New fatigue device for testing cables: Design and results

Abstract

The fracture of cables is often caused by fatigue phenomena. To analyse the fatigue behaviour of these elements, a device has been designed, manufactured, and validated. This machine can produce different load states for the specimens, combining variable axial loads and variable bending moments. The testing machine has been designed to achieve two goals: to avoid the fracture of the cable in the vicinity of the clamps and to assure that the fracture of the cable is in the middle of the length of the specimen. The type of failure will be due to a combination of global stresses and fretting fatigue phenomena. This work also shows the results of different fatigue tests for a specific strand configuration. Finally, the fracture and contact surfaces of the strand have been analysed with a scanning electron microscope (SEM). The results obtained with this device show that it is adequate for testing cables and strands subjected to different combinations of axial loads and bending moments.

Fatigue and fracture analysis of a seven‐wire stainless steel strand under axial and bending loads

“…Fatigue tests are performed with a device designed specifically for testing cables and strands . Figure shows a scheme of the test device used.…”

“…Fatigue tests are performed with a device designed specifically for testing cables and strands. 24 Figure 2 shows a scheme of the test device used. A variable bending moment is applied at the middle length of the strand by means of the force Q(t) through a bearing sheave of radius 25 mm, while an almost constant axial load P is applied at one end of the specimen.…”

Fretting‐fatigue analysis of shot‐peened aluminium and titanium test specimens

“…This situation is referred to as fretting fatigue, which is well known to be different from plain fatigue, mainly due to the high stress level that characterises the region near the contact surface. 3,[8][9][10] Fretting fatigue is recognised as a primary failure mode across a wide range of mechanical systems, such as dovetail joints, 11,12 bolt and riveted joints, [13][14][15] clamped joints, 16 bearings, 17 metallic cables [18][19][20] and turbine components. 21 Many attempts were made in order to carry out possible alleviation measures, in order to improve the fatigue life of fretting affected components.…”

On the Role of Contact and System Stiffness in the Measurement of Principal Variables in Fretting Wear Testing

“…In the literature, it is common to found screw-type mechanisms attached to springs [12,15,16], deadweight mechanisms [11,[17][18][19][20] or servohydraulic systems [10,21,22] to apply a constant normal contact load. The fretting motion and tangential or bulk load are usually imposed using servo-hydraulic systems [16,[22][23][24], mechanical In a fretting loop, the tangential contact stiffness is defined by the slope of the micro-slip regime. However, the micro-slip curve is theoretically non-linear as shown in its close form solution assuming elastic half-spaces and smooth surfaces [5,8].…”

“…However, in specific applications such as steam generator tubes, fiber Fabry-Perot force sensors with reduced volume and high performance have been developed to assess the fretting damage [13,14]. In the literature, it is common to found screw-type mechanisms attached to springs [12,15,16], deadweight mechanisms [11,[17][18][19][20] or servo-hydraulic systems [10,21,22] to apply a constant normal contact load. The fretting motion and tangential or bulk load are usually imposed using servo-hydraulic systems [16,[22][23][24], mechanical linkages [15,19] or piezo-electric actuators [17,20] depending on the load requirements in terms of frequency and magnitude.…”