Detachable Fasteners and Bolt Securing

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Questions and Answers

What are the two main types of bolted connection designs?

Tension and shear connections

How is the applied tensile load transmitted in a tension joint?

Through the clamped component through the joint by designing an appropriate balance of joint and bolt stiffness

What are the two types of non-rotational loosenings discussed in the text?

External (force) and Internal (force)

What are the three types of rotational loosenings (self-slacking) mentioned in the text?

Intermediate (force), Diversion loosening, Energy loosening Signup and view all the answers

What are the material constants used in Hooke's law to describe linear elastic elements?

Young's modulus (E) and Poisson's ratio (ν) Signup and view all the answers

How is the elongation of a beam loaded by force F calculated?

By the product of force, length, and cross-sectional area (AE) Signup and view all the answers

What is the stiffness of a linear elastic element?

The slope of the spring characteristic (F = f(f)) Signup and view all the answers

What does the pre-tensioned bolt and deformed members involve?

Elongation of bolt and compression of members Signup and view all the answers

What does the pre-tensioning triangle show?

The relationship between preload force (Fv), elongation (strain) of bolt (λ1), and compression of members (λ2) Signup and view all the answers

How is the stiffness of a bolt calculated?

Based on the elastic modulus (E) and the cross-sectional areas of each part (Ai) Signup and view all the answers

How is the stiffness of members calculated?

Using a simplified pressure-cone method Signup and view all the answers

What do load case models describe?

The relationship between load type and joint behavior Signup and view all the answers

What are the types of non-rotational loosening mentioned?

External force slackening, internal force slackening, and intermediate force slackening Signup and view all the answers

What is the critical force in the context of joint behavior?

The force at which the joint fully loosens Signup and view all the answers

How can the critical force be increased?

By using a stiffer bolt or softer members Signup and view all the answers

What are examples of non-rotational loosening?

External loosening, internal loosening, and intermediate loosening Signup and view all the answers

What are some causes of environmental slackenings?

Factors such as heat expansion, relaxation, creep, surface smoothenings, and corrosion Signup and view all the answers

When do energy slackenings occur?

When external energy is introduced into the bolt system Signup and view all the answers

What are the three commonly used bolt locking methods?

Friction locking, mechanical locking, and permanent locking Signup and view all the answers

How does the Nord lock washer prevent displacement and ensure a tight connection?

The Nord lock washer uses radial serrations on the outer surface that engage with the workpiece surface. Signup and view all the answers

What is the purpose of the cotter pin and slotted nut system?

To prevent the relative rotation of nuts and bolts. Signup and view all the answers

How do spring washers prevent nut loosening?

Spring washers generate continuous elastic force, which keeps a friction force between the nut and the threaded connection. Signup and view all the answers

What is the application of hot melt fastening technology?

It allows connection realization by direct tapping under closed profiles, widely used in the automotive industry. Signup and view all the answers

What are the categories of securing methods mentioned in the text?

Form closing, force closing, and material 'closing' bolt securings based on effects. Signup and view all the answers

What is the innovation introduced by the Nord-Lock patent?

Wedge-locking washers that use tension instead of friction to ensure steadfast joints. Signup and view all the answers

How do pre-coated bolts achieve joint connection?

Pre-coated bolts use a microcapsule compound with an adhesive applied to screw threads, causing a curing reaction when screwed in. Signup and view all the answers

What are the examples of form closing solutions mentioned in the text?

Lock nuts, taper nuts, notch nuts, and tab washer nuts. Signup and view all the answers

What are the two scenarios resulting in total slackening?

When external energy is equal or greater than the joint energy, and both stiffnesses (bolt and members) are small. Signup and view all the answers

What are the methods included in friction locking?

Double nuts, self-locking nuts, and wedge lock washers like the Nord lock washer. Signup and view all the answers

What type of locking does the double nut method create?

Two friction surfaces, one between the nut and fastener, and the other between the nuts. Signup and view all the answers

Study Notes

The total slackening occurs when external energy is equal or greater than the joint energy, resulting in a construction situation where both stiffnesses (bolt and members) are small.
Three commonly used bolt locking methods are friction locking, mechanical locking, and permanent locking.
Friction locking methods include double nuts, self-locking nuts, and wedge lock washers like the Nord lock washer.
Double nut method creates two friction surfaces, one between the nut and fastener, and the other between the nuts.
Self-locking nuts are generally self-locking by friction.
The Nord lock washer uses radial serrations on the outer surface of the wedge lock washer that engage with the workpiece surface, preventing displacement and ensuring a tight connection.
Cotter pin and slotted nut system prevents the relative rotation of nuts and bolts by using a cotter pin and slotted nut.
Lock washers, such as spring washers and double lock washers, are used to lock nuts to connectors.
Spring washers generate continuous elastic force, which keeps a friction force between the nut and the threaded connection, preventing nut loosening.
Hot melt fastening technology allows connection realization by direct tapping under closed profiles, widely used in automotive industry.
Securing methods protect against nut slackening, categorized into form closing, force closing, and material "closing" bolt securings based on effects.
Form closing solutions include lock nuts, taper nuts, notch nuts, and tab washer nuts.
Nord-Lock patent introduces wedge-locking washers that use tension instead of friction to ensure steadfast joints.
Bolt securing with added material includes glue application to bolted joint elements, and pre-coated bolts.
Pre-coated bolts use a microcapsule compound with an adhesive applied to screw threads, which seeps out and causes a curing reaction when screwed in.
Engineering guidelines cover thread run-out, screwing into plastic tubes, parallelism of mating surfaces, and supporting principle.

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Description

Test your knowledge of detachable fasteners, loosening, and bolt securing with this quiz. Topics covered include bolt joint models, spring basics, pretensional triangles, load case models, and different types of rotational and non-rotational loosenings.