A method to predict the fatigue life and the residual strength of composite materials subjected to variable amplitude (VA) loadings

2019 ◽  
Vol 228 ◽  
pp. 111338 ◽  
Author(s):  
Alberto D'Amore ◽  
Luigi Grassia
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Residual Strength ◽  
Variable Amplitude

scholarly journals A New Software Framework for Fatigue Life Prediction of Composite Materials under Irregular Loading

2006 ◽  
Vol 15 (1) ◽  
pp. 096369350601500 ◽  
Author(s):  
Anastasios P. Vassilopoulos
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Life Prediction ◽  
Complex Stress ◽  
Fatigue Life Prediction ◽  
Software Framework ◽  
Material System ◽  
Variable Amplitude ◽  
Stress States ◽  
Irregular Loading

A new software framework for fatigue life prediction of composite materials under irregular loading is presented herein. The entire work is based on a well established methodology for the life prediction of GRP laminates under variable amplitude complex stress states. The process consists of the sequential execution of four main tasks, each one of which copes with a single subproblem in a straight forward manner. The aim of this on-going work is to create a generic software framework that will enable rapid prototyping of various life prediction schemes. Based on the software design, a software library is under development. In the current paper, the software framework is analytically presented. Two different modules are prepared for the first task of the entire methodology. Cycle counting of two different variable amplitude spectra is performed by rainflow counting technique and by simple range-mean technique. Results of both analyses are then processed by routines that solve subsequent steps of the entire methodology in order to predict time up to failure of the material system under consideration, a [0/(±45)2/0]T multidirectional laminate. Theoretical predictions are plotted against experimental data for comparison, and pros and cons of each one of the cycle counting algorithms are discussed.

Fatigue Life and Residual Strength Analysis of Steel-Composite Joints

2004 ◽  
Vol 1-2 ◽  
pp. 81-86 ◽  
Author(s):  
S.W. Boyd ◽  
J.I.R. Blake ◽  
R.A. Shenoi ◽  
J. Mawella
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Axial Compression ◽  
Residual Strength ◽  
Damage Model ◽  
Construction Materials ◽  
Hybrid Structure ◽  
Fixed Number ◽  
Strength Analysis ◽  
Stress Concentrations

There are many instances where the use of weight saving composite materials for an entire structure is either; too complex, too expensive or unfeasible. In these circumstances the use of a hybrid structure can incorporate the benefits of traditional construction materials, for example steel, coupled with the advantages of composite materials in weight critical areas. In the present study, an investigation was undertaken into the fatigue life characterisation of a hybrid joint for marine application. In addition the residual strength of the joint, after a fixed number of fatigue cycles, was assessed under axial compression and bending loads. A progressive damage model was developed to predict the location of major stress concentrations, the path of damage and subsequent loss in stiffness of the joint under axial compression.

scholarly journals Comparative Study of Phenomenological Residual Strength Models for Composite Materials Subjected to Fatigue: Predictions at Constant Amplitude (CA) Loading

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3398 ◽  
Author(s):  
Alberto D’Amore ◽  
Luigi Grassia
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Residual Strength ◽  
Composite Structures ◽  
Peak Stress ◽  
Fatigue Properties ◽  
Constant Amplitude ◽  
Data Set ◽  
Life Data ◽  
Strength Models

The most popular methods of characterizing a composite’s fatigue properties and predicting its life are phenomenological, meaning the micro-mechanisms of composite structures under cyclic loading are not treated. In addition, in order to characterize the fatigue properties, only macro-parameters, namely strength and/or stiffness, are adopted. Residual strength models are mostly used in practice, given their strong relationship with safety and reliability. Indeed, since failure occurs when the strength degrades to the peak stress of fatigue loading, the remaining strength is used as a failure index. In this paper, based on a wide set of literature data, we summarize the capabilities of four models, namely Caprino’s, D’Amore’s, Sendekyj’s, and Kassapoglou’s models. The models are briefly described and then applied to the same data set, which is re-elaborated. The selected experimental data are recovered from a large experimental campaign carried out by the Federal Aviation Administration (FAA). Specimens of the same material were subjected to different loading in terms of peak stress, σmax, and stress ratio, R = σmin/σmax, ranging from pure tension (0 < R < 1) to prevalent tension (−1 < R < 0) to tension-compression (R = −1) to pure compression (1 < R < ∞). The data represent a formidable test bed to comparatively evaluate the models’ capabilities and their predictive prerogatives. The models are also tested with respect to their ability to replicate the principal responses’ feature of composite materials subjected to constant amplitude (CA) loadings. It is shown that Caprino’s and D’Amore’s models are equally capable of adequately fitting the experimental fatigue life data under given loading conditions and predicting the fatigue behavior at different loading ratios, R, with two fixed parameters. Sendekyj’s model required different parameters’ sets for each loading condition, and Kassapoglou’s model was unable to fit the majority of fatigue life data. When compared on the basis of the residual strength data, only the recently developed D’Amore’s model revealed its reliability.

Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes

2018 ◽  
Vol 763 ◽  
pp. 867-874
Author(s):  
Yu Shu Liu ◽  
Ke Peng Chen ◽  
Guo Qiang Li ◽  
Fei Fei Sun
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Structural Reliability ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Buckling Restrained Braces ◽  
Energy Dissipation Devices

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

scholarly journals S-N Curve Characterisation for Composite Materials and Prediction of Remaining Fatigue Life Using Damage Function

2021 ◽  
Vol 5 (3) ◽  
pp. 76
Author(s):  
Ho Sung Kim ◽  
Saijie Huang
Keyword(s):  
Fatigue Life ◽  
Composite Materials ◽  
Loading Rate ◽  
Theoretical Method ◽  
Damage Function ◽  
Simple Method ◽  
Arbitrary Choice ◽  
Number Of Cycles ◽  
First Time ◽  
Remaining Fatigue Life

S-N curve characterisation and prediction of remaining fatigue life are studied using polyethylene terephthalate glycol-modified (PETG). A new simple method for finding a data point at the lowest number of cycles for the Kim and Zhang S-N curve model is proposed to avoid the arbitrary choice of loading rate for tensile testing. It was demonstrated that the arbitrary choice of loading rate may likely lead to an erroneous characterisation for the prediction of the remaining fatigue life. The previously proposed theoretical method for predicting the remaining fatigue life of composite materials involving the damage function was verified at a stress ratio of 0.4 for the first time. Both high to low and low to high loadings were conducted for predicting the remaining fatigue lives and a good agreement between predictions and experimental results was found. Fatigue damage consisting of cracks and whitening is described.

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