Elastic hysteresis phenomena were observed in ULE and Zerodur glasses at elevated temperatures up to glass transition. These effects were found under load deformation testing using four-point bending. Permanent creep resulted in Zerodur at 900°C and in ULE at 1000°C. The deformation was monitored at mid-span of the samples with a capacitance-type transducer having 0.01 micrometer resolution. These hysteresis.effects may be classified as elastic bimodulus between loading and unloading; that is, two different elastic moduli were observed between loading and unloading. Upon complete unloading, a minimal deformation state promptly returned, indicating little or no viscoelastic creep. The hysteresis effect may be attributed to a change in glass structure as a function of stress state. A description of the test apparatus and procedure, test results for both glasses at several elevated temperatures, and an elementary discussion of continuum theory of constitutive behavior are included.

Date Published: 16 January 1989
PDF: 8 pages
Proc. SPIE 0970, Properties and Characteristics of Optical Glass, (16 January 1989); doi: 10.1117/12.948176

Published in SPIE Proceedings Vol. 0970:
Properties and Characteristics of Optical Glass
Alexander J. Marker III, Editor(s)