K. Manigandan

A Fatigue Model for Discontinuous Particulate-Reinforced Aluminum Alloy Composite: Influence of Microstructure

In this paper, the use of a microstructure-sensitive fatigue model is put forth for the analysis of discontinuously reinforced aluminum alloy metal matrix composite. The fatigue model was used for a ceramic particle-reinforced aluminum alloy deformed under conditions of fully reversed strain control. Experimental results revealed the aluminum alloy to be strongly influenced by volume fraction of the particulate reinforcement phase under conditions of strain-controlled fatigue. The model safely characterizes the evolution of fatigue damage in this aluminum alloy composite into the distinct stages of crack initiation and crack growth culminating in failure. The model is able to capture the specific influence of particle volume fraction, particle size, and nearest neighbor distance in quantifying fatigue life. The model yields good results for correlation of the predicted results with the experimental test results on the fatigue behavior of the chosen aluminum alloy for two different percentages of the ceramic particle reinforcement. Further, the model illustrates that both particle size and volume fraction are key factors that govern fatigue lifetime. This conclusion is well supported by fractographic observations of the cyclically deformed and failed specimens.

Mechanical Behavior of Two High Strength Alloy Steels Under Conditions of Cyclic Tension

The results of a recent study aimed at understanding the conjoint influence of load ratio and microstructure on the high cycle fatigue properties and resultant fracture behavior of two high strength alloy steels is presented and discussed. Both the chosen alloy steels, i.e., 300M and Tenax™ 310 have much better strength and ductility properties to offer in comparison with the other competing high strength steels having near similar chemical composition. Test specimens were precision machined from the as-provided stock of each steel. The machined specimens were deformed in both uniaxial tension and cyclic fatigue under conditions of stress control. The test specimens of each alloy steel were cyclically deformed over a range of maximum stress at two different load ratios and the number of cycles to failure recorded. The specific influence of load ratio on cyclic fatigue life is presented and discussed keeping in mind the maximum stress used during cyclic deformation. The fatigue fracture surfaces were examined in a scanning electron microscope to establish the macroscopic mode and to concurrently characterize the intrinsic features on the fracture surface. The conjoint influence of nature of loading, maximum stress, and microstructure on cyclic fatigue life is discussed.

The Bearing Strength and Fracture Behavior of Bolted Connections in Two Aluminum Alloys

In this paper, the bearing capacity, taken as a combination of strength, elongation, and failure by fracture characteristics of bolt holes in two aluminum alloys, 5052-H32 and 6061-T6, that were deformed in uniaxial tension is presented and discussed. The specific role played by bolt hole confinement on the bearing capacity of each aluminum alloy is highlighted. An increase in the bearing ratio caused plastic deformation around the holes to gradually increase. For both the chosen aluminum alloys the average bearing ratio at the time of failure of the test sample was found to vary with end distance. The experimentally determined strength was observably larger than the calculated bearing strength obtained using guaranteed minimum mechanical properties and recommended mathematical relationships. The nature of final fracture of each aluminum alloy is carefully examined and the intrinsic features present on the fracture surface are rationalized in concurrence with macroscopic mechanical response.

Quasi-Static, Cyclic Fatigue and Fracture Behavior of Alloy Steel for Structural Applications: Influence of Orientation

In this paper, the results of a study aimed at understanding the extrinsic influence of test specimen orientation, with respect to a wrought alloy-steel plate, on the stress-controlled cyclic fatigue properties and fracture behavior of a structural steel is highlighted. The alloy steel chosen was ASTM A572 grade 50. Samples of this alloy steel, prepared from both the longitudinal and transverse orientations, were cyclically deformed over a range of maximum stress and the corresponding number of cycles to failure (NF) was recorded. The influence of test specimen orientation and intrinsic microstructural effects on cyclic fatigue life and fracture behavior are presented and discussed. Overall, the macroscopic fracture mode was essentially identical regardless of orientation of the test specimen with respect to the wrought plate. The microscopic mechanisms governing cyclic deformation, fatigue life, and final fracture behavior are presented in light of the mutually interactive influences of magnitude of applied stress, intrinsic microstructural effects, orientation of test specimen, and deformation characteristics of the key microstructural constituents.

Influence of Cyclic Straining on Fatigue, Deformation, and Fracture Behavior of High-Strength Alloy Steel

K. Manigandan and T.S. Srivatsan, Department of Mechanical Engineering, The University of Akron, Akron, OH 44325-3903; and V.K. Vasudevan, D. Tammana, and B. Poorganji, School of Dynamic Systems, Materials Science and Engineering Program, University of Cincinnati, Cincinnati, OH 45221-0072. Contact e-mails: tss1@uakron.edu and vasudevk@ucmail.uc.edu. JMEPEG (2016) 25:151 ASM International DOI: 10.1007/s11665-015-1844-z 1059-9495/

On the Specific Role of Microstructure in Governing Cyclic Fatigue, Deformation, and Fracture Behavior of a High-Strength Alloy Steel

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The Quasi-static Deformation, Failure, and Fracture Behavior of Titanium Alloy Gusset Plates Containing Bolt Holes

In this paper, the results of an experimental study that focused on evaluating the conjoint influence of microstructure and test specimen orientation on fully reversed strain-controlled fatigue behavior of the high alloy steel X2M are presented and discussed. The cyclic stress response of this high-strength alloy steel revealed initial hardening during the first few cycles followed by gradual softening for most of fatigue life. Cyclic strain resistance exhibited a linear trend for the variation of elastic strain amplitude with reversals to failure, and plastic strain amplitude with reversals to failure. Fracture morphology was the same at the macroscopic level over the entire range of cyclic strain amplitudes examined. However, at the fine microscopic level, the alloy steel revealed fracture to be essentially ductile with features reminiscent of predominantly “locally” ductile and isolated brittle mechanisms. The mechanisms governing stress response at the fine microscopic level, fatigue life, and final fracture behavior are presented and discussed in light of the mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents during fully reversed strain cycling, cyclic strain amplitude, and resultant response stress.

The Cyclic Strain Resistance, Stress Response, Fatigue Life, and Fracture Behavior of a High Performance Alloy Steel

In this article, the influence of bolt holes, specifically their number and layout on strength, deformation, and final fracture behavior of titanium alloy gusset plates under the influence of an external load is presented and discussed. Several plates having differences in both the number and layout of the bolt holes were precision machined and then deformed under quasi-static loading. The specific influence of number of bolt holes and their layout on maximum load-carrying capability and even fracture load was determined. The conjoint influence of bolt number, bolt layout pattern, nature of loading, contribution from local stress concentration, and intrinsic microstructural effects in governing the macroscopic fracture mode and intrinsic microscopic mechanisms is presented and discussed.

Cyclic Strain Resistance, Deformation and Fracture Behavior of a Novel Alloy Steel

In this paper, the results of a recent study aimed at understanding the role of microstructure on cyclic stress response, cyclic strain resistance, deformation, fatigue life, and fracture behavior of the high strength alloy steel PremoMet 290 is presented and discussed. The cyclic strain amplitude-controlled fatigue properties, deformation, and resultant fracture behavior of the alloy steel specimens are discussed when cyclically deformed over a range of strain amplitudes. The intrinsic mechanisms governing stress response, stress versus strain response fatigue life, deformation, and final fracture behavior are presented and discussed in light of the competing and mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents, cyclic strain amplitude, and concomitant response stress.

Quasi‐Static, Fatigue and Fracture Behavior of Aluminum Alloy Composite Used in Brake Drums

In this paper, the results of a study on microstructural influences on cyclic strain response, deformation and fracture behavior of an alloy steel is presented Cyclic strain resistance exhibited a linear trend for the variation of both elastic strain amplitude with reversals-to-failure, and plastic strain amplitude with reversals-to-failure. Fracture morphology was observed to be the same at the macroscopic level over the entire range of cyclic strain amplitudes examined. However, at the fine microscopic level this alloy steel revealed fracture to be mixed-mode with features reminiscent of “locally” ductile and brittle failure mechanisms. The mechanisms governing strain response at the fine microscopic level, resultant fatigue life, and final fracture behavior are presented and discussed in light of the mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents during fully-reversed strain cycling, magnitude of cyclic strain amplitude, and resultant fatigue life.