# Flexible Patterns for Soft 3D Printed Fabrications

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## Abstract

**:**

## 1. Introduction

- We compared soft printing materials to check criteria that we specified in the experiment.
- We developed a specific design for the interior of soft 3D printed fabrications along with flexible patterns based on the non-homogenous hybrid honeycomb structure.
- We conducted experimental compression, tension and flexure tests to reveal the efficiency of each presented pattern.

## 2. Related Work

#### 2.1. Soft Materials

#### 2.2. Infill Patterns

## 3. Method

## 4. Flexibility of the Honeycomb Pattern

_{x}and A

_{y}are the affected areas of the element by compression load, b is the depth of the element;

_{x}and P

_{y}are the axial loads; ${M}_{x}$ and ${M}_{y}$ are the bending moments on the x and y directional beam;

_{1}and σ

_{2}are x and y directional forces;

## 5. Soft Printing Materials

## 6. Experimental Results

## 7. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 4.**Creation of patterns for each partitioned region, (

**a**) the size of the fish model is 14 cm × 8 cm × 2 cm, (

**b**) the size of the bunny model is 10 cm × 8 cm × 2 cm.

**Figure 5.**(

**a**) Honeycomb pattern and (

**b**) hexagonal trapezoid pattern. The size of the bear models is 14 cm × 8 cm × 2 cm.

**Figure 7.**Compression effects on bunny model, the size of bunny models is 10 cm × 8 cm × 2 cm. (

**a**) the bunny model with larger infills tested with a pen, (

**b**) the bunny model with smaller infills tested with a pen (

**c**) the bunny model with smaller infills tested with metallic stick.

**Figure 8.**Compression effects on the models filled with the homogenous honeycomb structure, the size of bunny models is 1 0 cm × 8 cm × 2 cm, the size of the cube model is 10 cm × 10 cm × 5 cm, (

**a**) the bunny model with fully filled homogenous honeycomb, it is tested with a metallic stick, (

**b**) the box model filled with homogenous honeycomb, its backside is tested with a metallic stick, (

**c**) the bunny model with sparse homogenous honeycomb, its back side is tested with a metallic stick, (

**d**) the bunny model with sparse homogenous honeycomb, its front side is tested with a metallic stick.

**Figure 9.**Thermoplastic polyurethane (TPU) categories and its with thermoplastic elastomer (TPE) hardness range.

A | B | C | D |
---|---|---|---|

${A}_{1}\le x\le {A}_{n}$ | ${B}_{1}\le x\le {B}_{n}$ | ${C}_{1}\le x\le {C}_{n}$ | ${D}_{1}\le x\le {D}_{n}$ |

or | or | or | or |

${A}_{1}\le y\le {A}_{n}$ | ${B}_{1}\le y\le {B}_{n}$ | ${C}_{1}\le y\le {C}_{n}$ | ${D}_{1}\le y\le {D}_{n}$ |

$Colum{n}_{1}\in \left[{A}_{n-1},{A}_{n}\right]$ | $Colum{n}_{2}\in \left[{B}_{n-1},{B}_{n}\right]$ | $Colum{n}_{3}\in \left[{C}_{n-1},{C}_{n}\right]$ | $Colum{n}_{4}\in \left[{D}_{n-1},{D}_{n}\right]$ |

Hardness scale (Shore A) | |||
---|---|---|---|

No. | Category of Objects | Hardness | |

1. | Shopping cartwheel | 100A | Hard |

2. | Phone cord | 90A | Medium Hard |

3. | Leather belt | 85A | Medium Soft |

4. | Tire tread | 60 A | |

5. | Pencil eraser | 40A | Soft |

6. | Rubber band | 20A |

No. | Model | Tension Strength | |
---|---|---|---|

Material | |||

TPU | TPE | ||

1 | Box 10 cm × 5 cm × 1.5 cm | 778N | 1400N |

No. | Model | Material | Compression Strength | |
---|---|---|---|---|

X-Directional | Y-Directional | |||

1 | Box Model with honeycomb patterns 10 cm × 10 cm × 5 cm | TPU | 503N | 122N |

No. | Model | Flexural Strength | |
---|---|---|---|

Honeycomb Pattern | Hexagonal Trapezoid | ||

1 | Box with TPU 10 cm × 10 cm × 5 cm | 212N | 343N |

2 | Box with TPE 10 cm × 10 cm × 5 cm | 75N | 216N |

No. | Model | Weight | |||

Honeycomb-like pattern | Hexagonal trapezoid | Grid pattern | |||

1. | TPU Printed 2D Fish 14 cm × 8 cm × 2 cm | 47 g | 51 g | 60 g | |

Non-Homogenous Based Honeycomb Pattern | Homogenous Honeycomb Based Pattern | ||||

2. | TPU Printed 2D Bunny 10 cm × 8 cm × 2 cm | 22 g | 26 g |

No. | Model | Weight | ||

Honeycomb-like Pattern | Grid Pattern | |||

1. | TPU Printed2D Bunny10 cm × 8 cm × 2 cm | 24 g | 22 g | 60 g |

No. | Model | Material | Weight | |

Honeycomb-like Pattern | Hexagonal Trapezoid | |||

1. | 2D Bear 14 cm × 8 cm × 2 cm | TPU | 34 g | 41 g |

2. | 3D Box 10 cm ×10 cm × 5 cm | TPU | 66 g | 103 g |

3. | 3D Box 10 cm ×10 cm × 5 cm | TPU | 62 g | 79 g |

4. | 3D Box 10 cm ×10 cm × 5 cm | TPE | 60 g | 80 g |

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**MDPI and ACS Style**

Chynybekova, K.; Choi, S.-M.
Flexible Patterns for Soft 3D Printed Fabrications. *Symmetry* **2019**, *11*, 1398.
https://doi.org/10.3390/sym11111398

**AMA Style**

Chynybekova K, Choi S-M.
Flexible Patterns for Soft 3D Printed Fabrications. *Symmetry*. 2019; 11(11):1398.
https://doi.org/10.3390/sym11111398

**Chicago/Turabian Style**

Chynybekova, Kanygul, and Soo-Mi Choi.
2019. "Flexible Patterns for Soft 3D Printed Fabrications" *Symmetry* 11, no. 11: 1398.
https://doi.org/10.3390/sym11111398