Strain localization and yielding dynamics in disordered collagen networks

Area of Science:

• Biomaterials Science
• Biophysics
• Extracellular Matrix Research

Background:

• Collagen is the primary structural protein in mammals, crucial for connective tissue mechanics and cellular regulation.
• Collagen networks exhibit strain-stiffening, but the link between local deformation and overall network failure remains unclear.

Purpose of the Study:

• To investigate the yielding dynamics and failure mechanisms of in vitro reconstituted type-I collagen networks.
• To correlate macroscopic network failure with local deformation and slippage phenomena.

Main Methods:

• Utilized shear rheology combined with in situ high-resolution boundary imaging to study collagen network mechanics.
• Employed colloidal tracer particles to measure local velocity profiles and identify strain localization.
• Developed a continuum affine network model to map network behavior and predict failure points.

Main Results:

• Observed an initial increase in differential shear modulus (K) followed by a drop beyond the yield strain, indicating network yielding.
• Identified strain localization and slippage at the network-rheometer interface preceding macroscopic failure.
• Demonstrated that these yielding dynamics are consistent across varying collagen concentrations, strain rates, and polymerization temperatures.

Conclusions:

• Macroscopic failure in collagen networks is driven by localized deformation, strain-localization, and interface slippage.
• The findings provide critical insights into the mechanical resilience of collagen networks, with implications for tissue engineering and biomaterial design.