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Full-Text Articles in Mechanical Engineering
Effect Of Plastic Prestrain On High Cycle Fatigue Of Ti–6al–4v, David Lanning, Theodore Nicholas, George Haritos
Effect Of Plastic Prestrain On High Cycle Fatigue Of Ti–6al–4v, David Lanning, Theodore Nicholas, George Haritos
Dr. George K. Haritos
The effect of initial plastic strain on the high cycle fatigue (HCF) lives of smooth cylindrical Ti–6Al–4V specimens is investigated. Specimens were monotonically, quasi-statically loaded under strain control in tension to produce plastic strains from 1% to 5% and under load control in compression to produce 9.5% plastic strain. A step-loading technique was then employed to establish the 106 or 107 cycle fatigue limit stress under load control conditions for stress ratios of R=0.1, 0.5 and 0.8 at frequencies of either f=50 or 400 Hz. Results are compared with baseline fatigue limit stresses for Ti–6Al–4V without prior plastic strain. Initial …
On The Use Of Critical Distance Theories For The Prediction Of The High Cycle Fatigue Limit Stress In Notched Ti–6al–4v ☆, David Lanning, Theodore Nicholas, George Haritos
On The Use Of Critical Distance Theories For The Prediction Of The High Cycle Fatigue Limit Stress In Notched Ti–6al–4v ☆, David Lanning, Theodore Nicholas, George Haritos
Dr. George K. Haritos
Methods are investigated for predicting the high cycle fatigue (HCF) lives of notched cylindrical Ti–6Al–4V specimens using critical distance concepts that employ the stress distribution in the vicinity of the notch. Cylindrical fatigue specimens had circumferential V-notches with a range of elastic stress concentration factors (kt=1.97–4.07). Notched and unnotched specimens were cycled to failure using a step-loading technique to generate points on a Haigh (Goodman) diagram for a constant fatigue life of 106 cycles. Finite element solutions were generated to provide stress distributions for the notched gage sections. The stress distributions were used in the search for a critical distance …
Notch Size Effects In Hcf Behavior Of Ti–6al–4v, George Haritos, Theodore Nicholas, David Lanning
Notch Size Effects In Hcf Behavior Of Ti–6al–4v, George Haritos, Theodore Nicholas, David Lanning
Dr. George K. Haritos
The high cycle fatigue (HCF) behavior of Ti–6Al–4V is investigated for cylindrical specimens having three sizes of geometrically similar circumferential V-notches, each with an elastic stress concentration factor, Kt, of approximately 2.78. A step loading technique for obtaining a point on a constant life (106 cycles) Haigh diagram from a single test specimen was implemented. Tests were performed at stress ratios of R=0.1, 0.5, and 0.8 for specimens machined from two different product forms of Ti–6Al–4V, bar and plate forgings. Results indicate that while there is a definite notch size effect in the Ti–6Al–4V bar within …
The Elastic Response Of A Cohesive Aggregate—A Discrete Element Model With Coupled Particle Interaction, George Jefferson, George Haritos, Robert Mcmeeking
The Elastic Response Of A Cohesive Aggregate—A Discrete Element Model With Coupled Particle Interaction, George Jefferson, George Haritos, Robert Mcmeeking
Dr. George K. Haritos
A model is presented for the deformation of a cohesive aggregate of elastic particles that incorporates two important effects of large-sized inter-particle junctions. A finite element model is used to derive a particle response rule, for both normal and tangential relative deformations between pairs of particles. This model agrees with the Hertzian contact theory for small junctions, and is valid for junctions as large as half the nominal particle size. Further, the aggregate model uses elastic superposition to account for the coupled force–displacement response due to the simultaneous displacement of all of the neighbors of each particle in the aggregate. …