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Wind-induced loads cause electrical transmission line fatigue. Evaluation procedures consider descriptors such as deflection amplitude (Y b) and far-field vibration (fy max), which cannot relate endurance limits and wire loads. The investigation uses the finite element (FE) strategy developed in part I to study Aluminum Conductor Steel Reinforced (ACSR) submitted to windinduced loads. The analysis underlines the Y b and fy max discrepancies. A factorial design leads to a model relating them with a precision of 92%. Comparisons with experimental ACSR data indicate that fatigue predictions from the Coffin-Manson relation associated with the FE model provide realistic evaluations of service lives.

Submitted to wind induced vibrations, overhead conductors are vulnerable to fatigue damage, especially at restraining fixtures such as the suspension clamp. This paper proposes an efficient finite element modeling approach providing a full 3D representation of both the conductor and suspension clamp. Validation based on experimental data shows the precision of the approach. An in-depth model response analysis also demonstrates its ability to describe inter-wire and conductor-clamp contact interactions. Finally, a study of conductor stress distributions reveals that in critical regions, conductor wires mostly sustain alternating bending loads.

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In computational fracture mechanics, great benefits are obtained from the reduced modeling dimension order and the accurate integral formulation of the boundary element method (BEM). However, the direct representation of co-planar surfaces (i.e., cracks) causes a degeneration of the standard displacement BEM formulation which can only be circumvented with special modeling techniques. Aiming to simplify the generalized application of the BEM to fracture mechanics problems, this paper presents a two-dimensional crack modeling approach. The method uses the direct BEM displacement formulation within a single-domain model to efficiently and precisely calculate any mixed mode crack tip stress intensity factor. Details of the application of the method are presented, while its accuracy and reliability are demonstrated through numerous comparisons with benchmark results.

A B S T R A C T Gear failure involving bending fatigue can have catastrophic consequences depending on the propagation path direction. Therefore, anticipating and preventing eventual critical fracture are crucial at the design stage. However, none of the methods available can give rapid and quantitative evaluation of gear fatigue crack evolution. Aiming to provide fast predictions of crack propagation paths, this paper proposes a factorial design approach for gear bending fatigue simulation. Six parameters related to gear geometry and initial crack configuration are considered in this study. Factorial design experiments are numerically conducted with an efficient 2D boundary element model assuming linear elasticity. Then, bending fatigue damage is modelled using polynomial functions. The resulting prediction model can instantly establish the crack trajectory in thin-rimmed gear for any cycle numbers. Application of the approach is illustrated by several case studies, while its precision and reliability are demonstrated through an exhaustive validation procedure. a = crack length a 0 = initial crack length da = crack propagation step h r = rim thickness K I , K II = mode I and II stress intensity factors m = gear module me = median N = crack propagation cycle number n p = pinion tooth number R = load ratio R v = gear speed ratio W = transmitted load α 0 = initiation point fillet relative position β = kurtosis γ = skewness δ = finite crack face separation θ 0 = initial crack orientation μ = mean of a distribution σ = standard deviation ϕ = pressure angle Correspondence:

The fatigue life of overhead conductors is usually evaluated through experimental tests on clamp/conductor assemblies. Some recent studies aim to estimate the fatigue life of conductors using uniaxial tests on individual strands. This paper presents an innovative method for assessing the fretting fatigue life of overhead conductors combining the effect of both tension and bending loadings. It consists of coupling a numerical approach based on modeling the clamp/conductor assembly using the finite element method and an experimental one based on fretting fatigue tests on individual wires. A biaxial fretting fatigue test rig has been developed and validated through preliminary tests performed on 1350-H19 aluminum wires under uniaxial and an equivalent biaxial loading. Tension and bending loadings obtained from the numerical model were then applied on individual wires. Results showed a good correspondence with existing experimental data of the fatigue tests carried on the aluminum conductor steel reinforced (ACSR) Bersfort conductor with a metal-to-metal suspension clamp.