Simulate Early, Simulate Often... In Rhino
Scan & Solve Pro provides the ability to do static stress simulations on designs for your product. This is beneficial for designing, as well as simply finding the maximum loads the structure can handle. You can test many different loading conditions, which can be beneficial to find the weakest area of the model for each condition. The results can be used to optimize the shape of your design and help with material selection. In this demonstration, a swim platform was analyzed to find how the design could be improved and find the load capacity when a person is standing on it. A swim platform is commonly used on ski boats by skiers and swimmers to get into and out of the water. Swim platforms are typically made of teak wood or fiberglass and are mounted on the back of the boat.
Figure 1. Swim Platform Designs. Two examples of teak swim platforms attached to the back of ski boats.
In this scenario, a teak design was used for the platform with stainless steel making up the three supports. The supports are attached to the back of the boat in a similar way to the image on the right in Figure 1. Many different loading conditions were used that resemble people standing on the swim platform. This was done to find the critical areas and the loading condition which makes the model most likely to fail. Initially, only simulations were done that modeled a single person standing on the platform. Then, additional simulations were conducted to test when multiple people are standing on the platform because this is expected at some point in its lifespan.
Figure 2. Swim Platform Design. Model of a swim platform created to analyze with Scan & Solve Pro
For the single person simulation, four loading conditions were tested with a loading of 300 lbs and are shown in Figure 3. They consist of a person standing in the front-center, back-center, front-side, and back-side of the platform. Since the platform is symmetric horizontally, the conditions were the person is standing to the side only needs to be simulated on one side because the results would be the same as the other side.
Figure 3. Single Person Loading Conditions. Locations of the four loading conditions tested when a person is standing on the swim platform. The arrows show the 300 lb force applied to the model where the person feet are located. Loading Conditions: Front-Side(Top Left) Back-Center(Top Right) Front-Center(Bottom Left) Back-Side(Bottom Right).
The results give plenty of useful data and visuals to show how the model performs. The danger level can be looked at to see how close the model is to failure. The model is also colored with a spectrum to view the value of the danger level at each point on the entire part. This gives an easy way to see where the part is prone to failure. The simulations showed that the platform was strong enough to hold the person at all four locations because the maximum danger levels were all less than 1. It was also observed that the locations of these maximum danger levels were near the central support of the platform. When redesigning this could be an area to consider improving by either using 4 supports instead of 3 or changing the way the teak is attached to the supports.
Figure 4. Danger Level Diagrams. Diagrams of the danger level in the swim platform under the four loading conditions. Loading Conditions: Front-Side(Top Left) Back-Center(Top Right) Front-Center(Bottom Left) Back-Side(Bottom Right).
The condition that resulted in the highest danger level was at the Front-Side location. The spot where the swim platform should fail first is at the point on the danger level diagram that corresponds to 0.18345. Knowing this data, we can also find the maximum weight the swim platform can handle in this situation by simulating with the front-side scenario. When the weight is set to 1635 lbs it gives a danger level of 0.99307 which means it is approximately the maximum weight the platform can hold in this scenario. Although this is the case, that is only for when one person is standing on it and 1635 lbs is unrealistic for the weight of a single person. This means our design is safe for all singe-person loading situations. We also want to analyze the situations when multiple people are on the platform to show that it is safe for every possible expected loading condition.
Four more simulations were conducted with two 300 lb loads to model two people at various locations. Once again, the danger level diagram and maximum danger level can be used for analysis. Here, the largest maximum danger level occurs when 2 people are standing on one side of the platform which is the bottom right scenario in Figures 5 and 6. It is also the largest of all the simulations tested including the single-person scenarios. This is our critical loading condition and the danger level is well below 1 meaning that our design is strong enough for this application.
Figure 5. Four Loading Conditions Used to Simulate Multiple People. Loading Conditions: Center(Top Left), Front(Top Right), Back(Bottom Left), Side(Bottom Right).
Figure 6. Danger Level Diagrams for Two Person Loading. Diagrams of the danger level in the swim platform under the four loading conditions. Loading Conditions: Center(Top Left), Front(Top Right), Back(Bottom Left), Side(Bottom Right).
Table 2. Danger Level Values. Maximum danger level for each 2-person loading condition tested.
Using Scan and Solve Pro we were able to simulate our design to validate it. We saw that this could be tested with many different loading conditions if your design is expected to be under different types of loading. Each case can be viewed to see where the part is most likely to fail which helps the designer find where to improve their design or prove that it is already safe enough to manufacture.