Vibration fatigue

About: Vibration fatigue is a research topic. Over the lifetime, 3460 publications have been published within this topic receiving 46297 citations.

Fatigue of 1 μm-scale gold by vibration with reduced resonant frequency

Abstract: In order to investigate the fatigue strength of micro-metal (1 μm-scale), a testing method using resonant vibration is developed. Although the loading by vibration can solve the difficulties associated with the fatigue experiment of micro-specimen (e.g., specimen gripping and high-cycle loading under tension-compression), it inherently has an excessively high resonance frequency (more than several GHz at least) in a 1 μm-scale metal specimen. For control of the fatigue cycle, the resonance frequency must be reduced to several hundreds of kHz by tuning the specimen shape. We design a cantilever specimen of 1 μm scale gold with a weight at the tip, which reduces the resonant frequency to about 330 kHz. The unique specimen with the test section of 1.26 μm×0.94 μm×1.52 μm is successfully fabricated by a novel technique using a focused ion beam and the tension-compression fatigue cycle is applied to it by means of a piezoelectric actuator. The test section breaks at about 1.6×106 cycles under Δσ/2=230 MPa, which is within the targeted range of this project. It is easy to extend this method to high-cycle fatigue for actual use (including the failure cycles of over 108 cycles). The slip bands observed on the surface, which have concavity and convexity similar to the intrusions/extrusions of PSBs, indicate that the failure is induced by the fatigue.

Load spectrum and fatigue life analysis of the blade of horizontal axis wind turbine

Abstract: This paper presents the load spectrum and an engineering estimating method of the fatigue life of GRP blade of large-scale wind turbine The distribution of aerodynamic loads which affect the fatigue life of the blade are analyzed using strip theory The stiffening effects of the rotating blade are discussed, using the multi-body dynamics method The influence of the dynamic stiffening effect on the blade vibration mode is then analyzed The dynamic stress response caused by the deterministic dynamic loads such as aerodynamic load, gravitational load and rotating centrifugal load, etc, is calculated using finite element mode superposition method The fatigue damage performance, fatigue damage rule and fatigue life estimate method of GRP blade are discussed Based on the Palmgren Miner linear fatigue damage accumulation rule, a safety life estimate method is developed The fatigue life estimate of the 15MW variable speed pitch regulated wind turbine blade shows that the GRP blade fatigue life estimate method is reliable and feasible

Effects of debonding length on the fatigue and vibration behaviour of sandwich composite

Abstract: The aim of this study is to investigate the effects of debonding length on the fatigue and vibration behaviour of sandwich material. The sandwich material used in this study is constructed with glass fibre laminates as skins and with PVC closed-cell foams as core. The tests were conducted using impulse frequency response technique and cyclic fatigue loading in three-point bending with various debonding lengths. The vibration test was used to study the effects of debonding length on modal parameters (frequency, loss factor). The effects of debonding lengths on the stiffness, hysteresis loops and damping were studied during fatigue tests. The different relative change in frequency, loss factor and maximum load is determined. These parameters are compared for vibration and fatigue tests.

Vibration Prediction Method of Electric Machines by using Experimental Transfer Function and Magnetostatic Finite Element Analysis

Abstract: This paper concerns the noise and structural vibration caused by rotating electric machines. Special attention is given to the magnetic-force induced vibration response of interior-permanent magnet machines. In general, to accurately predict and control the vibration response caused by the electric machines, it is inevitable to model not only the magnetic force induced by the fluctuation of magnetic fields, but also the structural dynamic characteristics of the electric machines and surrounding structural components. However, due to complicated boundary conditions and material properties of the components, such as laminated magnetic cores and varnished windings, it has been a challenge to compute accurate vibration response caused by the electric machines even after their physical models are available. In this paper, we propose a highly-accurate vibration prediction method that couples experimentally-obtained discrete structural transfer functions and numerically-obtained distributed magnetic-forces. The proposed vibration synthesis methodology has been applied to predict vibration responses of an interior permanent magnet machine. The results show that the predicted vibration response of the electric machine agrees very well with the measured vibration response for several load conditions, for wide frequency ranges.