Study Of A Pre Tensioned Bolt

Study Of A Pre Tensioned Bolt

Analysis can be made of the stresses and strains produced in a bolt after different methods of tightening, and allows modelling of the behaviour of a bolted connection when axially loaded.

Teaching objectives

• Deformations in a bolt after tightening with a spanner or with a torque wrench.
• Effect of bolt pre-tensioning using a hydraulic loading system.
• Effect of varying the loading position.
• Effect of varying the materials on the loading torque.
• Static analysis of sliding with friction on a helical screw contact surface or plane.
• Simple loading and stresses on a plane section.
• Mohr's Circles of stress, principal stresses and their directions.

Technical specifications

• A 16mm bolt on which are fixed three pairs of diametrically opposed 45° strain. These permit the measurement of extension and tension in the bolt.
• A tubular component with 2 strain gauges mounted at 180° to measure the compression in the assembly at different heights.
• A loading tube to apply bolt pre-load or to apply loading force at various positions along the bolted assembly.
• A manually operated hydraulic pump.
• A micrometer dial gauge to measure extensions over the complete assembly.
• Nuts and washers of various materials.

• Pre-loaded bolt assembly with hydraulic loading system and manual pump.
• A set of washers.
• Technical manual and teaching notes.

Dimensions and weight

• 15 diam. x 37 cm - 12 kg
• Pump: 40 x 10 x 14 mm - 3,5kg

Essential requirements

• Electrical supply : 220V, 50 Hz

Additional required equipment :

• Extensometer bridge.
• A ring spanner 24 mm.
• A torque wrench of capacity 40 - 200 Nm with 24 mm nut.