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Heat Release Rate (HRR), Average Rate of Heat Emission (ARHE) and the Maximum Average Rate of Heat Emission (MARHE)
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Due to limited production numbers, using additive manufacturing for the production of railway components, is proving more economical. Furthermore, strict requirements regarding flammability properties, standardised in EN 45545-2, are applied on trains. This work focuses on the production of transparent components made of Polycarbonate via 3D-printi...
Context in source publication
Context 1
... can be seen in Figure 2 the MARHE-value is the maximum of the ARHE (Average Rate of Heat Emission), while ARHE is calculated by summarizing and averaging all HRR-values, starting with the ignition of the sample. Th e Hazard Level (HL) is defi ned by the operation and the design of the railway vehicle and is standardized in EN 45545 part 1 and 2. While small electronic components must pass the Vertical Small Flame Test (ÖVE/ÖNORM EN 60 695-11-10), reaching V0 as test result. ...
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Citations
... A work on the fire behavior of various materials with regard to their suitability for fire-related use in rail vehicles is included in reference [5]. A work that focuses on the production of transparent components made of polycarbonate via 3D-printing is included in reference [6]. Processing and printing of the polymer causes thermal stress to the molecules. ...
... This may lead to a worsening of the flammability causing a decline of the properties compared to the virgin polycarbonate. In summary, the printing parameters and additives must be carefully considered in relation to the fire properties of the polymer [6]. Furthermore, an overview about the effect of important flame retardants, as used as additives, is given in the references. ...
The fire behavior of polymers is examined primarily with the time-dependent heat release rate (HRR) measured with a cone calorimeter. The HRR is used to examine the fire behavior of materials with and without flame retardants, especially Polypropylene (PP-Copo) and Polyethylene (PE-LD). Polypropylene is stored for up to 99 days under normal conditions and the heat release rate shows especially changes about 100 s after irradiation with cone calorimeter, which may be caused by aging effects. The effect of crosslinking to the burning behavior of PP was examined too. Polyamides (PA 6) are irradiated with a radiation intensity of 25 kW/m2 to 95 kW/m2 and fire-related principles between radiation intensity and time to ignition can be derived from the measurement results. In order to comprehensively investigate the fire behavior of PP (also with flame retardant additives), the samples were also exposed to a flame, according to UL 94 with small power (50 W) and is inflamed with the power of a few 100 W. The irradiation causes different trigger mechanisms for the flame retardant additives in a plastic than the flame exposure. It is shown that the compound, which is favorable for irradiation, is not necessarily good for flame exposure. It can be seen that expandable graphite alone or with the addition of other additives is a very effective flame retardant for PP.
Eklemeli imalat, geleneksel üretim yöntemlerine göre nesnelerin katman katman üretildiği yenilikçi bir yöntemidir. Son yıllarda eklemeli imalatın kullanım alanları hızla artmaktadır. Bu imalat yönteminin birçok sektörde olduğu gibi demiryolu sektöründe de kullanım potansiyeli yüksektir. Demiryolu endüstrisinde eklemeli imalatın genel olarak; demiryolu altyapısında ve demiryolu üstyapısında, demiryolu araçlarında kullanıldığı görülmektedir. Eklemeli imalatın özellikle parçaların özelleştirilmesine olanak tanıması, karmaşık parçaların üretimi ve tasarım özgürlüğü, hızlı prototipleme, malzeme tasarrufu, düşük üretim maliyeti gibi avantajları, demiryolu endüstrisinde ve diğer endüstrilerde kullanımının yaygınlaşmasına olanak sağlamaktadır. Eklemeli imalatın malzeme sınırlamaları ve üretim hızı gibi bazı sınırlamaları olsa da, bu avantajların sunduğu imkanlar birçok alanda yeniliği teşvik etmektedir. Bu çalışmayla, demiryolu endüstrisi ve eklemeli imalat hakkında genel bilgiler verilmiştir. Ayrıca, eklemeli imalatın demiryolu endüstrisinde kullanımı ve kullanıldığı alanlar hakkında inceleme yapılmıştır. Çalışma sonucunda, araştırmacılar için eklemeli imalatın demiryolu endüstrisinde hangi alanlarda kullanıldığı, hangi alanlarda ise kullanımının eksik olduğunun görülmesi ile kullanım alanının geliştirilmesi sağlanmaya çalışılmıştır.
The present study focuses on enhancing the mechanical, thermal, and degradation behavior of polylactic acid (PLA) by adding carbon nanotubes (CNTs) with different concentrations of 0.5, 1, 3, and 5%. The CNTs were prepared using catalytic chemical vapor deposition, and the prepared PLA/CNTs nanocomposite films were characterized using techniques such as FT-IR, Raman spectroscopy, TGA, SEM, and XRD. The distinct diffraction patterns of multi-walled carbon nanotubes (MWCNTs) at 2θ angles of 25.7° and 42.7° were no longer observed in the prepared nanocomposites, indicating uniform dispersion of MWCNTs within the PLA matrix. The presence of MWCNTs enhanced the crystallinity of PLA as the CNT loading increased. Mechanical tests demonstrated that incorporating CNTs positively influenced the elongation at the break while decreasing the ultimate tensile strength of PLA. The PLA-3%CNTs composition exhibited the highest elongation at break (51.8%) but the lowest tensile strength (64 MPa). Moreover, thermal gravimetric analysis confirmed that the prepared nanocomposites exhibited greater thermal stability than pure PLA. Among the nanocomposites, PLA-5% CNTs exhibited the highest thermal stability. Furthermore, the nanocomposites demonstrated reduced surface degradation in accelerated weathering tests, with a more pronounced resilience to UV radiation and moisture-induced deterioration observed in PLA-3% CNTs.
Additive manufacturing continues to see increased growth, with adoption in many industrial sectors and increased commercial market value. Market growth is attributed to continued technology and software improvements, growing availability of material types and the ability to produce functional parts with complex geometries. The technology also provides the freedom to optimise the design of both the internal structure and external contours of a component. Additive Manufacturing in South Africa has been driven by the biotechnical/medical, aerospace and automotive industries due to a focus on research and high-value components. To date, there has been limited research involvement from the railway sector. Within the railway environment, the rolling stock and rail infrastructure consists of numerous systems and components which may benefit from the technology in creating replacement spare parts, lightweight structures, improved jigs and fixtures, and new designs of consolidated part-assemblies. This paper presents an industrial view on the use of additive manufacturing and design optimisation techniques for the production of railway related components, together with requirements and challenges. It provides examples that illustrate existing and potential applications of the technology for the design, manufacture and repair of various railway related assets in South Africa.
