The aim of this guide is to provide procedures to enable the user to design a bolted connection where the dominant load acts parallel to the axes of the bolts making the connection (and therefore perpendicular to the connecting faces of the parts which constitute the joint). The guide provides sufficient additional data to enable the threaded elements to be selected and specified. Typical joint configurations where the threaded fasteners are in tension/bending, simple tension or shear are shown in the following figures:

Figure 1. Types of Bolted Connection covered by this Guide

Two approaches are included. The first covers “statically loaded joints” and the second “dynamically loaded joints”. The first approach is essentially a simplified version of the second and can be adopted when the variation of the axial load at the joint in service can be regarded as negligible and the number of times that the axial load is applied to the joint throughout its working life is less than 105 applications. The guide assumes that the component parts being connected are sufficiently rigid so as to not subject the threaded fasteners to bending stresses when the joint is being tightened or when it is under load in service. The guide does not consider the design of threaded connections where the threaded fastener is subject to lateral shear – clevis joints for example. In these cases, the threaded fastener is subject to high bearing stresses on its diameter and, invariably, bending stresses accompany the lateral shear stress. These situations are considered to be outside the scope of this guide.

Section 2 looks at the limits of the guide in greater depth. The guide advises in general terms on aspects of good practice relating to the positioning of fasteners in a joint. The number and position of fasteners to be used in a given situation tends to be influenced by other features of the design work being undertaken and there is a wide variety of possibilities which are difficult to categorise in a brief guide such as this. The symbols and nomenclature used throughout the guide are defined as they occur. No derivations of equations are presented; such derivations are available for those who require them in the Bibliography at the end of the guide.

Section 3 covers the selection of bolted connections which are statically loaded. This enables the user to design safe connections for static loading using a flow chart approach. Section 4 gives the necessary background and equations for determining the load distribution and corresponding stress levels imposed on the component parts of a joint subjected to fatigue loading. It also includes a table of screw thread strength reduction factors, which should be used in conjunction with the other strength reduction factors used in designing against fatigue. A second flow chart is included, giving the reader a step-by-step procedure for the safe design of bolted joints capable of sustaining fatigue loading. Section 5 examines and discusses the relationship between applied torque and induced load and the distribution of stress in normal threaded fasteners. Section 6 deals with ISO grading of threaded connector materials. Section 7 looks at the common thread system as well as touching on past systems. Section 8 shows how to select fasteners with the best characteristics for many applications.

[Description and screenshot taken from the SEED Curriculum for Engineering Design page for this guide. (c) The Design Society used under the terms of their (CC BY-NC-SA 3.0) license.]

This is an advanced course on modelling, design, integration and best practices for use of machine elements such as bearings, springs, gears, cams and mechanisms. Modelling and analysis of these elements is based upon extensive application of physics, mathematics and core mechanical engineering principles (solid mechanics, fluid mechanics, manufacturing, estimation, computer simulation, etc.). These principles are reinforced via (1) hands-on laboratory experiences wherein students conduct experiments and disassemble machines and (2) a substantial design project wherein students model, design, fabricate and characterize a mechanical system that is relevant to a real world application. Students master the materials via problems sets that are directly related to, and coordinated with, the deliverables of their project. Student assessment is based upon mastery of the course materials and the student’s ability to synthesize, model and fabricate a mechanical device subject to engineering constraints (e.g. cost and time/schedule).

[Description and screenshot taken from MIT OCW page for this course. (c) MIT used under the terms of their CC-NC-SA license.]

Lecture Archive
Microprocessors & Labs
Power Screw & Fastner
Bolt & Preload 1
Bolt & Preload 2
Fatigue Loading 1
Fatigue Loading 2
Rolling-Contact Bearings 1
Rolling-Contact Bearings 2
Gears 1
Gears 2
Gears 3
Gears 4
Gear Train 1
Gear Train 2
Gear Force
Review for Exam
Motors
Feedback Control
Electronics Components