UTM Bolted Joint Seminar 2024

Which one IS NOT a type of fasteners?

• Bolt

• Tapes

• Buttons

• Spring

Answer explanation

A spring is not considered a fastener. Springs are used for absorbing shock rather than for joining or securing components.

What are THREE forces involves in a bolted joint?

• Clamp force

• Preload

• Work load

• Torque

Answer explanation

Three forces in a bolted joints are clamp force, work load and preload.

Preload is the force applied to tighten a bolt

• True

• False

Answer explanation

Torque is the force applied to tighten a bolt, more torque means more preload.

Clamp load must always lesser than work load

• True

• False

Answer explanation

Clamp load must always be greater than work load to prevent joint opening

[DOUBLE POINTS!] Choose THREE causes of loss of preload in a bolted joint

• Settlement effect

• Tool accuracy

• Lubrication

• Friction variation

Answer explanation

Applying lubrication to a bolt can actually help in achieving the preload rather than causing it to lose preload.

All statements below are TRUE about settlement effect except:

• The settlement effect occurs when the bolted joint surfaces compress or deform slightly under load.

• The settlement effect can lead to a loss of preload in the bolted joint over time.

• The settlement effect helps in maintaining the preload of the bolted joint by preventing loosening.

• The settlement effect can be mitigated by retightening the bolt after initial installation.

The following statements is NOT TRUE about stress-strain curve except:

• The bolt yield point indicates the transition from elastic to plastic deformation.

• Tensile point is the maximum stress the a bolt can withstand.

• After reaching the ultimate tensile strength, the bolt immediately fractures.

Answer explanation

After it reaches tensile point, it will go through necking before fracture

The torque required to achieve the same preload is always the same regardless of whether the bolt is lubricated or not.

• True

• False

Answer explanation

Friction is reduced with lubrication. Remember, less torque is required when you use lubrication!

Nord-Lock washer effectiveness remains the same even when it's used with lubrication

• True

• False

Answer explanation

Nord-Lock washer uses the principle of tension, not friction, hence, with or without lubrication gives no effect.

What is the principle used by Nord-Lock washer to secure bolted joint?

• Tension-locking

• Wedge-locking

• Vibration-locking

Answer explanation

Nord-Lock washers use a wedge-locking principle to secure bolted joints.