Adaptive cycle jump and limits of degradation in micromechanical fatigue simulations of fibre-reinforced plastics

2019 ◽  
Vol 28 (10) ◽  
pp. 1523-1555 ◽  
Author(s):  
Caroline Lüders ◽  
Michael Sinapius ◽  
Daniel Krause

This research investigates the influence of numerical parameters of micromechanical fatigue damage models on the obtained progressive damage behaviour of fibre-reinforced plastics at transverse tensile fatigue loads. The simulated damage behaviour is evaluated using experimentally observed crack patters published in the literature. The investigated numerical model parameters are (1) whether or not the model considers static failure within a simulated load cycle, (2) the degree of material property degradation after sudden failure and (3) the size of the cycle jump. The results reveal a significant influence of the degree of material degradation and of the cycle jump on the simulated matrix crack formation at both higher and lower fatigue loads. Static failure within a simulated load cycle primarily affects the damage behaviour at higher fatigue loads. The paper gives recommendations of the parameter choice for plausible progressive fatigue damage simulation results. Regarding the cycle jump, an adaptive algorithm is proposed and implemented. This approach leads to plausible fatigue damage results paired with a significant reduction of computation time comparing to a cycle-by-cycle analysis.

2008 ◽  
Vol 385-387 ◽  
pp. 845-848
Author(s):  
Moe M.S. Cheung ◽  
Kevin K.L. So ◽  
Xue Qing Zhang

This paper proposes a life-cycle cost (LCC) management methodology that integrates corrosion deterioration and fatigue damage mechanisms. This LCC management methodology has four characterized features: (1) corrosion deterioration and fatigue damage models are used to predict the time when the pre-defined limits are reached; (2) the performance of the steel girder is measured by condition state sets in which deflection, moment and shear capacities and fatigue strength limits are considered altogether; (3) the cost-effectiveness of management strategies are measured by the performance improvement per unit of money spent; and (4) the LCC model includes initial design/construction cost, inspection cost, maintenance cost, repair/rehabilitation cost and failure cost. A steel girder bridge is used as an example to demonstrate the application of the proposed LCC management methodology.


Author(s):  
De Guang Shang ◽  
Guo Qin Sun ◽  
Jing Deng ◽  
Chu Liang Yan

1976 ◽  
Vol 98 (1) ◽  
pp. 348-353 ◽  
Author(s):  
A. K. Abu-Akeel

A method is presented that leads to accurate estimation of the cumulative fatigue damage incurred in a randomly loaded structural element when loading is given in the form of spectral density load, or stress, plots. The load plots are here approximated by a series of straight lines and a closed formula is obtained to yield the damage incurred by the load within each straight line segment. The method avoids the errors that result from human misjudgment in the commonly used curve-stepping approach. It is also adaptable for computer applications and can be incorporated in a stress calculation program to save on computation time. In comparison to curve stepping, five straight-line segments may give the same accuracy as a hundred curve steps. This contrast, however, depends on the degree of irregularity of the load curve.


Author(s):  
Aki M. Mikkola

Abstract Welded structures, such as hydraulically driven booms, are disposed to fatigue damage. Design against fatigue requires information on the fatigue resistance of a structure’s critical details and the fatigue loads that act on each detail. The present paper introduces a method based on dynamic simulation for determining the fatigue loads in a hydraulically driven log crane. The detailed simulation model was built up in the MBS-software environment in which the flexible mechanism model and the equations describing the hydraulic system were combined. The complete simulation model was verified by comparing measurements to numerical results. This comparison shows that there is a clear correspondence between the simulated and measured results. It was thus shown that it is possible to create a simulation model which can be used realistically for determining stresses in fatigue analysis. The model was employed in the study of the fatigue loads, which are formed when the crane is being loaded.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1768
Author(s):  
Lizhen Huang ◽  
Weilian Qu ◽  
Ernian Zhao

The multiaxial fatigue critical plane method can be used to evaluate the extremely-low-cycle fatigue (ELCF) damage of beam-to-column welded joints in steel frameworks subjected to strong seismic activity. In this paper, fatigue damage models using structural detail parameters are studied. Firstly, the fatigue properties obtained from experiments are adopted to assess ELCF life for steel frameworks. In these experiments, two types of welded specimens, namely, plate butt weld (PB) and cruciform load-carrying groove weld (CLG), are designed according to the structural details of steel beam and box column joints, in which both structural details and welded factors are taken into account. Secondly, experiments are performed on three full-scale steel welded beam-to-column joints to determine the contribution of stress and/or strain to damage parameters. Finally, we introduce a modification of the most popular fatigue damage model of Fatemi and Socie (FS), modified by us in a previous study, for damage evaluation, and compare this with Shang and Wang (SW) in order to examine the applicability of the fatigue properties of PB and CLG. This study shows that the modified FS model using the fatigue properties of CLG can predict the crack initiation life and evaluate the damage of beam-to-column welded joints, and can be subsequently used for further investigation of the damage evolution law.


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