- Pressure = Force / Area
- So Force = Pressure x Area
- We know that Pressure = 120 bar, Lets take cylinder bore = 60 cm
- So area of head = ㄫ r x r = 3.14 x 30 x 30 = 2826 cm2
- There for Force acting on cylinder head = 120 x 2826 = 339120 Ncm
- In order to keep cylinder head in place we need to apply a force that is greater than 330120
- Now cylinder head is tighten with 8 hydraulic nuts and assume area of one nuts as 100 cm2
- For safety we take the force needed to keep head in place as 800000 Ncm
- Now There are 8 nuts so total area = 8 x 100 = 800 cm2
- Pressure = 800000 / 800 = 1000 bar
So we need to tight nuts around 1200 bar
1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
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