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This is the continuation of the article by Gerhard H. Junker, of the European Research and Engineering Standard Pressed Steel Co, Unbrako. The first part, which appeared in October, covered the mechanism of self loosening. The E‐F‐N curves, surface integrity and test programme will be covered in the final part of this feature.

Bolted joints are commonly used to connect structural members. These joints can be disassembled whenever required. Various types of washers are used between nut and the connected member to keep the joints tight. However, these joints often become loose over time under dynamic loading conditions. The purpose of this paper is to know the reasons of loosening of bolted joints and to identify the main parameters that contribute to the bolt loosening, and to verify them with previous work.

This work studies loosening of bolted joint in a test rig under varying tightening torque as well as for various types of washers used as the number of load cycles increases. Four trial runs are taken for each case considered and the average results are found out to minimize possible sources of errors. For the purpose, a specifically made test rig is used which is capable of applying harmonic load on the bolted joint by the lever action.

The study compares the loosening of bolted joint with and without washer, and also under different initial tightening conditions. This study has shown the suitability of the test rig, methodology and parameters for study of loosening in bolted joints. This study presents an indigenous test, capable of applying harmonic load on bolted joint.

The results establish that the methodology and parameters selected were appropriate for the purpose of study of loosening of bolted joints. This study has provided a base line for further work to understand the loosening of bolted joints.

This is the final part of the article by Gerhard H. Junker of the European Research and Engineering Standard Pressed Steel Co, Unbrako. Previous parts have covered mechanism of self loosening, design to prevent self‐loosening and test methods.

A UNIQUE TEST method and apparatus now make it possible to reproduce conditions of vibration that are not only certain to loosen bolted joints but which also closely simulate actual conditions. It can be shown that properly preloaded fasteners loosen as a result of rotation as soon as relative motion occurs between the mating threads and between the bearing surfaces of the fastener and the clamped material.

The purpose of this paper is to give a brief introduction of helical spring locked washer along with extensive literatures survey on role of helical spring locked washer in bolted joint analysis. It is very small component of bolted joint assembly, but it play vital role in holding the assembly components together. Helical shape of it produces spring effect in the assembly which is used for keeping the assembly in tension and that is lock the assembly under dynamic loading due to vibrations to avoid the accident.

The critical literatures survey identifies role of helical spring locked washer in different areas such as design optimization, mechanism of loosening-resistant components, bolted joint analysis, finite element-based modeling, analysis and simulation. The related literatures show contribution of helical spring washers in evaluation of anti-loosening performance of assemblies as compare to other types of washers.

It proposed that design optimization of helical spring locked washer is needed as it improves the performance in the form of load-deflection characteristics, load bearing capacity and provides the best locking force for optimize functionality.

The originality or value of this paper is to finding research gaps in literatures by dividing literatures into seven different research areas and concentrating the only on role of helical spring locked washer in bolted joint analysis.

Bolted joints are the most common type of mechanical connections, and improving the anti-loosening performance of bolts for the reliable performance of mechanical and building structures is highly significant.

Because of the lack of sufficient theoretical basis for the evaluation and design of anti-loosening bolts, a quantitative evaluation model exhibiting the following two evaluation criteria for anti-loosening bolts is introduced: bolt rotation angular acceleration criterion and critical transverse load criterion. Based on the relationship among bolt tension, transverse load and bolt rotation angular acceleration, a critical transverse load calculation model is put forward, and the mechanism by which the critical transverse load increases with the increase of bolt tension is revealed.

Based on the above model, a new type of anti-loosening bolt is designed, which generates additional bolt tension when the transverse load increases, and then improves the critical transverse load of the bolt. The effectiveness of the new type of anti-loosening bolt is verified by theoretical calculations and experiments.

The proposed model and method set a preliminary theoretical foundation for the evaluation of bolt anti-loosening performance and the design of a new anti-loosening bolt.

This paper aims to study the dimensional characteristics such as fabric density variations, dimensional constant parameters, linear and area dimensional changes and spirality angle variations of 1 × 1 rib knitted structures made from cotton‐spandex core spun yarns, under laundering regimes till 10th washing cycle.

Samples of the above fabrics underwent dry, wet and full relaxation treatments and were subjected to standard atmospheric conditions prior to take the measurements. Washing was done in a front loading machine under normal agitation with machine 56 RPM. Each washing regime includes wash, rinse, spin, tumble dry steps. Washing temperature was set at 40°C and water intake for washing was 30 l and rinsed with cold water. 0.1 g/l standard wetting agent was used. The mass of the load was maintained constant to 3 kg to keep the material ratio as 1:10. Washing regimes were continued till 10th cycle.

Cotton‐spandex rib structures came to a more stable state (minimum energy state) after 10th laundering cycle under the experimental conditions. Cotton did not come to such a state, even after 10th cycle proceeded. ANOVA analysis done under 95 percent confidential level has shown that fabric tightness and relaxation procedures give significant effect on dimensional characteristics of cotton‐spandex and cotton rib structures. However, area shrinkage variations of cotton rib fabrics have shown an exception to this.

According to the dimensional constant values, evenafter 10th washing cycle, cotton rib structures did not come to a stable position. This should be further investigated to achieve a better stable rib knitted structure.

The number of washing cycles can be increased or tumble dry duration can be increased to 120 min. to get a more stable state of cotton rib structures.

The results are important for the knitting industry to predict the dimensional behavior of designed knitted fabric under relaxation. These data can be used to set the circular machine parameters to achieve a more stable fabric after laundering.

This paper aims to address the challenges of the capacitor tower maintenance robot during bolt tightening in high-voltage substations, including difficulties in bolt positioning due to tilted angles and anti-bird cover occlusion and issues with fast and accurate docking of bolts while the base is moving.

This paper proposes a visual servoing method for the capacitor tower maintenance robot, including bolt pose estimation and visual servoing control. Bolt pose estimation includes four components: constructing a keypoint detection network to identify the approximate position, precise positioning, rapid prediction and calculation of bolt pose. In visual servoing, an improved position-based visual servoing (PBVS) is proposed, which eliminate steady-state error and enhance response speed during dynamic tracking by incorporating integral and differential components.

The bolt detection method exhibits high robustness against varying lighting conditions, partial occlusions, shooting distances and angles. The maximum positioning error at a distance of 250 mm is 2.8 mm. The convergence speed of the improved PBVS is 10% higher than that of the traditional PBVS when the base and target remain relatively stationary. When the base moves at a constant speed, the improved method eliminates steady-state error in dynamic tracking. When the base moves rapidly and intermittently, the maximum error of the improved method in the tracking process is 30% smaller than that of traditional PBVS.

This method enables real-time detection and positioning of bolts in an unstructured environment with tilt angles, variable lighting conditions and occlusion by anti-bird covers. An improved PBVS is proposed to enhance its capability in tracking dynamic targets.

IN recent issues we have had contributionsion the future of Work Study as seen by Council members of the Institute of Industrial Technicians, the Society of Industrial Engineers and the Work Study Society.

It is now quite widely suggested that a post‐industrial revolution is in progress (see, for example, Handy, and Naisbitt). Mass unemployment, rapid obsolescence of established technologies and the emergence of new technologies are some of the more concrete examples of the dislocation and reshaping of the economic, social, political and value patterns which we had come to take for granted in previous decades.