Bicycle frame

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The bicycle's frame is constructed using SAE 4130 Alloy Steel, also known as Chrome Moly, which is commonly used in welded tubing applications. The framework consists of two different tubes with a wall thickness of 1.5 mm; one tube has a diameter of 1 inch and the other 2 inches, both made of SAE 4130 Alloy Steel. TIG welding was chosen for this project due to its suitability for thin-walled tubing. Static analysis considered factors such as a rider weighing approximately 80 kg who does not sit on the saddle, resulting in ¾ of their weight supported by the pedals and 1/3 supported by the handlebar. The bicycle is at rest initially before the rider uses leg power to reach a final velocity of 20 m/s under constant acceleration, with air resistance not taken into account or gear changes. Fatigue analysis considered two different loads of equal magnitude that support different pedals (right or left), applied sequentially as people typically pedal. The results indicated that the frame's life is virtually limitless due to the loads not being intense enough to reach the material's fatigue strength under infinite cycling conditions. A lower safety factor of approximately 4.5 was obtained from static analysis, suggesting that the tube section could be reduced compared to similar models. Some properties and parameters used in the fatigue analysis included a stress concentration factor (Kf) of 0.8 and Gerber line calculations. The attached .pdf provides further details and information on these analyses.