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Fatigue of continuous fiber reinforced metallic materials
Fatigue Abstracts This section contains abstracts of selected articles, technical reports, dissertations and patents concerned with fatigue. It is prepared in collaboration with Materials Information, a joint service of The Institute of Materials and ASM International. Readers wishing to obtain the full text of articles abstracted here should contact either: The Institute of Materials, 1 Carlton House Terrace, London SWlY 5DB, UK, or: ASM International, Metals Park, OH 44073, USA (not International Journal of Fatigue). The fees charged for photocopying articles are £7.00 for the first ten pages and £3.00 per additional ten pages (UK office), or $10.00 for the first ten pages and $4.00 per additional ten pages (US Office).
Fatigue of continuous fiber reinforced metallic materials. Johnson, W.S., Mirdamadi, M. and Bakuckas, J.G. N93-18379/6/XAB (1993) 12 pp The complex damage mechanisms that occur in fibre-reinforced advanced metallic materials are discussed. As examples, results for several layups of SCS-6/Ti-15-3 composites are presented. Fatigue tests were conducted and analysed for both notched and unnotched specimens at room and elevated temperatures. Test conditions included isothermal, non-isothermal and simulated mission profile thermomechanical fatigue. Test results indicated that the stress in the 0° fibres is the controlling factor for fatigue life for a given test condition. An effective strain approach is presented for predicting crack initiation at notches. Fibre-bridging models were applied to crack growth behaviour. Failure modes in transverse metal-matrix composite lamina under compression. Newaz, G.M. and Majumdar, B.S. J Mater Sci Lett (15 April 1993) 12, (8), 551-552 Transverse compressive load tests were made on an eight-ply unidirectional SCS-fi/Beta 21S transverse metal-matrix composite lamina. This silicon carbide fibre was fabricated using a foil-fibre-foil consolidation technique, and was approx 1.6 mm thick, with a nominal cross-sectional diameter of 140 i~m; Beta 21S is a bcc titanium alloy. Tests were conducted both at room temperature and at 649°C. After testing, metallographie specimens were examined optically, showing that damage in the transverse MMC lamina consisted of a new type of failure mode with radial fibre fracture primarily along the loading axis. It appears that the local transverse tensile stresses produced due to compressive loading initiated the fibre fracture; this failure mode seems to indicate that the fibres have low strain-to-faihire in the transverse direction. This failure mode under compression is a very different one and has not previously been reported for composites. Graphs, photomicrographs, 4 ref. Effect of particulate type on fatigue crack propagation in AI-Li based spray deposited metal matrix composites. Gupta, M.. Bowo, K., Lavernia, E.J. and Earthman, J. C. Scr Metall Mater (1 May 1993) 28 (9), 1053-1058 Preliminary information is presented on the microstructure and fatigue properties of a spray deposited AI-2.24Li-021Zr alloy reinforced with SiC and graphite particulates. Extruded composites showed a lower ~Kth value compared with their monolithic counterparts. Thermal annealing at 600 °C lowers the AKth value and fatigue crack propagation rates irrespective of the type of reinforcement used. Two possible mechanisms for crack propagation are proposed to explain the difference in crack growth rates observed in SiCreinforced and graphite-reinforced composites. Photomicrographs, graphs, 10 ref. Fatigue properties of continuous fibre reinforced ahiminlum alloys with silicon carbide particulates and whiskers. Saruki, K., Yamada, A., Towata, S.-i. and Yamada, S.-i. J Jpn Soc Strength Fract Mater (Mar. 1993) 27 (1), 1-8 (in Japanese) Hybrid fibre-reinforced metals (H-FRMs), which have silicon carbide whiskers and particulates distributed among the continuous fibres of silicon carbide or carbon, were prepared by a squeeze casting process using AI-5Mg alloy, AI-4.5Cu alloy or pure aluminium as the matrix metal. The bending fatigue strength and fracture mode of the H-FRMs were investigated by comparing them with those of non-hybrid fibre-reinforced metals (NH-FRMs). The results obtained are as follows. As to the C-fibre-reinforced metal, the fatigue strength of the H-FRMs was higher than that of the NH-FRMs because of the effect of hybrid technique. This difference between the two types of FRM was not so remarkable as that in static bending strength. As to the silicon carbide fibre-reinforced metal, the endurance limit of the FRM using pure Al was lower than that of the FRMs using Al alloy, although the static bending strength of the former was higher than that of the latter. The fatigue strength of the C-fibre-reinforced metal was higher than that of the silicon 0142-1123/94/040294-09 © 1994 B u t t e r w o r t h - H e i n e m a n n L t d
294 Fatigue, 1994, Vol 16, June
carbide fibre-reinforced metal. The model of fracture was classified into three types by the factor affecting the fracture directly: namely, the strength of fibre, interface, or matrix. Graphs, photomicrographs, 5 ref. A mieromechanics-based strength prediction methodology for notched metnlmatrix composites. Bigelow, C.A. Proc Conf on Fatigue and Fracture of Inorganic Composites, Cambridge, UK, 31 Mar-2 Apr 1992, 113-121 An analytical micromechanics-based strength-prediction methodology was developed to predict failure of notched metal-matrix composites. The stress-strain behaviour and notched strength of two metal-matrix composites, horon-aiuminium and silicon carbide-titanium (SCS-6/Ti-15-3), were predicted. The prediction methodology combines analytical techniques ranging from a three-dimensional finite element analysis of a notched specimen to a micromechanical model of a single fibre. In the B/AI laminates, a fibre failure criterion based on the axial and shear stress in the fibre accurately predicted laminate failure for a variety of lay-ups and notch-length:specimenwidth ratios with both circular holes and sharp notches when matrix plasticity was included in the analysis. For the SCS-6/Ti-15-3 laminates, a fibre failure criterion based on the axial stress in the fibre correlated well with experimental results for static and post-fatigue residual strengths when fibre-matrix debonding and matrix cracking were included in the analysis. The micromechanics-based strength-prediction methodology presented offers a direct approach to strength prediction by modelling behaviour and damage on a constituent level, thus explicitly including matrix non-linearity, fibre-matrix interface debonding and matrix cracking. Graphs, 19 ref. The use of highway bridge design codes for fatigue aspects of transit-only bridges. Buekland, P. G. J Constr Steel Res (1993), 25 (1-2), 83-94 The provisions of highway bridge design codes are sometimes used for the design of transit-only guideways and bridges. The transit vehicles are usually light- or medium-weight electric-powered passenger vehicles running on defined tracks. This contrasts with highway vehicles, which come in all sorts of weights and sizes and can range all over the roadway. Because of the large numbers of cycles of transit loading, perhaps > 10 million trains with 120 million bogies, fatigue governs much of the design of the supporting structure. Unlike highway loading, the trains always take the same route (on the rails) and the weights range only from empty to full vehicles and the impact effects are less variable than for highway bridges. The question thus arises as to whether the fatigue provisions of a highway bridge design code are suitable for a transit bridge. It is argued that the design procedures, such as assumed loading, assumed impact effects and assumed positions of vehicles, result in differing degrees of conservatism being present in highway bridges and in transit-only bridges. It is concluded that fatigue rules that are suitable for highway bridges may be unconservative for transit-only bridges and that allowable stress ranges should therefore be reduced. Graphs, 15 ref. Design of steel beams with end copes. Cheng, JJ.R. J Constr Steel Res (1993) 25 (1-2), 3-22 In steel beams with end copes, the strength and torsional stiffness at the coped section are reduced and a high stress concentration in the web at the cope corner is introduced. Therefore, besides yielding, coped beams can fail in three distinct failure modes: lateral-torsional buckling, local web buckling and fatigue cracking. Based on the behaviour and analytical studies of coped beams, design methods are proposed for these three failure modes. Simple interaction equations, which utilize the individual lateral buckling capacities of the coped region and the uncoped length, are developed for design of the lateral buckling of coped beams. Inelastic lateral buckling caused by the residual stresses and design of short-span coped beams are also considered. As for local buckling strength at the coped region, a plate-buckling model is developed for compression-flanged coped beams, and a lateral buckling model is adopted for double-flange coped beams. Yielding at the coped corner caused by the high local stress concentration is considered in the design. For
Fatigue of continuous fiber reinforced metallic materials. Johnson, W.S., Mirdamadi, M. and Bakuckas, J.G. N93-18379/6/XAB (1993) 12 pp The complex damage mechanisms that occur in fibre-reinforced advanced metallic materials are discussed. As examples, results for several layups of SCS-6/Ti-15-3 composites are presented. Fatigue tests were conducted and analysed for both notched and unnotched specimens at room and elevated temperatures. Test conditions included isothermal, non-isothermal and simulated mission profile thermomechanical fatigue. Test results indicated that the stress in the 0° fibres is the controlling factor for fatigue life for a given test condition. An effective strain approach is presented for predicting crack initiation at notches. Fibre-bridging models were applied to crack growth behaviour. Failure modes in transverse metal-matrix composite lamina under compression. Newaz, G.M. and Majumdar, B.S. J Mater Sci Lett (15 April 1993) 12, (8), 551-552 Transverse compressive load tests were made on an eight-ply unidirectional SCS-fi/Beta 21S transverse metal-matrix composite lamina. This silicon carbide fibre was fabricated using a foil-fibre-foil consolidation technique, and was approx 1.6 mm thick, with a nominal cross-sectional diameter of 140 i~m; Beta 21S is a bcc titanium alloy. Tests were conducted both at room temperature and at 649°C. After testing, metallographie specimens were examined optically, showing that damage in the transverse MMC lamina consisted of a new type of failure mode with radial fibre fracture primarily along the loading axis. It appears that the local transverse tensile stresses produced due to compressive loading initiated the fibre fracture; this failure mode seems to indicate that the fibres have low strain-to-faihire in the transverse direction. This failure mode under compression is a very different one and has not previously been reported for composites. Graphs, photomicrographs, 4 ref. Effect of particulate type on fatigue crack propagation in AI-Li based spray deposited metal matrix composites. Gupta, M.. Bowo, K., Lavernia, E.J. and Earthman, J. C. Scr Metall Mater (1 May 1993) 28 (9), 1053-1058 Preliminary information is presented on the microstructure and fatigue properties of a spray deposited AI-2.24Li-021Zr alloy reinforced with SiC and graphite particulates. Extruded composites showed a lower ~Kth value compared with their monolithic counterparts. Thermal annealing at 600 °C lowers the AKth value and fatigue crack propagation rates irrespective of the type of reinforcement used. Two possible mechanisms for crack propagation are proposed to explain the difference in crack growth rates observed in SiCreinforced and graphite-reinforced composites. Photomicrographs, graphs, 10 ref. Fatigue properties of continuous fibre reinforced ahiminlum alloys with silicon carbide particulates and whiskers. Saruki, K., Yamada, A., Towata, S.-i. and Yamada, S.-i. J Jpn Soc Strength Fract Mater (Mar. 1993) 27 (1), 1-8 (in Japanese) Hybrid fibre-reinforced metals (H-FRMs), which have silicon carbide whiskers and particulates distributed among the continuous fibres of silicon carbide or carbon, were prepared by a squeeze casting process using AI-5Mg alloy, AI-4.5Cu alloy or pure aluminium as the matrix metal. The bending fatigue strength and fracture mode of the H-FRMs were investigated by comparing them with those of non-hybrid fibre-reinforced metals (NH-FRMs). The results obtained are as follows. As to the C-fibre-reinforced metal, the fatigue strength of the H-FRMs was higher than that of the NH-FRMs because of the effect of hybrid technique. This difference between the two types of FRM was not so remarkable as that in static bending strength. As to the silicon carbide fibre-reinforced metal, the endurance limit of the FRM using pure Al was lower than that of the FRMs using Al alloy, although the static bending strength of the former was higher than that of the latter. The fatigue strength of the C-fibre-reinforced metal was higher than that of the silicon 0142-1123/94/040294-09 © 1994 B u t t e r w o r t h - H e i n e m a n n L t d
294 Fatigue, 1994, Vol 16, June
carbide fibre-reinforced metal. The model of fracture was classified into three types by the factor affecting the fracture directly: namely, the strength of fibre, interface, or matrix. Graphs, photomicrographs, 5 ref. A mieromechanics-based strength prediction methodology for notched metnlmatrix composites. Bigelow, C.A. Proc Conf on Fatigue and Fracture of Inorganic Composites, Cambridge, UK, 31 Mar-2 Apr 1992, 113-121 An analytical micromechanics-based strength-prediction methodology was developed to predict failure of notched metal-matrix composites. The stress-strain behaviour and notched strength of two metal-matrix composites, horon-aiuminium and silicon carbide-titanium (SCS-6/Ti-15-3), were predicted. The prediction methodology combines analytical techniques ranging from a three-dimensional finite element analysis of a notched specimen to a micromechanical model of a single fibre. In the B/AI laminates, a fibre failure criterion based on the axial and shear stress in the fibre accurately predicted laminate failure for a variety of lay-ups and notch-length:specimenwidth ratios with both circular holes and sharp notches when matrix plasticity was included in the analysis. For the SCS-6/Ti-15-3 laminates, a fibre failure criterion based on the axial stress in the fibre correlated well with experimental results for static and post-fatigue residual strengths when fibre-matrix debonding and matrix cracking were included in the analysis. The micromechanics-based strength-prediction methodology presented offers a direct approach to strength prediction by modelling behaviour and damage on a constituent level, thus explicitly including matrix non-linearity, fibre-matrix interface debonding and matrix cracking. Graphs, 19 ref. The use of highway bridge design codes for fatigue aspects of transit-only bridges. Buekland, P. G. J Constr Steel Res (1993), 25 (1-2), 83-94 The provisions of highway bridge design codes are sometimes used for the design of transit-only guideways and bridges. The transit vehicles are usually light- or medium-weight electric-powered passenger vehicles running on defined tracks. This contrasts with highway vehicles, which come in all sorts of weights and sizes and can range all over the roadway. Because of the large numbers of cycles of transit loading, perhaps > 10 million trains with 120 million bogies, fatigue governs much of the design of the supporting structure. Unlike highway loading, the trains always take the same route (on the rails) and the weights range only from empty to full vehicles and the impact effects are less variable than for highway bridges. The question thus arises as to whether the fatigue provisions of a highway bridge design code are suitable for a transit bridge. It is argued that the design procedures, such as assumed loading, assumed impact effects and assumed positions of vehicles, result in differing degrees of conservatism being present in highway bridges and in transit-only bridges. It is concluded that fatigue rules that are suitable for highway bridges may be unconservative for transit-only bridges and that allowable stress ranges should therefore be reduced. Graphs, 15 ref. Design of steel beams with end copes. Cheng, JJ.R. J Constr Steel Res (1993) 25 (1-2), 3-22 In steel beams with end copes, the strength and torsional stiffness at the coped section are reduced and a high stress concentration in the web at the cope corner is introduced. Therefore, besides yielding, coped beams can fail in three distinct failure modes: lateral-torsional buckling, local web buckling and fatigue cracking. Based on the behaviour and analytical studies of coped beams, design methods are proposed for these three failure modes. Simple interaction equations, which utilize the individual lateral buckling capacities of the coped region and the uncoped length, are developed for design of the lateral buckling of coped beams. Inelastic lateral buckling caused by the residual stresses and design of short-span coped beams are also considered. As for local buckling strength at the coped region, a plate-buckling model is developed for compression-flanged coped beams, and a lateral buckling model is adopted for double-flange coped beams. Yielding at the coped corner caused by the high local stress concentration is considered in the design. For