Additive manufacturing of viscoelastic materials
Described is a method of forming a structure having viscoelastic properties. The method can include a) depositing a layer of droplets of a solidifying material and a non-solidifying material, the droplets being deposited according to an occupancy matrix specifying voxels for the solidifying and non-solidifying materials, the solidifying and non-solidifying material being interspersed within the occupancy matrix, the occupancy matrix being generated by a probabilistic function; b) exposing the droplets of solidifying material to ultraviolet radiation to cure the solidifying material; and c) repeating a) and b) to deposit additional layers of droplets of solidifying and non-solidifying materials, thereby forming the structure having viscoelastic properties.
1. A method of forming a cellular foam having viscoelastic properties, the method comprising:
a) generating an occupancy matrix from a probabilistic function, wherein the probabilistic function is based on a prescribed percent liquid in a region of the cellular foam;
b) depositing a layer of droplets of a solidifying material and a non-solidifying material, the droplets being deposited according to the occupancy matrix specifying voxels for the solidifying and non-solidifying materials, the solidifying and non-solidifying material being interspersed within the voxels specified by the occupancy matrix;
c) exposing the droplets to ultraviolet radiation to cure the solidifying material, but not the non-solidifying material; and
d) repeating b) and c) to deposit additional layers of droplets of solidifying and non-solidifying materials, thereby forming the cellular foam having viscoelastic properties.
2. The method of claim 1 , wherein the probabilistic function is a random function.
3. The method of claim 1 , wherein the prescribed percent liquid is based on a predetermined physical property of the structure cellular foam.
4. The method of claim 3 , wherein the predetermined physical property of the cellular foam is storage modulus, loss modulus, or ratio of storage modulus to loss modulus.
5. The method of claim 3 , wherein the cellular foam has isotropic mechanical properties.
6. The method of claim 3 , wherein the cellular foam has anisotropic mechanical properties.
7. The method of claim 6 , wherein the percent liquid varies as a function of position.
8. The method of claim 6 , wherein the percent liquid is radially symmetric in two dimensions and varying in a third dimension.
9. The method of claim 8 , wherein the percent liquid varies with height.
10. The method of claim 1 , wherein each dimension of the voxels is between 5 μm and 50 μm.
11. The method of claim 1 , wherein 50% to 99% of the voxels are solidifying material.
12. The method of claim 11 , wherein 64% to 96% of the voxels are solidifying material.
13. The method of claim 1 , wherein the occupancy matrix has three dimensions.
14. The method of claim 1 , wherein the occupancy matrix has two dimensions.
15. The method of claim 1 , wherein the occupancy matrix specifies a region of the object.
16. The method of claim 1 , further comprising depositing a second solidifying material.
17. The method of claim 1 , further comprising depositing a second non-solidifying material.
18. The method of claim 1 , wherein the occupancy matrix for a subsequent layer is generated while depositing the layer of droplets of solidifying and non-solidifying materials.
19. The method of claim 1 , wherein the cellular foam is an open cellular foam.
20. The method of claim 1 , wherein the cellular foam is a closed cellular foam filled with liquid.