This paper involves the development of an analyticalnumerical crack growth model to predict surface and subsurface fatigue crack growth in the fibre metal laminate fml glare subjected to combined tension and bending. Reportpatent number nf1676l18069, doucment id 20140016386, 2014. Pdf fatigue crack propagation and delamination growth in glare. Reyndert christiaan alderliesten university of bologna.
Glare shows excellent crack growth characteristics due to the mechanism of delamination and fibre bridging. Fatigue crack propagation and delamination growth in glare, phd thesis, delft university of technology, 2005. Both the blind and recalibrated predictions are performed for specimens of three different layups under the air force tech scout 1 program. Open hole multilayer fatigue crack growth in glare under. To incorporate this delamination growth in prediction methods the energy release rate approach is applied. Delamination in fiber metal laminates glare during fatigue crack growth. This means that the crack growth can be described with linear elastic fracture. The stress intensity factor for glare can be divided into two parts. Methods have been developed to describe the fatigue initiation and propagation mechanisms in flat panels as well as mechanically fastened joints and to determine the residual strength of large flat panels. Chapter 8 summarizes the conclusions of the investigation.
Fatigue in fibre metal laminates wiley online library. The loads of crack region in metal layers are partly. A summary is given of reported trends in fatigue crack growth observed in variable amplitude fatigue tests on metallic materials, specifically on steels, under both simple and complex load histories. Fatigue and damage tolerance issues of glare in aircraft structures. Tensiletensile cyclic fatigue tests were conducted on centrally notched specimen at four stress levels with various maximum values. Summary fatigue crack growth in a fibre metal laminate like glare is accompanied by delamination growth at the interface between the aluminium and glass fibres. Fatigue crack propagation and delamination growth in glare tu. Developed, verified, and validated a model for crack growth and. As has been discussed, fatigue crack growth rates in glare are relatively low. Fibre metal laminate glare consists of thin aluminium layers bonded together. Predicting fatigue crack initiation and propagation in. In fmls, except for crack growth in the metal layers, fatigue crack propagation also causes delamination growth at the metalfiber interfaces in wake of the metal crack, that are both concerned with bridging effect of fibers. The shot peen forming of fiber metal laminates based on the aluminumlithium alloy.
Progressive failure monitoring of fiberreinforced metal. Fatigue crack growth tests have been performed on three types of material i. An approximate function between the applied stress, the layup parameters and the fatigue crack growth. Analytical prediction model for nonsymmetric fatigue. Chapter 21 fatigue resistance of fibermetal laminates. This thesis presents the investigation into the fatigue crack propagation behaviour and delamination growth behaviour of the fibre metal laminate glare. Fatigue and damage tolerance issues of glare in aircraft. Read analytical prediction model for fatigue crack propagation and delamination growth in glare, international journal of fatigue on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Fatigue crack propagation and delamination growth in glare. The fatigue insensitive fibres restrain the crack opening and transfer load over the.
Development of a fatigue damage propagation model for. The effects of load variables, specimen geometry, material properties, microstructure and environment are considered. A robust crack growth prediction tool has been developed for a class of hybrid skin materials known as fibre metal laminates fmls which has been. As a consequence, part of the load is transferred through the fibre layers instead of around the crack tip in the aluminium layers, reducing the crack growth rate. Analytical prediction model for fatigue crack propagation and delamination growth in glare article pdf available in international journal of fatigue 294. Experimental work fatigue tests were conducted on a series of glare specimens containing splice and doubler features. To investigate the fatigue cracking in the inner aluminum layers of glare332, the. Experimental study on fatigue crack propagation of glare3. Other properties and production aspects of glare are brie. Crack propagation an overview sciencedirect topics. Benedictus1 1technical university of delft, delft, the netherlands abstract.
The fatigue insensitive fibres restrain the crack opening and transfer load over. Pdf delamination in fiber metal laminates glare during. This phenomenon is studied for constantamplitude loading, which is significant for fatigue loading of. Experimental observation of crack propagation and delamination growth a. The prediction model has been validated with experimental crack growth data, and is considered accurate. The fibres are insensitive to the occurring fatigue loads and remain intact while the fatigue cracks occur in the aluminium layers. The fibres bridge the crack by leading the stresses through it. Analytical prediction model for fatigue crack propagation. Fatigue crack growth calculations are based on an analytical model which applies displacement compatibility at the delamination boundary, to solve for the crack tip stress intensity and subsequently calculate crack and delamination growth characteristics. Delamination and fatigue crack growth behavior in fiber metal laminates glare under single overloads. The crack closure effecthas been assessed by the identification of the nonlinearity in the compliance curve of the double cantilever testspecimen after the delamination extension. In the present chapter, fatigue crack growth in laminated sheet material without. A continuum damage and discrete the authors 2017 crack.
The shot peen forming of fiber metal laminates based on. Modelling fatigue crack propagation in glare, interim status report, report tdr02022, fibre metal laminates centre of competence, january 24. This paper describes work done to extend this application to fmls. The glare332 specimen consists of three 2024t3 aluminum alloy sheets and two layers of glassepoxy composite lamina. Delamination and fatigue crack growth behavior in fiber. This thesis presents the investigation into the fatigue crack propagation. Glass fibre layers have very positive effect on postponing of initiation and on retardation of propagation of already initiated fatigue cracks. Similarly, fatigue threshold was studied initially for fmls, 41 see, for example, figure 6, until it was understood that the interplay between a threshold in crack growth and the apparent absence of threshold in delamination growth yield different slow crack growth characteristics compared with monolithic metals. Analytical modeling of fiber metal laminate stiffened by. License, which permits use, distribution and reproduction in any. Highcycle fatigue investigations of notched glare under. The fatigue insensitive fibres restrain the crack opening and transfer. Fibre metal laminate glare consists of thin aluminium layers bonded together with preimpregnated glass fibre layers and shows an excellent fatigue crack.
Understanding the fatigue behavior of fml structures and. On the available relevant approaches for fatigue crack. Alderliesten rc 2007 analytical prediction model for fatigue crack propagation and delamination growth in glare. A common frml, glass layered aluminum reinforced epoxy glare, possesses a set of mechanical properties which was achieved by designing its layup structure to combine metal alloy and fiberreinforced polymer phases. Multiplesite damage msd is a dangerous scenario for aircraft structures due to the interaction of adjacent cracks in one structural element. On the available relevant approaches for fatigue crack propagation prediction in glare. The stress intensity factor at the crack tip is a function of the far field opening stress and the crack closing bridging stress in the aluminium layers. Buy fatigue crack propagation and delamination growth in glare stand alone dup on free shipping on qualified orders. Draft draft draft draft draft draft esis summer school, june 1819. Fatigue crack growth and delamination growth in glared. It can be concluded that with the proposed prediction model, the mechanism of crack propagation and delamination growth in glare is fully described and understood. Fatigue crack and delamination growth in fibre metal. This study is to investigate the fatigue crack growth behavior of glare332 under various stress levels. Developed, verified, and validated a model for crack growth and delamination propagation through variablestiffness glare panels.
Crack growthin fibre metal laminates under variable amplitude. Paris law was employed to predict crack growth rates. The composite nature of fmls creates a second load path, the bridging fibers, which attract load from the cracked metal reducing the fatigue crack growth rate. Analytical prediction model for fatigue crack propagation and delamination growth in glare. The calculated results are compared with each other in fig. Predicting the influence of temperature on fatigue crack.
Despite their excellent fatigue crack growth resistance, fibre metal laminates fmls may also encounter this damage scenario. Due to the balance between crack propagation and delamination growth, the observed crack growth rates are approximately constant over a significant period of the crack growth life. The chapter is completed with some general remarks. A continuum damage and discrete crackbased approach for. A continuum damage mechanics cdm approach is used for the fatiguedriven delamination initiation and propagation by insertion of a finite thickness interface layer at each ply interface. This interaction makes it harder for the prediction of crack growth rate and damage tolerance. Fibre metal laminate glare consists of thin aluminium layers bonded together with preimpregnated glass fibre layers and shows an excellent fatigue crack growth behaviour compared to monolithic aluminium.
Analytical prediction model for fatigue crack propagation and. The fatigue crack growth behavior of fmls is complex, which includes both crack growth in the metal layers and delamination growth at the metalfiber interfaces in wake of the metal crack. On the development of a prediction methodology for crack. The model describes the crack propagation of the fatigue cracks in the aluminium layers and the corresponding delamination growth at the aluminiumfibre interfaces perpendicular to the crack. When the fatigue crack grows in the metal layers, the fibers do not fracture and restrain the crack tip opening. Read layup optimisation of fibre metal laminates based on fatigue crack propagation and residual strength, composite structures on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Chang and yang 2008 examined fatigue crack growth in glare by modulating the stress intensity parameter with a bridging factor and obtained the sn curve based on the initiation and growth life of the crack. The objective of this paper is to investigate the contributionrole of the crack closure and the fibre bridging effectsin stressratio influence in mode i delamination growth in carbonepoxy composite laminates. Fatigue and damage tolerance of glare springerlink. Crack growth in glare is a selfbalancing mechanism with delamination growth between the aluminium and fibre layers. This work presents the investigation into the fatigue crack propagation and delamination growth of the fiber metal laminate glare stiffened by external titanium straps. This thesis investigation aims to address a gap in fatigue crack growth propagation prediction techniques. However, only few studies on fatigue crack growth in presence of msd in fmls has been reported.