Direct numerical simulations of three-dimensional surface instability patterns in thin film-compliant substrate...

Area of Science:

• Materials Science
• Computational Mechanics
• Surface Physics

Background:

• Surface wrinkling in thin films bonded to compliant substrates is a common phenomenon driven by in-plane compressive loading.
• Understanding these deformation instabilities is crucial for designing advanced materials and microdevices.

Purpose of the Study:

• To numerically investigate three-dimensional surface instability patterns.
• To simulate the entire process of wrinkle formation from pre-instability to post-instability.
• To analyze the influence of biaxial loading conditions on wrinkle morphology.

Main Methods:

• Employed a recently developed computational approach for direct simulation of surface wrinkling.
• Utilized embedded imperfections with perturbed material properties at the film-substrate interface.
• Covered the full spectrum of biaxial loading, from uniaxial to equi-biaxial compression.

Main Results:

• Successfully simulated complex wrinkle patterns, including sinusoidal, herringbone, labyrinth, and checkerboard morphologies.
• Demonstrated that the state of biaxiality significantly influences the resulting surface patterns.
• Correlated specific bifurcation modes with abrupt changes in the load-displacement response.

Conclusions:

• The computational approach enables prediction of temporal evolution of wrinkle patterns in a single simulation.
• Loading conditions are key determinants of the type and complexity of surface instability patterns formed.
• This work provides insights into controlling surface topography for functional applications.