An effective method to investigate short crack growth behaviour by reverse bending testing

Abstract

A reverse bending rig has the advantage of relatively cheap construction compared with servo-controlled machines, and its robustness and reliability make it ideally suited to long-term testing programmes. In this paper, the details of the mechanical mechanism of a bending rig, the methods of its strain measurement and stress-strain analysis have been presented. A series of tests has been carried out to investigate short crack growth behaviour of AISI type 316 stainless steel under creep-fatigue conditions at 550 o . The advantage of this type of test allows a comparison to be made, on one specimen, of the influence of both tensile and compressive hold periods on crack growth behaviour. It has been shown that predominantly intergranular long cracks form on the tensile side and transgranular short cracks on the compressive side and these are a prominent feature between 0.9 -2.5% strain range. C

Data Processing Package for Cyclic Integrated Reversible Bending Fatigue Testing

“…Pure bending test methods are preferred for materials whose failure is sensitive to shear. [14][15][16] A pure bending fatigue machine for reverse bending was first developed by Forrest and Penfold. 17 It was modified and used by UK turbine makers in testing high-strain fatigue related to thermal transients in low-alloy steels.…”

Theoretical study on Manson-Coffin equation for physically short cracks and lifetime prediction

“…(12) implies that for the same hardness or strength, the fatigue limit is controlled by the hardening exponent n. For low strength steel, the fatigue limit of smooth specimens under rotary bending test ( 1 ) reaches  slip , while for high strength steel, the defects participate in the crack initiation and cause  slip ≥  1 .…”

The Development of Reversible Bending Fatigue Tester and Its Application to High Burnup Spent Nuclear Fuel Vibration Integrity Investigation under Normal Transportation

“…14 Pure bend test methods are preferred for materials whose failure is sensitive to shear. 15,16,17 A pure bending fatigue machine for reverse bending was first developed by Forrest and Penfold. 18 It was modified and used by UK turbine-makers in testing high strain fatigue related to thermal transients on low alloy steels.…”