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Foundry Corporate News

09. March 2023

Conception, design, development and testing using the example of a new concept of electric scooters

Pressemitteilung | Reading time: min

Mobility is one of the biggest challenges for cities due to the increasing concentration of population. The lack of space, the increase in CO2 emissions and the inadequacy of conventional transport systems require new approaches that can counteract the use of private vehicles by the population. Shared mobility has emerged as a solution for a new model of urban development. Although the supply of electric scooters on the market is promising, it is currently not prepared for the new concept of shared mobility and the demographics of some cities. To remedy this, the Mobinext project, funded by the Portugal 2020 programme, aims to develop a new electric scooter model for shared mobility in cities.

The project consortium is made up of Portuguese companies and research centres - AJP, Almadesign, CEiiA, CITNM and Wyze - to develop a differentiated electric scooter with Portuguese know-how, adapted to the challenges of our cities. The proposal foresees the development of a lighter electric scooter with innovative structure and design, powertrain integration and a connectivity module that respects ergonomic principles and promotes better, simpler and safer human-machine interaction. The consortium will also develop a new mobility sharing platform supported by AI and IoT mechanisms to enable better connectivity, integration and optimisation of operations.

Consortium

AJP is a company specialised in the design, manufacture and sale of motorbikes. It is currently the only Portuguese motorbike manufacturer. AJP stands out for its creativity and technological innovation in the development of new motorbike models, which has been part of the brand's DNA since the beginning. AJP is leading the Mobinext project, providing the necessary skills for the design and manufacture of the scooter's components.

Almadesign's focus is on driving innovation through design and using it as a tool to bring people, skills and abilities together. The focus is on technology-based development, user-centred solutions for transport (air, rail, road and sea), industrial equipment, electronic devices, furniture and interior design. In the Mobinext project, Almadesign is responsible for the overall design of the scooter and the public communication of the developments.

CEiiA is an engineering and product development centre that designs, develops and produces new technologies, products and services for a more sustainable society. It is a link between cities, industry and universities in high-tech sectors such as automotive, aeronautics, maritime and space. Under this project, CEiiA will develop the scooter's connectivity module and management system.

The Centre for Innovation and Technology

N. Mahalingam (CITNM) is a non-profit association whose main objectives are to promote research, development and innovation (R&DI) and training in technologies related to metallurgy in the foundry and automotive sectors. CITNM promotes and stimulates specialised training, collaboration and technology transfer between companies, universities, organisations and other public and private entities in order to create synergies to increase R&Di capacity. CITNM contributes to the Mobinext project with its expertise in metallurgy and foundry processes to develop the scooter's rear swing arm and side beams.

WYZE is a start-up company that aims to provide cities with technology-based

technology-based, innovative micro-mobility solutions to make cities more liveable. Wyze has been developed with an approach that looks at life as a whole and mobility as a constant need in people's lives, targeting those who want to get around practically and efficiently with reduced environmental and social impacts. At the end of the project, it will be responsible for the integration of electric scooters in cities.

Main objectives

The project partners intend to revolutionise the way people get around in cities by developing a differentiated electric scooter model with a management system that enables communication between vehicles and a more organic human-machine interaction. The main objectives of the Mobinext project are:

-Conceptualise, design, develop and test a new concept of electric scooters for shared operation;

Develop a backend module for operations management and a mobile application for user experience management;

-Development of the scooter's connectivity module;

-Developing competing structures with advanced aluminium alloys using additive manufacturing and casting simultaneously;

Demonstration and validation of how the solution can add value to the shared mobility service by creating and engaging a pilot test community throughout the product/service development process.

The design of the electric scooter developed by Almadesign is shown in Figure 1.

Figure 1 - Final design of the Mobinext electric scooter, developed by Almadesign.

CITNM focuses on developing two structural parts of the electric scooter, produced in sand-cast aluminium alloy. Due to their relevance for the development, CITNM selected the scooter's rear swing arm and side beams (left and right).

The process - from development and optimization to production – is presented below. The castings of the prototype parts were carried out at Firmago – Fundição de Alumínios, S.A, in Portugal.

Rear swing arm

The rear swing arm was the highlight of component development. It connects the driving wheel to the frame and suspension of the scooter.

The primary goal in developing this part was to reduce the weight of the component, and thus the scooter's overall weight, without compromising its mechanical properties.

The first step was to optimize the traditional design of the rear swing arm using a generative design – Figure 2 – which served as a basis for the final swing arm design of the Mobinext scooter – Figure 3.

Figure 2 - Rear swing arm generative design.

Figure 3 - Rear swing arm first design, based on the generative software result.

This modification, from the traditional to the optimized design, resulted in a weight reduction of 10% for the same casting alloy

- A356.0. Although this was already a good achievement, some additional changes were performed to the alloy to improve even further the weight reduction.

A comparison of the mechanical properties of different aluminium sand-casting alloys showed that a reduction in thickness was possible by changing from A356.0 to A357.0. Tables 1 and 2 show both alloy's chemical composition and mechanical properties.

Table 1 - Chemical composition of the aluminium alloys.

%QC	A356.0	A357.0
Si	6,5-7,5	6,5-7,5
Mg	0,2-0,45	0,45-0,6
Fe	0-0,6	0-0,15
Mn	0-0,35	0-0,03
Zn	0-0,35	0-0,05
Cu	0-0,25	0-0,05
Ti	0-0,25	0-0,2
Outros	0-0,15	0-0,15

Source: Granta EduPack

Table 2 - Mechanical properties of the aluminium alloys.

Properties	A356.0-T6	A357.0-T6
Tensile strength (MPa)	205-226	345-380
Yield strength (MPa)	146-162	281-311
Young’s modulus (GPa)	71,5-74,5	70,6-73,4
Elongation (%)	2,1-2,5	2-2,4
Fatigue strength at 10⁷ cycles (MPa)	53,1-64,9	55,8-68,2
Fracture toughness (MPa.m^0,5)	19-21	20,7-23,9

Source: Granta EduPack

Together with the design optimization and alloy changes, the final version of the swing arm achieved an overall weight reduction of 20% – Figure 4.

Figure 4 - Rear swing arm optimized design, considering the alloy alteration.

After redesigning the rear swing arm, the challenge was how to produce it. It was not possible to use conventional sand moulds due to the part’s geometry. Therefore, the swing arm was casted in a 3D-printed sand mould.

To print the mould, it was first necessary to develop the gating system with its peculiarities. The development and production of the 3D printed mould was performed though a partnership between CITNM and BAMM (Spain).

Due to technical reasons, the mould was printed in 5 separate parts that were assembled before casting – Figure 5. After pouring, the sand mould was destroyed to extract the casting – Figure 6.

Figure 5 - 3D-printed sand mould (a) divided into 5 parts (b) closed.

Figure 6 - Rear swing arm first cast prototype, casted in a 3D-printed sand mould.

Finally, the casting was heat treated (T6), machined and painted to be assembled on the electric scooter prototype. It was the first rear swing arm prototype produced as part of the Mobinext project. To achieve maximum optimization there are still some adjustments to be done both in the part and process.

Side beams

The aim of producing a metallic side beam for the electric scooter was to increase its strength and reduce the damage caused by possible impacts/falls – Figure 7.

The side beams – left and right – were sand casted in A357.0-T6 aluminium, the same alloy used for the rear swing arm. Although it’s not a method of innovative manufacture, considering the dimensions (940x600 mm) and design of this component, it is often replaced by injection moulding. By selecting this process, the aim was to build a robust part and optimize the process parameters to overcome the geometric limitations that are associated with it. The prototype side beams were successfully casted and integrated into the electric scooter – Figure 8.

Figure 8 - Left side beam cast prototype. Internal and external side.

Prototype presentation

The Mobinext project is in its last development year.

The electric scooter prototype was presented at EICMA (International Motorcycle and Accessories Exhibition) in Milan on the 8th of November 2022, – Figure 9. It stands out for its aluminium frame, weight reduction, powerful e-motor, and by the front tire that is wider than usual, which aids in driving, even on uneven floors. These features were widely applauded by EICMA visitors. Removable batteries are housed under the seat, allowing for easy swapping. The driver's helmet is also stored inside the seat and it is planned to incorporate a top case to stow the passenger's helmet.

The start of road test is scheduled for the beginning of 2023. The Mobinext project will end in June 2023 with a national presentation of the final prototype.