Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

Abstract

Article HIGHLIGHTS• A loading frame was designed to simulate bearing overloads on the ENGIN-X strain diffractometer at ISIS neutron source, UK.• Neutron transmission imaging was used to map a Bragg edge fitting parameter, associated with material yielding.• It was demonstrated that bearing overloads generate regions of subsurface plasticity in overloaded roller bearings.• Subsurface deformation, observed during roller bearing overload events, appears to reduce the bearings life expectancy. Premature failure of wind turbine gearbox bearings is an ongoing concern for industry, with sudden overload events potentially contributing towards raceway damage, significantly hindering performance. Subsurface stresses generated along a line contact cause material yielding, and a probable crack initiation site. Currently, the ability to study subsurface plastic zone evolution using non-destructive techniques is limited. Neutron Bragg edge imaging is a novel technique, allowing for two-dimensional mapping of the Bragg edge broadening parameter, indicative of bulk plastic deformation. An experiment on the ENGIN-X strain scanning instrument, at the ISIS neutron source, UK, was setup for Bragg edge transmission imaging, to measure the effect of in situ loading on the raceway of a bearing, scaled-down from a traditional wind turbine gearbox bearing. Results demonstrate a strong correlation between load and the Bragg edge width, and allow for future experimental development in studying, not only the effect of overloads on fatigue life, but also the use of neutron imaging for evaluating plastic deformation in engineering components. GRAPHICAL ABSTRACT abstract article info

A review of non-destructive testing on wind turbines blades

“…Radiography has been also employed in bearings. Reid et al [86] have proposed the images from the Neutron Bragg edge to obtain two-dimensional mapping to detect the plastic deformation. The results showed that there is a strong correlation between the load and the width of the Bragg rim.…”

Bragg Edge Analysis for Transmission Imaging Experiments software tool: BEATRIX

“…Further development will be undertaken by the author to fully integrate Windows OS, making the software a cross-platform code. BEATRIX has already been used in a number of scientific studies (Vitucci et al, 2018;Kockelmann et al, 2018;Reid et al, 2018;Ramadhan et al, 2019), and this manuscript provides a useful introduction to the capabilities of this software tool. Moreover, a short illustration of BEATRIX is provided here for a typical data analysis of an energy-resolved imaging experiment.…”

“…As a result of the strong coherent elastic scattering interaction for thermal and cold neutrons, the measured transmission pattern contains important information about the crystalline state of the specimen. In particular, precise determination of the positions of Bragg edges provides a measure of lattice parameters (Santisteban et al, 2001(Santisteban et al, , 2002aSantisteban, 2005;Malamud & Santisteban, 2016;Tremsin et al, 2016;Ramadhan et al, 2018Ramadhan et al, , 2019Reid et al, 2018), while the heights of these edges give information about phase volume fractions (Steuwer et al, 2005;Woracek et al, 2014) and texture effects (Kockelmann et al, 2007;Santisteban et al, 2012;Malamud et al, 2014;Sato et al, 2017). The neutron wavelength shown in equation 3is a variable that is not directly measurable, and its value is usually determined at a pulsed neutron source via determination of the time of flight (TOF) for neutrons propagating at constant velocity along the instrument flight path.…”

Strain distribution visualization of punched electrical steel sheets using neutron Bragg-edge transmission imaging

“…The neutron Bragg-edge transmission imaging method, in which diffraction analysis is performed using neutron transmission, has been employed in several studies to nondestructively visualize the residual strain distribution inside bulk metallic materials. [18][19][20][21][22][23][24] The wavelength of neutrons can be determined with high accuracy using the time-of-flight (TOF) technique with a pulsed neutron beam. [21][22][23] The neutron transmission spectrum can be obtained pixel by pixel using a 2D and time-resolving detector.…”