Bolted joints possess a key advantage over other types of joint types such as riveted and welded joints, they can be dismantled. Although this is an important benefit, it can also cause potential problems if the bolt loosens as a result of operational conditions. Often this loosening occurs as a result of vibrational forces. At Peak innovations Engineering, we possess the knowledge and expertise to analyze a bolt’s characteristics and conditions of use to help prevent the problem of bolted joint vibration loosening and other issues.
What Causes Bolt Loosening?
The designer must be aware of the possible mechanisms of bolt loosening in order to design dependable connections. The major causes of bolt loosening fall into the categories of spontaneous loosening (from vibration, shock, and dynamic loads), and slackening (from creep, settlement, and relaxation).
The reason for bolt failure (including loosening) and its consequences relate to the purpose of the joint, the industry application, and the environment of its use.
Preventing Bolt Loosening
In order to prevent unexpected bolt loosening, the slip located in between the parts joined together must be either reduced below a critical level or removed altogether. This is possible in one of three ways:
- Increase the friction between the clamped parts
- Increase the tension between the clamped parts
- Reduce the cyclic loading (i.e., cyclic thermal, vibration, or shock loading)
The Need for Testing and Analysis to Predict Bolt Loosening
Bolted joints are often designed and installed with proper analysis in advance to ensure they function optimally and for the long term without loosening or failure. Bolt testing and bolt loosening analysis are essential to ensure the reliability of bolted joints and prevent loosening in the field. The reasons are two-fold.
First, the element of a product or structure that undergoes the highest level of stress is often the threaded fasteners. As the stress on the fastener increases, the impact of the material and dimensional characteristics of the fastener is magnified. Through testing and analysis, our team can predict the occurrence of bolt loosening.
Also, since it is usually not feasible to tighten a production fastener to a specified tension based on the joint design, torque and other parameters are evaluated instead. The material and dimensional features and variations impact the relationship between bolt tension and torque, which is something our team can evaluate and identify.
Get Bolt Loosening Analysis
To learn about bolt loosening and other forms of fastener analysis and testing we offer, call us today at 815.420.3802 or use our contact form to send us a message.
