Fig. 2.
a The standard linear model for viscoelastic materials. This model consists of two springs and a dashpot. b The applied square shape force with time. The samples were exposed for 15 s
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.