Introduction: FEA-Optimised Novel Touch Less All-in-One Tool for COVID-19
Hygiene ! Nowadays, this word is a part of our everyday life, especially with recent implications, but despite all of the advice not enough is being done for reducing contact with frequently touched objects . COVID-19 is an example of an easily spreadable disease which can often linger on objects (fomites) . Commonly touched objects can pose health risks and can increase the transmission . An example of a commonly interacted object is door handles, which users commonly make direct contact to open. For many this has been a challenge, from using elbows to legs, COVID-19 has changed our interactions with everyday objects. There are solutions on the market which claim to open doors and press buttons. However, there are no solutions which have all the necessary features, forcing many to carry multiple devices with them which can be a hassle at the very least.
What will you learn?
- Introduction to Finite Element Analysis (FEA) via Fusion 360 and ANSYS Mechanical
- Introduction into the design process
- Introduction into 3D Printing and Optimisation
(Disclaimer: I am not responsible for any damage, harm or otherwise caused by following any instructions or using any content created, so try at your own risk)
- Fusion 360
- ANSYS Mechanical
- PLA Filament
- 3D Printer (Generic FDM)
Step 1: Introduction to the Design Process
For every project, there is a high likelihood you will be faced with creating a certain process and workflow. In engineering, this is called "The Design Process". For this project, my design process involved these steps:
- Concept Creation
- Concept Evaluation
- Final Concept
- Final Design
This is a basic design process which when followed can output a chosen design, which has been rigorously evaluated. However, not every design which comes out of the design process will be the correct solution. It is always important to evaluate the final outcome impartially. For this project, there were key considerations which I made, which will be explained in further detail later on:
- Value Engineering
- Human-Centred Design Approach
- Lean Design
- Design Thinking
Step 2: Introduction to Value Engineering
Value engineering is a way of reducing costs of a product, whilst not impairing the product's function. This is normally achieved for product which require mass-production, as every cost-cutting measure can significantly decrease production costs. It is important when considering value engineering , the function of the product should be reduced or altered. For this design, the following value engineering techniques will be used:
- Mass Reduction: Using FEA Analysis we can target regions which require higher amounts of material for function whilst reducing regions which do not require any.
- Design Specification: By also ensure a pre-determine criteria is in place, we can reduce the cost and mass of the design whilst ensuring all our necessary specification points are met
As part of value engineering, we can also implement lean manufacturing and design techniques which aims to reduce material.
Step 3: Introduction to Human-Centred Design
Human-centred design has been a staple in designing for sustainability. However, recently the adoption of this framework has increased in mainstream engineering. The process entails for a product to be adopted, it must be a mix of three aspects (adapted from E4C):
- User Desirability
- Technology Feasibility
- Business viability
By applying these aspects to a product, customer adoption is more likely to be higher. The design framework also incorporates ergonomics and anthropometrics. When designers require a human centred design approach the following types of data are collect:
Primary: Questionnaires, focus groups etc.
Secondary: Ergonomics and Anthropometrics
Step 4: Introduction to Design Thinking
Design thinking is a very important part of the design process at it allows user understanding and to help with innovation. The steps are:
Empathize: Contextual research and understanding user needs
Define: Project constraints and problem development
Ideate: Solution brainstorming and development
Prototype: CAD or modelling
Step 5: Contextual Research
When researching int your chosen problem and issue, it is important to consider your target market. In many different countries, this problem may be affecting people differently. It is important to consider a range of factors.For this design my intended target market is: "children up until older adults, who need an effective solution to interact with commonly interacted objects, including and not limited to: handle, knobs, touchscreens, buttons. They require an affordable, functional and aesthetic product which has a small form factor for easy portability."
Now considering the target market, to maximise product interactions the following considerations must be made:
- Anthropometrics: Measurements of human data, in this scenario hand measurements are the most suitable
- Ergonomics: Human use optimisation of a product
- Stimulus Modalities: The senses enhanced when using a product, in this case mechanoreception is the most important. Research shows multisensory design (when multiple sense interact) can provide better usability and satisfaction.
Step 6: Data Collection
For this project I collected some data to better understand my user. In this case I used a questionnaire and posted into forums. Data collection is an important process of informing your design, and should always be done impartially. Stratified sampling is one way to determine the needs of multiple groups, whilst providing greater precision than random sampling and also requires less participants.
Step 7: Developing a Design Specification
The design specification allows for easy constraints providing guidance for the product. A good specification will have 5 must points, 4 should points and 3 could points. Here is a list of guidance for a design specification:
- Specification points are feasible
- Specification points are measurable
- Specification points are quite specific
- Specification points are based on research and data
Step 8: Design Brief
A brief outlines the problem you will solve and should be/contain:
- The predefined problem
- The target market
- The product environment/ where it will be used
It is important that this design brief is achieved before thoughts on producing a product, otherwise issues such as design fixation and poor design will occur later down the line. It is also important that your design brief is not too overambitious.
Step 9: Product Concepts
With all of the design constraints and overall data completed, the next stage is to design concepts. Blue-sky thinking is an effective way of brainstorming before refining ideas into concepts based on predetermined factors. I created and sketched out 3 concepts, with a small overview for each.
Step 10: Evaluating Concepts
The evaluation process of concept designs is an important part of your project, and one of the best ways to analyse is based on the design specification, using decision matrices. Decision matrices numerically compare specification points (usually out of 5) for each idea, and are often weighted based on relevant importance. The scores are then totalled and the design with the highest score should be chosen. I have posted an example (not for this project) which indicates an basic decision matrix
Step 11: Sketching in Fusion 360
With my design chosen,the next steps is to create my model using CAD software. I am new to Fusion 360, but since it is accessible to more people I decided it was best to used it. These steps are quite similar to many other CAD software, and can be followed on with other popular software.
I began by creating the basic outline of the design using knob size data for the the inner diameter of the larger hole.
For the grip pattern I used a rectangular pattern. For the kerf cuts, I used a circular pattern to easily produce the cuts. I then extruded it a 15mm height, to provide the minimum comfortable grip
Step 12: Scaling the Extrusion
After realising the design needs to be slightly bigger, I decided to add a scale of 1.2 to better adjust the design for the intended usage.
Step 13: Adding the Finger Holds
For a more ergonomic grip I decided to add some finger holds. These finger holds were of 15mm diameter, which I found the best to suit a wide range of people. However, you can change this your self if your prefer a different grip.
- Start by creating a mirror line directly in the middle of the piece
- Add one circle and using the smart dimension tool size it accordingly (15mm).
- Using the rectangular pattern feature space out three holes accordingly ensuring the last one is not too close to the bending regions.
- Mirror the pattern to the other side and extrude cut through the entire body
- Add fillets to reduce the sharpness of the cut
Step 14: Stress Analysis and Design Refining
Before starting there are limitations to this modelling. PLA does not behave linearly (mostly) and using FDM 3D printing the material will ultimately behave anisotropically
Before we move on to mass reduction, it is important we remove any regions which are structurally poor which can easily break. The best way to do this is stress analysis. For this project we will used a static stress analysis.
- Start by adding a physical material to your model. This can be achieved by navigating the project tree, right clicking on the body and choosing the physical material section. For this project we can use polystyrene (due to the similarity in the properties) but it is recommended you create your own material using the custom datasheet for your filament.
- Navigate to the simulation tab and choose static stress analysis. Start by adding your forces as a structural load. Remember to visualise where the forces will be coming from, in this case it will be primarily with the finger grips. Ensuring the direction is correct, choose the magnitude of your force. Remember force is a vector quantity so magnitude and direction is important
- Add constraints, consider which parts of the design should not be moving when the force is applied. I decided to place a constraints on the outside curve.
- Solve your overall design see the weak points in your design. Above in the image, you can see an earlier iteration of my design, where there were kerfs either end of the design, which were causing trouble so I removed the section.
- I also tested out the internal stresses to ensure there was no damage to the design when slid over larger diameters.
Step 15: Shape Optimisation on Fusion 360
(Right)Images used courtesy of ANSYS, Inc. created using ANSYS Mechanical 2020 R1
This is the first part of mass reduction, and this will be used in conjunction with ANSYS software.
- After creating a new simulation choose shape optimisation, please note this cannot be done locally and will use cloud credits !
- Repeat the steps before into adding all necessary forces, I recommend choosing a worst case scenario to ensure increase reliability of the optimisation.
- After solving, use the slider to determine the material required and promote the mesh. Then export the mesh as an .obj (for ansyis) and a .stl for slicing
- Return to the original design and export the file as an iges or step file (step is easier)
Step 16: CAD Files
Step 17: ANSYS Shape Optimisation
Images used courtesy of ANSYS, Inc. created using ANSYS Mechanical 2020 R1
- Navigate to the workbench and create a new static structural study and import the model as geometry
- Open the model and begin to recreate the stress simulation as you did on Fusion 360
- Solve the model and I recommend to view total deformation before solving equivalent stress to ensure everything is fully functional and as you want.
- Navigate to the solution hierarchy and right click on the stress button and click on equivalent stress and solve.
- Click on the undeformed version and create a capped isosurface (bottom)
- Drag the slider to determine the required amounts of material needed and once happy export the mesh as an STL file
Images courtesy of ANSYS
Step 18: Slicing
The next parts involve prepping the files ready to be printed ! If you prefer to skip these steps just download the .3mf which should provide most of the settings needed already ! Or if you want there are the .stl files which you can follow along with in the next steps
Step 19: Manufacturing Files
You can use the stl files and carry on with the steps or simply use the .3mf file to use with the slicer and then fine tune
Step 20: Setting Up PrusaSlicer
Navigate to the print settings tab and ensure the infill type is Rectilinear and 10 % fill density. The strongest layer height is 0.15mm for this print and the material is PLA.
Step 21: Import Fusion 360 File
Import the file( in this project it is named "Mass Reduction Infill" ) into the workspace, by dragging and dropping the file . If you do not see anything when you import, ensure you are in 3D view not layer view. You can changes the view in the bottom left
Step 22: Adding the Second Part From ANSYS As a Load Modifier
Ensuring you are on expert mode, navigate to the hierarchy on the right hand side of the screen. On the first file navigate to the editing icon button, which is under the 'Editing' text next to the model. Click on Add Modifier and click 'Load'. Then select the second file named 'File.stl' (this is the default name for ANSYS)
Step 23: Repair the Model
Using the netfabb service, by right clicking on the alert triangle you should be able to automatically repair any problems with the model
Step 24: Changing Infill on the Load Modifier
Click on the settings gear icon under the editing section of the load modifier, then choose infill and for best results choose 100 % fill density as rectilinear type.
Step 25: (Optional for Keyring Hole) Add a Cylinder Modifier
For better ease of use, you can also add a keyring hole. Start by adding a cylinder modifier to entire object (highest in hierarchy).
Step 26: (Optional for Keyring Hole) Modifying Cylinder Dimensions
Modify the dimensions to a suitable diameter and for ease of use, create the height of the cylinder to be taller than the thickness of the object, this should help to see where your hole will be placed.
Step 27: (Optional for Keyring Hole) Creating the Cylindrical Hole
To create the hole, click on the cylinder's settings (gear icon under the editing section on the right of the screen), and add 'Layers and Perimeters' and set the bottom, perimeters and top settings to 0. Finally, add an infill setting and set it to 0.
Step 28: Slicing
Once everything is ready, hit the slice button and export your file as g-code. This can then be transferred to your 3D printer !
Step 29: Print !
Transfer the g-code to your printer and after a few hours success !
Huge thanks to community members who 3D printed the design ! Overall the prints came out quite well, both of the prints were printed in PLA. However, it is recommended to use PET-G as it is stronger and more flexible so if you have access to the material use it !
Step 30: Conclusion
This was a great project ! My first instructable project as well as my first 3D printing project. Whilst I do not own a 3D printer, it was great to see the entire manufacturing process and I hoped many of you have learnt a thing or two about 3D printing. It would be great if you could share images of your 3D prints with me along with feedback. If you like my instructable please vote for me in the first time authors competition !
I have also posted some more cad files on GrabCad: https://grabcad.com/library/novel-no-touch-utility...
(Disclaimer: I am not responsible for any damage, harm or otherwise caused by following any instructions, so try at your own risk) In order to clean/disinfect the device, isopropyl alcohol could possibly used to disinfect the device, but I recommend you find out what is best for you based on your filament. It is important to avoid placing the object under high heat, as it may deform.
Participated in the
First Time Author Contest
2 years ago
A very impressive effort with well presented arguments.
A question about using the device: please can you explain how the contaminated, used tool is carried safely?
Reply 2 years ago
Hello, thank you for your comments. I have updated the instructable, but in order to use the device safely I recommend using the key chain hole to attach and use safely (e.g. add to belt loops or keys).
2 years ago
Thanks for sharing your design :)
Reply 2 years ago
No worries, it was great fun !