Establishment of new design criteria for GlidCop^®X-ray absorbers

Abstract

An engineering research program has been conducted at the Advanced Photon Source (APS) in order to determine the thermomechanical conditions that lead to crack formation in GlidCop 1 , a material commonly used to fabricate X-ray absorbers at X-ray synchrotron facilities. This dispersion-strengthened copper alloy is a proprietary material and detailed technical data of interest to the synchrotron community is limited. The results from the research program have allowed new design criteria to be established for GlidCop 1 X-ray absorbers based upon the thermomechanically induced fatigue behavior of the material. X-ray power from APS insertion devices was used to expose 30 GlidCop 1 samples to 10000 thermal loading cycles each under various beam power conditions, and all of the samples were metallurgically examined for crack presence/geometry. In addition, an independent testing facility was hired to measure temperature-dependent mechanical data and uniaxial mechanical fatigue data for numerous GlidCop 1 samples. Data from these studies support finite element analysis (FEA) simulation and parametric models, allowing the development of a thermal fatigue model and the establishment of new design criteria so that the thermomechanically induced fatigue life of X-ray absorbers may be predicted. It is also demonstrated how the thermal fatigue model can be used as a tool to geometrically optimize X-ray absorber designs.

A Mini-Review on the Thermal Fatigue Properties of Copper Materials Applied at the Front-End of Synchrotron Radiation Facilities

“…It can be found that the strain generated in the first heating cycle causes plastic deformation if the yield point is exceeded, leading to the kinematic strain hardening, which locally increases the yield strength of the material [19]. Strain hardening is caused by crystal defects in the material, which can be grain boundaries, grain boundaries, cracks, or defects.…”

“…A multi-linear kinematic hardening model was also used, then the typical equivalent stress-equivalent total strain hysteresis curves were obtained, as shown in Figure 9. Typical equivalent stress-equivalent total strain hysteresis curves for specimens [19]. Figure 9.…”

“…The image on the right shows a magnified view of the bright field. The lower left image shows a highly magnified cross-section through the 1.8 mm long scratch above [19].…”

“…Figure9. Typical equivalent stress-equivalent total strain hysteresis curves for specimens[19]. Figure9.…”