Generative Designed Flooding Habitat

This habitat was created using Autodesk Fusion 360 for the "Make it Resilient" contest. It incorporates several of Fusion 360's unique features, including the Generative Design tool.

Flooding has become a more prevalent natural disaster worldwide, exacerbated by the threat of climate change. In response to this growing issue, a number of preventive and protective measures and developments have been taken to identify the occurrence of flooding before it happens and to build shelters and homes that can withstand such situations.

Statistics that establish a problem

• "Flooding is the most common type of natural disaster worldwide" - NFI
• "In 2022 there were 176 flood disasters recorded" - Statista
• "By 2050, US government agencies predict that sea levels along the coast could rise by another 25–30 centimeters" - National Ocean Service

This instructable features one such potential flood shelter designed to protect its inhabitants from the threat of flooding. This design can be divided into three main components, as shown in the attached diagram: the main housing, the legs, and the anchors. An animation that showcases an in-depth exploded view of the habitat is also attached.

Several crucial dimensions of the habitat had to be determined. These included the height clearance of the legs and the height within the main housing itself. According to OceanService, major flooding can reach up to 4 feet in height, which is why I conservatively designed the legs a little above 6 feet (2 meters) in height. Using anthropometric information regarding the 95th percentile height from Herman Miller and reviewing average heights of indoor spaces, I decided upon an 8ft (2445mm) height for the main housing. The 95th percentile male height (6ft 1in) falls well within this measurement.

For the shape of the main housing, I took inspiration from the hexagon-like shape of the starter model by the Aurelia Institute. The changes were that I gave it a much bigger base such that it could comfortably seat 10 and fill up with even more.

For the housing's overall material, I chose galvanized steel (wall thickness = 20mm) due to its strength and resistance to corrosion and moisture. I also added strips of layered tempered glass along the top for lighting and the sides so that the inhabitants are aware of their surroundings.

As seen in the rendered image, 5 sides of the housing contain seating and storage space for supplies such as food, communication, power, etc. The other side contains a water-sealed doorway that connects to a detachable staircase for users to climb into the housing. The seating was dimensioned using industry averages (e.g., seat width = 470x500mm, height = 480mm).

For the wall behind the seating, I used Fusion 360's automated modeling tool to generate some fillets, which helped structurally strengthen the main housing (see attached images).

Furthermore, the top of the main housing contains a trap door (as a form of emergency exit) and space for solar panels (allowing for it to be self-sufficient).

The design of the legs required considerable consideration. Therefore, I started by calculating rough estimates for the forces they would experience. The two forces would be the compressive force from the main housing (and everything within it) and the lateral force from the flood.

I started off by designing a base geometry for the legs. I made 6 hollow ellipse tubes mounted onto a hexagonal plate on each side. I chose to make the tubes ellipses since there would be less surface area facing outwards (in the direction of the flooding). This could help decrease the lateral force upon the structure. Moving forward, I decided to use Fusion 360's generative design tool to optimize the design further.

Generative design is a process that uses computational methods to iteratively generate optimized solutions to given design problems. Through iterations, material is removed and added, monitoring how that affects the factor of safety and overall mass of the structure. In this section I have attached several images that detail the process I went through in setting up my generative design study.

Calculations:

Compressive load - This load had several components, including the weight of the main housing, the inhabitants, and any supplies/appliances within.

The weight of the main housing was calculated by utilizing its volumetric information in Fusion 360 and multiplying that by the density of galvanized steel.

total volume - 9.35800m^3

density of galvanized steel - 7,850kg/m^3

mass of main housing = 7850 x 9.358 = 73,460kg

I then used the 95th percentile weight of men (because it's higher than women) and multiplied that by ten to account for the ten inhabitants

112x10 = 1,120kg

Finally, I added 300kg, which should more than account for a week's worth of food for ten and any additional appliances I had missed out on.

Total mass = 74,880kg

Total Weight = 74,880 x 9.81 = 734,572.8 N

I rounded this up to 735,000N for good measure

Lateral load - Through research (https://www.weather.gov/pbz/floods), I found that for each foot, a flood can exert up to 500 pounds of force (2224N). Since I designed the habitat for up to 6ft of flooding I multiplied this by 6.

Total Lateral Force = 2224x6 = 13344

Rounded up to 13,500 for good measure.

I also inputted some symmetricity constraints since I wanted the base to be symmetric. Following this, I ran the generative design study. Attached are images of a couple of the different bodies that were generated. Some of the bodies generated were not viable (as seen in the scene in the image). Following my selection of the leg design (with an FOS (Factor of safety) of 10.3 (Material: Titanium 6Al-4V), I ran a finite element analysis simulation under the expected loads to confirm the factor of safety (images attached). The FOS from the finite element analysis was 1.8, which is different from that given by the Gen design tool. While an FOS of 1.8 means that the design can withstand 1.8x the load case, ideally for a structure like this, an FOS of at least 3 is optimal. Given in the image, most of the design is blue (has a FOS above 8); with some small changes to the geometry, the FOS can be raised above 3.

Another concern would be the manufacturability of this part. While generatively designed parts are currently difficult to manufacture on a large commercial scale, breakthroughs in large-scale metal 3D printing will still make this design viable in the foreseeable future.

The anchors are the lowest part of the structure, they're intended to dig 3 or more feet into the earth and act as anchors for the structure itself. This helps prevent flooding waters from moving the structure vertically and laterally.

Overall, using generatively designed structures to combat natural disasters could very well be a new, more efficient method of protecting communities. While some changes need to be made to the design and the establishment of a truly accurate load case, the outcome seems very promising. Generative design can be utilized to improve current "standard geometries" across industries in the near future.

Thank you for reading (I've attached the step file for my cad)