Abstract

1. Introduction

2. Literature review of battery modularity for electric vehicles

3. Approach to the concept of ‘replacing battery’ stations

4. Challenges of ‘battery replacement’ stations

5. Envisaged I4.0 solutions

6. Discussion

7. Conclusions and outlook

Acknowledgments

References

Abstract

     Energy and environmental impacts are at the top of the list of major global challenges to be addressed within the next few years. With transportation being one of the most pollutant sectors, focus has been directed towards Electric Vehicles, due to their significantly less dependency on fossil fuels. Nevertheless, electric mobility is currently characterized by a limited driving range, leading manufacturers to investigating new methods that could increase range and charging efficiency. Current research is mainly focused on increasing battery performance and reducing charging time. This study concentrates on presenting a novel approach, based on replacing battery stations, where the vehicle’s batteries are replaced with a fully charged one (available at the station), while new modular batteries could be made on the spot. The existing gas station networks could be used for the replacement of electric car batteries. This will be addressing the issue of time-consuming charging of batteries. Through the assimilation of Industry 4.0 Key Enabling Technologies, the respective challenges can be addressed. This is illustrated through a holistic framework, whereby the requirements for the context-aware design of the car itself are also given and a specific solution, based on the mechanical mounting of batteries is discussed..

Introduction

     Car manufacturers enter the space of the electric vehicle (EV) (Gnann et al. 2018; Nanaki 2021). This is highly correlated to the fact that the consumers find the green aspect very appealing (Rezvani, Jansson, and Bodin 2015). Reduction in the consumption of the emissions and the resources (Athanasopoulou, Bikas, and Stavropoulos 2018) are also in support of this trend. Moreover, the green agenda in Europe seems to have had a great impact on manufacturing in general (‘White Paper 2011 | Mobility and Transport’ 2021). Statistical figures show the correlation between market uptake and GDP, in the European Union (EU), with Germany, the United Kingdom and France having the highest EV market share in the EU for 2018, highlighting the importance of the EV market (‘Interactive Map – Correlation between Uptake of Electric Cars and GDP in the EU – ACEA – European Automobile Manufacturers’ Association’ 2021; Hanžič, Marksel, and Božičnik 2019). Electric vehicles, in particular, seem to be having a very specific related issue, that of the battery. Some intelligence (Arora, Shen, and Kapoor 2016; Albright and Kappel 2003) has been embodied in the design of the car and the battery, but the issue of its charging still remains, despite the fact that the stakeholders’ number has now been increased drastically, by offering many differentiating choices.

Conclusions and outlook

     The investigation of I4.0 KETs, under the concept of battery modularity and the development of intermediate battery replacement stations, could have high potential on addressing significant barriers, related to the time-consuming battery charging. The particular study focuses on bringing together the modular batteries concept, which is still at a very early stage, with the new concept of intermediate battery replacement stations.

     From a product development perspective, modularization correlates with a radical change in the automotive industry. The modular battery pack design and distribution, under the concept of battery swapping stations, could lead to improved network capabilities and to manufacturing mobility. Modularity could be considered as a new milestone in the automotive industry, targeting at the optimization of global production networks and operational flexibility. Latest achievements in the field of complex assembly decision-making and the use of advanced technologies in design under the concept of I4.0, have rendered the necessary feasibility and adaptability possible, towards the implementation of modular concepts in the industrial sector (Remco, Halman, and Hofman 2016).

Abstract

Nomenclature

1. Introduction

2. Vehicle model and driver model

3. Design of DYC for energy-efficiency

4. DYC for stability and stability judgement

5. Performance of the DYC for energy-efficiency and the DYC for stability

6. Switching principle

7. Results of combining DYC for energy-efficiency and DYC for stability

8. Conclusion

References

Abstract

     A direct yaw moment control (DYC) for energy-efficiency and a DYC for stability of electric vehicles (EVs) are proposed. The DYC for energy-efficiency is active during non-safety-critical cornering manoeuvres to improve the energy-efficiency of EVs. The DYC for stability is active during safety-critical manoeuvres to keep the vehicle stable. A combination of the DYC for energy-efficiency and the DYC for stability is studied. A stability judgement based on the yaw rate and slip angle is designed for evaluating the criticality of the vehicle’s working state. A switching principle for alternating between the DYC for energy-efficiency and the DYC for stability is designed. During non-safety-critical cornering manoeuvres, it is shown that the DYC for energy efficiency can save considerable percentage of energy compared to both equal torque driving and the DYC for stability. During cornering manoeuvres containing both non-safety-critical parts and safety-critical parts, the simulation results in this work show that the combination of the DYC for energy-efficiency and the DYC for stability can give 12% to 18% energy savings compared to the DYC for stability only for the vehicle and manoeuvres studied.

Introduction

     Electric vehicles (EVs) are an important component of a fossil-fuel-free future and the number of EVs on the roads is increasing rapidly. There are several solutions for electrified powertrains, one of which is in-wheel motor technology. In the case of 4 in-wheel motors (4IWMs), the propelling power of each wheel can be independently controlled. Therefore, 4IWM EVs can provide more control flexibility than traditional centralised driving vehicles. For example, direct yaw moment control (DYC) can easily be implemented in a 4IWM EV.

     The DYC usually follows a hierarchical structure consisting of a high-level yaw moment controller and a low-level torque distribution controller. Based on a reference model, the high-level controller can determine the stability yaw moment which provides an effective way to stabilise the vehicles. Tahami et al. [1] used a fuzzy logic controller, which adopted the yaw rate error (compared to the desired yaw rate) and this yaw rate error rate of change as inputs and the torque difference between the right and left wheels as the output to generate the DYC, for the purpose of enhancing the vehicle stability. Raksincharoensak et al. [2] proposed two types of desired yaw rate: one for the lane-keeping function and the other for vehicle stability control to improve the vehicle handling and stability. A driver steering behaviour recognition algorithm, using the steering wheel angle and the steering wheel velocity as inputs, was designed to determine the type of desired yaw rate. Geng et al. [3] took, besides the desired yaw rate, the desired body slip angle into account and adopted the linear quadratic regulator method to calculate the optimal yaw moment.

Conclusion

     A DYC for energy-efficiency based on the desired lateral acceleration is designed for non-safety-critical cornering manoeuvres. A DYC for stability tracking the desired yaw rate is designed for safety-critical cornering manoeuvres. In order to improve the energy efficiency and keep the vehicle safe during cornering manoeuvres which contain both non-safety-critical parts and safety-critical parts, a DYC is proposed which combines DYC for energy-efficiency and DYC for stability, which has been evaluated by simulations. A stability judgement, consisting of the yaw rate and body slip angle, is suggested and a switching principle for alternating between DYC for energy-efficiency and DYC for stability has been developed.

     The following five driving strategies have been analysed: 4WETD, 2WETD, DYC for energy-efficiency, DYC for stability and combined DYC. During non-safety-critical cornering manoeuvres, the DYC for energy-efficiency can make a considerable percentage of energy saving compared to 4WETD, 2WETD and DYC for stability. It has been shown that during cornering manoeuvres containing both non-safety-critical parts and safety-critical parts, only the DYC for stability and combined DYC can keep the vehicle safe and besides the combined DYC consumes less energy than the DYC for stability.

Abstract

Introduction

Literature review

Electric vehicles — key concepts

Overview of hybrid three‑wheeler

Current state of the art of electric three‑wheeler

Policy gap

Methods

Duration

Rickshaw cost

Usage statistics

Expenditures and earnings

Sustainability analysis

Discussion

Reduced GHG emissions for environmental sustainability

Development of indigenous technology

Government easy loan scheme

Poverty amelioration for economic sustainability

Easily available charging stations

Promoting gender equality

Conclusions

Declarations

References

Abstract

     Transportation sector is one of the major contributors to GHG emissions, and it is essential to investigate the role of electric vehicles in economic and environmental performance of developing countries. In this research work, the authors seek to investigate the usage pattern of three-wheeler vehicle by taking a Pakistan-based survey approach and analyzing the responses from various three-wheeler drivers across the country. The survey results indicate that the adoption of hybrid and electric three-wheelers in Pakistan would be welcomed by the users due to increased economic benefits, despite having a high initial capital cost. On an average basis, the regular three-wheeler is run for more than 5 days a week, 101–150 km daily across more than 10 h, and enables the owner to make around PKR 20,000–25,000 (~ US $119–US $149) after approximately PKR 15,000 (~ USD $89) is spent every month on fuel and maintenance. The adoption of hybrid or electric three-wheelers can easily improve the monthly earnings by 50%. In addition to this, the GHG emissions from the transportation sector will be considerably lowered around 3–6 tonnes of CO2 emissions per year per three-wheeler. At an investment return period of 13–16 months, the electric three-wheeler is a highly lucrative opportunity.

Introduction

     The industrial revolutions brought about a paradigm shift in the quality of lives of individuals; the world became a global village and the technological advancements resulted in extensive economic gains. However, the environmental impact of the economic gains was often overlooked and it eventually culminated in the pressing issue of climate change where the annual temperatures are forecasted to rise by 0.5–4.5 °C over the next century (GoP, 2016) if stringent measures are not taken. In this context, it is incumbent upon the stakeholders and policymakers to identify the areas where the carbon footprint can be reduced through conscious eforts. Transportation sector is one of the major contributors to environmental pollution1 and the conventional internal combustion engines require stringent protocols for curbing the environmentally detrimental greenhouse gas emissions. Therefore, countries have promoted the use of electric vehicles (Kwon et al., 2020; Daina et al., 2017) to reduce the environmental impact of transportation, in addition to numerous clean energy initiatives. The commercially available electric vehicles are broadly classifed into two categories: (i) plug-in hybrid electric vehicles or PHEVs and (ii) battery electric vehicles or BEVs and share the common aim of reducing the GHG emissions by reducing or eliminating the use of fossil fuels (Cofman et al., 2017). The worldwide adoption of hybrid technology vehicles has been an outcome of spreading awareness followed by relevant actions among governments, consumers, and producers.

Conclusions

     In this research work, the authors have sought to understand the usage pattern of three-wheeler vehicles and the general consensus on the adoption of electric threewheelers. Using a survey-based approach, data from 534 three-wheeler drivers were collected from the major metropolitan cities of Pakistan and it was observed that there exists an opportunity to introduce electric three-wheelers to achieve holistic sustainability. Many researchers have discussed the importance of adoption of electric vehicles and their economic benefts; however, the case of threewheelers from driver/owner viewpoint has remained an unexplored avenue. To the best of authors’ knowledge, this is the frst study that describes the usage pattern of three-wheelers and performs the sustainability analysis of adoption of three-wheeler vehicles in Pakistan, and it can be said with confdence that the results can be extended to other countries with similarity in socioeconomic demography. The higher price point of the electric or hybrid threewheeler will not afect the buyer as the investment can easily be recouped within 13 months if the three-wheeler is bought on lump sum basis, whereas the return period is 16 months if the electric or hybrid three-wheeler is bought through a government loan scheme. The adoption of electric three-wheelers will result in improved environmental performance as on average 3–6 tons of CO2 emissions is produced from a single three-wheeler throughout the year at a driving cycle of 101–150 km a day for 6 days a week. With more than 100,000 three-wheelers running across the country,

1- Introduction

2- Experimental rotor/AMB system

3- Strain measurement system

4- Strain measurement calibration

5- Dynamic results

6- Conclusions

References

Abstract

Active magnetic bearing systems provide contact-free rotor levitation, which allows near frictionless rotation and high rotational speeds when they operate normally. Under certain operational conditions, a transient fault, overload condition, or disturbance may occur. Touchdown bearings or bushings are therefore implemented in such systems to prevent contact between rotor and stator laminations. If the rotor makes contact with a touchdown bearing, the rotor dynamics may become transient or persistent in contact. Appropriate control strategies through the magnetic bearings to restore contact-free rotor operation may extend the life of touchdown bearings, and minimise operational downtime. To achieve this, an understanding of the contact dynamics is required, together with the relationship between contact and magnetic bearing forces. In this paper, rotor/touchdown bearing contact conditions are investigated experimentally using an active magnetic bearing system with a flexible rotor. Design methodology is presented for a measurement system capable of providing rotor/touchdown bearing contact related data, based on strain measurement. Strain induced contact signals are calibrated against applied magnetic bearing forces. The frequency dependent behaviour of the active magnetic bearing system is considered using evaluated force and phase measurements. The measurement data represent system identification for the potential of active magnetic bearing force-based contact control.

Introduction

The ability of Active Magnetic Bearings (AMBs) to provide contactless rotor levitation with vibration control has a number of benefits, including high-speed rotor operation, the elimination of the need for lubrication, long life and reliability, and energy efficiency due to the low friction losses. However, passive bearings are also used in AMB systems as Touchdown Bearings (TDBs) to prevent potentially damaging rotor/magnetic bearing stator contact from occurring. TDBs support the rotor while the AMB system is not operating, but also limit excursions of the rotor during operation, such as in cases of power loss, component failure, rotor mass loss, or other significant external disturbances. Such cases may cause rotor/TDB contact. Since TDBs are functional components of AMB systems, it is crucial to understand their influence on rotor dynamic behaviour in contact cases, in order to minimise potential damage. This is particularly important as TDB life and condition impacts directly on the reliability of AMB systems.

1- Introduction

2- Materials and methods

3- Results and discussions

4- Conclusions

References

Abstract

Advanced heat removal technologies are critical for high-performance automotive engines. The conventional fluids being used today are based on a mixture of distilled water (DW) and ethylene glycol (EG), which widens the operational temperature range but at the same time limits the heat removal. Therefore, the use of nanofluids for improving heat transfer performance has soared over the past few years. The problem is that most of the reports highlight the short-term heat transfer results which may not be true over time. In this paper, a suggested best practice for analyzing the usage of nanofluids in heat transfer applications is presented, specifically for an actual car radiator. This work investigates the use of aluminum oxide (Al2O3) and titanium dioxide (TiO2) nanoparticles dispersed in DW and EG at 50:50 volumetric proportions. The choice of these oxide-based nanofluids is motivated by their anti-corrosive properties that are usually not analyzed or discussed in most of the articles. Furthermore, the emphasis is given on the presentation of a comprehensive characterization of the nanofluids including thermophysical properties (size, density, viscosity, thermal conductivity, corrosive behavior) and long-term stability (zeta potential) which are essential for an end-user to have. The results showed a maximum enhancement of the thermal performance by 24.21% using Al2O3 at a volume fraction of 0.3%. Friction factor and performance evaluation criterion (PEC) for the radiator experiments are calculated in order to determine the penalty in the pressure drop and to evaluate it properly. Finally, it is found that the values of PEC lie in the range of 1.03–1.31 which indicates significant flow enhancement.

Introduction

The improvement in automotive technologies has led to increased thermal loads, and therefore higher cooling rates are required [1]. The addition of fins, microchannel, and turbulators are the traditional approaches used to increase cooling rates of the radiator which are already extended to their limits [1,2]. In recent years, the automotive industry has been focused on the weight reduction of the vehicle as it improves the fuel economy and the associated running costs [3]. Weight reduction can be achieved in the engine cooling system. Furthermore, many conventional coolants (lubricants and water) have characteristically shown poor heat transfer properties due to their lower thermal conductivities (TCs) [1,4]. Engine performance, fuel efficiency, and emissions are specific parameters of an automobile which are profoundly affected by convective heat transfer [5,6]. Therefore, a new compact and innovative coolants and/or coolant systems are needed to fulfill the growing needs for heat removal in a clean and eco-friendly way [7].

1. Introduction

2. NVH Robustness Analysis Based on Subjective Rating Attenuation

3. NVH Robustness Example Analysis of High Mileage Automobile Based on Subjective Rating Attenuation

4. Conclusion

5. Acknowledgement

6. References

This paper explains the concept of high mileage automobile NVH(Noise Vibration and Harshness ) robustness. Based on the NVH characteristic subjective rating method, a quantitative analysis and evaluation method for NVH robustness of high mileage automobile is proposed. By using the subjective rating attenuation method of high mileage automobile NVH robustness and combine the actual parameters of three different types of cars, According to the calculation and analysis of the decline and attenuation of subjective rating attenuation method, the NVH robustness characteristics and change rules of three different types of cars at different mileage stages are obtained, which provides a reference for the NVH robustness analysis of high mileage automobile and the development of automobile NVH.

Introduction

The current research on the NVH characteristics of automobile is mainly focused on the vibration, noise and comfort of the new automobile, but less research on the vibration, noise and comfort of high mileage automobile after use. With the gradual increase of the mileage of the automobile, the automobile parts, components and the performance of the automobile must be attenuated to a certain extent. The attenuation of its comprehensive performance will inevitably lead to the gradual reduction of the NVH characteristics of the high mileage automobile. High mileage automobile NVH robustness refers to the holding capacity of original acoustic quality in the automobile, when the vehicle is purchased by the user and will be influenced by various factors in the process of use, from the gradual increase of the mileage from zero to a mileage1,2,3 . This paper proposes a quantitative analysis and evaluation method based on subjective rating attenuation for high mileage automobile NVH, and studies the robustness of automobile NVH characteristics.

1- Introduction

2- Numerical model

3- Validation of the numerical model

4- Results and discussion

5- Conclusion

References

Abstract

A computational fluid dynamics (CFD) simulation model has been established to study the effects of toluene content in surrogate fuel on combustion and emissions for a large two-stroke marine diesel engine. In order to find more accuracy simulation model, the effects of toluene physical parameters were researched. Meanwhile the paper suggests a multi-components mechanism as surrogate fuel of diesel. The results indicate that the toluene content in surrogate fuel has an important impact on performance of marine engine. The ignition delay times increases with an increase in toluene content. However, the nitrogen oxide and soot mass are increase. The combustion will be influenced when the physical parameters of toluene are used in liquid fuel mixture. The nitrogen oxide has a peak value when the toluene content is used in the liquid fuel mixture. However, it has little influence on the in-cylinder pressure. The liquid parameters have also effect on the accuracy of simulation model. The in-cylinder pressure and emissions are higher when n-tetradecane is used in the liquid fuel mixture. By comparing the key parameters determined from simulations and experiments, it is found that the n-tetradecane-toluene with 30% of toluene is applicable to use as surrogate fuel of diesel.

Introduction

The introduction and enforcement of stringent environmental regulations has made it necessary for engine manufacturers to produce marine diesel engines with lower exhaust emissions. According to the International Marine Organization Tier III regulations, nitrogen oxide (NOx) emissions need to be reduced from 14.4 g/kWh (Tier II regulations) to 3.4 g/kWh [1]. Various techniques have been developed over the years to produce marine diesel engines that fulfil this requirement such as exhaust gas recirculation (EGR), selective catalytic reduction (SCR) and humid air motors (HAMs) [2–4]. Numerical simulations are now widely used to simulate the performance and exhaust emissions of marine diesel engines with advances in computer technology and software. Compared with real-world testing, numerical simulations are used to investigate the performance and exhaust emissions of marine diesel engines over a wide range of conditions while reducing significant resources and time associated with conventional experimentation. Ji et al. [5] researched the effects of Miller cycle, exhaust gas recirculation and intake air humidification coupled with fuel injection strategies on the NOx emissions using CFD software CONVERGE. A CTC/SHELL model was used to simulate auto-ignition of fuel. The surrogate fuel and combustion model were also used by Jiang et al. to research the effects of multiple-Injection coupled with EGR on combustion and NOx emissions in a marine diesel engine [6]. Zhou et al. [7] investigated the effect of injection direction and exhaust valve close timing on performance and emissions for a slow speed marine engine. The multi-zone sub-model was selected in combustion model. Sigurdsson et al.

1- Introduction

2- Loads modeling for robust life predictions and endurance rig tests

3- An application of a cooling package mounted on the chassis of a truck

4- Conclusions

References

Abstract

We focus on applications from the automotive industry, on mechanical components submitted to vibration loads. On one hand, the characterization of loading for dimensioning new structures in fatigue is enriched and updated by customers data analysis. In a second hand, the loads characterization also aims to provide robust specifications dedicated to the simulation or test rigs. We aim to provide vibration specifications that are adapted to a calculation time or physical test durations in accordance with the pace imposed by the projects timeframe. The vibration specifications need to be robust by taking care of the diversity of vehicles and markets considered in the projects. In the trucks industry, the dynamic behavior can vary significantly from one configuration to another. For non-stiff structures, the lifetime depends, among other things, on the frequency content of the loads, as well as the interactions between the components of the multi-input loads. In this context, this paper proposes to compare sets of multi-input loads applied on the non-stiff structure, i.e for which the frequency content of loads impacts the damage.

Introduction

Durability feature aims to understand and predict failure modes and fatigue phenomena in structures submitted to in-service loads, that are constant or variable amplitude loads. This paper focus on application from automotive industry, especially trucks. We concentrate on load vibration applied on mechanical components. One of the targets of the loads characterization is to capture damaging events and model them (Johannesson & Speckert, 2014). Loads model is necessary for different reasons: to adapt the rig capability where the components is tested, to understand the scatter of a population of customers, to compare them. The trucks architecture impacts the load environment of components of the truck (e.g chassis packaging hung on the chassis). The manufacturers aim to get common structures among different trucks silhouettes. For dimensioning new structures, loads from different trucks need to be compared, in order to identify the most severe truck configuration. An approach to compare variable amplitude multi-input loads applied on non-stiff structures is proposed. After the method description, a two-input example is presented. A cooling package installed on different trucks architecture is used as an illustration.

1. Introduction

2. Trailer FEA model

3. Fatigue enhanced structural stress analysis

4. Vehicles inspection and comparison

5. Conclusion

Acknowledgements

References

A FE seam weld model has been built for advanced fatigue structural stress analysis. The shell element model allows both weld toe and weld root fatigue assessment. In order to validate the model, this project deals with the complete analysis of a last decade manufactured vehicle for which experience feedback is possible. The vehicle structure is mainly built with steel sheets and the assembly is performed by seam welding. Shell element model is appropriate for FEA. The entire FEM preparation is presented hereafter and each step is detailed: 3D CAD weld building, mid-surface idealization, weld leg imprint creation, weld mesh connection and load application. Fatigue analysis is performed based on a fatigue limit approach and IIW FAT data. For every structure location a Haigh diagram is built. Different diagrams are presented for plain metal, cut edge, weld toe and weld root. The FEA results are post processed and each appropriate tensor component is taken into account. For plain metal, stress variation along the worst principal stress orientation is calculated. In welds, for both toe and root locations, the structural stress computation based on grid point forces extraction is described. Longitudinal shear stress in weld and at weld toe as well as weld longitudinal normal stress calculations are detailed. Fatigue results are displayed for each location over the whole chassis model. Finally, vehicles built during the last decade are inspected back from the customers experience field. Observed crack types and locations are compared to fatigue analysis predictions.

Introduction

LOHR Industrie products car carrier vehicles, railway semi-trailer transport systems and urban electric people transportation solutions. All products are steel made and assembled by welding. For vehicle structure analysis, LOHR Industrie has developed FEA models for assemblies relative to seam weld and bolt [1]. Seam weld fatigue assessment model has been described in numerous publications [2, 3, 4] and validation based on simple assembly specimens has been detailed. A project has been launched in order to verify the proposed FEA model and the associated fatigue behaviour prediction by comparison with long mileage vehicle structure inspections. An old generation car carrier trailer model is built. The fatigue analysis based on advanced structural stress approach is performed.

1. Introduction

2. Cyclic fatigue tests

3. Stress analysis

4. Conclusions

Acknowledgements

References

Tie-rods are connecting elements used in an aircraft and they basically consist of a straight tube and two screwed in adapter ends. In order to optimize the tie-rod in terms of weight reduction a detailed knowledge of its fatigue strength is important. However, the complex load and contact distribution within the threaded connection between tube and adapter end make a secure and efficient fatigue design challenging. Moreover, the connection is realized with a thread insert to assure smooth adjustability of the adapter ends, which further increases the complexity of a fatigue strength assessment. Thus, cyclic fatigue tests with a load ratio of R = 0.01 are performed to investigate the influences of thread insert length and position on the fatigue life of three different configurations. The experimental results are explained by Finite Element analyses using a detailed Finite Element model of the threaded connection. Finally microscopic examinations as well as the Finite Element analyses are utilized to further optimize the threaded connection in terms of reduced weight and high fatigue strength.

Introduction

Tie-rods are commonly used connecting elements in an aircraft and attach, e.g., galleys, lavatories or storage bins to the fuselage structure. The specific design of tie-rods varies depending on the installation purpose and manufacturer. In this paper the threaded connection of interior tie-rods from RO-RA Aviation Systems is investigated. Fig. 1 shows a schematic sketch of such tie-rods with a straight tube and two adapter ends, which are screwed into the tube in order to adjust the length of the complete assembly. The threaded connection between the tube and the adapter end consists of two parts: a threaded sleeve and a screw insert in order to maintain a smooth-running connection to the adapter end. The sleeve is firmly attached to the tube. Such tie-rods are subjected to tension and compression loads with variable amplitude and must meet the high requirements of the aeronautic industry. Structural components in aircrafts in general have to be designed for a certain service life and therefore a detailed knowledge of their fatigue behavior is of great importance [1]. Furthermore, tie-rods have to meet weight requirements because of their large number in an aircraft. Previous fatigue tests carried out in the test facilities of the Institute of Structural Lightweight Design have shown that the threaded connection between tube and adapter end is a critical failure location.

1. Introduction

2. Obtaining of loading signal during standard operational cycle

3. Signal processing

4. Damage model

5. Calculation of fatigue life time distribution function

6. Conclusion

Acknowledgment

Reference

Fatigue lifetime estimation of load bearing parts of construction is a key factor in a design of technique used for long term operation. Complex loading in combination with complex geometry of the most loaded parts represents only one of many problems that engineers have to deal with. One of the most commonly used approaches how to deal with this problem is to use the technical standards. This approach, despite its indisputable advantages (clear and comprehensible steps of calculation), has several significant shortcomings (non-economical oversized design). In this paper we propose procedure of how to estimate fatigue lifetime of construction parts that are loaded with random operational loading. The result of proposed procedure is distribution function of fatigue lifetime which takes into account the complex geometry of the designed part and random character of the complex loading (multiaxial stress state) in a hotspot. This approach is then demonstrated on fatigue lifetime estimation of bearing pin of a console manipulator loaded by random operational loading. Loading process was obtained using set of strain gages. The measured loading process was then transformed into stress histories in critical hotspot using FEM. Method of processing the stress loading histories in critical hotspot into a form usable in combination with hypotheses for fatigue damage calculation under multiaxial stress states is presented.

Introduction

Estimation of fatigue life time of mechanical components working under real operational loadings (usually multiaxial variable amplitude loading) could be considered as an ultimate task in a field of fatigue life time analysis. Due to the complexity of the problem, there are many factors that have crucial influence on the final lifetime estimation. Moreover, a great deal of these problems do not have widely accepted solution and usually there are multiple ways how to solve them. One way how to tackle these problems is to use the methodology given by standards. These standards normally use some simplification to make the estimation more feasible for engineers. However, as a result of these simplifications, the methodology given by standards is normally suitable only for infinite life calculation, and when used in finite fatigue life time estimation, it usually leads to oversized components, or in some cases, it can even lead to the design error on non-conservative side. Due to these facts, enormous effort was and still is put forth to postulate methodology for finite fatigue life estimation under variable non-proportional random loading [1,2,3,4,5]. In the pages below, authors show how to deal with problems that engineers have to overcome during fatigue life time estimation under multiaxial random loadings. Step by step, analysis of real component (bearing pin of pneumatic handler) loaded with random loading is shown. Usage of multiple techniques is shown for various problems and brief comparison of results and small critical discussion is provided.

1. Introduction

2. Manufacturing process simulation

3. Fatigue simulation

4. Conclusion

Acknowledgements

References

In the automotive light-duty passenger vehicles, double dry clutch provides high comfort and fuel efficiency to passengers with automated gear box. Its functional performance and quality depends on its diaphragm spring. Fatigue analysis on this component and correlation is quite complex because of several manufacturing processes involved like stamping, heat stabilization and shot-peening. The procedure to predict the diaphragm fatigue strength is described in the paper; also it integrates the new simulation softwares capabilities to handle the process effects for evaluation of diaphragm. This paper outlines the different simulation stages involved to access the fatigue assessment on diaphragm spring; also it is done at various life situations of vehicle: normal, parking, overloading conditions. A great attention is paid for correlation through measurement fitting in simulation. Between each manufacturing process simulation, the deformed shape and its residual stress-strain data are mapped using customized scripts. After the process simulations, fatigue actuation on diaphragm is done for new, semi-worn and worn positions of clutch. Miner’s damage and its summation are done at each critical point in diaphragm to determine its total life under nominal design.

Introduction

Improvement in modern simulation tools enables to integrate complex process simulations in design assessment for efficient fatigue validation. Double dry clutch diaphragm springs undergoes several manufacturing processes such as stamping, heat stabilization and shot-peening to improve its fatigue strength under various operating conditions.

1. Introduction

2. Theoretical background: method for calculating the global dynamic factor KAV

3. Practical case: accessories gearbox for aerospace application

4. Results and discussion

5. Conclusions

References

The present paper aims to propose a method, in ISO Standard environment, in order to calculate a single global dynamic factor KAV, replacing both KA and KV, in case of gears subjected to variable velocity and loading conditions. This procedure, based on the Miner damage rule, allows to process a given load spectrum and to calculate a value of the equivalent tangential force that includes all dynamic effects; this force value is useful for bending and pitting calculation of the service life. In this work a practical case for bending strength is presented, based on a recorded flight mission, referring to a gear box for aerospace applications. Obtained results in terms of equivalent forces and global dynamic factor values have been compared to those calculated by means of the classical ISO Standard formulae, based on the corresponding experimental data.

Introduction

Classical design formulae available in literature to determine the load capacity of spur and helical gear drives are intended, both for pitting resistance and bending strength, to establish uniformly acceptable methods to assess the corresponding life estimation. The most common approach, widely described in ANSI/AGMA Standard 2001-D04 [1] and in ISO 6336-1 Standard [2-6], compares the calculated maximum stress values (tensile and contact, for bending and pitting respectively) to the permissible ones representing the limit value for stresses (tensile and contact) derived from material tests using meshing gears as test pieces. Referring as an example to the bending case [1, 3], discussed in detail in the present paper, the permissible bending stress σFP provides damage curves characterized by the nominal stress number σFlim and by the life factor YNT, and then corrected using the relative influence factors for notch sensitivity, surface roughness, size. For as concerns the calculated stress, the tooth root stress σF is the maximum tensile stress at the surface in the root and it can be obtained by multiplying the nominal tooth root stress (which is the maximum local principal stress produced at the tooth root) by the so called overload factors. Overload factors [1-4] are generally influence factors, independent each other, that aim to take into account uneven overloading conditions of gears.