Conception and Structural Analysis of a Motorcycle Frame Pedro Fonseca Serrador [email protected] Mechanical Engineering, Instituto Superior Técnico, Lisboa, Portugal October 2016 Abstract In the present Master’s Thesis, it’s intended to create a new frame on the basis of the Famel z3 motorcycle and to validate the proposed structure using analytic models and finite element models (Siemens NX). It starts by analyzing the market of electric motorcycle, showing its medium-term growth perspective. From the study performed are selected the most suitable motor and number of batteries required for a stipulated range of 100 Km in city, obtaining an estimate for the weight of the structure in order of 6,5 Kg. Based on a table built of Needs vs Metrics, were created three concepts of different structure and modeled in SolidWorks. To select the winning concept, these were subjected to multiple comparison tests, supplemented with finite element analysis using Siemens NX. Finally, two materials were tested for the winning concept, steel S235J2H and aluminum 6061. Using static failure and fatigue test methods (Mechanical Design) at critical points found with the critical loads calculated, there were made the necessary changes so that the structure verified security for the calculated safety factor. To select the winning material, their structures were subjected to multiple comparison tests. These analyses were supplemented with finite element analysis using Siemens NX and an analysis of production costs, using the tables of Formula SAE. As final result it was obtained a validated structure of concept 3 in aluminum, with a unit cost of production of 69,35 €, for a total production of 1000 frames. Keywords: Electric Motor, Famel z3, Finit Elements, Formula SAE, Needs vs Metrics, Mechanical Design 1. Introduction Famel, Fábrica de Produtos Metálicos, was EEC in 1986 Famel found itself confronted founded in 1949 in Águeda. In the 50s with some problems, forced to declare began to produce mopeds with engines from bankruptcy in 2002. However, Joel Sousa, Pachancho, Victoria and JLO and in the 80s 28, car engineer, recently bought the right to launched the Famel z3 model, known for its the brand and intends to bring it back into Zündapp engine with only 3 speeds. Despite focus. In an interview to Marketeer [1], he its small 50cc engine, this motorcycle could reveals that in 2017, if all goes as planned, reach high speeds as it was lightweight and the first new model, based on the XF-17, of a 2-troke engine, making it quite amusing. the reborn brand Famel will be released. “A With the bankruptcy of Zündapp in 1984 and motorização elétrica é o futuro. (…) Estamos the opening of the market to Europe by the convictos que podemos revolucionar a 1 maneira como se encara o veículo elétrico characterized by its single section beam with em Portugal…”. Famel z3 is part of the high dimensions, used mostly in low-cylinder product development portfolio of the motorcycles, or motorcycles where the company and will be the subject of this weight must be rationalized and when it is document. desired to lower production costs, due to ease of manufacture. Dual Sport Motorcycles A very important factor is the material to be Dual Sport bikes, where the bike under study used in the structure because, for a given fits, are, according to Motor Sport Rider [2], shape and specific load, the thickness can characterized by having dual purpose, as change as well as the geometry of the they are not only able to be ridden in structure, depending on the resistance of the highways with safety and comfort, but also material. because of their agility, lightweight and high In order to study the frame resistance and maneuverability, making them suitable for whether it supports the critical loads applied, off-road riding. is necessary to take into account criteria Motorcycle Frame Modeling such as stress, strength and fatigue. The To model the frame of a bike it is necessary methods to do so are shown and explained to take several factors into account. by Richard G. Budynas and J. Keith Nisbett According to Tony Foale [3], the frame has [4], and Carlos Moura Branco [5], such as two main functions: static and dynamic. Von Mises method and modified Goodman In static terms this should support the weight method. of the driver and the passenger as well as Electric Motor the engine, fuel tank and oil and accessories Nowadays, people seem to be more that the bike may have, such as bags of concerned and aware of environmental luggage. pollution and its effect on our planet, and On the other hand, in dynamic terms, it transports are one of the major contributors should have stable and precise direction, to this degradation. According to EPA [6], in have good adhesion to the ground, good United States motor vehicles are handling and must be comfortable. Each responsible for about 70% of air pollution. bike has a purpose of use and typical efforts Despite the electric motors not showing any that is submitted to, so there are several type kind of emissions, the truth is that electricity of frame formats, each modeled in order to has to come from somewhere and often, or better support a particular type of loads. mostly, it is produced with polluting Therefore, to build a motorcycle and know resources such as coal, fossils, low-carbon the best format to use on your frame, it is or mixtures [7]. Though, Portugal is a country necessary to know the type of use intended. where renewable energies are one of the There are 5 main type of frames: major power suppliers, making it possible for triangulated frames, monocoque, structural the energy that reaches electric motors to be engine, tubular backbone and twin-spar [3]. clean of pollutants. This is the only way it can This project is based on a motorcycle, which be said that electric motors do not show any uses a tubular backbone type of frame, 2 kind of emissions, making Portugal a good 120 with 12,3 Kg. As for the batteries the country to use them. most suitable ones are the Shenzen WS- According to Navigant Research [8], it is NCM20AH-3.7V20C. expected that the two-wheel electric vehicle Table 2.1 - Electric Motorcycles Market industry reaches a stable and continuous weight Power Price (thousands of Brand Model economic growth over the coming years. It is (Kg) (KW) euros) Brammo / Victory 213 40 20 expected that annual sales of electric Polaris Impusle S 171-205 40 11-16,7 motorcycles will grow from 1,2 million SR 188-208 50 16-18,7 DS 173-207 40 11-16,7 DSR 190-210 50 16-18,7 vehicles in 2015 to 1,5 million in 2024, while Zero FX/FXS 112-114 20 8,5 for electric scooters is expected that there is 3.3 FX/FXS 131 33 11 a sales increase of 4,1 million to 4,4, making 6.5 MX 115 19-30 15 Alta a total of 5,3 million in 2015 and 5,9 million SM 124 19-30 15,5 Freeride 106 11-16 11 in 2024. Therefore, this matter will be taken E-SX Freeride KTM 110 11-16 11,3 in account. E-XC Freeride 110 11-16 11,6 E-SM C 2. Problem Statement BMW 265 11-35 15,5 Evolution Motor and Batteries To get an idea of the loads involved in the Based on its properties and taking in account structure caused by the motor and batteries, the performance of the FXS model from is necessary to know specifically what will be Zero, it was calculated the number of used, being also useful to, in terms of batteries needed for a range of 100km in city geometry, know if it fits in the frame. So, to was around 55 with a total weight of choose the most suitable engine it was 24,75Kg. Hence if 55 batteries can provide a performed a study of electric motorcycle range of 100km to a model with 112Kg it can, market, in order to realize the weight/power for sure, provide the same range or more for ratio practiced in the industry, Table 2.1. a less heavy motorcycle. So taking in As is intended to model a frame of a bike, it account the model on which this project is is understandable not to know the final based on, Famel z3, weights about 63,6Kg weight of the bike, so to choose the engine and have a frame with 6,5Kg, the new frame was decided to set a desired value for the being modeled should weight about the power of the bike. According to the same or less, if possible. Portuguese Institute of Mobility and Geometry Modeling transport [9], holders of category B driving According to Karl T. Ulrich and Steven D. license are also qualified to drive Eppinger [10], the best way to develop a new motorcycles with power up to 11KW, if they product is to follow a specific procedure are over 25 years old, or so, or are holders consisting of several well-defined steps. This of mopeds driving license. way it was produced a Table of needs vs This way, and based on projects of the metrics, in which the main parameters are students from DEM in IST, FST and TL shown in Table 2.2, based on final moto, the most suitable motor to choose is a consumer’s opinions, to help create a variety Double-sided Synchronous Motor – PMS of concepts. 3 Table 2.2 - Needs vs Metrics Center Max.