  Collagen is the key protein of connective tissue (i.e., skin, tendons and
ligaments, cartilage, among others) accounting for 25% to 35% of the whole-body
protein content, and entitled of conferring mechanical stability. This protein
is also a fundamental building block of bone due to its excellent mechanical
properties together with carbonated hydroxyapatite minerals. While the
mechanical resilience and viscoelasticity have been studied both in vitro and
in vivo from the molecule to tissue level, wave propagation properties and
energy dissipation have not yet been deeply explored, in spite of being crucial
to understand the vibration dynamics of collagenous structures (e.g., eardrum,
cochlear membranes) upon impulsive loads. By using a bottom-up atomistic
modelling approach, here we study a collagen peptide under two distinct
impulsive displacement loads, including longitudinal and transversal inputs.
Using a one-dimensional string model as a model system, we investigate the
roles of hydration and load direction on wave propagation along the collagen
peptide and the related energy dissipation. We find that wave transmission and
energy-dissipation strongly depend on the loading direction. Also, the hydrated
collagen peptide can dissipate five times more energy than dehydrated one. Our
work suggests a distinct role of collagen in term of wave transmission of
different tissues such as tendon and eardrum. This study can step towards
understanding the mechanical behaviour of collagen upon transient loads, impact
loading and fatigue, and designing biomimetic and bio-inspired materials to
replace specific native tissues such as the tympanic membrane.
