamic loads, those on the impact from the modification of bridge cross-section profiles are rather rare. A scaled bridge section model with vehicle models distributed on the bridge section has been tested in the wind tunnel laboratory. With the FDs obtained from the wind tunnel experiments of various modified bridge cross-section profiles by stochastic traffic, the present study is to numerically evaluate the impact on the wind-induced performance of the long-span bridge, such as the buffeting response and fatigue damage accumulation.

scholarly journals Micro-mechanical investigation of railway ballast behavior under cyclic loading in a box test using DEM: effects of elastic layers and ballast types

2019 ◽  
Vol 21 (4) ◽  
Author(s):  
Nishant Kumar ◽  
Bettina Suhr ◽  
Stefan Marschnig ◽  
Peter Dietmaier ◽  
Christof Marte ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Early Stage ◽  
Damage Model ◽  
Simulation Models ◽  
Railway Track ◽  
Maintenance Cost ◽  
Particle Movement ◽  
Railway Ballast ◽  
Elastic Layers ◽  
The Impact

Abstract Ballasted tracks are the commonly used railway track systems with constant demands for reducing maintenance cost and improved performance. Elastic layers are increasingly used for improving ballasted tracks. In order to better understand the effects of elastic layers, physical understanding at the ballast particle level is crucial. Here, discrete element method (DEM) is used to investigate the effects of elastic layers – under sleeper pad ($$\text {USP}$$USP) at the sleeper/ballast interface and under ballast mat ($$\text {UBM}$$UBM) at the ballast/bottom interface – on micro-mechanical behavior of railway ballast. In the DEM model, the Conical Damage Model (CDM) is used for contact modelling. This model was calibrated in Suhr et al. (Granul Matter 20(4):70, 2018) for the simulation of two different types of ballast. The CDM model accounts for particle edge breakage, which is an important phenomenon especially at the early stage of a tamping cycle, and thus essential, when investigating the impact of elastic layers in the ballast bed. DEM results confirm that during cyclic loading, $$\text {USP}$$USP reduces the edge breakage at the sleeper/ballast interface. On the other hand, $$\text {UBM}$$UBM shows higher particle movement throughout the ballast bed. Both the edge breakage and particle movement in the ballast bed are found to influence the sleeper settlement. Micro-mechanical investigations show that the force chain in deeper regions of the ballast bed is less affected by $$\text {USP}$$USP for the two types of ballast. Conversely, dense lateral forces near to the box bottom were seen with $$\text {UBM}$$UBM. The findings are in good (qualitative) agreement with the experimental observations. Thus, DEM simulations can aid to better understand the micro-macro phenomena for railway ballast. This can help to improve the track components and track design based on simulation models taking into account the physical behavior of ballast. Graphical Abstract

On the Impact Behavior of a Material With a Yield Point

1949 ◽  
Vol 16 (1) ◽  
pp. 39-52
Author(s):  
Merit P. White
Keyword(s):  
Yield Stress ◽  
Yield Point ◽  
Impact Behavior ◽  
Longitudinal Impact ◽  
Stress Strain ◽  
California Institute Of Technology ◽  
Static Yield ◽  
Institute Of Technology ◽  
Probable Nature ◽  
The Impact

Abstract An analysis of longitudinal impact tests that were made by Drs. D. S. Clark and P. E. Duwez at the California Institute of Technology on an iron and a steel with definite yield points is described. From this analysis is deduced the probable nature of the dynamic stress-strain relations for such materials. These appear to differ greatly from the static stress-strain relations, unlike the case for materials without yield points. As pointed out by Duwez and Clark, the upper yield stress for undeformed material is several times as great under impact as the static yield stress. The present analysis indicates that under impact, the material with a definite yield point is made harder at a given deformation, and ruptures at a higher (engineering) stress and smaller strain than when loaded statically. The critical impact velocity, defined as that at which nearly instantaneous failure occurs in tension, is discussed, and the factors upon which it depends are given.

The Specific Characteristics of Shock and Blast Impacts on Construction Sites

2021 ◽  
pp. 81-88
Author(s):  
A.A. Komarov ◽  
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Dynamic Loads ◽  
Potential Hazard ◽  
Construction Sites ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Plane Crash ◽  
Nuclear Plants ◽  
The Impact

The practices of hazardous and unique facilities’ construction imply that specific attention is paid to the issues of safety. Threats associated with crash impacts caused by moving cars or planes are considered. To ensure safety of these construction sites it is required to know the potential dynamic loads and their destructive capacity. This article considers the methodology of reducing dynamic loads associated with impacts caused by moving collapsing solids and blast loads to equivalent static loads. It is demonstrated that practically used methods of reduction of dynamic loads to static loads are based in schematization only of the positive phase of a dynamic load in a triangle forms are not always correct and true. The historical roots of this approach which is not correct nowadays are shown; such approach considered a detonation explosion as a source of dynamic load, including TNT and even a nuclear weapon. Application of the existing practices of reduction of dynamic load to static load for accidental explosions in the atmosphere that occur in deflagration mode with a significant vacuumization phase may cause crucial distortion of predicted loads for the construction sites. This circumstance may become a matter of specific importance at calculations of potential hazard of impacts and explosions in unique units — for instance, in the nuclear plants. The article considers a situation with a plane crash, the building structure load parameters generated at the impact caused by a plane impact and the following deflagration explosion of fuel vapors are determined.

scholarly journals A multi-dimensional approach for managing open innovation in NPD

2017 ◽  
Vol 37 (10) ◽  
pp. 1366-1385 ◽  
Author(s):  
Hanna Bahemia ◽  
Brian Squire ◽  
Paul Cousins
Keyword(s):  
Product Development ◽  
Competitive Advantage ◽  
New Product Development ◽  
New Product ◽  
Three Dimensions ◽  
Longitudinal Impact ◽  
Product Innovativeness ◽  
Content Type ◽  
The Impact ◽  
Positive Effect

Purpose This paper explores openness within new product development (NPD) projects. The purpose of this paper is to examine the impact of breadth, depth and partner newness on product innovativeness and product competitive advantage. The authors also seek to examine the contingent effects of the appropriability regime. The authors make suggestions to academics and practitioners based on the findings. Design/methodology/approach The authors use a structured survey instrument producing an empirical analysis of 205 NPD projects in the manufacturing sector in the UK. The authors use an ordinary least squares regression model to test hypothesised relationships between openness (breadth, depth and partner newness), product innovativeness, product competitive advantage and the appropriability regime. Findings The authors find that each of the three dimensions of openness, depth, breadth and partner newness, have a significant but differing impact on product innovativeness. Specifically, the study indicates that breadth has a positive effect but only in the presence of a strong appropriability regime, partner newness has a direct positive effect, and depth a direct negative effect. The authors also find that product innovativeness has a positive impact on product competitive advantage. Research limitations/implications Further research should focus on replicating the findings in other countries, search for further moderating factors, such as the stage of the NPD process, and analyse the longitudinal impact of openness within NPD projects. Practical implications Organisations are encouraging managers to be more open in their approach to NPD. The authors’ findings suggest that managers need to think about the three dimensions of openness, breadth, depth and partner newness. Their engagement with each of these dimensions depends on the desired outcomes of the innovation project and the strength of patents. Originality/value The research extends the extant supplier involvement in new product development literature to examine the effect of up to 11 types of external actor in NPD projects. The authors test a new multi-dimensional measurement scale for the openness construct. The authors show that each dimension has a different relationship with product innovativeness.

scholarly journals The Specific Energy Modal Components of the Impact Dynamic Loads in a Solid

2015 ◽  
Vol 111 ◽  
pp. 556-560 ◽  
Author(s):  
Zhanna G. Mogilyuk ◽  
Mikhail S. Hlystunov ◽  
Valery I. Prokopiev
Keyword(s):  
Specific Energy ◽  
Dynamic Loads ◽  
The Impact

Aeroelastic Tailoring of Helicopter Blades

2013 ◽  
Author(s):  
Donatien Cornette ◽  
Benjamin Kerdreux ◽  
Yves Gourinat ◽  
Guilhem Michon
Keyword(s):  
Dynamic Behaviour ◽  
Vertical Shear ◽  
Dynamic Loads ◽  
Modal Approach ◽  
Aeroelastic Tailoring ◽  
Helicopter Blades ◽  
Shear Modification ◽  
Elastic Couplings ◽  
The Impact ◽  
Aerodynamic Lift

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization is done thanks to couplings between the flapwise-bending motion and the torsion motion. The impact of elastic couplings (composite anisotropy) on the blade dynamic behaviour and on dynamic loads are evaluated in this paper. Firstly, analytical results, based on a purely linear modal approach, are given to understand the influence of those couplings in terms of frequency placement, aerodynamic lift load and vertical shear modification. Then, those elastic couplings are introduced on a simplified but representative blade (homogeneous beam with constant chord) and results are presented.

scholarly journals Making Choices and Reducing Risk (MCARR): School Counseling Primary Prevention of Substance Use

2021 ◽  
Vol 11 (3) ◽  
pp. 352-369
Author(s):  
Louisa L. Foss-Kelly ◽  
Margaret M. Generali ◽  
Michael J. Crowley
Keyword(s):  
Substance Use ◽  
Alcohol Use ◽  
Student Attitudes ◽  
School Community ◽  
Longitudinal Impact ◽  
Addictive Behaviors ◽  
Making Choices ◽  
Drug And Alcohol Use ◽  
The Impact ◽  
Drug And Alcohol

The consequences of adolescent drug and alcohol use may be serious and far-reaching, forecasting problematic use or addictive behaviors into adulthood. School counselors are particularly well suited to understand the needs of the school community and to seamlessly deliver sustainable substance use prevention. This pilot study with 46 ninth-grade students investigates the impact of the Making Choices and Reducing Risk (MCARR) program, a drug and alcohol use prevention program for the school setting. The MCARR curriculum addresses general knowledge of substances and their related risks, methods for evaluating risk, and skills for avoiding or coping with drug and alcohol use. Using a motivational interviewing framework, MCARR empowers students to choose freely how they wish to behave in relation to drugs and alcohol and to contribute to the health of others in the school community. The authors hypothesized that the implementation of the MCARR curriculum would influence student attitudes, knowledge, and use of substances. Results suggest that the MCARR had a beneficial impact on student attitudes and knowledge. Further, no appreciable increases in substance use during the program were observed. Initial results point to the promise of program feasibility and further research with larger samples including assessment of longitudinal impact.

scholarly journals Impact Coefficient Analysis of Curved Box Girder Bridge Based on Vehicle-Bridge Coupling

2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Fei Guo ◽  
Heng Cai ◽  
Huifang Li
Keyword(s):  
Shear Force ◽  
Primary Beam ◽  
Dynamic Loads ◽  
Box Girder ◽  
Impact Coefficient ◽  
Force Impact ◽  
Girder Bridge ◽  
The Moment ◽  
The Impact ◽  
Load Weight

In the current vehicle-bridge dynamics research studies, displacement impact coefficients are often used to replace the moment and shear force impact coefficients, and the vehicle model is also simplified as a moving-load model without considering the contribution of vehicle stiffness and damping to the system in some concerned research studies, which cannot really reflect the mechanical behavior of the structures under vehicle dynamic loads. This paper presents a vehicle-bridge coupling model for the prediction of dynamic responses and impact coefficient of the long-span curved bending beam bridge. The element stiffness matrix and mass matrix of a curved box girder bridge with 9 freedom degrees are directly deduced based on the principle of virtual work and dynamic finite element theory. The vibration equations of vehicle-bridge coupling are established by introducing vehicle mode with 7 freedom degrees. The Newmark-β method is adopted to solve vibration response of the system under vehicle dynamic loads, and the influences of flatness of bridge surface, vehicle speed, load weight, and primary beam stiffness on the impact coefficient are comprehensively discussed. The results indicate that the impact coefficient presents a nonlinear increment as the flatness of bridge surface changes from good to terrible. The vehicle-bridge coupling system resonates when the vehicle speeds reach 60 km/h and 100 km/h. The moment design value will maximally increase by 2.89%, and the shear force design value will maximally decrease by 34.9% when replacing moment and shear force impact coefficients with the displacement impact coefficient for the section internal force design. The load weight has a little influence on the impact coefficient; the displacement and moment impact coefficients are decreased with an increase in primary beam stiffness, while the shear force impact coefficient is increased with an increase in primary beam stiffness. The theoretical results presented in this paper agree well with the ANSYS results.

scholarly journals Empirical Analysis of the Impact Strength of Textile Knitted Barrier Meshes

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zbigniew Mikołajczyk ◽  
Beata Szałek ◽  
Katarzyna Pieklak
Keyword(s):  
Measurement Data ◽  
Test Stand ◽  
Dynamic Loads ◽  
Measuring System ◽  
Electronic Measuring ◽  
Computer Data ◽  
Analysis System ◽  
Data Analysis System ◽  
Dynamic Stress Distribution ◽  
The Impact

AbstractThe assumptions of instrumental methodology for measuring dynamic loads of knitted barrier meshes were defined. A test stand was built, original in terms of both mechanical construction and electronic measuring system, connected to a computer data analysis system. Maximum values of dynamic forces in the mesh fastening strings were determined. The correctness of the strain gauges construction and measurement data transmission systems was confirmed. Tests of multidirectional resistance to dynamic loads in the mesh fastening strings were carried out. The experiment involved dropping a ball with a mass of 5 kg and a diameter of 10 cm, from a height of 1 m and 2 m onto the mesh surface. The potential impact energy equaled Ep1 = 49.05 J and Ep2 = 98.1 J. The tests showed that the highest force values were observed for meshes with square-shaped a-jour structure, and for mesh with diamond-shaped a-jour geometry the force values were lower. A symmetrical forces distribution was observed in all the strings. The highest forces were recorded in the middle strings and the lowest in the outer ones. The conducted tests confirmed the correctness of the adopted constructional solutions of test stand for identification of dynamic stress distribution in mesh fastening strings. The developed method is a useful verification tool for numerical analysis of mechanical properties of barrier meshes.

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