Aaltodoc Repository :: Browsing by Author "Bossuyt, Sven"

Browsing by Author "Bossuyt, Sven"

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Analysis and design of heavy-duty multi-directional wheel for heavy industry
(2019-05-06) Debowski, Aleksander; Tani, Tuomas; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Anisotropic Plastic Behavior of Additively Manufactured PH1 Steel
(2021-04-01) Liu, Wenqi; Li, Zinan; Bossuyt, Sven; Forsström, Antti; Que, Zaiqing; Björkstrand, Roy; Salmi, Mika; Partanen, Jouni; Lian, Junhe; Department of Mechanical Engineering; Advanced Manufacturing and Materials; VTT Technical Research Centre of Finland
Metals made by additive manufacturing (AM) have intensely augmented over the past decade for customizing complex structured products in the aerospace industry, automotive, and biomedical engineering. However, for AM fabricated steels, the correlation between the microstructure and mechanical properties is yet a challenging task with limited reports. To realize optimization and material design during the AM process, it is imperative to understand the influence of the microstructural features on the mechanical properties of AM fabricated steels. In the present study, three material blocks with 120×25×15 mm3 dimensions are produced from PH1 steel powder using powder bed fusion (PBF) technology to investigate the anisotropic plastic deformation behavior arising from the manufacturing process. Despite being identical in geometrical shape, the manufactured blocks are designed distinguishingly with various coordinate transformations, i.e. alternating the orientation of the block in the building direction (z) and the substrate plate (x, y). Uniaxial tensile tests are performed along the length direction of each specimen to characterize the anisotropic plastic deformation behavior. The distinctly anisotropic plasticity behavior in terms of strength and ductility are observed in the AM PH1 steel, which is explained by their varied microstructure affected by the thermal history of blocks. It could also be revealed that the thermal history in the AM blocks is influenced by the block geometry even though the same process parameters are employed.
Characterization of pulse electric current sintered Ti-6Al-4V ternary composites : Role of YSZ-Si3N4 ceramics addition on structural modification and hydrogen desorption
(Elsevier, 2023-08) Akinwamide, Samuel Olukayode; Bossuyt, Sven; Fangnon, Eric A.K.; Akinribide, Ojo Jeremiah; Olubambi, Peter Apata; Department of Mechanical Engineering; Materials to Products; University of Johannesburg
In this study, we fabricated Ti-6Al-4V composites using pulse electric current (spark plasma) sintering technique and examined the influence of yttria-stabilized zirconia (YSZ) and silicon nitride (Si3N4) particles on microstructural, mechanical properties. Moreover, we investigated the effects of YSZ and Si3N4 on hydrogen uptake rate of the fabricated composites. The formation of new phases in addition to the parent α and β phases corroborates the increased hardness property exhibited by the Ti-6Al-4V composites. Further, the improvement in the hardness property was ascribed to Orowan strengthening effect due to resistance offered by cross dislocation pinning effect of closely packed particles. From the nanomechanical test, the penetration depth of the unreinforced Ti-6Al-4V alloy was maximum at a value of 272.57 nm, while all the reinforced alloys exhibited reduced penetration depth, thereby increasing the stiffness and strength of the Ti-6Al-4V composites. Other nanomechanical analyses such as nanohardness, elastic modulus, and creep were also improved in the reinforced composites in comparison with the Ti-6Al-4V alloy. The amount of hydrogen absorbed by the specimens was measured, and the Ti-6Al-4V composite with the highest proportion of Si3N4 reinforcement exhibited the highest hydrogen concentration.
Characterization of strain aging with full-field strain measurements
(2017-02-20) Pihlajamäki, Tuomas; Bossuyt, Sven; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Coupled Digital Image Correlation and Quasi-Static Elasticity Imaging of inhomogeneous orthotropic composite structures
(2018-11-09) Smyl, Danny; Antin, Kim-Niklas; Liu, Dong; Bossuyt, Sven; Department of Mechanical Engineering; Engineering Materials; University of Science and Technology of China
The ability to accurately determine elastic properties of orthotropic materials is important in the design and health assessment of composite structures. Direct methods using strain gauges and extensometers for estimating orthotropic properties have become popular in recent years. In cases where strains are highly localized, the material properties are inhomogeneous, or the material has localized damage, the use of these measurement schemes often provides insufficient information. To address this, we propose an inverse method, based on quasi-static elasticity imaging (QSEI) for determining inhomogeneous orthotropic elastic properties using distributed displacement measurements obtained from digital image correlation (DIC). The QSEI-based approach is first tested with simulated noisy displacement data considering in-plane deformations of plate geometries undergoing stretching and bending. Following this, experimental DIC measurements are applied to test the feasibility of the QSEI-based approach. Elastic properties of uni-directional CFRP beams with and without localized damage are estimated using the proposed approach. Results demonstrate the feasibility of the proposed inverse approach.
Damage assessment of friction stir welded copper cross-weld specimens
(2021-08-23) Vihko, Jani; Rantala, Juhani; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Nuclear power is one of the largest forms of energy production in Finland. The main challenges of nuclear power relate to the final disposal of spent nuclear fuel. In Finland, the spent fuel will be stored in final disposal canisters, which will then be buried approximately 430 meters deep into the bedrock, later filling the tunnels with bentonite clay. The final disposal canister consists of a nodular graphite cast iron insert and a phosphorus alloyed oxygen-free copper (Cu-OFP) overpack. The lid of the Cu-OFP overpack will be welded shut with friction stir welding (FSW). Careful study of the canister, as well as the whole disposal system, is extremely important for ensuring the safety of humans and the environment. The final disposal canister has been studied intensively during the final disposal project. However, additional studies with different test parameters are still required for ensuring the safety of final disposal. Therefore, this thesis assesses the damage of creep tested, friction stir welded Cu-OFP cross-weld specimens. The damage is assessed by calculating the cavity density and grain size of the specimens, as well as studying the distribution of the damage throughout the samples. Calculating the cavity density of the entire surface area of multiple samples manually is extremely tedious and time consuming. For these purposes, this thesis develops methods for utilizing image processing software to automate the process. An open-source image processing software called ImageJ is used for the analysis. Different processing tools were tested, and a macro code for ImageJ was written based on the test results. In order to gain as accurate results as possible, different sample preparation methods and programs were also tested for use with Cu-OFP. Based on the results, an optimized sample preparation program was created. Finally, the grain size of the samples was estimated by using the intercept method in standard SFS-EN ISO 2624. The images used in the analysis were obtained using a light optical microscope (LOM). In total, over 2300 LOM images were taken and analyzed. The results of the analysis in this thesis show that ImageJ is a viable tool for use in damage assessment due its efficiency and accuracy. In the future, different tools and macros can be developed for improved function as well as different or more specific applications.
Design and analysis of proof testing setup for high strength optical fiber
(2022-10-10) Doshi, Gandhali; Innila, Matti; Insinööritieteiden korkeakoulu; Bossuyt, Sven
The increasing demand of the thick fiber proof testing has been problematic for Rosendahl Nextrom for whom this research has been carried out. The standing machine OFC 35 is designed for telecom fiber with approx. 250micron diameter and ~30N of proof stress. However, it is not sufficient for many of the high strength fiber solutions that would need greater proof stress. The study concentrations on post draw process which is proof testing of high strength 2mm optical fiber in which specified tensile load is applied to the continuous fiber and checking the quality of the produced fiber. The existing machine from the company served as a reference point against which new designs are made. The aim of this thesis is to develop a testing setup of first capstan with the belt which has weight carrying capacity of 50kg attached to the thick fiber. The setup stress for 2mm fiber is set at 500N whereas initial reel tension is considered as 10N. In summary, new proof testing setup is designed with iterative CAD principles and capstan equation as the central focus. Three different tests were performed with the quick prototype to understand the belt material, contact angle and driving element behavior. The findings were presented as an individual test result which can be used as a base point for the entire machine design. The factors prioritized in this testing were mainly belt tension and its material along with the fiber contact angle. Nitrile based vulcanized rubber belt was found to be appropriate for targeted weight capacity whereas it is concluded that angle of contact have negligible effect on the fiber tension. The proposed design demonstrates promising results and can be a good starting point for the company to get the research deeper into the entire machine design.
Developing methods of using Digital Image Correlation for ice research
(2023) Ahmad, Waqas; Prasanna, Malith; Gharamti, Iman E.; Bossuyt, Sven; Tuhkuri, Jukka; Department of Mechanical Engineering; Marine and Arctic Technology; Materials to Products
This paper discusses the methods that have been developed to conduct ice fracture experiments with Digital Image Correlation (DIC). While conventional measurement methods provide information on ice response at specific locations, DIC provides full-field data at different areas of the specimen surface. Both test specimen in air and floating in a basin have been studied. The results show that DIC provides localized deformation zone information which could not be studied with conventional measurement techniques used in ice mechanics due to low spatial resolution.
DIC Analyses and Parameter Calibration of a Strain Aging Sensitive Ductile Cast Iron
(Academie des Sciences, 2024) Valmalle, Malo; Widell, Kim; Ilola, Risto; Bossuyt, Sven; Department of Mechanical Engineering; Materials to Products; Materials to Products; Aalto University
In the present work, the mechanical response of strain aging sensitive ductile cast iron was studied when subjected to uniaxial tension in temperatures ranging from 20°C up to 300°C. Digital Image Correlation (DIC) was used to measure the strain localization patterns due to dynamic strain aging. A constitutive law based on the Kubin–Estrin–McCormick model (KEMC) was used to model the behavior of the ductile cast iron in temperatures ranging from 20° up to 300°. The displacement fields were successfully measured and the strain localization patterns were observed. These measurements were employed to calibrate the parameters of the constitutive law. Numerical simulations are shown to be in agreement with experimental measurements at the macroscopic scale.
Digital image correlation analysis of ice fracture experiments
(2019-12-16) Ahmad, Waqas; Bossuyt, Sven; Insinööritieteiden korkeakoulu; Tuhkuri, Jukka
Digital Image Correlation is now commonly used in the fields of solid and fracture mechanics to measure full-field displacements for both ductile and brittle materials. However, no detailed study of application of DIC on fracture test of freshwater ice is available in the literature. This thesis focuses on DIC analysis of fracture experiments, for S2 columnar freshwater ice, conducted at Aalto Ice Tank. DIC is used to find the crack path along with crack tip location using optimization approach based on singular field around the crack. Because of low signal to noise ratio of DIC displacement fields, kinematic displacement fields based on William's elasticity solution are also implemented to estimate the crack tip and find stress intensity factor for the extended crack length. The implemented methodology is capable of finding the fracture characteristics after the application of the peak load on the crack mouth of edge cracked rectangular plate for different specimen sizes at different loading rates. Improving the signal to noise ratio of the measured DIC displacement fields can reduce the uncertainties in the results.
Digital image correlation for identification of vibration modes
(2012) Puustinen, Olli; Bossuyt, Sven; Koneenrakennustekniikan laitos; Insinööritieteiden korkeakoulu; School of Engineering; Hänninen, Hannu
Digital image correlation (DIC) is a non-contact optical measuring method for displacement and strain measurements. DIC uses visual information from an object to calculate strains and displacements on the surface of a specimen. With DIC it is possible to perform 2D or 3D measurements. A single camera is used to measure 2D in-plane deformation. 3D stereo-vision system uses two or more cameras to measure 3D surface displacements on curved or planar specimens. In a forward problem, analytical or numerical solutions are for example found for differential equations with known initial conditions, boundary conditions and known constants in the equation. So a forward problem can be described as problem where both the system and the input are known and only the response is unknown. The inverse problem, on the other hand, is a problem where something about the system or the input is unknown, but that can be solved by using measured response information. In this thesis the unknown vibration parameters are calculated from the measured response of the vibrating plate. The object of this thesis is to investigate the suitability of digital image correlation for the applications in mechanical engineering and especially for the vibration identification. In the experimental part static and dynamic strain and displacement measurements are performed with La Vision StrainMaster Digital Image Correlation system. In the static part the deformation of the tensile test specimen and the thin plate is imaged and measured and displacements and strains are calculated. The dynamic part includes the imaging of the vibration of the thin plate and the inverse calculation of the natural frequencies and the mode shapes of the plate.
Dull punch line is not a joke – Worn cutting edge causes higher iron losses in electrical steel piercing
(Elsevier Limited, 2019-02-01) Laakso, Sampsa V.A.; Väänänen, Arijussi; Bossuyt, Sven; Arkkio, Antero; Department of Materials Science and Engineering; Department of Mechanical Engineering; Department of Electrical Engineering and Automation; Department of Chemical and Metallurgical Engineering; Advanced Manufacturing and Materials; Aalto University
Electrical steel is used for the active parts in electrical machinery that form the magnetic circuits because the material experiences low iron loss, and thus, has superior magnetizing properties. A typical electrical sheet has a thickness of 0.5 mm and is punched into its final shape via a piercing process. Piercing causes large deformations and residual stresses in the narrow zone of the cut surface. The deformations and stresses weaken the magnetic properties of the electrical sheet and result in additional losses, as the iron loss increases after piercing [1]. This paper presents a simulation model of the piercing process to evaluate the deformations and stresses on the cut surface. The model is constructed using the commercial FEM solver Deform. There has been an attempt to simulate the magneto-mechanical state of the punched surfaces, but the piercing process itself was not simulated [2]. The electrical steel sheet investigated in this paper is isotropic electrical silicon steel M400-50A (EN 10106-96).
The effects of static strain aging on the mechanical performance of nodular cast iron
(2021-08-23) Björklund, Ville; Hänninen, Hannu; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Finland and Sweden are amongst the first countries moving forward with the plans regarding geological disposal of spent nuclear fuel. Spent nuclear fuel is intended to be placed in long-term geological repositories in accordance with the KBS-3 method where the spent nuclear fuel is placed in large copper canisters that are sealed and buried deep in the bed rock. The load-bearing element in these canisters is an insert made of nodular cast iron of grade EN-GJS-400-15U. Questions regarding the possible role of strain aging in the material properties of the cast iron insert in the repository conditions have been largely overlooked and have not been thoroughly studied yet. This thesis explores the phenomenon of static strain aging in the nodular cast iron to be used for this application, and its effects on the mechanical performance of the material. Static strain aging was studied by pre-straining tensile specimens made from the given material to 1 %, 2 % and 3 % nominal strains. The pre-strained specimens were aged at various temperatures ranging from room temperature (RT) to 400 ℃ for varying times. The static strain aging brought pronounced yield point to the material for all studied pre-strain levels, temperatures, and aging times despite the as received material behaving smoothly with no pronounced yield point. Increasing the pre-strain raised the yield strength of the material more compared to lower pre-strain. The maximum yield strength levels were already achieved with aging in 100 ℃ for 1 day and aging at higher temperature of 200 ℃ and/or increasing aging time to 11 days had no significant effect on the yield strength. Aging at higher temperatures of 300 ℃ and 400 ℃ resulted in lower increase in yield strength and the yield point became less pronounced as the aging temperature was raised over 200 ℃. Aging non-pre-strained specimens had no effect on the yielding behavior compared to as received material. Digital image correlation was used to study how the static strain aging affect the strain localization in the material. Strain aging was found to manifest as formation of complex Lüders bands at the onset of yielding. Formation of multiple bands inhibited the band propagation and lead to premature localization of strain in these areas, which lead to earlier fracture.
Error characterization for digital image correlation measurements in industrial environments
(2017-08-28) McCluskey, Michael; Bossuyt, Sven; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Digital image correlation (DIC) is a non-contact, full field displacement measurement technique. It is primarily suited to making high precision and high accuracy measurements, and is therefore commonly used in laboratories for experimental work. However, in recent years, improvements to technology and commercial interest in the industrial internet have created the potential for methods such as DIC to be utilized widely in industry. This thesis makes a preliminary investigation of errors that are likely to occur when DIC is performed in an uncontrolled environment. The characteristics of displacement and strain field measurements affected by camera motion, changing focus and inconsistent illumination are compared. To achieve this, computer graphics software is used to simulate a scene in which a stationary plate is viewed by a stereo imaging system. Animations of systematic changes to camera position, focus and lighting are made, and a ray-tracing render engine is used to produce the resultant photo-realistic images. In later simulations, the plate is substituted for a cylinder in different orientations, to investigate how error characteristics vary with surface angle and distance. The DIC algorithms are found to be robust, allowing viable measurements even when significant changes are made to the imaging environment. Changes to illumination and focus are seen to produce random noise, most likely resulting from incorrect matching of subsets. Conversely, camera motion is seen to result in systematic error, with each transformation component displaying distinct characteristics. This observation is significant, since it indicates a possibility for identifying and correcting for such errors in industrial applications. Surface curvature is found to have minimal impact on the error characteristics for most camera transformations, but significant differences are observed for camera translations along the y-axis and rotations around the x-axis.
Exploration of an adhesive peel test for failure and crack analysis of overmoulded MEMS packages
(2021-01-25) Hall, Michael; Nurmi, Sami; Insinööritieteiden korkeakoulu; Bossuyt, Sven
The proliferation of inertial MEMS sensors into automotive safety systems has contributed to annually declining road accidents and deaths. Being the integral sensing components for vehicular safety, the reliability of inertial MEMS is stringently tested in a wide range of thermal conditions, pushing the boundaries of the designs and materials. For this reason, die attach mediums are often subject to cracking or delamination during development qualification. Fully understanding the mechanisms behind these defects is essential in preventing and fixing them. This research set out to develop an adhesive peel test method for identifying and studying die attach adhesive cracks in over-moulded lead frame-based packages. This presented two main challenges, how to expose the die pad for peeling, and how to perform the peel test itself. Various de-capsulation methods were explored, resulting in the samples being ground to the die pad backside and die pad edge to allow access for peeling. Several peel methods were trialled with different levels of success. A manual peel test was successfully implemented, which effectively revealed the die attach surfaces for analysis. The peeled surfaces clearly revealed cracked adhesive surface morphology in three dimensions, which could be studied in detail with a SEM. The peels also revealed other die pad surface artefacts, the relevance of which could be investigated further in future research. All cracks and surface artefacts were clear and could be successfully measured using software tools.
Facilities for production of bulk amorphous metals, and evaluation thereof using alloy Zr55Cu30Al10Ni5
(Aalto University, 2012) Soinila, Erno; Bossuyt, Sven; Koneenrakennustekniikan laitos; Department of Engineering Design and Production; Insinööritieteiden korkeakoulu; School of Engineering; Hänninen, Hannu
Bulk metallic glasses (BMG) are alloys that can be solidified into a diameter larger than 1 mm without detectable crystallization. The resulting amorphous solid state satisfies the thermodynamic definition of a glass: upon heating above a glass transition temperature, they reach a metastable super-cooled liquid region before crystallizing. There are many known methods for producing amorphous metals. The material properties and the ease of manufacturing amorphous metal specimens depend on the manufacturing methods and facilities used. Studying and developing such facilities contributes both to practical applications of these materials and to advances in basic science of liquid and amorphous states of matter. In this thesis, the merits of different facilities for producing bulk metallic glass are evaluated anecdotally using literature and interviews, and then in practice by designing, building and finally using different facilities to make various metallic glass specimens with composition Zr55Cu30Al10Ni5 (at.%). The results demonstrate that the process and equipment for producing metallic glass can be significantly simplified by constructing a combined arc melter and tilt casting furnace. A novel design for such a furnace, using ultra-high vacuum fittings making it possible to tilt the entire chamber, eliminates the need to use separate furnaces for alloying and for casting, and enables a practical manner to produce metallic glass specimens of the highest purity and highest mechanical quality. Further shaping of bulk metallic glass preforms into large aspect ratio metallic glass parts was shown to be feasible, without elaborate process control, in a tensile viscous flow configuration. Induction heating specially designed preforms results in a self-stabilizing thermoplastic forming process for metallic glass wires. Magnetron sputtering was used to produce amorphous coatings of the same nominal composition as the BMG specimens, directly attached to heat sensitive polymeric materials. Adhesion was found to be controllable via sputtering process parameters.
Full-field Strain Measurements for Microstructurally Small Fatigue Crack Propagation Using Digital Image Correlation Method
(JOURNAL OF VISUALIZED EXPERIMENTS, 2019-01-16) Malitckii, Evgenii; Remes, Heikki; Lehto, Pauli; Bossuyt, Sven; Advanced Manufacturing and Materials; Marine Technology; Department of Mechanical Engineering
A novel measurement approach is used to reveal the cumulative deformation field at a sub-grain level and to study the influence of microstructure on the growth of microstructurally small fatigue cracks. The proposed strain field analysis methodology is based on the use of a unique pattering technique with a characteristic speckle size of approximately 10 µm. The developed methodology is applied to study the small fatigue crack behavior in body centered cubic (bcc) Fe-Cr ferritic stainless steel with a relatively large grain size allowing a high spatial measurement accuracy at the sub-grain level. This methodology allows the measurement of small fatigue crack growth retardation events and associated intermittent shear strain localization zones ahead of the crack tip. In addition, this can be correlated with the grain orientation and size. Thus, the developed methodology can provide a deeper fundamental understanding of the small fatigue crack growth behavior, required for the development of robust theoretical models for the small fatigue crack propagation in polycrystalline materials.
Heat distribution analysis and electrothermal modelling of two large prismatical li-ion cells with computational tools
(2020-03-16) Niutanen, Vili-Valtteri; Farkas, Péter; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Hydrogen embrittlement of nodular cast iron
(WILEY-V C H VERLAG GMBH, 2021-01) Sahiluoma, Patrik; Yagodzinskyy, Yuriy; Forsström, Antti; Hänninen, Hannu; Bossuyt, Sven; Department of Mechanical Engineering; Advanced Manufacturing and Materials
Ferritic nodular cast iron, intended for use as the material for inserts of canisters for long-term geological disposal of spent nuclear fuel, was studied for hydrogen sensitivity. In the canisters, the insert provides the mechanical strength against external loads. Hydrogen was charged from 0.1 N H(2)SO(4)solution in free-corrosion tests and under controlled cathodic potential. Hydrogen uptake and trapping were then measured using thermal desorption spectroscopy. The hydrogen desorption rate after hydrogen charging manifests two distinct peaks. Plastic deformation during hydrogen charging increases the hydrogen uptake considerably. Hydrogen reduces the elongation to fracture and time to fracture in slow strain rate testing and constant load testing (CLT), respectively. Especially, the strain rate in CLT is dramatically increased. The appearance of hydrogen-induced cracking in the ferrite phase changes from ductile dimple fracture to brittle cleavage fracture due to hydrogen charging, which initiates from the interphases of the graphite nodules. The results are discussed in terms of the role of hydrogen and the graphite nodules in hydrogen embrittlement of ductile cast iron.
The impact on engine components and engine systems when using ammonia as fuel in internal combustion engines
(2022-12-12) Lagström, Tommy; Portin, Kaj; Insinööritieteiden korkeakoulu; Bossuyt, Sven
Rising global greenhouse gas emissions have increased interest towards alternative carbon-free fuels such as hydrogen and ammonia. Ammonia is an attractive option due to its favourable physical properties and existing infrastructure for storing and transportation. Research has shown that ammonia can be used as an alternative to fossil fuels in internal combustion engines. However, few studies have addressed the possible long-term complications of using ammonia as a fuel in internal combustion engines. Consequently, this thesis evaluates the suitability of different materials and engine components through a literature review, as well as using laboratory and in-engine testing. In the literature review, a theoretical evaluation of components in the engine’s air intake, exhaust system and parts in contact with the engine lubrication oil, regarding suitability with ammonia, is assessed. It was found that components containing copper alloys, namely bearings, are at risk of ammonia-induced corrosion. Similarly, seals made from fluoroelastomer (FKM) are not suitable with ammonia. Moreover, the low flammability of ammonia leads to small amounts of unignited ammonia entering the exhaust pipe, called ammonia slip. The inevitable ammonia slip could theoretically be exploited in a conventional selective catalytic reduction (SCR) system to reduce nitrogen oxide emissions. Since ammonia is highly soluble in water, an exhaust gas scrubber is another feasible solution for removing ammonia slip. Additionally, the in-engine tests showed that exposure to low levels of ammonia during 50 running hours over 108 days had no negative effect on the multiple copper alloy, sealant and FKM seal test samples. However, the accelerated aggressive tests showed that copper alloys are susceptible to ammonia-induced corrosion when exposed to higher concentrations of ammonia gas in an enclosed container over a 360-hour period. This test also showed that seals made from FKM will lose their physical properties and experience a significant volume increase when exposed to high concentrations of ammonia gas. The results of this thesis showed that further material tests with lower ammonia concentrations are needed, as well as field follow-up of the first engines operating on ammonia.

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