Relatively High Strain Rate Behavior of Structural Silicone Sealants
In 2002, eight silicone sealant products were tested at GE’s Global Research & Development Center on tensile testing equipment capable of producing relatively high crosshead speeds. The sealants were tested at different strain rates and different configurations (shear and tensile) to assess their material response characteristics under higher-than-typical strain rates in an effort to simulate atypical loadings (high wind events, seismic, blast, etc.), which impart energy into glazing systems differently that typical wind pressure loads. The study was useful to: (1) screen for formulations that provide the desired characteristics necessary to absorb the energy imparted into an affected glazing system, and (2) compare the mechanical properties of each formulation when pulled at a near-instantaneous strain rate (meters per second) versus the well-known mechanical properties of these products when pulled at a standardized (i. e., slow) strain rate (inches per minute).
The results of a two-part high modulus structural silicone from the 2002 testing is presented below as it is relevant to the topic of this paper. The data revealed increasing load and elongation values in both tension and shear as strain rate increases, and is reported in Table 1 and shown in Figs. 18-27. These findings are generally in agreement with Karpati’s findings from 1972 . Similar data has also been reported by Yarosh .