Additive Manufacturing

PROJECT 3

Synopsis and Description

In this project we will make an introduction to designing a bar, with some AM considerations taken in to account. In summary you will design, analyze, and compare various bars with and without infill.

Suppose you are tasked with designing a 3D printed bar that will carry some load.

Task-1: Create 3D solid model of a 25x25 mm square hollow bar with 20x20 mm inner void (wall thickness 2.5 mm). Make the height of bar 50 mm. This is a hollow bar, in other words infill is 0%. Call this “Bar-1”.

Task-2: Create 3D solid model of a 25x25 mm square bar with 2.5 mm wall thickness and with 19% infill (use infill strut 0.5 mm). Call this “Bar-2”.

Here is a representative image of cross section of Bar-2:

Note: In Bar-2, there are four 0.5 mm infill struts in vertical and horizontal directions. Next, we will do some finite element analysis. You can create solid models for both bars in SW (or your choice of CAD software) and then run simulation for stress analysis. (Alternatively you can try using slicer software to create the infill and then convert your STL back to CAD file for the next task.)

Task-3: After creating your solid models, setup and run a simulation for stress analysis in SW (or your preferred CAD program).

• Define one end as fixed, and apply 450 N compressive force (in normal direction) on the other end. Note: “Normal direction” means normal to the cross section, in other words it means ‘normal to your screen when looking at the cross section given on page-1’. 
• Use ABS as material.
• Find the maximum stress on the model and take note of this max stress figure.

Make sure to complete Task-3 for both Bar-1 and Bar-2.

Deliverables: Put the following items in a MS-Word document and submit on Blackboard.

1. Write a brief INTRO paragraph to describe your work. State which software packages you use for every step (CAD, slicing, etc).

2. Insert 3D models’ views (screen shot of 3D model, as many different views as needed, minimum 1 view for each bar required)

3. Insert images of stress analysis with maximum stress value and location, for each bar (see the last image below).

4. For simplicity, we did not get into bending scenario. Write a paragraph (Max 15 sentences) on what factors would be important to consider for example if Bar-2 was subjected to bending load?

5. Now, suppose you will create another bar (Bar-3) comparable to Bar-2, in an attempt to increase performance (strength) of the bar, in other words your objective is to have less stress under same load. This time you will use a different infill design. Basically you will use the same wall dimensions as in Bar-2. You will also use the same infill % that of Bar-2, but you will try different infill patterns instead of simple straight orthogonal lines. For example you will use honeycomb infill, or any other infill pattern of choice.

5a- How would same infill % with different pattern affect performance in compression? Give your answer without actually simulating this, just hypothetically. Max 8 sentences.

5b- How would same infill % with different pattern affect performance in bending? Give your answer without actually simulating this, just hypothetically. Max 8 sentences.

6. OPTIONAL for EXTRA CREDIT (Extra 10% of this Project’s grade): Create this new Bar-3 as described in #5 (same walls, same infill %, different infill pattern) and test it same load. Then compare to Bar-2.

Solid model files to be emailed to Dr. Halim Ayan ( halim.ayan@utoledo.edu ). 

Due date: Monday 5:00 PM EST, August 1^st (8/1/2022)

Appendix

Here are some resources for SW simulation.

SW simulation – cantilever stress analysis

https://www.youtube.com/watch?v=4pbIAQQ9tGc

SW simulation

https://www.youtube.com/watch?v=7fQ0gxq3bMs

Material selection: ABS

Meshed solid model (a cylindrical bar) in SW

Stress analysis results 

Instructions on “How to find max value”:

Right Click on the Stress Result in the tree and select "Chart Options".  There is an option to "Show max annotation".  If you select that it should put a flag and pointer to the location of the maximum stress.

Stress results with max stress value and location