Effectiveness of the Modified Fatigue Criteria for Biaxial Loading of Notched Specimen in High-Cycle Region

Abstract

This article deals with multiaxial fatigue strength of notched round bars made of Cr-Al-Mo steel and tested under combined tension and torsion loading. Fatigue life is one of the important factors in design since majority of engineering components are subjected to variable loading. Most of mechanical components in engineering practice are subjected to combined loading, which can lead to sudden fatigue failure. In present work the fatigue life of specimens made of low-alloy Cr-Al-Mo high-strength steel is studied. Experiments were focused on the high-cycle fatigue region (over 100 000 cycles to final failure). The most relevant goal of this paper is to verify the efficiency of modified classical multiaxial fatigue criteria. The criterion proposed by Goncalves, Araujo and Mamiya was found to be the best in the fatigue life prediction for bending-torsion loading of notched specimens.

Fatigue life prediction of pedicle screw for spinal surgery

“…Further mechanical properties are elongation at break A = 14%, reduction area Si = 25% and Vickers hardness 350 HV. The crack growth properties were measured on Standard test method for measurement of fatigue crack growth rates introduced by ASTME 647 [9]. This test method covers the determination of fatigue crack growth rates from nearthreshold to Kmax controlled instability.…”

“…or theoretical analysis of fatigue process was used new method proposed by Navarro [7,8] and multiaxial fatigue criteria modified for notched specimens were tested [9]. Model proposed by Navarro combined initiation and propagation phase, without the need to define boundary length of crack, to differentiate between the two phases of crack growth.…”

“…The prediction of fatigue failure is important forprevention of serious medical complications. For the fatigue life P prediction of pedicle-screws was used the method proposed by Navarro [6,7,8] and comparison with other methods used in multiaxial fatigue [9]. In the work, fatigue resistance of hollow pedicle-screw and solid pedicle-screws were compared.…”

“…Other methods of lifespan forecast have been tested for a comparison with our new method. In article [9], there are described various multiaxial criteria, adapted for lifespan forecast of notched samples, which corresponds to the case of the screw. A criterion proposed by Goncalves gives the best forecast of all criteria described in [9].…”

“…In article [9], there are described various multiaxial criteria, adapted for lifespan forecast of notched samples, which corresponds to the case of the screw. A criterion proposed by Goncalves gives the best forecast of all criteria described in [9]. Goncalves criterion has been modified with help of AG and BG parameters for sample analysis.…”