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This study aims to solve the problems of ambiguous localization, large calculation, poor real-time and limited applicability of bolt thread defect detection.

First, the acquired ultrasound image is used to acquire the larger area of the image, which is set as the compliant threaded area. Second, based on the determined coordinates of the center point in each selected region, the set of coordinates on the left and right sides of the bolts is acquired by DBSCAN method with parameters eps and MinPts, which is determined by data set dimension D and the k-distance curve. Finally, the defect detection boundary line fitting is completed using the acquired coordinate set, and the relationship between the distance from each detection point to the curve and d, which is obtained from the measurement of the standard bolt sample with known thread defect, is used to locate the bolt thread defect simultaneously.

In this paper, the bolt thread defect detection method with ultrasonic image is proposed; meanwhile, the ultrasonic image acquisition system is designed to complete the real-time localization of bolt thread defects.

The detection results show that the method can effectively detect bolt thread defects and locate the bolt thread defect location with wide applicability, small calculation and good real-time performance.

This paper gives a review of the finite element techniques (FE) applied in the analysis and design of machine elements; bolts and screws, belts and chains, springs and dampers, brakes, gears, bearings, gaskets and seals are handled. The range of applications of finite elements on these subjects is extremely wide and cannot be presented in a single paper; therefore the aim of this paper is to give FE researchers/users only an encyclopaedic view of the different possibilities that exist today in the various fields mentioned above. An Appendix included at the end of the paper presents a bibliography on finite element applications in the analysis/design of machine elements for 1977‐1997.

Fatigue is a problem which all designers have to face. If they are starting on the design of an aeroplane, they will work out all the high loading cases first, make sure that the design will be good enough to meet them, then they will turn their thoughts to the survival of the proposed structure within the lower stress levels of every‐day operations.

LIKE all other branches of aeronautical engineering, the technology of aircraft fasteners has made rapid progress during the last decade. Not only has there been continual development in the design and production of screws, bolts, nuts, washers and retaining clips but parallel developments in materials have encouraged the use of titanium, zirconium, Nimonic and other special alloys for fastener applications.

Fatigue damage of internal threads has gradually become the main failure mode of force sensor. To make the internal thread structure of force sensor meet the fatigue performance requirements, the design criteria of static strength and fatigue life are comprehensively considered in this paper.

The variation of static stress and fatigue life with the size of the main structure is obtained by simulation. By changing the number of thread turns, the hub height and outer diameter of the hub, the optimized design of the spoke force sensor is determined.

The experiment was carried out based on the determined optimized structure, and the results showed that the fatigue life meets the design requirements.

This research has certain guiding significance for the design and developments of high-cycle fatigue force sensors.

DRILLING, REAMING, COUNTERBORING, THREADBORING, ETC. THROUGHOUT the design of every machined part the designer should follow the practice of visualizing the machining involved, and make a genuine effort to design for “machinability” by avoiding all difficult operations. This factor cannot be over‐emphasized, as it is only too easy to complicate the machining of a part unnecessarily by lack of forethought during the design.

More than 500 engineer‐surveyors are currently employed in this country by the above company to inspect, test and certify periodically a very wide range of mechanical and electrical plant, the primary objective being safe and efficient operation. Detection of faults due to corrosion plays a large part in these investigations, and to exemplify the work of the company's engineers in this field we reproduce below three case histories, the last of which involved the evolution of a special test method which could prove generally useful in similar problems of corrosion fatigue arising through vibration.

This paper is devoted to the theoretical and numerical study of a new topological sensitivity concerning the insertion of a small bolt connecting two parts in a mechanical structure. First, an idealized model of bolt is proposed which relies on a non-local interaction between the two ends of the bolt (head and threads) and possibly featuring a pre-stressed state. Second, a formula for the topological sensitivity of such an idealized bolt is rigorously derived for a large class of objective functions. Third, numerical tests are performed in 2D and 3D to assess the efficiency of the bolt topological sensitivity in the case of no pre-stress. In particular, the placement of bolts (acting then as springs) is coupled to the further optimization of their location and to the shape and topology of the structure for volume minimization under compliance constraint.

The methodology relies on the adjoint method and the variational formulation of the linearized elasticity equations in order to establish the topological sensitivity.

The numerical results prove the influence of the number and locations of the bolts which strongly influence the final optimized design of the structure.

This paper is the first one to study the topology optimization of bolted systems without a fixed prescribed number of bolts.

A WIDE range of reliable threaded fasteners have been developed to meet the increasingly exacting demands of the aerospace industry.