Fourth International Conference on Material and Component Performance under Variable Amplitude Loading
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Multiaxial Loading (1)

Session chair: Papuga, Jan, Dr. (FME, Czech Technical University in Prague, Dept. of Mechanics, Biomechanics and Mechatronics, Prague 6, Czech Republic)
 
Shortcut: J
Date: Tuesday, 31. March 2020, 11:00
Room: Hall B
Session type: Oral

Contents

11:00 J-01

Operating loads on Electrically Power Assisted Cycles (EPAC) (#121)

E. Groß1

1 Technische Universität Hamburg, Hamburg, Hamburg, Germany

DIN EN 15194: 2017 " Cycles – Electrically power assisted cycles – EPAC Bicycles" specifies both the electrical and the mechanical requirements with regard to safety-related specifications. DIN EN 15194: 2017 is based on the mechanical requirements of DIN EN ISO 4210: "Cycles – Safety requirements for bicycles". As a result, two problem areas can be formulated.

The currently valid DIN EN 15194: 2017 contains no information regarding the total payload or the total weight of EPAC bicycles to which the requirements apply. Manufacturers can offer cycles for a high payload, without making higher demands on the mechanical components of the bicycle.
At the moment it is not possible to test an EPAC bicycle with high payload according to DIN EN 15194. It is currently unknown how much the mechanical requirements for the components have to be changed, as this aspect has not been sufficiently investigated in the standardization work so far.

Task:
The aim of this study is to determine the operating loads on electrically power assisted cycles that occur during normal driving and

• to validate the normative requirements (static strength and fatigue) of DIN EN 15194: 2017 for the mechanical components of EPAC bicycles;
• to investigate the influence of the load (driver mass and luggage) on the mechanical requirements;
• to investigate the possible influence of the type of use (sporty / relaxed, practiced / untrained).

In particular, the influence of a high payload (driver mass + vehicle mass + payload) should be highlighted. In particular, it is therefore necessary to examine whether the previous requirements are sufficient and from which payload on the requirements should be changed.
Among the mechanical components of the bicycle to be examined are the components that are currently being tested in DIN EN 15194: 2017, ie the handlebar and stem assembly, the frame, the seat-post and the front fork.

Proposals will be developed to consider the results of this study for a revision of DIN EN 15194: 2017. Already for the general class with rider weights up to 95 kg or a permissible total weight of 120 kg (corresponding to a typical vehicle weight of approx. 25 kg) adjustments should be made to the frame (fatigue test with a vertical force) and the seat post. For heavier riders, with the exception of the handlebar and stem assembly, generally higher requirements result, which are finally presented.

Keywords: Operating loads, Electrically Power Assisted Cycles, EPAC
11:20 J-02

New modern materials in design for high speed freight wagon bogies and their components: laboratory tests and track measurements (#137)

J. Chvojan1, J. Vaclavik1

1 Vyzkumny a zkusebni ustav Plzeň s.r.o. (Research and testing Institute in Pilsen), Pilsen, Czech Republic

The use of carbon or glass fiber composite materials has recently experienced significant growth in all leading industries. This happens for many reasons, the most important being their high strength with significantly lower specific gravity, the development of a whole range of manufacturing technologies and, last but not least, the affordability of these materials compared to the ever-increasing price of conventional construction materials. In addition, composite products have a final shape, no additional machining costs.

Unlike to the aviation industry, the use of composites in the railway industry is still negligible, despite the conservative nature of rail transport. Numerous decrees, regulations, standards and mandatory guidelines that are required by Authorization and Approval National Authorities across the world greatly hamper the use of structural materials other than certified steels and aluminium alloys, technically well-researched, and guidelines for the minimum characteristics of components. In addition to plastics in the form of various holders, covers and coverings, composite materials in this sector have already "worn through" as elements used in the ergonomics of railway vehicle housings or as an active part in reducing the aerodynamic drag of a railway vehicle.

Steel has been used as a construction material for bogies since the first railway vehicle bogie was designed. The basic concept that must remain unchanged is the fact that the bogie frame must be rigid to withstand the fatigue-related operational stresses. The result is a relatively rigid structure. Using glass fiber reinforced plastic (GFRP) it is possible to obtain the necessary strength without the frame having to be so rigid with a great negative impact on the track infrastructure. This is possible because the GFRP composite material and its construction have a favorable combination of material properties such as:

• low weight of sprung masses
• long component life
• low forces between wheel and track with a positive impact on wheel wear reduction due to self-steering of the wheel set
• reducing the effects of rolling contact fatigue due to low lateral stiffness
• Low maintenance due to functional component integration
• High operating speed - up to 200 km per hour at 16t axle load
• noise and vibration reduction

The use of modern fiber -reinforced plastics for highly stressed parts of rolling stocks, in addition to the specific functions, is a subject of research and development which results are given in the paper. This contribution summarized the tests and measurements which were performed on the both fifth scale freight bogie designed and made from GFRP and the full scale bogie frame as itself and its components.

This paper is prepared as results of the international project E!1891 Eurobogie in the frame of the Eureka programme which was solved by Research and Testing Institute and co-financed by the Ministry of Education of the Czech Republic.

References

Chvojan, J., Vaclavik, J., Mayer, R.: Static and dynamic tests of a glass reinforced plastic bogie.  In: 15th International Conference of Experimental Mechanics, ICEM15, Porto, Portugal, 2012, pp. 757-758. ISBN: 978-972-8826-25-3.

Chvojan, J., Vaclavik, J., Mayer, R.: Experimental methods of the GRP bogie testing. In: 9th International Conference on Bogies and Running Gears, BOGIE´13, Budapest, Hungary, 2013, pp. 315-317, ISBN: 978-963-313-103-9.

Chvojan, J., Heller, P., Kepka, M.: Applications of new materials in design of rail vehicles and laboratory verification of their dynamic and fatigue properties. In: Railway_2014, Corsa, France, 2014, pp. 326, ISSN: 1759-3433, ISBN: 978-1-905088-59-1.

Chvojan, J., Vaclavik, J., Mayer, R.: Dynamic and static behaviour of side beam SET for composite bogie. In: 16th International Conference of Experimental Mechanics, ICEM16, Cambridge, UK, 2014.

Chvojan, J., Kepka, M., Špirk, S.: Laboratory fatigue tests as important part of design and development of new vehicles.  In: 3rd International Conference on Railway Technology: Research, Development and Maintenance, Cagliary, Sardinie, Italy, 2016, ref. 193, pp. 1-17, ISSN: 1759-3433.

Keywords: high speed, freight wagon, measurement
11:40 J-03

A transient method for nonproportionality under random loading conditions (#47)

X. Sun1, S. Shi1, X. Chen1

1 Tianjin University, School of Chemical Engineering & Technology, Tianjin, China

Multiaxial random loading conditions are general situations for structure and mechanical components. However, under the variable amplitude loading, load sequence is not like to the regular loading which has a complete path. The description and characteristics of nonproportional loading are challenges in such conditions. In this work, a transient method based on Itoh’s approach is used to evaluate the nonproportionality of random loading path. The method is modified in the section of integration by using the transient maximum principle strain other than that of whole cycle. The data of SS304 were obtained from presented literature. History effect considering with and without loading sequence were discussed, and found there are just slightly differences. A new method combining the transient nonproportionality with weight factor calculation in the weighted critical plane determination was proposed and it was used to predict the fatigue life with several fatigue life models (FS model, KBM model, CXH model), which has a satisfactory result.

Keywords: multiaxial fatigue, nonproportionality, critical plane method, life prediction