Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
Phys Rev Lett. 2016 Feb 26;116(8):085502. doi: 10.1103/PhysRevLett.116.085502.
Quasistatic strain-controlled measurements of stress versus strain curves in macroscopic amorphous solids result in a nonlinear-looking curve that ends up either in mechanical collapse or in a steady state with fluctuations around a mean stress that remains constant with increasing strain. It is therefore very tempting to fit a nonlinear expansion of the stress in powers of the strain. We argue here that at low temperatures the meaning of such an expansion needs to be reconsidered. We point out the enormous difference between quenched and annealed averages of the stress versus strain curves and propose that a useful description of the mechanical response is given by a stress (or strain) -dependent shear modulus for which a theoretical evaluation exists. The elastic response is piecewise linear rather than nonlinear.
在宏观非晶固体中，通过准静态应变控制测量应力-应变曲线会得到一条看起来是非线性的曲线，该曲线最终要么在力学破坏中结束，要么在一个围绕平均值的稳定状态下波动，而平均值随着应变的增加保持不变。因此，非常诱人的是将应力在应变的幂次上进行非线性展开。在这里，我们认为在低温下，这种展开的意义需要重新考虑。我们指出了淬火和退火平均的应力-应变曲线之间的巨大差异，并提出了一个有用的力学响应描述，即存在理论评估的与应力（或应变）相关的剪切模量。弹性响应是分段线性的，而不是非线性的。
