Evaluation of the surface strength of glass plates shaped by hot slumping process

• Published in: arXiv.org
• Main Authors: Proserpio, L, Basso, S, Borsa, F, Citterio, O, Civitani, M, Ghigo, M, Pareschi, G, Salmaso, B, Sironi, G, Spiga, D, Tagliaferri, G, D'Este, A, Dall'Igna, R, Silvestri, M, Parodi, G, Martelli, F, Bavdaz, M, Wille, E
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 09.07.2014
• Subjects: Astronomy; Borosilicate glass; Destructive testing; Finite element method; Glass plates; Molds; Nonlinear analysis; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Detectors; Physics - Instrumentation and Methods for Astrophysics; Plates; Radius of curvature; Segmented mirrors; Slumping; Space missions; Statistical analysis; Structural design; Telescope design; Thermal transformations; X ray telescopes
• DOI: 10.48550/arxiv.1402.3445

The Hot Slumping Technology is under development by several research groups in the world for the realization of grazing-incidence segmented mirrors for X-ray astronomy, based on thin glass plates shaped over a mould at temperatures above the transformation point. The performed thermal cycle and related operations might have effects on the strength characteristics of the glass, with consequences on the structural design of the elemental optical modules and consecutively on the entire X-ray optic for large astronomical missions like IXO and ATHENA. The mechanical strength of glass plates after they underwent the slumping process was tested through destructive double-ring tests in the context of a study performed by the Astronomical Observatory of Brera with the collaboration of Stazione Sperimentale del Vetro and BCV Progetti. The entire study has been realized on more than 200 D263 Schott borosilicate glass specimens of dimension 100 mm x 100 mm and thickness 0.4 mm, either flat or bent at a Radius of Curvature of 1000 mm through the particular pressure assisted hot slumping process developed by INAF-OAB. The collected experimental data have been compared to non-linear FEM analyses and treated with Weibull statistic to assess the current IXO glass X-ray telescope design, in terms of survival probability, when subject to static and acoustic loads characteristic of the launch phase. The paper describes the activities performed and presents the obtained results.