page_title: Fracture of soft materials
section_title: Interface cracks
hierarchical_section_title: Fracture of soft materials / Interface cracks
caption_attribution_description: This figure represents the parabolic shape of the crack tip in a interface crack problem.
context_page_description: Soft materials consist of a type of material that e.g. includes soft biological tissues as well as synthetic elastomers, and that is very sensitive to thermal variations. Hence, soft materials can become highly deformed before crack propagation. Consequently, the stress field close to the crack tip is significantly different from the traditional formulation encountered in the Linear elastic fracture mechanics. Therefore, fracture analysis for these applications requires a special attention.
  The Linear Elastic Fracture Mechanics and K-field are based on the assumption of infinitesimal deformation, and as a result are not suitable to describe the fracture of soft materials. The reason for this is that soft materials usually become highly deformed and blunted before crack propagation. However, LEFM general approach can be applied to understand the basics of fracture on soft materials.
  Alternatively to the linear approach of fracture in LEFM, the solution for the deformation and crack stress field in soft materials considers large deformation and is derived from the finite strain elastostatics framework and hyperelastic material models.
context_section_description: To approach the interaction of adhesion between soft adhesives and rigid substrates, the asymptotic solution for an interface crack problem between a GNH material and a rigid substrate is specified. The interface crack configuration considered here is shown in Fig.3 where the lateral slip is disregarded.
  For the special neo-Hookean case with n=1, and  , the solution for the deformed coordinates is
  ,
  which is equivalent to
  .
  According to the above equation, the crack on this type of interface is found to open with a parabolic shape. This is confirmed by plotting the normalized coordinates  vs   for different  ratios (see Fig. 4).
  To go through the analysis of the interface between two GNH sheets with the same hardening characteristics, refer to the model described by Gaubelle and Knauss.
caption: Figure 4: Soft material and rigid substrate interface. A) Plot of the crack tip deformed coordinates. B) Parabolic shape of the crack tip.
exif: {}