The failure of a key is due to

Explanation:

Key:

• In mechanical engineering, a key is a machine element used to connect a rotating machine component (like a gear or pulley) to a shaft. This connection prevents relative motion between the two components and allows for torque transmission. The failure of a key is often attributed to shearing, which occurs when the material of the key is subjected to excessive shear stress, exceeding its shear strength. This leads to the key material being physically separated or sheared off.
• A key is inserted between the shaft and the hub of a rotating component. When torque is transmitted, the key experiences forces in the form of shear and compressive stresses. The key must be designed to withstand these stresses within the material's permissible limits. If the applied torque generates a shear force greater than the shear strength of the key material, the key fails by shearing.

Why Shearing is the Primary Cause of Key Failure:

• Stress Concentration: The keyway (slot in which the key is inserted) introduces stress concentration points, making the key more susceptible to shearing compared to other types of failure.
• Design Considerations: The dimensions of the key (length, width, and height) and the material used are designed primarily to resist shearing forces. If these are not adequately designed, the key will fail under shear stress.
• Overloading: If the torque transmitted exceeds the design specifications, the key experiences excessive shear stress, leading to failure.
• Material Properties: The shear strength of the material used for the key plays a crucial role. Low-quality materials or improper material selection can result in shearing failure.

Preventive Measures:

• Proper material selection with sufficient shear strength.
• Accurate design and dimensioning of the key and keyway to distribute stress evenly.
• Avoiding overloading of the system to prevent excessive torque transmission.
• Regular inspection and maintenance of the key and keyway for wear and tear.

Applications: Keys are widely used in mechanical systems for torque transmission, such as in gears, couplings, pulleys, and flywheels. Ensuring that the key does not fail under normal operating conditions is critical to the reliability of these systems.