This example is the third in a series describing the "cell growth" material in FEBio. To better understand the material presented here, please refer to the examples on Single Cell Growth and Internal Constraints to Growth.
In this example we consider the influence of external constraints on cell growth. External constraints may consist of structures against which a growing cell or tissue may abut, or a substrate to which the growing cell or tissue is attached. Two such cases are considered here.
The next example in this series demonstrates the interaction of Growth and Buckling.
Gerard
In this example we consider the influence of external constraints on cell growth. External constraints may consist of structures against which a growing cell or tissue may abut, or a substrate to which the growing cell or tissue is attached. Two such cases are considered here.
- Constrained Cell Growth
(click on image to see movie)
ConstrainedCellGrowth.feb
In this first example of externally constrained growth, consider a single circular cell, which is set to grow fivefold by increasing its intracellular membrane-impermeant solute and solid content accordingly. The cell is placed between two parallel rigid platens that constrain its growth along the direction normal to the plates. In FEBio, sliding contact interfaces are defined between the cell and these rigid platens. To facilitate convergence of the contact algorithm, an isotropic solid matrix is associated with the cell to represent is cytoskeletal stiffness, with a Young's modulus of 1 kPa. Thus, the material representing the cell is a "solid mixture" consisting of the "cell growth" and a "neo-Hookean" material. A 2D analysis is performed for illustration. As is apparent from the attached movie, the cell grows by elongating along the parallel platens, even though its solid matrix is isotropic. Therefore, growth is easily guided by external constraints such as these rigid platens. - Growth of One Layer in a Bilayered Strip
(click on image to see movie)
BilayeredStrip.feb
In this second example of externally constrained growth, consider two bonded layers of tissue where cell growth occurs only in the top layer. Both layers have a neo-Hookean solid matrix with a Young's modulus of 100 kPa. The cell growth in the top layer is achieved using a 2.5 fold increase in the intracellular membrane-impermeant solute and solid content. The resulting effect of the growth is apparent in the curling of the bilayered strip into a nearly perfect circular shape. This example shows that external constraints may guide growth toward the morphogenesis of circular and tubular structures.
The next example in this series demonstrates the interaction of Growth and Buckling.
Gerard
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