Failure Analysis and the Evaluation of Forced-in Joint Reliability for Selected Operation Conditions

Sławomir Kowalski,Zdeněk Aleš,Martin Pexa,Jakub Čedík

doi:10.3390/coatings11111305

Sławomir Kowalski, Zdeněk Aleš + Show 2 more

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https://doi.org/10.3390/coatings11111305

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Abstract

In this article, sample damage and wear of forced-in joints is presented, and their reliability evaluated. Compared were shafts without additional finish treatment, rolled shafts and those with a TiSiN coating. Tribological samples under investigation operated in rotational bending conditions. Recorded was the number of fatigue cycles at which damage might occur. Reliability indicators were plotted, which demonstrated that coated shafts are distinguished by the highest reliability and low damage intensity. Macroscopic observations of shaft surfaces demonstrated the traces of adhesive wear and, in the case of shafts without additional treatment and in the case of rolled shafts, fretting wear traces in the form of a ring comprising the entire shaft circumference. Microscopic observations showed numerous build-ups on the surface, microcracks, and the occurrence of wear products in the gap between the shaft and sleeve. The highest fatigue strength was demonstrated by shafts with a TiSiN coating. The shaft section change area was the place where fatigue wear occurred.

Highlights

The dynamically growing transport market requires the manufacture of dependable vehicles whose subassemblies are distinguished by durability permitting long-term safe operation
The observations were performed in the backscattered electron composition (BEC), backscattered electron shadow (BES) and secondary electron image (SEI) modes with the electron beam acceleration voltage equal to 15 kV and 20 kV
The stored data concerning the number of cycles of shaft/sleeve tribological kinematic pair performance permitted the preparation of the failure analysis of the forced-in joints

Summary

Introduction

The dynamically growing transport market requires the manufacture of dependable vehicles whose subassemblies are distinguished by durability permitting long-term safe operation. The various components are fitted into subassemblies by various methods, from threaded connections through welded joints to push-fit joints, which may be a weak link reducing the reliability of the device. The latter joints are often used in the manufacture of motor and rail vehicles, sea-going vessels and aircraft. Rail vehicle wheel sets may be given as an example of such a situation. Those elements operate under a static load from the rail car body and dynamic forces from the contact surface between the wheel and rail at the same time. Premature wheel set damage during operation may lead to great disasters, as the world has witnessed many times over the years

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